Patent Publication Number: US-2007106982-A1

Title: Method, apparatus, and computer program product for model based traceability

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates generally data processing and, in particular, to providing a model based traceability framework in a software development environment.  
      2. Description of the Related Art  
      Traceability is a technique for managing and analyzing impact, coverage, and derivation of artifacts in a software development project. An artifact is any item that is used or produced in a software development project. The specific items are defined by each project for its own needs. For example, one project may consider complete source files as artifacts, while another project may consider individual methods as artifacts.  
      A traceability link is a one-way relationship between two artifacts. A traceability link is a general association that indicates that the source of the link is used to either create or modify the target of the link. For example, a requirement is used to create a model element, which is also used to create specific instances of code artifacts. As another example, a defect report is used to modify existing requirements, model elements, or code artifacts.  
      Typically, traceability management and analysis are cumbersome processes. Software developers often manage traceability by recording traceability links on large whiteboards or by manual data entry into databases, which are not integrated into the software development environment.  
     BRIEF SUMMARY OF THE INVENTION  
      The present invention recognizes the disadvantages of the prior art and provides a traceability mechanism for model based traceability. The traceability mechanism provides a traceability model. The traceability mechanism creates a plurality of traceability links based on the traceability model. The traceability system provides a tool for managing the plurality of traceability links.  
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS 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 the accompanying drawings, wherein:  
       FIG. 1  depicts a pictorial representation of a network of data processing systems in which aspects of the present invention may be implemented;  
       FIG. 2  is a block diagram of a data processing system in which aspects of the present invention may be implemented;  
       FIG. 3  is a diagram illustrating the functionality of a model based traceability engine in accordance with exemplary aspects of the present invention;  
       FIGS. 4A-4G  are example screens of display of traceability tool user interfaces in accordance with exemplary aspects of the present invention;  
       FIG. 5  is a block diagram illustrating a model based traceability engine exposed in an application programming interface and persisted in a database in accordance with exemplary aspects of the present invention;  
       FIG. 6  is a block diagram illustrating a model based traceability engine providing traceability via a database instance in accordance with exemplary aspects of the present invention;  
       FIG. 7  is a block diagram illustrating a model based traceability engine providing traceability on the same database instance with a different schema qualifier in accordance with exemplary aspects of the present invention;  
       FIG. 8  is a block diagram illustrating a model based traceability engine providing traceability on the same database instance with a custom schema in accordance with exemplary aspects of the present invention;  
       FIG. 9  illustrates example table schemas for model based traceability in accordance with exemplary aspects of the present invention;  
       FIG. 10  depicts an example of traceability information in accordance with exemplary aspects of the present invention;  
       FIG. 11  illustrates a physical view of example tables formed from traceability information in accordance with exemplary aspects of the present invention;  
       FIG. 12  is a flowchart illustrating operation of a traceability application in accordance with exemplary aspects of the present invention; and  
       FIG. 13  is a flowchart illustrating the operation of querying traceability links in accordance with exemplary aspects of the present invention.  
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       FIGS. 1-2  are provided as exemplary diagrams of data processing environments in which embodiments of the present invention may be implemented. It should be appreciated that  FIGS. 1-2  are only exemplary and are not intended to assert or imply any limitation with regard to the environments in which aspects or embodiments of the present invention may be implemented. Many modifications to the depicted environments may be made without departing from the spirit and scope of the present invention.  
      With reference now to the figures,  FIG. 1  depicts a pictorial representation of a network of data processing systems in which aspects of the present invention may be implemented. Network data processing system  100  is a network of computers in which embodiments of the present invention may be implemented. Network data processing system  100  contains network  102 , which is the medium used to provide communications links between various devices and computers connected together within network data processing system  100 . Network  102  may include connections, such as wire, wireless communication links, or fiber optic cables.  
