Abstract:
A method of responding to a request from a client to a Web service is disclosed. The method includes the steps of: a) processing the request to identify a resource file and a requested action, wherein the request is encoded in one of a plurality of protocols; b) accessing the resource file which includes data describing the Web service; c) processing the request using at least a portion of the data to produce a response; and d) returning a response to the client. A computer system is also disclosed. The computer system includes a client adapted to send a request to a Web service, and a middleware which receives the request from the client. The computer system also includes a resource file accessible to the middleware. The resource file includes data describing the Web service. The middleware identifies the resource file and requested action from the request, which is encoded in one of a plurality of protocols.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention relates to Internet application software, and in particular to software for developing and communicating with web services.  
         BACKGROUND OF THE INVENTION  
         [0002]    As the popularity of the Internet has increased, so have the complexity of the services available on the Internet. Much of the Internet&#39;s use is conducted through the World Wide Web, hereinafter referred to as “WWW,” or simply the “Web,” in which linked pages of static content, composed of a variety of media, such as text, images, audio, and video, are described using hypertext markup language (HTML)  
           [0003]    As businesses began to conduct transactions via the Web, they developed Internet-based applications. Typically, these applications were powered by web application servers which dynamically generated HTML documents from server-side programming logic. These applications were written in programming languages such as Java™.  
           [0004]    The popularity of conducting transactions over the Web has led to an increasing demand for businesses to integrate their Internet applications with Internet applications of other businesses. However, these Internet applications are often implemented using proprietary software written in differing programming languages.  
           [0005]    One known solution for integrating heterogeneous Internet-based services introduced the concept of a “Web service”, which is defined as one or more application functions which can be programmatically invoked over the Internet using a protocol. One such standard protocol is the Simple Object Access Protocol (SOAP) which is used by Internet-based application servers (also known as Web servers) running Web services.  
           [0006]    SOAP is a protocol for exchange of information in a decentralized, distributed environment. The protocol is based on the Extensible Markup Language (XML) and consists of three parts: (i) an envelope that defines a framework for describing what is in a message and how to process it; (ii) a set of encoding rules for expressing instances of application-defined data types; and (iii) a convention for representing remote procedure calls and responses.  
           [0007]    In addition to using a common communication protocol, an application must have certain information in order to programmatically invoke a Web service over the Internet. This information is defined in a standard language adopted by developers of Internet-based applications. One such language is the Web services Description Language (WSDL). WSDL documents can be indexed in searchable Universal Description, Discovery, and Integration (UDDI) Business Registries to permit developers and applications to locate target Web services.  
           [0008]    One known SOAP implementation which allows developers to build Web services is a software product offered by the Apache XML Project. However, the Apache software can be cumbersome to use, reducing a software developer&#39;s ability to efficiently deploy and test a Web service.  
           [0009]    Another known solution for integrating heterogeneous Web services is a framework provided by Microsoft .NET. However, the .NET framework is a closed implementation which cannot be extended by developers  
           [0010]    Accordingly there is a need for an open and extendable Web service framework which improves developer productivity by reducing the time required to deploy a Web service. In addition, there is a need for an open and extendable Web services framework which is compatible with HTTP requests.  
         SUMMARY OF THE INVENTION  
         [0011]    According to a first aspect of the invention, a method of responding to a request from a client to a Web service is provided. The method comprising:  
           [0012]    a) processing the request to identify a resource file and a requested action;  
           [0013]    b) accessing the resource file, the resource file including data describing the Web service, wherein the request is encoded in one of a plurality of protocols;  
           [0014]    c) processing the request using at least a portion of the data to produce a response; and  
           [0015]    d) returning the response to the client.  
           [0016]    In a preferred embodiment the request comprises a URL, which is parsed to identify the resource file and to identify the requested action as a SOAP request, a HTTP GET request, or a HTTP POST request. Step (b) preferably includes checking if the resource file is loaded, or if already loaded, determining if the resource file has changed. If necessary, the resource file is reloaded in runtime, thereby improving developer productivity by eliminating the need to restart the middleware.  
