Abstract:
A method of processing a document object model (DOM) tree having at least one tag located at a given node in the tree. The tag serves as a marker that initiates the invocation of a tag handler that, in turn, performs a simple macro substitution or a more complex algorithmic reorganization and manipulation of the tree. Upon encountering the tag, given information is passed to a method. In a first embodiment, the given information is a text representation of XML in the DOM tree at the given node and any child nodes of the given node. In an alternate embodiment, the given information is the given node of the DOM tree itself. The method generates an XML string, which is then parsed into a new DOM tree having a root node. The given node and any child nodes are then replaced by the new DOM tree, with the root node of the new DOM tree being positioned at the given node in the original DOM tree. The process may then be repeated for any additional tags.

Description:
COPYRIGHT NOTICE 
   A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in the Patent and Trademark Office patent file or records but otherwise reserves all copyright rights whatsoever. 
   BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The present invention relates generally to Internet publishing technologies and, in particular, to techniques for dynamically serving web page content. 
   2. Description of the Related Art 
   A Hypertext Markup Language (HTML) file uses a limited set of tags to convey basic information about the structure of a web document, e.g., whether given text is a heading or a paragraph. With HTML, the style and logic of the document are hardcoded. HTML does not provide tags that define the meaning of the page element. To address this limitation, web content is now being authored ineXtensible Markup Language (XML), which provides a way for an author to create a custom markup language to suit a particular kind of document. In XML, each document is an object, and each element of the document is an object. The logical structure of the document typically is specified in a Document Type Definition (DTD). A DTD may be used by the author to define a grammar for a set of tags for the document so that a given application may validate the proper use of the tags. A DTD comprises a set of elements and their attributes, as well as a specification of the relationship of each element to other elements. Once an element is defined, it may then be associated with a stylesheet, a script, HTML code or the like. Thus, with XML, an author may define his or her own tags and attributes to identify structural elements of a document, which may then be validated automatically. An XML document&#39;s internal data structure representation is a Document Object Model (DOM). The DOM makes it possible to address a given XML page element as a programmable object. It is basically a tree of all the nodes in an XML file. 
   Page serving technologies are evolving at a rapid pace. Since 1997, three new major technologies have attempted to supplement, if not replace, dynamically generated HTML, i.e. database or CGI scripts used to generate a web page on the fly. These technologies are Microsoft&#39;s active server page (ASP), Sun Microsystems&#39;s Java server page (JSP), and the Extensible Style Sheet Language (XSL/XSLT) being promoted by the World Wide Web Consortium(W3C). They provide for the generation and serving of dynamic web page content by enabling a page creator to write HTML and then to embed pure programming logic inside the page markup. Microsoft&#39;s ASP and Sun&#39;s JSP are very similar in that they both are essentially web templates that enable given code (e.g., code written in Java) to be embedded in static HTML to be served in response to a client browser request. In an illustrative example, a server (and, in particular, a Java runtime servlet) responds to a client.jsp request as follows: the servlet retrieves a flat file corresponding to the requested page, translates that file into a Java servlet, compiles the servlet, class loads the servlet, and then invokes the servlet to cause given (e.g., customized) web content to be returned to the requesting browser. XSL/XSLT, to the contrary, is rooted in formatting and manipulating XML. XSLT, in particular, provides extensible mechanisms for defining templates to manipulate XML of any custom DTD. 
   The existing techniques for serving dynamic content have various limitations. Conventional server-side scripting on a web page can be complicated and, therefore, such scripting is usually difficult to maintain and evolve. Further, with existing technologies, typically only a single scripting language is allowed on a web page. This limitation is acceptable, so long as only one author is responsible for editing the page, or if all of the responsible authors know and use the same scripting language and the language of choice is supported by the web server. Microsoft&#39;s ASP technology supports multiple scripting languages, but only one language may be used on a page. Moreover, multiple languages cannot be embedded in one another, and their order of execution is undefined. Further, page-serving technologies such as ASP and JSP are not XML-compliant, and neither ASP nor JSP provides an extension mechanism to allow authors to add custom tags. 
   It is also known in the art to provide a web page author with a library of preexisting custom tags. An illustrative product of this type is Cold Fusion, which is HTML-centric. This product, however, does not afford the author the ability to create custom tags. Macromedia&#39;s Dreamweaver product has a tag construction mechanism, but this product does not allow for the embedding of custom tags, nor does it allow the document to be reorganized by the tags. It also keeps the script code on the page. In particular, the script is hidden from the user, but it is still present on the page, and it may be viewed and/or edited from within another editor. However, the modifications made in another tool are not maintained. Microsoft provides a similar technology, called design-time control (DTC), that hides code from the user but still maintains the code on the page. DTC is not XML-compliant and it does not allow DTCs to be embedded within one another. Nor does the DTC mechanism allow the document to be reorganized. In addition, the DTC syntax is quite cumbersome for the page author. Moreover, while other DTC-aware tools will hide the script code correctly, basic text-editors can still edit the code, and the changes made will not be importable back into the DTC-aware tools. DTC also does not provide access to the Document Object Model. Other products or technologies that have custom tag extensions include HeiTML and Meta-HTML. Essentially, these are tag macro definition languages for HTML. Such languages, however, are not XML compliant. 
   There remains a need in the art to provide new techniques for publishing Internet content that can fully leverage the manipulation and template mechanism of XSLT with the scripting capability of the JSP/ASP model. The present invention addresses this need. 
   BRIEF SUMMARY OF THE INVENTION 
   A server page handling mechanism enables custom tags to be extended with XML/DOM. As used herein, a “custom” tag is a element that defines a semantic of given content in the page, which may be uniquely specified by a web page author. Web page authors can use this mechanism to add custom tags to the page markup. 
   According to the present invention, a method is provided for processing a document object model (DOM) tree having at least one tag located at a given node in the tree. The tag serves as a marker that initiates the invocation of a tag handler that, in turn, performs a simple macro substitution or a more complex algorithmic reorganization and manipulation of the tree. Upon encountering the tag, given information is passed to a method. In a first embodiment, the given information is a text representation of XML in the DOM tree at the given node and any child nodes of the given node. In an alternate embodiment, the given information is the given node of the DOM tree itself. The method generates an XML string, which is then parsed into a new DOM tree having a root node. The given node and any child nodes are then replaced by the new DOM tree, with the root node of the new DOM tree being positioned at the given node in the original DOM tree. The process may then be repeated for any additional tags. 
   The foregoing has outlined some of the more pertinent objects and features of the present invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention as will be described. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the following Detailed Description of the Preferred Embodiment. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the present invention and the advantages thereof, reference should be made to the following Detailed Description taken in connection with the accompanying drawings in which: 
       FIG. 1  is a simplified illustration of a client-server environment in which the present invention may be implemented; 
       FIG. 2  is a high level flowchart illustrating a servlet generation routine of the present invention; 
       FIG. 3  is a flowchart illustrating how one preferred technique for preprocessing a flat file into XML compliant code; 
       FIG. 4  is a flowchart illustrating a preferred algorithm for processing custom tags according to the present invention; 
       FIG. 5  is a flowchart illustrating a custom DOM tag XSL handler routine for an XSL style sheet; 
       FIG. 6  is a flowchart illustrating a custom DOM tag Java handler routine for a Java object; 
       FIG. 7  is a flowchart illustrating the operation of a DOM In, Text Out tagbean; 
       FIG. 8  is a flowchart illustrating the operation of a Text In, Text Out Text tagbean; 
       FIG. 9  is a flowchart illustrating a routine for supporting multiple scripting languages in a single page; 
       FIG. 10  is a flowchart illustrating a routine for collapsing a DOM tree into a fewest number of method calls according to the present invention; and 
       FIG. 11  is a flowchart illustrating a routine for verifying the context of related XML tag elements in a DOM tree. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The present invention is a page handling framework and runtime engine operative on a server in a computer network such as the Internet. As is well-known, in the Internet paradigm as illustrated in  FIG. 1 , a client machine, such as machine  10 , may use an application, such as a web browser  12 , to access a server  14  via a computer network  16 . Network  16  typically includes other servers (not shown) for control of domain name resolution, routing and other control functions. A representative server  14  is a computer or workstation having at least one processor  18 , system memory (e.g., RAM)  20 , disk or other permanent storage  22 , I/O devices  24   a–n , an operating system  26 , a server program  28 , and an application programming interface (API)  30  that provides extensions to enable application developers to extend and/or customize the core functionality thereof through software programs including plug-ins, CGI programs, Java servlets, and the like. One such software program is an inventive page handling mechanism  32 , which processes an HTTP page request and generates a response by feeding data into an output stream as will be described. In an illustrative embodiment, the page handling mechanism is implemented in Java and is executable in a Java Virtual Machine(JVM) by a processor in a known manner. Alternatively, the program may be written in whole or in part in native code. The inventive functionality, of course, may be part of the integral web server program. 
   A representative server machine is an IBM Netfinity platform running the Unix operating system and a server program such as IBM WebSphere Version 2.0. Of course, any other computer hardware or software may be used. 
   A representative client is a personal computer, notebook computer, Internet appliance or pervasive computing device (e.g., a PDA or palm computer) that is Pentium-, Power PC®- or RISC-based. The client includes an operating system such as Microsoft Windows, Microsoft Windows CE or PalmOS. A typical client includes a suite of Internet tools including a Web browser, such as Netscape Navigator or Microsoft Internet Explorer, that has a Java Virtual Machine (JVM) and support for application plug-ins or helper applications. Communications between the client and the server typically conform to the Hypertext Transfer Protocol (Version 1.0 or higher), and such communications may be made over a secure connection. 
   The flowcharts of  FIGS. 2–11  illustrate the inventive functionality of the page handling mechanism. 
   Servlet Generation 
     FIG. 2  illustrates how a flat web page file is processed according to the present invention to generate a servlet. The routine begins at step  200  by retrieving a flat file from the server&#39;s database. At step  202 , a test is made to determine whether a timestamp for the flat file is later than a timestamp for the class load for the file. If the outcome of the test at step  202  is negative, the file has already been processed. Control then branches to step  214 , where the file is invoked as a runtime operation. If the outcome of the test at step  202  is positive, the routine continues at step  204  to preprocess the flat file into XML compliant code and, at step  206 , to transform the XML into a Document Object Model (DOM) data representation. The Document Object Model is a platform- and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure and style of documents. In particular, the Document Object Model provides a standard set of objects for representing HTML and XML documents, a standard model of how these objects can be combined, and a standard interface for accessing an manipulating them. The Document Object Model (DOM) Level 1 Specification is available from the World Wide Web Consortium. 
   Step  204  is illustrated in more detail in  FIG. 3 . Preferably, steps  204 – 206  are accomplished concurrently using an XML parser, such as the IBM WebSphere XML4J parser. The routine then continues at step  208 . At this step, the DOM along with its namespaces are interpreted to produce a Java object, such as a servlet. This process is illustrated in more detail in  FIG. 4 . Thus, according to the invention and, in particular, steps  204 ,  206  and  208 , the present invention generates a page template via DOM translation of the flat file. At step  210 , the servlet is compiled. The routine then continues at step  212  to class load the servlet. Control then continues at step  214 , which has been previously described. 
   Steps  204 – 212  preferably occur at page translation time. Page translation typically occurs the first time the page (namely, the request for the flat file) is accessed or hit. Step  214  is executed to serve the requested page in response to the originating HTTP client request. In particular, the servlet is invoked with standard Http Request and HttpResponse objects, and it generates a response by feeding data into an output stream. The data is provided to the client browser for rendering in the usual manner. 
   File Preparsing 
     FIG. 3  illustrates a preferred technique preparsing a flat file into XML compliant code. This was step  204  in  FIG. 2 . 
   The routine begins at step  302  by passing the flat file to the preprocessor. At step  306 , the input stream comprising the flat file is broken into tokens. The routine then performs a test at step  308  to determine whether the stream has any more tokens to process. If so, the routine continues at step  310  to test whether the token is a known JSP (or ASP) symbol. If the outcome of the test at step  310  is positive, the routine branches to step  312  to turn the JSP symbol into an XML tag. If the outcome of the test at step  310  is negative, the routine branches to step  314  to identify any text that violates XML constraints. Following either step  312  or step  314 , the routine continues at step  316  to place the token in an output stream holder. Control then returns to step  308  to process additional tokens. If the outcome of step  308  is negative, however, the routine branches to step  318  to verify that the “jsp:root” tag exists in the stream. At step  320 , the parser turns tag libraries into “jsp:root” namespace attributes. The routine then continues at step  322  by constructing the output stream. This completes the preparsing routine. 
   Processing a DOM with Custom Tags 
   A preferred algorithm for processing a DOM with custom tags is illustrated in  FIG. 4 . Preliminary processing is provided by steps  402 – 412 . These steps may be omitted. In particular, the routine begins at step  402  by verifying the DOM, for example, with a JSP DTD. At step  404 , the routine adds servlet generation variables to the root element of the DOM for later handling. The routine then continues at step  406  to gather all jsp:directive.pagetags to ensure a consistent state. At step  408 , the jsp tag libraries (which provide support for JSP 1.0 mechanisms) are registered with the root element. Thus, for example, custom tags are registered through an XML &lt;taglib =“tag-library.xml”&gt;tag, according to the JSP 1.0 specification. 
   By way of brief background, where a plurality of custom tags exist, it is desired to provide a cataloging and registration mechanism to organize the tags and to prevent naming collisions. According to the present invention, a tag library, or “taglib,” is used for this purpose. As will be described below, the tag library is preferably specified by a URI and comprises a page, preferably XML, identifying the tag namespace and listing the tags recognized in the namespace as well as the directives on how to load the appropriate tag handlers. Thus, in a representative embodiment, in the tag-library-xml file, the name of the custom tag is listed, as well as a Java object name, or a URL identifying an XSL stylesheet. 
   The following is an example of a custom tag library: 
   In the JSP context: 
                                           &lt;jsp:root xmlns:sample=“/xsp/sample/sample-taglib.xml”&gt;           &lt;/jsp:root&gt;                        
Here, a namespace “sample” is defined by the relative URL of “/xsp/sample/sample-taglib.xml”.
 