      In the depicted example, server  104  and server  106  connect to network  102  along with storage unit  108 . In addition, clients  110 ,  112 , and  114  connect to network  102 . These clients  110 ,  112 , and  114  may be, for example, personal computers or network computers. In the depicted example, server  104  provides data, such as boot files, operating system images, and applications to clients  110 ,  112 , and  114 . Clients  110 ,  112 , and  114  are clients to server  104  in this example. Network data processing system  100  may include additional servers, clients, and other devices not shown.  
      Server  104  or server  106  may provide server applications for an integrated development environment. Clients  110 ,  112 ,  114  may provide client applications that interact with the server software to access software development tools in the integrated development environment. An integrated development environment is a set of programs that run from a single user interface. For example, programming languages often include a text editor, a compiler, and a debugger, which are all activated and function from a common menu.  
      In accordance with exemplary aspects of the present invention, a model based traceability framework is provided in an integrated development environment. The model based framework is embeddable, or deployable, in any application or plugin within the integrated development environment. A database provides scalable persistence of the model and traceability links created using the model.  
      Traceability links are used, for example, for requirements, defects, documentation, etc. For an artifact, for instance, a traceability link may trace back to the code that created the artifact. As a particular example, a defect tracking system that extracts bug reports may use traceability to trace bug reports to the code that caused the bugs.  
      The framework comprises an underlying model that is created by an administrator through a schema or meta model. Tools using the framework allow the creation and management of traceability links, which may be created during code generation or manually through a user interface. The tools allow a user to query traceability links by identification (ID), uniform resource identifier (URI), UREF, which is a reference to a uniform resource locator (URL), traceability type, and who/what/when criteria, for example.  
      An administrator manages the model by creating and maintaining artifact information, traceability link types, and traceability link information in tables. Traceability link types may include, for example, artifact-to-artifact links, model-to-model links, model-to-code links, and artifact-to-model/code links. A traceability tool, which may a standalone application or a plugin to an existing tool, allows users to create, update, and delete traceability links. The traceability tool may also allow users to query traceability links. In addition, the traceability tool may mark links as suspect.  
      In the depicted example, network data processing system  100  is the Internet with network  102  representing a worldwide collection of networks and gateways that use the Transmission Control Protocol/Internet Protocol (TCP/IP) suite of protocols to communicate with one another. At the heart of the Internet is a backbone of high-speed data communication lines between major nodes or host computers, consisting of thousands of commercial, government, educational and other computer systems that route data and messages. Of course, network data processing system  100  also may be implemented as a number of different types of networks, such as for example, an intranet, a local area network (LAN), or a wide area network (WAN).  FIG. 1  is intended as an example, and not as an architectural limitation for different embodiments of the present invention.  
      With reference now to  FIG. 2 , a block diagram of a data processing system is shown in which aspects of the present invention may be implemented. Data processing system  200  is an example of a computer, such as server  104  or client  110  in  FIG. 1 , in which computer usable code or instructions implementing the processes for embodiments of the present invention may be located.  
      In the depicted example, data processing system  200  employs a hub architecture including north bridge and memory controller hub (MCH)  202  and south bridge and input/output (I/O) controller hub (ICH)  204 . Processing unit  206 , main memory  208 , and graphics processor  210  are connected to north bridge and memory controller hub  202 . Graphics processor  210  may be connected to north bridge and memory controller hub  202  through an accelerated graphics port (AGP).  
      In the depicted example, local area network (LAN) adapter  212  connects to south bridge and I/O controller hub  204 . Audio adapter  216 , keyboard and mouse adapter  220 , modem  222 , read only memory (ROM)  224 , hard disk drive (HDD)  226 , CD-ROM drive  230 , universal serial bus (USB) ports and other communications ports  232 , and peripheral component interconnect (PCI) and PCI express (PCIe) devices  234  connect to south bridge and I/O controller hub  204  through bus  238  and bus  240 . PCI/PCIe devices may include, for example, Ethernet adapters, add-in cards and PC cards for notebook computers. PCI uses a card bus controller, while PCIe does not. ROM  224  may be, for example, a flash binary input/output system (BIOS).  
