Abstract:
The present invention modifies the implementation of the Netscape security model to use an apparatus to set and get extended class data. More specifically, use of the apparatus to store the additional security information for later retrieval at the point where this information would have been written into the Java class data structure, and retrieve this information at the point it would have been read from the Java class data structure. The apparatus is implemented by creating a hash table of objects that store the extended class information. The hash key function uses the original class reference to lookup the classes shadow data structure.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to both a method and an apparatus for decoupling a Java Virtual Machine (JVM) from an internet browser. Specifically, the system involves the storage of extended security information in a data structure that shadows a Java class object. 
     2. Description of Related Art 
     Internet, also referred to as an “internetwork”, in communications is a set of computer networks, possibly dissimilar, joined together by means of gateways that handle data transfer and the conversion of messages from the sending network to the protocols used by the receiving network (with packets if necessary). When capitalized, the term “Internet” refers to the collection of networks and gateways that use the TCP/IP suite of protocols. 
     The Internet has become a cultural fixture as a source of both information and entertainment. Many businesses are creating Internet sites as an integral part of their marketing efforts, informing consumers of the products or services offered by the business or providing other information seeking to engender brand loyalty. Many federal, state, and local government agencies are also employing Internet sites for informational purposes, particularly agencies which must interact with virtually all segments of society such as the Internal Revenue Service and secretaries of state. Operating costs may be reduced by providing informational guides and/or searchable databases of public records online. 
     Currently, the most commonly employed method of transferring data over the Internet is to employ the World Wide Web environment, also called simply “the web”. Other Internet resources exist for transferring information, such as File Transfer Protocol (FTP) and Gopher, but have not achieved the popularity of the web. In the web environment, servers and clients effect data transaction using the Hypertext Transfer Protocol (HTTP), a known protocol for handling the transfer of various data files (e.g., text, still graphic images, audio, motion video, etc.). Information is formatted for presentation to a user by a standard page description language, the Hypertext Markup Language (HTML). In addition to basic presentation formatting, HTML allows developers to specify “links” to other web resources identified by a Uniform Resource Locator (URL). A URL is a special syntax identifier defining a communications path to specific information. Each logical block of information accessible to a client, called a “page” or a “web page”, is identified by a URL. The URL provides a universal, consistent method for finding and accessing this information by the web “browser”. A browser is a program capable of submitting a request for information identified by a URL at the client machine. Retrieval of information on the web is generally accomplished with an HTML-compatible browser. 
     When a user desires to retrieve a page, a request is submitted to a server connected to a client computer at which the user is located and may be handled by a series of servers to effect retrieval of the requested information. The information is provided to the client formatted according to HTML. Typically, personal computers (PCs) along with work stations are typically used to access the Internet. 
     Often applications or programs may be sent to a computer from a web server across the Internet. Java applications are becoming increasingly more prevalent as the type of application sent between web servers and client computers. Java applications are common on the Internet and becoming more increasingly common in intranets and in other types of networks used in businesses. 
     Java is an object oriented programming language and environment focusing on defining data as objects and the methods that may be applied to those objects. Java supports only a single inheritance, meaning that each class can inherit from only one other class at any given time. Java also allows for the creation of totally abstract classes known as interfaces, which allow the defining of methods that may be shared with several classes without regard for how other classes are handling the methods. 
     The Java virtual machine (JVM) is a virtual computer component that resides only in memory. The JVM allows Java programs to be executed on a different platform as opposed to only the one platform for which the code was compiled. Java programs are compiled for the JVM. In this manner, Java is able to support applications for many types of data processing systems, which may contain a variety of central processing units and operating systems architectures. To enable a Java application to execute on different types of data processing systems, a compiler typically generates an architecture-neutral file format—the compiled code is executable on many processors, given the presence of the Java run-time system. The Java compiler generates bytecode instructions that are non-specific to a particular computer architecture. A bytecode is a machine independent code generated by the Java compiler and executed by a Java interpreter. A Java interpreter is a part in the JVM that alternately decodes and interprets a bytecode or bytecodes. These bytecode instructions are designed to be easy to interpret on any computer and easily translated on the fly into native machine code. 
     Many currently available web browsers, such Netscape Communicator, which is available from Netscape Communications Corporation, incorporate JVMs as part of the web browser. Presently, however, JVMs updates are provided more often than web browser updates. Such a situation prevents users from taking advantage of improved versions of WMs until the web browser is updated. Therefore, it would be advantageous to have an improved method and apparatus for providing users an ability to use more recent versions of JVMs without having to wait for an updated version of the web browser. However, Netscape redefined the JVM&#39;s internal (non-overrideable and non-replaceable) class data structure to include additional security information. Specifically, Netscape added their certificate model called “ziggy” to this internal structure. While this works as an implementation, a change to the internals of a JVM to store additional security information breaks the security capabilities. Therefore, to provide the required Netscape security capabilities, an alternative design is needed. 