The content at the URL would look as follows:
 
   
     
       
             
           
             
             
           
             
             
           
             
             
           
             
           
             
             
           
             
           
         
             
                 
             
           
           
             
               &lt;?xml version=“1.0”?&gt; 
             
             
               &lt;taglib&gt; 
             
           
        
         
             
                 
               &lt;tag name=“currentTime” 
             
           
        
         
             
                 
               class=“xsp.sample.CurrentTimeTagBean” 
             
             
                 
               dtd=“currentTime.dtd”/&gt; 
             
           
        
         
             
                 
               &lt;tag name=“currentTimeXSL” 
             
           
        
         
             
               styleSheet=“http://localhost/xsp/sample/currentTimeCustomTag.xsl” 
             
           
        
         
             
                 
               dtd=“currentTime.dtd”/&gt; 
             
           
        
         
             
               &lt;/taglib&gt; 
             
             
                 
             
           
        
       
     
   
   This registers a Java TagBean to handle sample:currentTime tags and registers the currentTimeCustomTag.xsl as an XSL handler for sample:curentTimeXSL. As a bonus, both register currentTime.dtd to verify the correctness of the sample:currentTime and sample:currentTimeXSL tags before the formatting of those tags occurs. 
   Returning now to  FIG. 4 , the routine then continues at step  410 . In particular, any additional tag libraries are gathered and registered with a main tag handler. According to the present invention, a tag handler is a process that is used to hand-off execution (of a custom tag in the DOM) to some other process, e.g., a Java object (through a custom tag interface), or via an XSL stylesheet. The routine then continues at step  412  by inserting a — jspServicemethodDefinition as the last child of the jsp:root element. The methodDefinition preferably has the content of most of the servlet code. As will be described in more detail below, the jsp:block element is appended to the methodDefinition to begin the servlet&#39;s definition as a Java code block by default or with as the value of the jsp page directive attribute (if it is specified). 
   The main processing of the routine begins at step  416 . At this step, a test is made to determine whether the DOM tree has any custom tags that have not been processed. If so, the routine branches to step  418  to locate preferably the left-most leaf node of the tree that satisfies its requirements as a custom tag. The routine then continues at step  420  to invoke an appropriate tag handler (e.g., a Java object, the XSL stylesheet, or the like). Two variations of step  420  are illustrated in the flowcharts of  FIGS. 5–6 . As will be seen, the appropriate tag handler is given a current tag element and is expected to process it. Typically, a new DOM is returned from the tag handler and is then processed for new tag libraries. At step  422 , the new tag libraries are registered in the tag library registry. The routine then continues at step  424  to gather all new jsp:directive tags. The routine then returns to step  416 . 
   This loop continues until all custom tags have been processed in a like manner. When the outcome of the test at step  416  is negative, the routine branches to step  426  to collapse the resulting DOM tree into as few as possible method blocks. This operation is illustrated in  FIG. 10 . The routine then continues at step  428  to generate the servlet by interpreting scriptlet, expression, declaration and methodDefinitions. Thus, for example, at step  428 , the routine interprets the DOM by replacing “jsp:scriptlets” with inlined code, by replacing “jsp.expressions” with prints, by replacing “jsp:declarations” with variables and method definitions, by replacing “xsp:methodCalls” with method calls, and by replacing “xsp:methodDefinitions” with method definitions. As described in  FIG. 2 , the resulting servlet is then compiled and class loaded to be ready for use by the runtime code. 
   Custom Tag Definition 
   Preferably, the DOM tree identifies custom tags as follows. As noted above, the JSP 1.0 specification included a tag library mechanism that defines how to plug in a tag. The specification, however, left the details of the taglib mechanism completely open, with the exception that a url must be used to specify the location of the taglib. According to the present invention, this abstract concept has been unified with an XML namespace and mapped into an XML file. In an illustrative embodiment, the Document Type Definition (DTD) for a taglib according to the invention is: 
                                                                     &lt;!ELEMENT taglib (tag)*&gt;       &lt;!ELEMENT tag EMPTY&gt;       &lt;!-- Note: either class or styleSheet must exist (but preferably not       both) --&gt;       &lt;!ATTLIST tag                name   CDATA #REQUIRED           class   CDATA #IMPLIED                styleSheet CDATA #IMPLIED                dtd   CDATA #IMPLIED&gt;                        
This data structure defines that a tag library is composed of zero or more tags. Each tag is defined with a name and optional attributes class, styleSheet, and dtd. A tag must have either a class or styleSheet attribute (but preferably not both) to specify a correct tag handler. The value of name is used to identify what tags it handles. If a tag&#39;s name is “scriptlet” and its taglib prefix is “jsp”, then this rule handles any tag named “jsp:scriptlet”. The class and styleSheet attribute dictate which of the two mechanisms are used to handle a custom tag. If the rule specifies a class, then a Java object, e.g., an object satisfying a custom tag interface, is used to process the tag. If the rule specifies a stylesheet, then an XSLT styleSheet is used to process the tree. The optional dtd parameter is used to verify the contents of the custom tag, for example, whether the tag has the proper attributes.
 