      Hard disk drive  226  and CD-ROM drive  230  connect to south bridge and I/O controller hub  204  through bus  240 . Hard disk drive  226  and CD-ROM drive  230  may use, for example, an integrated drive electronics (IDE) or serial advanced technology attachment (SATA) interface. Super I/O (SIO) device  236  may be connected to south bridge and I/O controller hub  204 .  
      An operating system runs on processing unit  206  and coordinates and provides control of various components within data processing system  200  in  FIG. 2 . As a client, the operating system may be a commercially available operating system such as Microsoft® Windows® XP (Microsoft and Windows are trademarks of Microsoft Corporation in the United States, other countries, or both). An object-oriented programming system, such as the Java™ programming system, 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  200  (Java is a trademark of Sun Microsystems, Inc. in the United States, other countries, or both).  
      As a server, data processing system  200  may be, for example, an IBM eServer™ pSeries® computer system, running the Advanced Interactive Executive (AIX®) operating system or LINUX operating system (eServer, pSeries and AIX are trademarks of International Business Machines Corporation in the United States, other countries, or both while Linux is a trademark of Linus Torvalds in the United States, other countries, or both). Data processing system  200  may be a symmetric multiprocessor (SMP) system including a plurality of processors in processing unit  206 . Alternatively, a single processor system may be employed.  
      Instructions for the operating system, the object-oriented programming system, and applications or programs are located on storage devices, such as hard disk drive  226 , and may be loaded into main memory  208  for execution by processing unit  206 . The processes for embodiments of the present invention are performed by processing unit  206  using computer usable program code, which may be located in a memory such as, for example, main memory  208 , read only memory  224 , or in one or more peripheral devices  226  and  230 .  
      Those of ordinary skill in the art will appreciate that the hardware in  FIGS. 1-2  may vary depending on the implementation. Other internal hardware or peripheral devices, such as flash memory, equivalent non-volatile memory, or optical disk drives and the like, may be used in addition to or in place of the hardware depicted in  FIGS. 1-2 . Also, the processes of the present invention may be applied to a multiprocessor data processing system. In some illustrative examples, data processing system  200  may be a personal digital assistant (PDA), which is configured with flash memory to provide non-volatile memory for storing operating system files and/or user-generated data.  
      A bus system may be comprised of one or more buses, such as bus  238  or bus  240  as shown in  FIG. 2 . Of course the bus system may be implemented using any type of communications fabric or architecture that provides for a transfer of data between different components or devices attached to the fabric or architecture. A communications unit may include one or more devices used to transmit and receive data, such as modem  222  or network adapter  212  of  FIG. 2 . A memory may be, for example, main memory  208 , read only memory  224 , or a cache such as found in north bridge and memory controller hub  202  in  FIG. 2 . The depicted examples in  FIGS. 1-2  and above-described examples are not meant to imply architectural limitations. For example, data processing system  200  also may be a tablet computer, laptop computer, or telephone device in addition to taking the form of a PDA.  
       FIG. 3  is a diagram illustrating the functionality of a model based traceability engine in accordance with exemplary aspects of the present invention. An administrator manages traceability types. A traceability tool allows a traceability user to create, update, and delete traceability links. The traceability tool also allows users to query on links. This engine, while simple, provides a powerful tool for managing traceability links in an integrated development environment. The client applications are capable of presenting and modifying traceability links in a manner that is very useful within the integrated development environment.  
       FIGS. 4A-4G  are example screens of display of traceability tool user interfaces in accordance with exemplary aspects of the present invention. More particularly,  FIG. 4A  depicts traceability tool interface window  400 , which comprises navigator display portion  410 , properties display portion  420 , links view portion  430 , and tasks display portion  440 . A user, such as a developer, may switch to the traceability perspective shown in  FIG. 4A  by selecting button  402 , for example.  
       FIG. 4B  depicts a query wizard interface in accordance with exemplary aspects of the present invention. The developer opens the query wizard by selecting query button  432 , which causes traceability query wizard dialog  434  to be presented. The developer selects a query type, in this case “Link Type,” which causes traceability query wizard dialog  462  to be presented. In this dialog, the developer chooses a link type and selects “Finish” button to execute the query. The query types presented in dialog  462  may be as shown in traceability link type table  1130  in  FIG. 11 , for example.  