     SUMMARY OF THE INVENTION 
     The present invention modifies the implementation of the Netscape security model to use an apparatus to set and get extended class data. More specifically, use of the apparatus to store the additional security information for later retrieval at the point where this information would have been written into the Java class data structure, and retrieve this information at the point it would have been read from the Java class data structure. The apparatus is implemented by creating a hash table of objects that store the extended class information. The hash key function uses the original class reference to lookup the classes shadow data structure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with accompanying drawings, wherein: 
     FIG. 1 is a pictorial representation of a distributed data processing system in which the present invention may be implemented; 
     FIG. 2 is a block diagram of a data processing system that may be implemented as a server; 
     FIG. 3 is a block diagram of a data processing system in which the present invention may be implemented; 
     FIG. 4 is a block diagram of the present invention illustrating the creation of a class shadow apparatus outside of the JVM; 
     FIG. 5 illustrates the Java class data structure and the class extension data structure maintained in the shadow apparatus; 
     FIG. 6 is a flow chart of the method of setting a class extension in the apparatus; and 
     FIG. 7 is a flow chart of the method of getting a class extension in the apparatus. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference now to the figures, and in particular with reference to FIG. 1, a pictorial representation of a distributed data processing system in which the present invention may be implemented is depicted. 
     Distributed data processing system  100  is a network of computers in which the present invention may be implemented. Distributed data processing system  100  contains a network  102 , which is the medium used to provide communications links between various devices and computers connected together within distributed data processing system  100 . Network  102  may include permanent connections, such as wire or fiber optic cables, or temporary connections made through telephone connections. 
     In the depicted example, a server  104  is connected to network  102  along with storage unit  106 . In addition, clients  108 ,  110 , and  112  also are connected to a network  102 . These clients  108 ,  110 , and  112  may be, for example, personal computers of network computers. For purposes of this application, a network computer is any computer, coupled to a network, which receives a program or other application from another computer coupled to the network. In the depicted example, server  104  provides data, such as boot files, operating system images, and applications to NCs  108 - 112 . NCs  108 ,  110 , and  112  are clients to server  104 . Distributed data processing system  100  may include additional servers, clients, and other devices not shown. FIG. 1 is intended as an example, and not as an architectural limitation for the processes of the present invention. 
     Referring to FIG. 2, a block diagram of a data processing system which may be implemented as a server, such as server  104  in FIG. 1, is depicted in accordance to the present invention. Data processing system  200  may be a symmetric multiprocessor (SMP) system including a plurality of processors  202  and  204  connected to system bus  206 . Alternatively, a single processor system may be employed. Also connected to system bus  206  is memory controllercache  208 , which provides an interface to local memory  209 . I/O bus bridge  210  is connected to system bus  206  and provides an interface to I/O bus  212 . Memory controllercache  208  and I/O bus bridge  210  may be integrated as depicted. 
     Peripheral component interconnect (PCI) bus bridge  214  connected to I/O bus  212  provides an interface to PCI local bus  216 . A number of modems  218 - 220  may be connected to PCI bus  216 . Typical PCI bus implementations will support four PCI expansion slots or add-in connectors. Communications links to network computers  108 - 112  in FIG. 1 may be provided through modem  218  and network adapter  220  connected to PCI local bus  216  through add-in boards. 
     Additional PCI bus bridges  222  and  224  provide interfaces for additional PCI buses  226  and  228 , from which additional modems or network adapters may be supported. In this manner, server  200  allows connections to multiple network computers. A memory mapped graphics adapter  230  and hard disk  232  may also be connected to  10  bus  212  as depicted, either directly or indirectly. 
     Those of ordinary skill in the art will appreciate that the hardware depicted in FIG. 2 may vary. For example, other peripheral devices, such as optical disk drive and the like also may be used in addition or in place of the hardware depicted. The depicted example is not meant to imply architectural limitations with respect to the present invention. 
     The data processing system depicted in FIG. 2 may be, for example, an IBM RISC/System 6000 system, a product of International Business Machines Corporation in Armonk, N.Y., running the Advanced Interactive Executive (AIX) operating system. 