   As noted above,  FIGS. 5–6  illustrate the preferred tag handling routines. As described, there are two types of tag handling: tags handled by XSLT ( FIG. 5 ) and tags handled by Java code ( FIG. 6 ). Each of these handlers will now be described in more detail. 
   XSL Custom Tag Handler 
   The XSL tag handler routine begins at step  502  by receiving the DOM element as input. At step  504 , the tag handler then finds the appropriate stylesheet for the element as supplied by the taglib rules. The routine then continues at step  506  with the tag handler obtaining the element&#39;s parent document. At step  508 , the routine invokes a stylesheet processor on the document and stylesheet. Finally, at step  510 , the tag handler returns the new document to complete the translation. 
   Java Object Custom Tag Handler 
     FIG. 6  illustrates a preferred operation of the custom DOM tag Java object handler. By way of brief background, as used herein, a “tagbean” is a Java object that implements a TagBean interface. Preferably, the interface according to the invention is as follows: 
                                                               public interface TagBean           {                public void           process(Element element);                }                        
The TagBean interface defines a process method that takes an element in from the DOM tree and performs some function against that element. The context of the entire DOM tree is available to the process method for manipulation through the DOM APIs.
 
   The routine begins at step  602  with the Java tag handler receiving the DOM element as input. At step  604 , the handler then obtains the appropriate tagbean for the element as supplied by the taglib rules. A number of tagbean routines are illustrated in  FIGS. 7–9  and will be described in more detailed below. At step  606 , the handler extracts an attributeList from the element. The routine then performs a test at step  608  to determine whether there are any unprocessed attributes. If so, the routine branches to step  610  to determine whether the attribute maps to a setter property on the tagbean. If the outcome of the test at step  610  is negative, control returns to step  608 . If, however, the outcome of the test at step  610  is positive, the routine continues at step  612  to set the value of the attribute on the tagbean. Control then continues at step  614  to remove the attribute from the attributeList. Processing then continues back at step  608 . 
   Thus, for each attribute in the attributeList, the handler checks for a corresponding setter property on the tagbean. If a corresponding setter property exists, the value of the attribute is set on the tagbean and the attribute is removed from the attribute list. When the outcome of the test at step  608  indicates that all attributes have been checked against the tagbean, routine branches to step  616 . At this step, the tagbean&#39;s process method is called given the DOM element so that it can manipulate the tree in whatever manner it deems fit. When tagbean.process( ) is complete, the new document is returned from the tag handler at step  618 . This completes the processing. 
     FIGS. 7–9  illustrate tagbeans that are useful in the present invention. 
   DOM In, Text Out Tagbean 
     FIG. 7  illustrates a simple DOM in, Text out macro that has the following class: 
   public abstract class Simple TagBean implements TagBean 
   
     
       
             
             
           
             
             
           
             
             
           
         
             
                 
                 
             
           
           
             
                 
               { 
             
           
        
         
             
                 
               public abstract String 
             
             
                 
               translateElement(Element element); 
             
             
                 
               public final void 
             
             
                 
               process(Element element); 
             
           
        
         
             
                 
               } 
             
             
                 
                 
             
           
        
       
     
   
   Simple TagBean is a class created to simplify the task of writing a tagbean. Using this class, the developer merely has to implement the translateElement method, which takes in a DOM element and returns the corresponding text macro expansion. In particular, the routine reads the DOM tree (e.g., using the DOM APIs), produces an XML block (typically a scriplet), and uses the XML block to replace the current element in the tree. This is advantageous to the writer of the tagbean because, using the invention, he or she does not need to know how to create new nodes and to populate them with values. All the writer has to do is create an XML expanded form of the element passed in. While this approach requires increased execution time at translation, translation only happens once every time the page changes; thus, the technique has little impact on server performance. 
   The SimpleTagBean class works as demonstrated in the flowchart of  FIG. 7 . The routine begins at step  702  with the Java tag handler calls SimpleTagBean.process with the appropriate tag element. At step  704 , the SimpleTagBean hands the element off to its subclass&#39;s “overwritten” translateElement method. In the translateElement method, at step  706 , the subclass looks at the element and its sub-elements and attributes to produce a text macro expansion of the node. The routine then continues at step  708  with the text expansion being returned to the SimpleTagBean.process method. At step  710 , the XML is parsed backed into DOM. At step  712 , the top node of the new document object replaces the element that was passed in from the previous document. In particular, in step  712 , the top node of the new DOM replaces the element was passed into translateElement( ). This completes the processing. 
   Text In, Text Out Tagbean 
     FIG. 8  illustrates a Text in, Text out tagbean that may be used to isolate the developer from the DOM API. This is especially useful if the element contains only simple information or does simple query string replacement. A representative class is as follows: 
                                                     public abstract class TextTagBean extends SimpleTagBean           {                public abstract String           translateText(String text);           public final String           translateElement(Elementelement);           public final void           process(Element element);           }                        
TextTagBean extends the SimpleTagBean functionality. In particular, the TextTagBean extends the SimpleTagBean class and implements the translateElement function to inherit the String V DOM output functionality. Instead of the developer writing translateElement, however, he or she now writes translateText.
 