       FIG. 4C  depicts example traceability tool interface window  400 , which presents a links view. Suspect link indicator  438  identifies traceability link  436  as a suspect link. A developer may select suspect link  436 . The link information is presented in display portion  422 . The link information is integrated with the native property sheet of the integrated development environment.  FIG. 4D  illustrates seamless tool integration and navigation in accordance with exemplary aspects of the present invention. If the developer double-clicks the suspect link, the corresponding artifact information  442  is opened using the standard integrated development environment tools associated with the artifact, and artifact information  442  is presented in tasks display portion  440 . Linked artifacts are also presented in tasks display portion  440 . Property sheet  424  reflects the artifact information.  
      The traceability engine may also link multiple tools.  FIG. 4E  illustrates seamless integration across heterogeneous tools in accordance with exemplary aspects of the present invention. Using integrated development tools, the developer is able to see which code artifacts are linked to bug artifacts, for example. In the depicted example, traceability link  442  shows that bug “1” is linked to code “SAMPL00000028.” Furthermore, as shown in  FIG. 4E , controls  444  allow a user to add, delete, or modify traceability links.  
       FIG. 4F  depicts extended tools for traceability in accordance with exemplary aspects of the present invention. A developer may right-click on an artifact to generate context menu  452 . Selecting the “Link” option causes context-aware traceability dialog box  454  to open requesting the URI/UREF of the target artifact to create a new traceability link. The source URI/UREF is pre-filled. As shown in  FIG. 4G , if the developer expands the artifact in the traceability links display portion, the newly created link  456  between artifacts is presented.  
       FIG. 5  is a block diagram illustrating a model based traceability engine exposed in an application programming interface and persisted in a database in accordance with exemplary aspects of the present invention. End user&#39;s machine  510  has running thereon integrated development environment  512 . Integrated development system  512  may have a plurality of plugin tools, such as application plugin  514 , documentation tool plugin  516 , and other plugin tool  518 . Integrated development system  512  may be, for instance, software based on the Eclipse open source technology. End user&#39;s machine  510  may also have running thereon application client  520 .  
      Application client  520  and application plugin  514  communicate with application server  546 . In the depicted example, the application may be a defect tracking, requirements, test management, and version control application. Documentation tool  516  communicates with documentation tool server  544 . Documentation tool  516  is an example of a tool that may cause artifacts to be generated. Therefore, documentation tool  516  is a candidate for traceability functionality. Similarly, other tool plugin  518  communicates with other tool server  542 . A bug report plugin tool may be an example of other plugin tool  518 . Such a plugin tool may be a candidate for traceability functionality in accordance with exemplary aspects of the present invention.  
      In the depicted example, traceability plugin  522  is a plugin to other plugin tool  518 . The Eclipse open source technology allows a plugin to piggyback onto another plugin. In alternative embodiments, traceability functionality may be provided in a standalone application or integrated within a tool plugin, such as application plugin  514 , documentation tool plugin  516 , or other plugin tool  518 . Alternatively, traceability functionality may be provided within integrated development system  512 .  
      Application programming interface (API)  530  exposes model framework  532 , i.e. the table schema, to tools, such as application plugin  514 , documentation tool plugin  516 , and traceability plugin  522 , as well as servers, such as documentation tool server  544  and application server  546 . Application client  520 , application plugin  514 , and application server  546  can leverage API  530  for creating from-to-who traceability, as well as read, query, update, and delete traceability links. The table schema and the traceability link information are persisted in database  534 . Other tools, such as documentation tool plugin  516  and documentation tool server  544  can leverage API  530  for traceability.  
       FIG. 6  is a block diagram illustrating a model based traceability engine providing traceability via a database instance in accordance with exemplary aspects of the present invention. End user&#39;s machine  610  has running thereon integrated development environment  612 . Integrated development system  612  may have one or more plugin tools, such as application plugin  614 . Integrated development system  612  may be, for instance, software based on the Eclipse open source technology. End user&#39;s machine  610  may also have running thereon application client  620 .  