           [0017]    In a preferred embodiment, the response may be a WSDL file, a HTML test page, or a XML Schema Description (XSD), to facilitate developer testing and implementation of web services.  
           [0018]    According to a second aspect of the invention, a computer readable medium including a computer program that causes a computer to respond to a request from a client to a Web service is provided. The computer program causes the computer to perform the steps of:  
           [0019]    a) processing the request to identify a resource file and a requested action, wherein the request is encoded in one of a plurality of protocols;  
           [0020]    b) accessing the resource file, the resource file including data describing the Web service;  
           [0021]    c) processing the request using at least a portion of the data to produce a response; and  
           [0022]    d) returning the response to the client.  
           [0023]    According to a third aspect of the invention, a computer system is provided comprising:  
           [0024]    a) a client adapted to send a request to a Web Service;  
           [0025]    b) a middleware the middleware adapted to receive the request from the client; and  
           [0026]    c) a resource file accessible to the middleware, the resource file including data describing the Web service;  
           [0027]    wherein the middleware is adapted to identify the resource file and the requested action from the request, the request being encoded in one of a plurality of protocols.  
           [0028]    In a preferred embodiment, the system is an extension of the Apache server, which provides support for HTTP GET and POST requests, as well as automatic generation of a test page, WSDL, and XSD for a selected Web service 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]    The present invention will now be described by way of example only with reference to the accompanying drawings, in which:  
         [0030]    [0030]FIG. 1 is a block diagram of a computer system according to the present invention;  
         [0031]    [0031]FIG. 2 is a block diagram of a middleware according to a preferred embodiment of the present invention;  
         [0032]    [0032]FIG. 3 is a block diagram of the middleware components which control resource file management;  
         [0033]    [0033]FIG. 4 is a block diagram showing the middleware components which are subclassed to extend the capabilities of the present invention; and  
         [0034]    [0034]FIG. 5 is a flow chart of the processing logic of the preferred embodiment. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0035]    Referring to FIG. 1, a computer system in accordance with the present invention is shown and generally designated as  10 . The computer system includes at least one client device  12  connected to an application server  14  via a network  16 . Preferably, the network  16  is the Internet. The client device may be a personal computer, Personal Digital Assistant (PDA), wireless telephone, or any other Internet-enabled computing device known in the art. The client may also be another server running an application. It will be understood that the client device  12  connects to the Internet by telephone modem, cable modem, DSL modem, local area network (LAN), wide area network (WAN), T1, or any other means known in the art.  
         [0036]    Continuing to refer to FIG. 1, the application server  14  preferably includes a middleware  18  (described in detail below) which is capable of communicating with a Web service  20 , such as a Java Bean or a database. Although only one Web service  20  is shown, any number of Web services may be deployed. In addition, although FIG. 1 shows the Web service  20  as local to the application server  14 , it will be understood by those skilled in the art that the middleware  18  may communicate with a remote Web service via the Internet or other network.  
         [0037]    In FIGS.  2 - 4 , blocks which are connected to other blocks by arrows are intended by the inventor to represent subclasses of the blocks to which the arrows point.  
         [0038]    Referring now to FIG. 2, the middleware includes a router servlet  30  which communicates with the client device  12 . The router servlet  30  includes logic to process the client request to determine a requested resource file and a requested action. The resource file contains information which defines the Web service  20 , such as parameters, arguments, and data types. Examples of known types of resource files are document access definition extension (DADX) files and SOAP deployment descriptor files (also known as ISD files)  
         [0039]    Preferably, the router servlet  30  includes a remote procedure call (RPC) servlet  32  which provides support for processing SOAP requests for a particular Web service. Preferably, the RPC servlet  32  is a component of the Apache 2.2 SOAP server implementation. A service invoker  34  is provided as a subclass of the RPC servlet  32 . The service invoker  34  loads the resource file into memory and creates an object model of the Web service  20  from the resource file. The service invoker also provides support for HTTP GET and POST requests, as well as providing support for generation of test pages, Extensible Markup Language Schema Description (XSD), and web service description (WSDL). The service invoker  34  may include a number of sub-classes. For example, an ISD invoker  36  may be provided to enable the middleware  18  to facilitate loading of SOAP deployment descriptor resource files (ISD files) that describe the Web service  20 , such as a Java Bean.  