   Referring now to  FIG. 8 , the routine begins at step  802  with the Java custom DOM tag handler handing the SimpleTagBean.process the appropriate element. At step  804 , the routine hands the element off to the “overwritten” translateElement method. At step  806 , the translateElement method converts the DOM directly into its corresponding XML. In particular, the TextTagBean.translateElement( ) takes the element and flattens it into XML without interpreting any of the XML. The routine then continues at step  808 , with the XML then being passed to the translateText method of the subclass. At step  810 , the translateText method reads the string and processes it to return a new XML string. In particular, translateText looks at the XML string and manipulates it to produce another text representation of it and returns this representation to TextTagBean.translateElement( ). At step  812 , the new XML string is returned to the TextTagBean.translateElement, which returns the string to SimpleTagBean.process. SimpleTagBean.process finishes the processing at step  814 , by turning the string into DOM and, at step  816 , by replacing the previous element with the root of the new document. Thus, in step  816 , the top node of the new DOM replaces the element that was passed into translateElement( ). This completes the processing. 
   The above-described tagbeans are quite advantageous. Significantly, these tagbeans enable the implementation to use DOM or text data structures, which is unique in the art. Further, these beans enable the developer to use DOM structures, which are difficult to process, by simple translation into text, which are simpler to process. As a consequence, the invention enables the developer to use DOM data structures in a manner heretofore unknown in the prior art. 
   Multiple Scripting Language Blocks 
   Another tagbean is illustrated in  FIG. 9 . This routine, called jsp:block, enables page developers to use multiple scripting languages in the same page. As will be seen, this enables people with different skill sets to add value to the same page. It also enables the developer to chose another language that might be more suitable for a specific job. 
   The routine begins at step  902  with each jsp:block handed off to the JSPBlockTagBean. At step  904 , the JSPBlockTagBean chooses the appropriate BlockTagBean according to the language attribute of the jsp:block element. At step  906 , the language-specific BlockTagBean creates a methodDefinition element which, at step  908 , is then filled with code to set up an appropriate runtime environment for the target language. At step  910 , the methodDefinition element is inserted as a child of the root element in the document. The routine then continues at step  912  to create a methodCall element to replace the originaljsp:block element. 
   DOM Tree Processing 
     FIG. 10  illustrates a preferred routine for collapsing the DOM tree into the fewest possible methodCalls. The routine begins at step  1002  to test whether there are any unprocessed methodCalls in the document. If not, the routine is done. If, however, the outcome of the test at step  1002  is positive, the routine continues at step  1004  by setting a variable mc equal to the right-most unprocessed leaf node that is a method call. At step  1006 , the routine sets a variable collapse equal to an attribute mc.getAttribute(collapse). At step  1008 , the collapse attribute is checked. If this attribute is not true, control returns to step  1002 . If the outcome of the test at step  1008  is positive, then the contents of the corresponding methodDefinition are expanded in place, and the methodDefinition and methodCalls are removed from the tree. In particular, the routine continues at step  1010  by setting a variable md equal to the methodDefinition for the methodCall. At step  1012 , a test is run to determine whether any child nodes exist in the methodDefinition element. If not, the routine branches to step  1014  to remove mc from the document, and control returns to step  1002 . If, however, the outcome of the test at step  1012  is positive, the routine continues at step  1016  to let c equal the last child node in the methodDefinition. At step  1018 , c is removed from the methodDefinition. The routine then continues at step  1020  to insert c before mc in the document. Control then returns back to step  1012 . This completes the processing. 
   For optimization purposes, it is desired to verify context between multiple related XML tags in a DOM. One or more of these related XML tags are custom tags within the context of the inventive framework. By way of brief background, when processing a single custom tag element, that element may need access to all other related tags, processed and unprocessed, within the DOM. Unfortunately, however, there may be other unprocessed custom tags in the DOM that, when processed, would result in one or more related tags the current element is interested in. One solution to this problem is to pass some state information from the current element through the page handling engine. A preferred technique, however, is to use the DOM itself to indicate state. 
   Clean-up Processing 
     FIG. 11  is a flowchart illustrating this clean-up processing. The routine begins at step  1102  during the processing of the DOM tree with a current element being processed replacing itself with a placeholder element. The placeholder element includes attributes indicating its state. At step  1104 , a test is performed to determine if a clean-up element already exists for the element being processed. If not, the current element then creates a clean-up element at step  1106 . At step  1108 , this clean-up element is added to the DOM in a position where it will be processed after all elements related to the current element have been processed. Thus, for example, the clean-up element is added to the DOM as a child node to the root position. If the outcome of the test at step  1104  indicates that such a clean-up element already exists, the current element need not create another clean-up element; rather, the current element need only move the existing clean-up element later in the DOM to ensure it is processed after any other related elements might be processed. This is step  1110 . When the processing routine finally encounters the clean-up element, as indicated by a positive outcome of the test at step  1112 , this element scans the entire DOM for all the related tags (now placeholders) of interest. This is step  1114 . At step  1116 , the clean-up element loads the state information from each and, at step  1118 , processes them accordingly. When complete, at step  1120 , the clean-up element removes itself from the DOM. In this way, the technique shifts processing from each individual element to a single, last-processed element. 
   Thus, in the preferred embodiment, a two-pass solution is implemented. In the first pass, simple translation is performed on the tag, creating new tag place holders to be handled by a clean-up phase. For example, assume the DOM includes the following tags: system:macro1, system:macro2, and system:macro3. It is also assumed that each relies on specific information from other tags but not all the information is available until all of them have been touched once. On the first pass, system:macro1 expands to  — system — macro1 and performs all the metadata expansion it can perform at this time to assist the clean-up node. At this time, it also inserts a system:cleanup in the tree as the last child of jsp:root (assuming it is not already there). 
   The second pass is triggered when the clean-up node is hit. For proper processing, it should check to make sure the first pass has completed (no system:macro1 or macro2 or macro3 tags in the tree). If other clean-up nodes exist in the tree, it should remove itself from the tree and let the other nodes handle the clean-up later. Once the clean-up node has determined that the tree is in the correct state, it goes through all the artifacts left by the first process and expands them with all the context available. 
   Tagbean Code Reduction 
   Another optimization reduces the amount of code in the tagbeans. By way of background, if a developer expands everything necessary to perform a function of a tag, that process may produce large amounts of code. In particular, the writing of custom tagbeans may result in a large amount of Java code being generated into the resulting servlet. Because this code may be largely common across-servlets generated from the same tagbean (variable names might change, but little else), according to the invention, the functionality is delegated to outside code as much as possible. Preferably, the code is factored into a separate Java bean, and the most convenient place to delegate is the very tagbean generating the code. Thus, the tagbean need only generate enough Java code for the servlet to call out to the separate bean. This dramatically reduces the code in the tag bean handler. 
   As a result, this optimization improves maintainability and greatly simplifies debugging. In addition, because the code is not expanded, the function is hidden from anyone who has access to the generated servlet code. In addition, as a separate Java bean, developers are encouraged to put more error-handling code in the system that may not get put in otherwise. It also further stabilizes the system. 
   Thus, in a preferred embodiment, instead of doing inline expansion of code, the developer may take runtime values of attributes and sub-elements and generate code to make them parameters of a method on the very same bean that can be called at runtime to do the real work. Thus, according to the invention, at translation time, a custom tag in the DOM tree is replaced, e.g., with a script that results in a line of code in a generated servlet. In that way, when the servlet is then executed at request time, the line of code invokes a method in a custom tagbean to perform a given function. 
   A more detailed example of this optimization technique is set forth later in this disclosure. 
   EXAMPLES 
   As has been previously described, the flowchart of  FIG. 2  illustrates the basic translation functionality of the present invention. An example of this operation is now provided. In the following example, mixedLanguages.xsp is a flat input file, mixedLanguagesDOM1.txt is a representation of the DOM after the input file has been parsed and some metadata has been added to the DOM, mixedLanguagesDOM2.txt is a representation of the DOM after the custom tags in the input file have been processed (in this case, the &lt;block&gt;tag is a custom tag, with the inner tag processed before the outer tag, with the resulting DOM then ready to be walked by the servlet generator routine), and mixedLanguagesServlet.java is the servlet generated by walking the DOM that complies with the JSP 1.0 specification. 
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             mixedLanguages.xsp            &lt;?xml version=“1.0”?&gt;       &lt;jsp:root&gt;                &lt;jsp:block language=“java”&gt;           &lt;jsp:scriptlet&gt;           String user = request.getParameter(“user”);           if (user == null) {           &lt;/jsp:scriptlet&gt;                &lt;b&gt;No one is logged in.&lt;/b&gt;           &lt;jsp:block language=“javascript”&gt;           &lt;jsp:scriptlet&gt;           var int x = 0;           x = x + 1;           &lt;/jsp:scriptlet&gt;           &lt;/jsp:block&gt;                &lt;jsp:scriptlet&gt;           }           else {           &lt;/jsp:scriptlet&gt;                &lt;b&gt;Welcome:           &lt;jsp:scriptlet&gt;           out.println(user);           &lt;/jsp:scriptlet&gt;           &lt;/b&gt;                &lt;jsp:scriptlet&gt;           }           &lt;/jsp:scriptlet&gt;           &lt;/jsp:block&gt;            &lt;/jsp:root&gt;            mixedLanguagesDOM1.txt            &lt;jsp:root servletPath=“c: top xsp demo test mixedLanguagesServlet.java”       servletPackageName=“xsp.test.scripting” servletClassName=       “mixedLanguagesServlet”&gt;                &lt;jsp:methodDefinition name=“ — jspService”&gt;                &lt;jsp:block language=“java”&gt;                &lt;jsp:block language=“java”&gt;                &lt;jsp:scriptlet&gt;                String user = request.getParameter(“user”);                if (user == null) {                &lt;b&gt;                No one is logged in.                &lt;jsp:block language=“javascript”&gt;                &lt;jsp:scriptlet&gt;                var int x = 0;                x = x + 1;                &lt;jsp:scriptlet&gt;                }                else {                &lt;b&gt;                Welcome:           &lt;jsp:scriptlet&gt;                out.println(user);                &lt;jsp:scriptlet&gt;                }            mixedLanguagesDOM2.txt            &lt;jsp:root servletPath=“c:\top\xsp\demo\test\mixedLanguagesServlet.java”       servletPackageName=“xsp.test.scripting” servletClassName=       “mixedLanguagesServlet”&gt;                &lt;jsp:methodDefinition name=“javascriptBlock1”&gt;                &lt;jsp:scriptlet&gt;                BSFManager bsfManager = new BSFManager();           BSFEnvironment bsfEnvironment = new           BSFEnvironment();           bsfEnvironment.tempDir = “c:\\top\\”;           bsfEnvironment.classPath =            “c:\\top\\;c:\\prog\\jdk118\\lib\\classes.zip;c:\\top;c:\\prog\\xml4j\\xml4j — 1 — 1 — 16.jar;c:\\prog\\lotusxsL — 0 —         17 — 0\\lotusxsl.jar;c:\\prog\\SQLLIB\\java\\db2java.zip;c:\\prog\\SQLLIB\\java\\runtime.zip;c:\\prog\\       websphere\\appserver\\lib\\ibmwebas.jar;c:\\prog\\websphere\\appserver\\lib\\jsdk.jar;c:\\prog\\websphere\\       appserver\\lib\\jst.jar;c:\\top\\bsf-1.0b6\\lib\\bsf.jar;c:\\top\\bsf-1.0b6\\lib\\js.jar;c:\\top\\bsf-1.0b6\\lib\\       NetRexxC.zip;c:\\prog\\websphere\\appserver\\lib\\x509v1.jar;.;c:\\prog\\websphere\\appserver\\lib\\ejs.       jar;c:\\;c:\\prog\\websphere\\appserver\\properties\\ejs;C:\\prog\\jdk116\\bin\\. . .\\classes;C:\\prog\\jdk1       16\\bin\\. . .\\lib\\classes.zip;C:\\prog\\jdk116\\bin\\. . .\\lib\\classes.jar;C:\\prog\\jdk116\\bin\\. . .\\lib\\rt.jar;C:\\       prog\\jdk116\\bin\\. . .\\lib\\i18n.jar”;                bsfEnvironment.classLoader = this.getClass().getClassLoader();           bsfManager.setBSFEnvironment(bsfEnvironment);           BSFEngine javascriptInterpreter =                bsfManager.loadScriptingEngine(“javascript”);                javascriptInterpreter.setDebug(true);           bsfManager.registerBean(“request”, request);           bsfManager.registerBean(“response”, response);           bsfManager.registerBean(“session”, session);           bsfManager.registerBean(“out”, out);           bsfManager.registerBean(“pageContext”, pageContext);           bsfManager.registerBean(“page”, this);           try {                javascriptInterpreter.eval(“var request = bsf.lookupBean( “request ”); nvar response =            bsf.lookupBean( “response ”); nvar session = bsf.lookupBean( “session ”); nvar out =       bsf.lookupBean( “out ”); nvar pageContext = bsf.lookupBean( “pageContext ”); nvar page =       bsf.lookupBean( “page ”); n n  var int x = 0; n  x = x + 1; n  ”);                } catch (BSFException e) {                Throwable realException = e.getTargetException();           while (realException instanceof BSFException) {                realException = ((BSFException)realException).getTargetException();           while (realException instanceof java.lang.reflect.InvocationTargetException) {                realException = ((java.lang.reflect.InvocationTargetException)            realException).getTargetException();                }                }           realException.printStackTrace();           throw new ServletException(realException.getMessage());                }           bsfManager.unregisterBean(“request”);           bsfManager.unregisterBean(“response”);           bsfManager.unregisterBean(“session”);           bsfManager.unregisterBean(“out”);           bsfManager.unregisterBean(“config”);           bsfManager.unregisterBean(“pageContext”);           bsfManager.unregisterBean(“page”);                &lt;jsp:methodDefinition name=“ — jspService”&gt;                &lt;jsp:scriptlet&gt;                String user = request.getParameter(“user”);                if (user == null) {                &lt;b&gt;                No one is logged in.                &lt;jsp:methodCall name=“javascriptBlock1”&gt;           &lt;jsp:scriptlet&gt;                }                else {                &lt;b&gt;                Welcome:           &lt;jsp:scriptlet&gt;                out.println(user);                &lt;jsp:scriptlet&gt;                }            mixedLanguagesServlet.java            package xsp.test.scripting;       import org.w3c.dom.*;       import java.beans.*;       import com.lotus.xsl.xml4j2tx.*;       import java.io.*;       import com.ibm.bsf.*;       import java.util.*;       import com.sun.server.http.*;       import javax.servlet.jsp.*;       import com.lotus.xsl.*;       import javax.servlet.*;       import xsp.*;       import com.ibm.servlet.pagecompile.*;       import com.ibm.xml.parser.*;       import java.net.*;       import com.sun.server.util.*;       import java.lang.*;       import javax.servlet.http.*;       import com.ibm.servlet.engine.*;       public class mixedLanguagesServlet                extends xsp.ContractServlet            {                public void             — jspService(HttpServletRequestreq,                HttpServletResponseres)                throws ServletException, IOException                {                // Cast to HttpService objects for setAttribute/callPage           HttpServiceRequest request = (HttpServiceRequest) req;           HttpServiceResponseresponse =                new PCHttpServletResponseProxy((SEHttpServiceResponse)res);                JspWriter out = null;           // Create the JspFactory and obtain the PageContext           JspFactory factory = JspFactory.getDefaultFactory();           PageContext pageContext =                factory.getPageContext(this,// JSP page                request, // Servlet request           response, // Servlet response           null, // Error page  URL           true, // Servlet session           0, // JSP buffer size           true); // JSP autoflush                try {                // Initialize all the implicit variables           HttpSession session = request.getSession(true);           out = pageContext.getOut();           Object page = this;           response.setContentType(“text/html;charset=ISO-8859-1”);           // Now generate fixed template and script code                String user = request.getParameter(“user”);           if (user == null) {                out.print(“&lt;b&gt;”);           out.println();           out.println(“No one is logged in.”);           out.println(“&lt;/b&gt;”);           javascriptBlock1(request,                response,           session,           out,           pageContext,           page);                }           else {                out.print(“&lt;b&gt;”);           out.println();           out.println(“Welcome:”);                out.println(user);                out.println(“&lt;/b&gt;”);                }                } finally {                out.close();           ((PCHttpServletResponseProxy)response).writeOutResponse();           factory.releasePageContext(pageContext);                }                }           public void           javascriptBlock1(HttpServiceRequestrequest,                HttpServiceResponseresponse,           HttpSession session,           JspWriter out,           PageContext pageContext,           Object page)                throws ServletException, IOException                {                BSFManager bsfManager = new BSFManager();           BSFEnvironment bsfEnvironment = new BSFEnvironment();           bsfEnvironment.tempDir = “c: top ”;           bsfEnvironment.classPath =            “c:\\top\\;c:\\prog\\jdk118\\lib\\classes.zip;c:\\top;c:\\prog\\xml4j — 1 — 1 — 16.jar;c:\\prog\\lotusxsl — 0 —         17 — 0\\lotusxsl.jar;c:\\prog\\SQLLIB\\java\\db2java.zip;c:\\prog\\SQLLIB\\java\\runtime.zip;c:\\prog\\       websphere\\appserver\\lib\\ibmwebas.jar;c:\\prog\\websphere\\appserver\\lib\\jsdk.jar;c:\\prog\\websphere\\       appserver\\lib\\jst.jar;c:\\top\\bsf-1.0b6\\lib\\bsf.jar;c:\\top\\bsf-1.0b6\\lib\\js.jar;c:\\top\\bsf-1.0b6\\lib\\       NetRexxC.zip;c:\\prog\\websphere\\appserver\\lib\\x509v1.jar;.;c:\\prog\\websphere\\appserver\\lib\\ejs.       jar;c:\\;c:\\prog\\websphere\\appserver\\properties\\ejs;C:\\prog\\jdk116\\bin\\. . .\\classes;C:\\prog\\jdk1       16\\bin\\. . .\\lib\\classes.zip;C:\\prog\\jdk116\\bin\\. . .\\lib\\classes.jar;C:\\prog\\jdk116\\bin\\. . .\\lib\\rt.jar;C:\\       prog\\jdk116\\bin\\. . .\\lib\\i18n.jar”;                bsfEnvironment.classLoader = this.getClass().getClassLoader();           bsfManager.setBSFEnvironment(bsfEnvironment);           BSFEngine javascriptInterpreter =                bsfManager.loadScriptingEngine(“javascript”);                javascriptInterpreter.setDebug(true);           bsfManager.registerBean(“request”, request);           bsfManager.registerBean(“response”, response);           bsfManager.registerBean(“session”, session);           bsfManager.registerBean(“out”, out);           bsfManager.registerBean(“pageContext”, pageContext);           bsfManager.registerBean(“page”, this);           try {                javascriptInterpreter.eval(“var request = bsf.lookupBean(\“request\”);\nvar response =            bsf.lookupBean(\“response\”);\nvar session = bsf.lookupBean(\“session\”);\nvar out =       bsf.lookupBean(\“out\”);\nvar pageContext = bsf.lookupBean(\“pageContext\”);\nvar page =       bsf.lookupBean(\“page\”);\n\n  var int x = 0;\n  x = x + 1;\n  ”);                } catch (BSFException e) {                Throwable realException = e.getTargetException();           while (realException instanceof BSFException) {                realException = ((BSFException) realException).getTargetException();           while (realException instanceofjava.lang.reflect.InvocationTargetException) {                realException = ((java.lang.reflect.InvocationTargetException)            realException).getTargetException();                }                }           realException.printStackTrace();           throw new ServletException(realException.getMessage());                }           bsfManager.unregisterBean(“request”);           bsfManager.unregisterBean(“response”);           bsfManager.unregisterBean(“session”);           bsfManager.unregisterBean(“out”);           bsfManager.unregisterBean(“config”);           bsfManager.unregisterBean(“pageContext”);           bsfManager.unregisterBean(“page”);                }            }                The following illustrates more generally how an input file is translated into a            DOM data structure. In particular, for a given input file:       &lt;a&gt;                &lt;b&gt;                &lt;c/&gt;           &lt;d/&gt;                &lt;/b&gt;           &lt;e&gt;                &lt;f/&gt;                &lt;g/&gt;                &lt;h/&gt;                &lt;/e&gt;            &lt;/a&gt;,                    
the DOM data structure would look as follows:
 