     With reference now to FIG. 3, a block diagram of a data processing system  300  in which the present invention may be implemented is illustrated. Data processing system  300  is an example of a client computer. Data processing system  300  employs a peripheral component interconnect (PCI) local bus architecture. Although the depicted example employs a PCI bus, other bus architectures such as Micro Channel and ISA may be used. Processor  302  and main memory  304  are connected to PCI local bus  306  through PCI bridge  308 . PCI bridge  308  also may include an integrated memory controller and cache memory for processor  302 . Additional connections to PCI local bus  306  may be made through direct component interconnection or through add-in boards. In the depicted example, local area network (LAN) adapter  310 , SCSI host bus adapter  312 , and expansion bus interface  314  are connected to PCI local bus  306  by direct component connection. In contrast, audio adapter  316 , graphics adapter  318 , and audio/video adapter (A/V)  319  are connected to PCI local bus  306  by add-in boards inserted into expansion slots. Expansion bus interface  314  provides a connection for a keyboard and mouse adapter  320 , modem  322 , and additional memory  324 . SCSI host bus adapter  112  provides a connection for hard disk drive  326 , tape drive  328 , and CD-ROM  330  in the depicted example. Typical PCI local bus implementations will support three or four PCI expansion slots or add-in connectors. 
     An operating system runs on processor  302  and is used to coordinate and provide control of various components within data processing system  300  in FIG.  1 . The operating system may be a commercially available operating system such as OS/2, which is available from International Business Machines Corporation. “OS/2” is a trademark of from International Business Machines Corporation. An object oriented programming system such as Java may run in conjunction with the operating system and provides calls to the operating system from Java programs or applications executing on data processing system  300 . Instructions for the operating system, the object-oriented operating system, and applications or programs are located on storage devices, such as hard disk drive  326  and may be loaded into main memory  304  for execution by processor  302 . 
     Those of ordinary skill in the art will appreciate that the hardware in FIG. 3 may vary depending on the implementation. For example, other peripheral devices, such as optical disk drives and the like may be used in addition to or in place of the hardware depicted in FIG.  3 . The depicted example is not meant to imply architectural limitations with respect to the present invention. For example, the processes of the present invention may be applied to multiprocessor data processing system. 
     Referring to FIG. 4, a block diagram  400  is presented that illustrates both the method and the apparatus of the present invention. An internet browser  402  is coupled to a Java virtual machine (JVM)  404 . The JVM  404  contains class data structures for various classes. The JVM is queried (step  408 ) to get the Java class information. The Java class information is returned to the browser (step  410 ), Next, the class extensions are set (step  412 ) in the class shadow apparatus  406 . The class extensions are set based on the class information retrieved in step  410 . During use of the class shadow apparatus  406 , the apparatus  406  can be queried to get class extension information (step  414 ). When successfully queried, the class extensions are returned (step  416 ) to the browser  402 . 
     FIG. 5 illustrates the data structures in both the  600  and in the shadow apparatus. The JVM&#39;s data structure  500  contains the class name  502 , the class data  504 , class methods  506 , and the parent class  503  as well as additional data  510 . The class extension data structure  512  contains an array of security principals  514 , the security signature for the class  516 , and a pointer to the signed Java Archive (JAR) file that the class was stored in, as well as other data  520 . 
     FIG. 6 provides a flow chart of the method  600  of setting a class extension in the shadow apparatus. First, a hash value is set based on the class name (step  602 ). Next, a search is performed on a hash table based on the value (step  604 ). Next, the method must decide if the class extension is found for the class in question (step  606 ). If the class extension is found, then an updated entry is made in the hash table with the extension information (step  608 ). If the class extension is not found, then a new entry is created and filled with extension information (step  610 ). 
     FIG. 7 illustrates the method  700  of getting a class extension from the shadow apparatus. First, a hash value is created based on the class name (step  702 ). Next, the hash table is searched based on this value (step  704 ). A decision is made whether a class extension is found for that class (step  706 ). If so, then the class extension information is returned (step  708 ). If not, then blank or null class extension information is returned. (step  710 ). 
     It is important to note that while the present invention has been described in the context of a fully functioning data processing system, those of ordinary skill in the art will appreciate that the processes of the present invention are capable of being distributed in a form of a computer readable medium of instructions and a variety of forms and that the present invention applies equally regardless of the particular type of signal bearing media actually used to carry out the distribution. Examples of computer readable media include recordable-type media such a floppy disc, a hard disk drive, a RAM, and CD-ROMs and transmission-type media such as digital and analog communications links. 
     The description of the present invention has been presented for purposes of illustration and description, but is not limited to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to best explain the principles of the invention the practical application and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.