         [0040]    Continuing to refer to FIG. 2, a servlet context  38  may be provided, which is accessible to the RPC servlet  32 . The servlet context  38  is a Java object which maintains information relating to the RPC servlet  32 . The information is shared with other components, such as a service manager  40 .  
         [0041]    Referring again to FIG. 2, the service manager  40  is preferably a component of the Apache 2.2 server implementation, which maintains a list of deployed Web services by referring to a configuration manager  42 . The RPC servlet  32  accesses the service manager  40  associated with the servlet context  38 . The service manager  40  accesses the configuration manager  42  which is also preferably a component of the Apache 2.2 server implementation. The configuration manager  42  reads a data file which lists resource files for all of the Web services deployed by the developer. Each deployed Web service  20  has a resource file associated with it. One type of resource file is an Apache deployment descriptor (ISD file)  44 , which lists methods performed by the Web service  20 . For convenience, only one deployment descriptor is shown. However, it will be understood by those skilled in the art that any number of deployment descriptors may be provided, depending on the number of Web services  20  deployed. The service invoker  34  obtains parameters and the name of the requested Web service from the deployment descriptor  44 , and calls a service provider  48  corresponding to the requested Web service. The service provider  48  is a subclass of a provider  46 . The service provider  48  implements execution of requests by retrieving the service object and executing the request via the specified operation object, as explained in more detail in FIG. 3. The group  50  includes subclasses corresponding to specific resource files, such as an ISD group  52  corresponding to the Apache deployment descriptors. The ISD invoker  36  identifies the ISD group  52  as the subclass of Group  50  to be used with the group of services handled by the ISD Invoker  36 .  
         [0042]    [0042]FIG. 3 shows the components of the middleware  18  which control the management of the resource files, such as retrieving, caching, and executing the service object. A resource cache  60  provides the logic to check if the resource file referred to in the client request has been loaded. If not, the resource cache  60  loads the resource file. Even if the resource file is loaded, the resource cache  60  determines if the current copy should be used or if the resource file should be checked for changes. The decision is defined by a reload policy which is part of the properties of a group  50 , which in turn is a subclass of the resource group  61 . For example, the reload policy for ISD files may be included as part of the ISD group  52 . The reload policy may be set to never check for changes, or to check for changes after a specified expiration time. In the latter case, if the time has expired (for example, by looking at the system clock) then the resource file is checked for changes (for example, by looking at the time stamp of files). The resource file is reloaded if necessary.  
         [0043]    Once loaded, the requested resource file is referred to as a cached resource  62 . Preferably, the content of each cached resource  62  is an arbitrary Java object. The actual type of content is determined by a content handler  64  associated with the cached resource  62 . A resource loader  66  reads the resource and produces a byte stream that the content handler  64  converts into an object  68 . For example, if a resource is an ISD file, then an ISD content handler  70  converts it into an ISD service  74 . The object  68  is an instance of the Web service  20 . The content handler  64  refers to subclasses which correspond to specific types of resource files. For example, an ISD content handler  70  processes ISD resource files. The object  68  refers to a service  72  which is a subclass of object  68 . The Service may refer to subclasses, such as a ISD service  74 . The service  72  is a class which represent an abstract Web service. The ISD service  74  is a subclass of service  72  which represents a concrete Web service implemented by, for example, a Java bean.  
         [0044]    Referring again to FIG. 2, the service invoker  34  provides support for generation of test pages, WSDL, and XSD. Specifically, the preferred embodiment described above provides a ISD invoker  36  to support automatic generation of test pages, WSDL, and XSD, as well as automatic deployment of a Web service based on a SOAP deployment descriptor file (ISD file). The present invention may also be configured to provide such support for other Web services. In order to do so, the user has to subclass certain components of the present invention, as described below.  