                                                                             a           |--b                |   |--c           |   |--d           |                |--e                |--f           | |--g           |--h                        
Thus, in this example, node a is a parent node that has child nodes b and e. Node b has child nodes c and d, and node e has child nodes f and h. Node f has child node g. In the preferred embodiment, the order of node execution would then be as follows: c, d, b, g, f, h, e and a. The value of executing the nodes in an inside-out fashion is that the innermost tagbean can replace itself with a JSP syntax element that is well known to an outer tagbean so that the outer tagbean knows how to process the internal element.
 
   For example, in the case of the multi-language support, like: 
                                                                                                       &lt;block language=“java”&gt;                &lt;jsp:scriplet&gt;           javaExpression;           javaExpression2;           &lt;/jsp:scriptlet&gt;           &lt;block language=“javascript”&gt;                &lt;jsp:scriptlet&gt;                javascriptExpression;           javascriptExpression2;                &lt;jsp:scriptlet&gt;                &lt;/block&gt;                &lt;/block&gt;                        
The block tag is a custom tag. When this tag executes, it transforms everything inside it into Java code. The invention is able to transform the contained custom tag because the innermost custom tag preferably is handled first, and such processing leaves behind a well known tag that the outer most custom tag handler knows how to transform.
 
   The following code illustrates how scripting language blocks may be used to support multiple scripting languages in a single web page. As described above, nesting of different scripting languages is supporting by marking where one section, or “block”, of code begins and where it ends. For example, the following snippet has JavaScript code nested within REXX code nested within Java code: 
   
     
       
             
             
             
           
             
             
           
             
             
           
             
             
           
         
             
                 
                 
             
           
           
             
                 
               if (true) 
               { 
             
             
                 
                 
               say I am true 
             
             
                 
                 
               if also Tue then do 
             
           
        
         
             
                 
               var i = 5; 
             
           
        
         
             
                 
               end 
             
             
                 
               System.out.println(bean.getProperty()); 
             
           
        
         
             
                 
               } 
             
             
                 
                 
             
           
        
       
     
   
   If this code were to appear in a web page, the blocks of code may be marked as follows: 
                                                                                                 &lt;BLOCK language=“java”&gt;                if (true)   {               &lt;BLOCK language=“netrexx”&gt;               say I am true               if also True then do                &lt;BLOCK language=“javascript”&gt;           var i = 5;                &lt;/BLOCK&gt;                end           &lt;/BLOCK&gt;           System.out.println(bean.getProperty());                }           &lt;/BLOCK&gt;                        
In the above example, it can be seen that “end” is associated with “if also True then do” and not, for example, with “var i=5.” This enables the code to correctly process all the languages at runtime. In the above example, it should be noted that the blocks are nested. This is not a limitation. Indeed, there is no reason they cannot be peers, as below:
 
   
     
       
             
             
           
         
             
                 
                 
             
           
           
             
                 
               &lt;BLOCK language=“java”&gt; 
             
             
                 
               // a little Java code here 
             
             
                 
               &lt;/BLOCK&gt; 
             
             
                 
               &lt;BLOCK language=“javascript”&gt; 
             
             
                 
               /* some JavaScript code here */ 
             
             
                 
               &lt;/BLOCK&gt;. 
             