         [0045]    [0045]FIG. 4 shows the components which must be subclassed by the user to extend the functionality of the system to other types of Web services. The system includes the following main classes: group manager  76 , group  50 , service  72 , operation  77 , operation parameter  79 . The user may define groups of services. A group consists of a set of services of the same type that share common properties. For example, a DADX group shares a database. One of the properties of a DADX group is the database connection information. A Web application (servlet context) may contain several groups. A group manager class  76  keeps track of the set of groups defined in the servlet context  38  and stores common information such as the context name and class loader. The service class  72  models a Web service. A service  72  has a set of operations and each operation  77  has a set of operation parameters  79 .  
         [0046]    By way of example, a number of ISD subclasses to support ISD resources are shown in FIG. 4. These subclasses are ISD group  52 , ISD service  74 , and ISD operation  78 .  
         [0047]    The logic of the present invention may be contained on a data storage device with a computer readable medium, such as a computer diskette. Or, the instructions may be stored on a magnetic tape, conventional hard disk drive, electronic read-only memory, optical storage device, or other appropriate data storage device or transmitting device thereby making a computer program product, i.e., an article of manufacture according to the invention. In an illustrative embodiment of the invention, the computer-executable instructions may be lines of Java code.  
         [0048]    The flow charts herein illustrate the structure of the logic of the present invention as embodied in computer program software. Those skilled in the art will appreciate that the flow charts illustrate the structures of computer program code elements including logic circuits on an integrated circuit, that function according to this invention. Manifestly, the invention is practiced in its preferred embodiment by a machine component that renders the program elements in a form that instructs a digital processing apparatus (for example, a computer) to perform a sequence of function steps corresponding to those shown.  
         [0049]    The operational logic of the present invention will now be described with reference to FIG. 5. The logic begins at state  80 . At box  82 , an HTTP request is received from the client device  12  by the router servlet  30  of the middleware  18 .  
         [0050]    At box  84 , the router servlet  30  parses the universal resource locator (URL) in the request into a resource file and a requested action. For example, the URL, “HTTP://localhost:8080/services/beans/TemperatureConverter.isd/TEST”, is interpreted by the router servlet  30  as identifying “TemperatureConverter.isd” as the SOAP deployment descriptor resource file which is deployed to an application called “services” in a directory named “beans”. The router servlet  30  identifies “TEST” as the requested action, which is a command to generate a test page.  
         [0051]    At box  86 , the service invoker reads the resource file into memory and creates an instance of the Web service object model from it. The resource is read and converted into a Web service object instance by the content handler  64 , which understands the format of the resource. As described in detail above, checks are performed by the resource cache  60  to determine whether the resource file has already been loaded, and if it has been loaded, whether it should be automatically reloaded.  
         [0052]    The Web service object model may include a service object that contains information about the Web service  20  as a whole, such as the name of the Web service  20  and a descriptive document. The service object may also contain a list of operation objects that each contain information about the operations of the Web service. For example, the operation object may contain the name of the operation, descriptive documentation, and a list of parameter objects. Each parameter object may contain the name of the parameter, its XML data type, and its mode (input, output, or input/output).  
         [0053]    At decision diamond  88 , the service invoker  34  determines whether the request is a GET or POST request. It the request is a POST request, the logic flow moves to decision diamond  90 , where the service invoker  34  determines whether the POST request is XML encoded or URL encoded. If the request is XML encoded, the service invoker  34  determines if the request is a SOAP request at decision diamond  92 . If the request is not a SOAP request, an error message is returned at box  94 .  
         [0054]    If the request is a GET request or a URL encoded POST request, the service invoker  34  determines if the requested action is an operation at decision diamond  96 . If the requested action is not an operation, the flow moves to decision diamond  98 , where it is determined if the requested action is a request for XSD.  
         [0055]    If the requested action is XSD, XSD is generated at box  100 . The service invoker  34  selects all complex types associated with parameters and writes their definitions into the XSD response. Further, the service invoker  34  generates additional XSD types that define the input and output messages as a whole. An input or output message is defined by combining the input or output parameters into a complex XML type. The complex XML types associated with the messages are also written to the XSD response. Each parameter in the Web service  20  has an associated XML data type. Some of these types are simple types defined by the XSD specification. For example, numbers and text strings are simple types. Other types are complex types and are defined by the Web service. For example, the result of a database query is a complex type. Its XSD definition is generated when the Web service object instance is generated from the resource file.  