             
                 
                 
             
           
        
       
     
   
   As described, the implementation compiles a web page into a XML (eXtensible Markup Language) DOM (Document Object Model), and from there, into a Java servlet. In the DOM stage, the routine looks for BLOCK nodes. When encountering one, the routine creates a new node representing a Java method definition as a child of the root element, and replaces the BLOCK node with a node representing a Java method call to the new method definition. The block&#39;s child nodes are then moved under the method definition. Java servlet code is then generated under the method definition to pass the script code contained in the block to an appropriate interpreter for the scripting language specified by the block&#39;s “language” attribute. 
   The same operation is done for nested blocks. The innermost block is turned into a method definition and replaced by the method call node. When the next outer block is processed into its method definition, the block must turn any method call nodes among its children into valid method calls into the servlet written in the outer block&#39;s language. In the nested example above, the resulting Java servlet might then contain code as follows: 
                                                                                             protected void       javaBlock0(args)       {                if (true)   {               netrexxBlock0(args);               System.out,println(bean.getProperty());                }            }       protected void       javascriptBlock0(args)       {                javascriptInterpreter.process(“var i = 5;”);            }       protected void       netrexxBlock0(args)       {                netrexxInterpreter.process(“say I am true \n if alsoTrue then do \n            thisServlet.javascriptBlock()(args)\n end”);       }                    
The bolded text above represents the method call node transformed into a valid method call in the particular scripting language. Because in the preferred embodiment the runtime is written in Java, a special interpreter is not required to handle the javaBlock( ) script code.
 
   The following illustrates how the invention verifies context between multiple related XML tags. This example starts with a sample input XML chunk and ends with a code chunk for use in the final servlet: 
   
     
       
             
           
             
             
           
             
           
             
             
           
             
           
             
             
           
             
           
             
             
           
             
           
             
             
           
             
             
           
             
           
             
             
           
             
             
           
             
             
           
             
           
             
             
           
             
           
             
             
           
             
             
           
             
           
             
             
           
             
           
             
             
           
             
             
           
             
             
           
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
         
             
                 
             
           
           
             
               (1) xml 
             
             
               &lt;trace:sink file=“/myTrace.out”&gt; 
             
           
        
         
             
                 
               &lt;trace:output&gt;foo + bar&lt;/trace:output&gt; 
             
           
        
         
             
               &lt;/trace:sink&gt; 
             
             
               (2) trace:output is handled by TagBean 
             
           
        
         
             
                 
               - creates a marker with all currently known state 
             
             
                 
               - creates a trace:cleanup-markers tag which will signal the 2nd pass 
             
           
        
         
             
               &lt;trace:cleanup-markers/&gt; 
             
             
               &lt;trace:sink file=“/myTrace.out”&gt; 
             
           
        
         
             
                 
               &lt; — trace — output — marker&gt;foo + bar&lt;/ — trace — output — marker&gt; 
             
           
        
         
             
               &lt;/trace:sink&gt; 
             
             
               (3) trace:sink is handled 
             
           
        
         
             
                 
               - produces scriptlets to handle body of the work 
             
             
                 
               - adds metadata to  — trace — output — marker 
             
           
        
         
             
               &lt;trace:cleanup-markers/&gt; 
             
             
               &lt;jsp:scriptlet&gt; 
             
           
        
         
             
                 
               try 
             
           
        
         
             
                 
               FileWriter fileWriter = new FileWriter(“/myTrace.out”); 
             
             
                 
               PrintWriter printWriter = new PrintWriter(fileWriter); 
             
           
        
         
             
               &lt;/jsp:scriptlet&gt; 
             
             
               &lt; — trace — output — marker output=“printWriter”&gt;foo + 
             
             
               bar&lt;/ — trace — output — marker&gt; 
             
             
               &lt;jsp:scriptlet&gt; 
             
           
        
         
             
                 
               } finally { 
             
           
        
         
             
                 
               printWriter.flush(); 
             
             
                 
               fileWriter.flush(); 
             
             
                 
               printWriter.close(); 
             
             
                 
               fileWriter.close(); 
             
           
        
         
             
                 
               } 
             
           
        
         
             
               &lt;/jsp:scriptlet&gt; 
             
             
               (4) trace:cleanup-markers is handled 
             
           
        
         
             
                 
               - replaces  — trace — output — marker with a jsp:scriptlet 
             
           
        
         
             
               &lt;jsp:scriptlet&gt; 
             
           
        
         
             
                 
               try 
             
           
        
         
             
                 
               FileWriter fileWriter = new FileWriter(“/myTrace.out”); 
             
             
                 
               PrintWriter printWriter = new PrintWriter(fileWriter); 
             
           
        
         
             
               &lt;/jsp:scriptlet&gt; 
             
             
               &lt;jsp:scriptlet&gt; 
             
           
        
         
             
                 
               printWriter.println(foo + bar); 
             
           
        
         
             
               &lt;/jsp:scriptlet&gt; 
             
             
               &lt;jsp:scriptlet&gt; 
             
           
        
         
             
                 
               } finally { 
             
           
        
         
             
                 
               printWriter.flush(); 
             
             
                 
               fileWriter.flush(); 
             
             
                 
               printWriter.close(); 
             
             
                 
               fileWriter.close(); 
             
           
        
         
             
                 
               } 
             
           
        
         
             
               &lt;/jsp:scriptlet&gt; 
             
             
               (5) final translation step of jsp:scriptlet to Java code 
             
           
        
         
             
                 
               try 
             
           
        
         
             
                 
               FileWriter fileWriter = new FileWriter(“/myTrace.out”); 
             
             
                 
               PrintWriter printWriter = new PrintWriter(fileWriter); 
             
             
                 
               printWriter.println(foo + bar); 
             
           
        
         
             
                 
               } finally { 
             
           
        
         
             
                 
               printWriter.flush(); 
             
             
                 
               fileWriter.flush(); 
             
             
                 
               printWriter.close(); 
             
             
                 
               fileWriter.close(); 
             
           
        
         
             
                 
               } 
             
             
                 
                 
             
           
        
       
     
   
   As also noted above, the present invention provides a technique for reducing the amount of code in the tagbeans. An example of this optimization technique is now provided. 
   The following ServletTagBean.j is the original code file: 
   package xsp.was; 
   
     
       
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
           
             
             
           
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
           
         
             
                 
             
           
           
             
               import xsp.*; 
             
             
               import java.util.*; 
             
             
               import org.w3c.dom.*; 
             
             
               import javax.servlet.jsp.*; 
             
             
               public class ServletTagBean extends SimpleTagBean 
             
             
               { 
             
           
        
         
             
                 
               protected String name = null; 
             
             
                 
               protected String code = null; 
             
             
                 
               protected String codebase = null; 
             
             
                 
               public void 
             
             
                 
               setName(String name) 
             
             
                 
               { 
             
           
        
         
             
                 
               this.name = name; 
             
           
        
         
             
                 
               } 
             
             
                 
               public void 
             
             
                 
               setCode(String code) 
             
             
                 
               { 
             
           
        
         
             
                 
               this.code = code; 
             
           
        
         
             
                 
               } 
             
             
                 
               public void 
             
             
                 
               setCodebase(String codebase) 
             
             
                 
               { 
             
           
        
         
             
                 
               this.codebase = codebase; 
             
           
        
         
             
                 
               } 
             
             
                 
               public String 
             
             
                 
               translateElement(Element element) 
             
             
                 
               { 
             
           
        
         
             
                 
               Hashtable initParams = parseInitParams(element); 
             
           
        
         
             
                 
               // For each param sub element, add the name/value to a map for later 
             
           
        
         
             
                 
               Hashtable paramMap = Utility.parseParams(element); 
             
           
        
         
             
                 
               // The name or code parameter must be set. 
             
           
        
         
             
                 
               if (name == null &amp;&amp; code == null) { 
             
           
        
         
             
                 
               // Error!!! 
             
           
        
         
             
                 
               System.out.println(″Error: name and code can not be null the same time″); 
             
             
                 
               return null; 
             
           
        
         
             
                 
               } 
             
             
                 
               StringBuffer buff = new StringBuffer( ); 
             
             
                 
               buff.append(″\n″) 
             
           
        
         
             
                 
               .append(″&lt;″) 
             
             
                 
               .append(SCRIPTLETTAG) 
             
             
                 
               .append(″&gt;\n\n″) 
             
             
                 
               .append(″try {\n″) 
             
             
                 
               .append(″ String  — code = null;\n″); 
             
           
        
         
             
                 
               if (name == null) { 
             
           
        
         
             
                 
               buff.append(″ String  — name = null;\n″); 
             
           
        
         
             
                 
               } 
             
             
                 
               else { 
             
           
        
         
             
                 
               buff.append(″ String  — name = \″″) 
             
           
        
         
             
                 
               .append(name) 
             
             
                 
               .append(″\″;\n″); 
             
           
        
         
             
                 
               } 
             
             
                 
               if (code != null) { 
             
           
        
         
             
                 
               buff.append(″  — code = \″″) 
             
           
        
         
             
                 
               .append(code) 
             
             
                 
               .append(″\″;\n\n″); 
             
           
        
         
             
                 
               } 
             
             
                 
               buff.append(″\n if ( — name == null ||  — name.equals(\″\″)) {\n″) 
             
           
        
         
             
                 
               .append(″  — name =  — code;\n″) 
             
             
                 
               .append(″ }\n\n″) 
             
             
                 
               .append(″ Servlet — s = \n″) 
             
             
                 
               .append(″ getServletConfig( ).getServletContext( ).″) 
             
             
                 
               .append(″getServlet( — name);\n″) 
             
             
                 
               .append(″ if ( — s == null) {\n″) 
             
             
                 
               .append(″ Properties  — init = new Properties( );\n″) 
             
             
                 
               .append(″  — init.put(\″name\″, \″″) 
             
             
                 
               .append(name) 
             
             
                 
               .append(″\″);\n″); 
             
           
        
         
             
                 
               if (code != null) { 
             
           
        
         
             
                 
               buff.append(″  — init.put(\″code\″, \″″) 
             
           
        
         
             
                 
               .append(code) 
             
             
                 
               .append(″\″);\n″); 
             
           
        
         
             
                 
               } 
             
             
                 
               if (initParams.size( ) &gt; 0) { 
             
           
        
         
             
                 
               Enumeration e = initParams.keys( ); 
             
             
                 
               while (e.hasMoreElements( )) { 
             
           
        
         
             
                 
               String key = (String) e.nextElement( ); 
             
             
                 
               String value = (String) initParams.get(key); 
             
             
                 
               buff.append(″  — init.put(\″″) 
             
           
        
         
             
                 
               .append(key) 
             
             
                 
               .append(″\″, \″″) 
             
             
                 
               .append(value) 
             
             
                 
               .append(″\″);\n″); 
             
           
        
         
             
                 
               } 
             
           
        
         
             
                 
               } 
             
             
                 
               if (codebase != null) { 
             
           
        
         
             
                 
               buff.append(″  — init.put(\″codebase\″, \″″) 
             
           
        
         
             
                 
               .append(codebase) 
             
             
                 
               .append(″\″);\n″) 
             
             
                 
               .append(″  — s = ″) 
             
             
                 
               .append(″com.sun.server.http.pagecompile.\n″) 
             
             
                 
               .append(″\tServletUtil.loadServlet(this,″) 
             
             
                 
               .append(″\n\t\t\t\t — name,\n\t\t\t\t — code, ″) 
             
             
                 
               .append(″ \n\t\t\t\t\″″) 
             
           
        
         
             
                 
               .append(codebase) 
             
           
        
         
             
                 
               .append(″\″, \n\t\t\t\t — init);\n″); 
             
           
        
         
             
                 
               } 
             
             
                 
               if (codebase == null) { 
             
           
        
         
             
                 
               buff.append(″  — s = ″) 
             
           
        
         
             
                 
               .append(″com.sun.server.http.pagecompile.\n\tServletUtil.″) 
             
             
                 
               .append(″loadServlet(this,″) 
             
           
        
         
             
                 
               .append(″\n\t\t\t\t — name,″) 
             
           
        
         
             
                 
               .append(″ \n\t\t\t\t — code,\n\t\t\t\tnull,″) 
             
             
                 
               .append(″\n\t\t\t\t — init);\n″); 
             
           
        
         
             
                 
               } 
             
             
                 
               buff.append(″ }\n\n″); 
             
             
                 
               if (paramMap.size( ) &gt; 0) { 
             
           
        
         
             
                 
               buff.append(″ java.util.Hashtable  — parm = new ″) 
             
           
        
         
             
                 
               .append(″ java.util.Hashtable( );\n″); 
             
           
        
         
             
                 
               Enumeration e = paramMap.keys( ); 
             
             
                 
               buff.append(″ String[ ]  — vals; \n″); 
             
             
                 
               while (e.hasMoreElements( )) { 
             
           
        
         
             
                 
               String key = (String) e.nextElement( ); 
             
             
                 
               String value = (String) paramMap.get(key); 
             
             
                 
               buff.append(″  — vals = new String[1];\n″) 
             
           
        
         
             
                 
               .append(″  — vals[0] = \″″) 
             
             
                 
               .append(value) 
             
             
                 
               .append(″\″;\n″) 
             
             
                 
               .append(″  — parm.put(\″″) 
             
             
                 
               .append(key) 
             
             
                 
               .append(″\″,  — vals);\n″); 
             
           
        
         
             
                 
               } 
             
           
        
         
             
                 
               } 
             
             
                 
               buff.append(″\n out.flush( );″); 
             
             
                 
               buff.append(″\n if ( — s != null) {\n″); 
             
           
        
         
             
                 
               if (paramMap.isEmpty( )) { 
             
           
        
         
             
                 
               buff.append(″ com.sun.server.http.pagecompile.″) 
             
           
        
         
             
                 
               .append(″ServletUtil.″) 
             
             
                 
               .append(″callServlet( — s,  — name, request, response);\n″); 
             
           
        
         
             
                 
               } else { 
             
           
        
         
             
                 
               buff.append(″ HttpServletRequest — r;\n″) 
             
           
        
         
             
                 
               .append(″\n  — r = new \n com.sun.server.http.″) 
             
             
                 
               .append(″pagecompile.ParamsHttpServletRequest(″) 
             
           
        
         
             
                 
               .append(″request,\n\t\t\t\t\t\t\t  — parm);\n″) 
             
           
        
         
             
                 
               .append(″ com.sun.server.http.pagecompile.″) 
             
             
                 
               .append(″ServletUtil.callServlet( — s,″) 
             
             
                 
               .append(″\n\t\t\t\t\t\t\t  — name,″) 
             
           
        
         
             
                 
               .append(″\n\t\t\t\t\t\t\t  — r, ″) 
             
             
                 
               .append(″\n\t\t\t\t\t\t\t response);\n″); 
             
           
        
         
             
                 
               } 
             
             
                 
               buff.append(″ }\n″) 
             
           
        
         
             
                 
               .append(″} catch(Exception e) {\n″) 
             
             
                 
               .append(″ e.printStackTrace( ); \n″) 
             
             
                 
               .append(″ throw new ServletException(\″Exception ″) 
             
             
                 
               .append(″caught for servlet: \″ +\n e.getMessage( ));\n″) 
             
             
                 
               .append(″}\n″) 
             
             
                 
               .append(″\n&lt;/″) 
             
             
                 
               .append(SCRIPTLETTAG) 
             
             
                 
               .append(″&gt;″); 
             
           
        
         
             
                 
               return buff.toString( ); 
             
           
        
         
             
                 
               } 
             
             
                 
               public Hashtable 
             
             
                 
               parseInitParams(Element element) 
             
             
                 
               { 
             
           
        
         
             
                 
               Hashtable initParams = new Hashtable( ); 
             
             
                 
               NamedNodeMap namedNodeMap = element.getAttributes( ); 
             
             
                 
               int attributeLength = namedNodeMap.getLength( ); 
             
             
                 
               Node attributeNode = null; 
             
             
                 
               String nodeName = null; 
             
             
                 
               String nodeValue = null; 
             
             
                 
               for (int i = 0; i &lt; attributeLength; i++) { 
             
           
        
         
             
                 
               attributeNode = namedNodeMap.item(i); 
             
             
                 
               nodeName = attributeNode.getNodeName( ); 
             
             
                 
               nodeValue = attributeNode.getNodeValue( ); 
             
           
        
         
             
               // 
               System.out.println(″nodeName==″ + nodeName + 
             
             
               // 
                         ″ nodeValue==″ + nodeValue); 
             
           
        
         
             
                 
               if (!(nodeName.equals(″type″)) &amp;&amp; 
             
           
        
         
             
                 
               !(nodeName.equals(″Name″)) &amp;&amp; 
             
             
                 
               !(nodeName.equals(″Code″)) &amp;&amp; 
             
             
                 
               !(nodeName.equals(″Codebase″))){ 
             
             
                 
               initParams.put(nodeName, nodeValue); 
             
           
        
         
             
                 
               } 
             
           
        
         
             
                 
               } 
             
             
                 
               return initParams; 
             
           
        
         
             
                 
               } 
             
           
        
         
             
               } 
             
           
        
         
             
                 
               The following class, ServletTagBean.java, is the recoded class using the 
             
           
        
         
             
               delegation model of the invention. 
             
             
               package xsp.was; 
             
             
               import xsp.*; 
             
             
               import java.io.*; 
             
             
               import java.util.*; 
             
             
               import org.w3c.dom.*; 
             
             
               import javax.servlet.*; 
             
             
               import javax.servlet.http.*; 
             
             
               import javax.servlet.jsp.*; 
             
             
               import com.sun.server.http.pagecompile.*; 
             
             
               public class ServletTagBean extends SimpleTagBean 
             
             
               { 
             
           
        
         
             
                 
               protected static int count = 0; 
             
             
                 
               public String 
             
             
                 
               translateElement(Element element) 
             
             
                 
               { 
             
           
        
         
             
                 
               Properties initParameters = parseInitParams(element); 
             
             
                 
               Hashtable runtimeParameters = Utility.parseParams(element); 
             
             
                 
               String name = (String) initParameters.get(″name″); 
             
             
                 
               String code = (String) initParameters.get(″code″); 
             
             
                 
               String codebase = (String) initParameters.get(″codebase″); 
             
             
                 
               // The name or code parameter must be set. 
             
             
                 
               if ((name == null) &amp;&amp; 
             
           
        
         
             
                 
               (code == null)) { 
             
             
                 
               System.out.println(″Error: name and code can not be null the same time″); 
             
             
                 
               return null; 
             
           
        
         
             
                 
               } 
             
             
                 
               int currentCount = ++count; 
             
             
                 
               String initParametersName = 
             
           
        
         
             
                 
               ″ — xsp — servletTagBean — initParameters″ + currentCount; 
             
           
        
         
             
                 
               String runtimeParametersName = 
             
           
        
         
             
                 
               ″ — xsp — servletTagBean — runtimeParameters″ + currentCount; 
             
           
        
         
             
                 
               String output = 
             
           
        
         
             
                 
               INDENT2 + ″&lt;jsp:scriptlet&gt;\n″ + 
             
             
                 
               INDENT2 + ″Properties″ + initParametersName + ″=″ + 
             
             
                 
               ″ new Properties( );\n″ + 
             
             
                 
               INDENT2 + ″Properties″ + runtimeParametersName + 
             
             
                 
               ″ = new Properties( );\n″; 
             
           
        
         
             
                 
               Enumeration enumeration = initParameters.keys( ); 
             
             
                 
               while (enumeration.hasMoreElements( )) { 
             
           
        
         
             
                 
               String key = (String) enumeration.nextElement( ); 
             
             
                 
               String value = (String) initParameters.get(key); 
             
             
                 
               output += 
             
           
        
         
             
                 
               INDENT2 + initParametersName + ″.put(″ + 
             
             
                 
               stringify(key) + ″,″ + 
             
             
                 
               stringify(value) + ″);″; 
             
           
        
         
             
                 
               } 
             
             
                 
               enumeration = runtimeParameters.keys( ); 
             
             
                 
               while (enumeration.hasMoreElements( )) { 
             
           
        