         [0056]    The XSD response is returned to the client device  12  at box  102 . The logic then ends at state  104 .  
         [0057]    If the requested action is not XSD, the flow moves to decision diamond  106 , where it is determined if the requested action is a test page request.  
         [0058]    If the requested action is a test page request, it is generated by the service invoker  34  at box  108 . The service invoker  34  generates the test page by adding a reference to the service object model instance to the HTTP request and forwarding the request to a JavaServer Page (JSP) document which renders the user interface for the test page. The JSP consists of an HTML frameset which contains three HTML frames. The frames contain the list of operations, the input form for the selected operation, and the output from invoking the operation. The list of operations frame is generated by a JSP document that creates a link for each operation in the service. The link contains the name of the operation and links to the input form JSP document. The input form JSP generates an HTML form that contains an input box for each parameter in the selected operation, and a button to invoke the operation. The invoke button uses the HTTP POST binding to invoke the operation. The results are sent to the output frame for display.  
         [0059]    At box  110 , the HTML test page is returned to the client device  12  at box  110 . The logic then ends at state  104 .  
         [0060]    If the requested action is not for a test page, the flow moves to decision diamond  112 , where it is determined if the requested action is WSDL.  
         [0061]    If the requested action is WSDL, the flow moves to box  114  where the WSDL response is generated. A WSDL file consists of a set of definitions for types, messages, portTypes, bindings, and services. The type definitions are generated by including the XSD definitions described above. The message definitions are generated as follows. For each operation in the service, and input and output messages are generated and these reference the corresponding parameter and message XML types which are contained in the XSD definitions. Two portType definitions may generated, one for SOAP over HTTP and one for both HTTP GET and HTTP POST. Each portType contains all the operations defined in the Web service  20 . The SOAP portType uses message definitions suitable for the SOAP binding and the HTTP GET/POST portType uses message definitions suitable for the http GET/POST bindings. Three binding definitions may be generated, one each for SOAP over HTTP, HTTP GET, and HTTP POST. The SOAP binding binds the SOAP portType, the HTTP GET binding binds the HTTP GET/POST portType, and the HTTP POST binding binds the HTTP GET/POST portType. One service definition is generated and it contains ports for each of the three bindings.  
         [0062]    The WSDL definitions can also be requested in a form that can be conveniently used with UDDI. In UDDI, it is recommended to split the WSDL definitions into two parts, one for the service and one for the remaining elements. These parts can be requested using the WSDLservice and WSDLbinding actions on the request URL. The WSDLbinding response contains all the definitions except the service definition. The WSDLservice response imports the WSDLbinding response and contains the service definition.  
         [0063]    The WSDL response is returned at box  116 . The logic then ends at state  104 .  
         [0064]    If the requested action is not WSDL, an error message response is returned to the client device at box  118 . The logic then ends at state  104 .  
         [0065]    If the requested action is an operation or a SOAP request, the logic flow moves to box  120 , where the service invoker  34  unmarshalls the request parameters. The service provider  48  corresponding to the requested Web service  20  is invoked at box  122 . At box  124 , the service provider  48  marshalls the response parameters. At box  126 , a service response is returned to the client device  12 . The logic then ends at state  104 .  
         [0066]    The present invention extends the Apache SOAP framework by adding URL access control, support for HTTP POST and GET requests. The present invention also provides automatic generation of WSDL to describe the Web service, automatic generation of a test page, and automatic generation of XSD. In addition, the present invention provides automatic deployment of a Web service and automatic reloading of the Web service when its resource changes. These features make the Apache SOAP framework more productive for developers and reduce the number of times that the SOAP server is restarted.  
         [0067]    While the present invention as herein shown and described in detail is fully capable of attaining the above-described objects of the invention, it is to be understood that it is the presently preferred embodiment of the present invention and thus, is representative of the subject matter which is broadly contemplated by the present invention, that the scope of the present invention fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural and functional equivalents to the elements of the above-described preferred embodiment that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present invention, for it is to be encompassed by the present claims.