         
             
                 
               String key = (String) enumeration.nextElement( ); 
             
             
                 
               String value = (String) runtimeParameters.get(key); 
             
             
                 
               output += 
             
           
        
         
             
                 
               INDENT2 + runtimeParametersName + ″.put(″ + 
             
             
                 
               stringify(key) + ″,″ + 
             
             
                 
               stringify(value) + ″);″; 
             
           
        
         
             
                 
               } 
             
             
                 
               output += 
             
           
        
         
             
                 
               INDENT2 + ″xsp.was.ServletTagBean.runServlet(this, \n″ + 
             
             
                 
               INDENT3 + ″request,\n″ + 
             
             
                 
               INDENT3 + ″response,\n″ + 
             
             
                 
               INDENT3 + initParametersName + ″,\n″ + 
             
             
                 
               INDENT3 + runtimeParametersName + ″);″; 
             
           
        
         
             
                 
               output += 
             
           
        
         
             
                 
               INDENT2 + ″&lt;/jsp:scriptlet&gt;\n″; 
             
           
        
         
             
                 
               return output; 
             
           
        
         
             
                 
               } 
             
             
                 
               protected static final String 
             
             
                 
               normalize(String input) 
             
             
                 
               { 
             
           
        
         
             
                 
               if (input == null) { 
             
           
        
         
             
                 
               return null; 
             
           
        
         
             
                 
               } 
             
             
                 
               input = input.trim( ); 
             
             
                 
               if (input.equals(″″)) { 
             
           
        
         
             
                 
               return null; 
             
           
        
         
             
                 
               } 
             
             
                 
               return input; 
             
           
        
         
             
                 
               } 
             
             
                 
               protected static final String 
             
             
                 
               stringify(String input) 
             
             
                 
               { 
             
           
        
         
             
                 
               if (input == null) { 
             
           
        
         
             
                 
               return ″null″; 
             
           
        
         
             
                 
               } 
             
             
                 
               return ″\″″ + input + ″\″″; 
             
           
        
         
             
                 
               } 
             
             
                 
               public static void 
             
             
                 
               runServlet(Servlet containingServlet, 
             
           
        
         
             
                 
               HttpServletRequest request, 
             
             
                 
               HttpServletResponse response, 
             
             
                 
               Properties initParameters, 
             
             
                 
               Properties runtimeParameters) 
             
           
        
         
             
                 
               throws ServletException, IOException 
             
           
        
         
             
                 
               { 
             
           
        
         
             
                 
               String name = normalize((String) initParameters.get(″name″)); 
             
             
                 
               String code = normalize((String) initParameters.get(″code″)); 
             
             
                 
               String codebase = normalize((String) initParameters.get(″codebase″)); 
             
             
                 
               if ((name == null) &amp;&amp; 
             
           
        
         
             
                 
               (code == null)) { 
             
             
                 
               throw new IllegalStateException(″name or code must be non-null″); 
             
           
        
         
             
                 
               } 
             
             
                 
               if (name == null) { 
             
           
        
         
             
                 
               name = code; 
             
           
        
         
             
                 
               } 
             
             
                 
               initParameters.put(″name″, name); 
             
             
                 
               if (code != null) { 
             
           
        
         
             
                 
               initParameters.put(″code″, code); 
             
           
        
         
             
                 
               } 
             
             
                 
               Servlet servlet = ServletUtil.loadServlet(containingServlet, 
             
           
        
         
             
                 
               name, 
             
             
                 
               code, 
             
           
        
         
             
                 
               codebase, 
             
             
                 
               initParameters); 
             
           
        
         
             
                 
               if (!runtimeParameters.isEmpty( )) { 
             
           
        
         
             
                 
               request = new ParamsHttpServletRequest(request, runtimeParameters); 
             
           
        
         
             
                 
               } 
             
             
                 
               ServletUtil.callServlet(servlet, name, request, response); 
             
           
        
         
             
                 
               } 
             
             
                 
               public Properties 
             
             
                 
               parseInitParams(Element element) 
             
             
                 
               { 
             
           
        
         
             
                 
               Properties initParams = new Properties( ); 
             
             
                 
               NamedNodeMap namedNodeMap = element.getAttributes( ); 
             
             
                 
               int attributeLength = namedNodeMap.getLength( ); 
             
             
                 
               Node attributeNode = null; 
             
             
                 
               String nodeName = null; 
             
             
                 
               String nodeValue = null; 
             
             
                 
               for (int i = 0; i &lt; attributeLength; i++) { 
             
           
        
         
             
                 
               attributeNode = namedNodeMap.item(i); 
             
             
                 
               nodeName = attributeNode.getNodeName( ); 
             
             
                 
               nodeValue = attributeNode.getNodeValue( ); 
             
             
                 
               initParams.put(normalize(nodeName), 
             
           
        
         
             
                 
               normalize(nodeValue)); 
             
           
        
         
             
                 
               } 
             
             
                 
               return initParams; 
             
           
        
         
             
                 
               } 
             
           
        
         
             
               } 
             
             
                 
             
           
        
       
     
   
   The developer need not write code generation code to produce code that will be robust for every possible input scenario. Instead, the developer need only write the code once, and the only code generation is used to delegate to the method that is written once. 
   So, to provide a generic example:
         1. String output=“out.write(\““+string+”\”);”; becomes:   2. String output=“PrintTagBean.print(out, \““+string+”\”);”;       

   The out.write( ) is moved into a method print( ) on PrintTagBean: public static void 
   
     
       
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
         
             
                 
                 
             
           
           
             
                 
               print(Writer out, 
             
           
        
         
             
                 
               String string) 
             
           
        
         
             
                 
               { 
             
           
        
         
             
                 
               out.write(string); 
             
           
        
         
             
                 
               } 
             
             
                 
                 
             
           
        
       
     
   
   As can be seen, in the first case, the code relies upon a variable ‘out’ that exists in the servlet. The write( ) method was called on ‘out’ passing it a string. Thus, to perform proper delegation, a method on PrintTagBean is created that takes ‘out’ and the ‘string’ and calls“out.write(string)”. 
   Thus, according to the invention, at translation time, a custom tag in the DOM tree is replaced, e.g., with a script that results in a line of code in a generated servlet. In this way, when the servlet is then executed at request time, the line of code invokes a method in a custom tagbean to perform a given function. 
   If the code generated to handle runtime requests is longer than the code generated to pass the necessary variables to a method to be processed, there are several benefits to this approach. First, writing code to generate code is a very tedious and error-prone task; thus, reducing this code even slightly reduces the numbers of errors drastically. Second, using this approach, all the code handling of a task is actually handled in a single method that can be carefully crafted to handle correct inputs to produce the right output. Because this code is in the tagbean, it can be compiled immediately and checked for language syntax errors. If, instead, the code is generated each time, it will not be compiled until an XSP is written to test the functionality. Moreover, with branching (if statements) in code generation, it may take several tests just to test the syntax of all the possible code generations. Further, if the developer needs to change the function and “optimization” has already taken place, then the developer need only update a single method. Otherwise, the developer must go through the process of updating all the code generating code. Because of this reduction in code and code complexity, the maintenance of the code will be much lower. 
   The present invention provides numerous other advantages over the prior art. In effect, the inventive page handling mechanism combines the manipulation and template mechanism of XSLT with the scripting capabilities of the JSP/ASP model. In addition, the invention provides a framework for enabling any programming language to be plugged into that model. Further, given that most languages are easily defined in Java byte code, the invention is economical to implement in a runtime using, for example, a Java Virtual Machine. 
   The present invention uses custom DOM tags together with a framework and runtime that provides a powerful macro language to XML/JSP. The custom DOM tags allow a web page author the ability to define a simple markup language tag, e.g., &lt;SHOPPING — CART&gt;, that, at page translation time, is converted into script code by a generic Java object or an XSL stylesheet. This script code is then compiled into Java code and then into a Java servlet, yielding excellent performance servicing a client&#39;s request. Because the custom tag replaces the script code in the authored page, the page is kept clean and easy to maintain. The script code is kept separate and, thus, need only be debugged once. Normal ASP development, on the contrary, would force this code to remain in the page, and it would have to be debugged after every modification. 
   The inventive framework is quite advantageous in that it is built on top of XML. Moreover, one of ordinary skill will appreciate that the framework is defineable programmatically or with XSL. In addition, macros written according to the invention can affect the output of an entire page and not just the content between a given pair of tags. 
   The invention also enables one or more web page authors to support multiple scripting languages in a single web page. Further, in a preferred embodiment, the context of multiple related XML tags in a DOM may be verified by using theDOM itself to indicate state information. 
   As noted above, the inventive mechanism is preferably implemented in or as an adjunct to a web server. Thus, the invention does not require any modifications to conventional client hardware or software. Generalizing, the above-described functionality is implemented in software executable in a processor, namely, as a set of instructions (program code) in a code module resident in the random access memory of the computer. Until required by the computer, the set of instructions may be stored in another computer memory, for example, in a hard disk drive, or in a removable memory such as an optical disk (for eventual use in a CD ROM) or floppy disk (for eventual use in a floppy disk drive), or downloaded via the Internet or other computer network. 
   In addition, although the various methods described are conveniently implemented in a general purpose computer selectively activated or reconfigured by software, one of ordinary skill in the art would also recognize that such methods may be carried out in hardware, in firmware, or in more specialized apparatus constructed to perform the required method steps. 
   Further, as used herein, a Web “client” should be broadly construed to mean any computer or component thereof directly or indirectly connected or connectable in any known or later-developed manner to a computer network, such as the Internet. The term Web “server” should also be broadly construed to mean a computer, computer platform, an adjunct to a computer or platform, or any component thereof. Of course, a “client” should be broadly construed to mean one who requests or gets the file, and “server” is the entity which downloads the file.