      Application client  620  and application plugin  614  communicate with application server  625 . As stated above, application client  620 , application plugin  614 , and application server  625  may provide defect tracking, requirements, test management, and version control functionality, for example. Application programming interface (API)  640  exposes model framework  650 , i.e. the table schema, to application server  625 . Application client  620  and application plugin  614  access traceability functionality through application server  625 , which can leverage API  640  for creating from-to-who traceability. Application client  620  and application plugin  614  can read, query, update, and delete traceability links. Application database  632  may store artifacts, such as change requests, requirements, and tests, for example. The table schema and the traceability link information are persisted in database  634 . Application database  632  and traceability database  534  may be on the same database server machine  630 . Alternatively, traceability database  634  may reside on a different machine.  
       FIG. 7  is a block diagram illustrating a model based traceability engine providing traceability on the same database instance with a different schema qualifier in accordance with exemplary aspects of the present invention. End user&#39;s machine  710  has running thereon integrated development environment  712 . Integrated development system  712  may have one or more plugin tools, such as application plugin  714 . Integrated development system  712  may be, for instance, software based on the Eclipse open source technology. End user&#39;s machine  710  may also have running thereon application client  720 .  
      Application client  720  and application plugin  714  communicate with application server  725 . Application programming interface (API)  740  exposes model framework  750  to application server  725 . Application client  720  and application plugin  714  access traceability functionality through application server  725 , which can leverage API  740  for creating from-to-who traceability, as well as read, query, update, and delete traceability links. Application database  732  may store artifacts, such as change requests, requirements, and tests, for example. The traceability link information is also persisted in database  732 .  
       FIG. 8  is a block diagram illustrating a model based traceability engine providing traceability on the same database instance with a custom schema in accordance with exemplary aspects of the present invention. End user&#39;s machine  810  has running thereon integrated development environment  812 . Integrated development system  812  may have one or more plugin tools, such as application plugin  814 . Integrated development system  812  may be, for instance, software based on the Eclipse open source technology. End user&#39;s machine  810  may also have running thereon application client  820 .  
      Application client  820  and application plugin  814  communicate with application server  840 . Application programming interface (API)  842  exposes model framework  844  to application server  820 . In this depicted example, traceability is provided on the same machine in the same instance of the database with custom schema. Traceability functionality is embedded within the using application, in this case application client  820  and application plugin  814 . Application server  840  can leverage API  842  for creating from-to-who traceability, as well as read, query, update, and delete traceability links. Application database  832  may store artifacts, such as change requests, requirements, and tests, for example. The traceability link information is also persisted in database  832 .  
       FIG. 9  illustrates example table schemas for model based traceability in accordance with exemplary aspects of the present invention. Artifact URI table  910  defines the fields used to define an artifact. Traceability link type table  920  defines the fields used to define traceability link types. Traceability links table  930  defines the fields used to define traceability links. Together, the tables in the depicted example form a table schema, which serves as the model for creating, updating, and querying traceability links.  
       FIG. 10  depicts an example of traceability information in accordance with exemplary aspects of the present invention. Example traceability information  1000  includes an identifier (ID) of an artifact, where the artifact traces from, where the artifact is traceable to, what/who/when information, whether the traceability information is suspect, and whether the traceability information is valid.  
       FIG. 11  illustrates a physical view of example tables formed from traceability information  1000  in accordance with exemplary aspects of the present invention. Traceability links table  1110  identifies the ID for an artifact, the source ID and target ID of the artifact, the traceability type ID, the originator, a time stamp, whether the traceability link is suspect, and whether the traceability link is valid. Traceability links table  1110  also includes a field for extension URI. The source ID and target ID refer to artifact URI table  1120 , which associates an artifact ID with the artifact URI/UREF. The traceability type ID refers to traceability link type table  1130 , which associates a traceability type ID with a traceability type and description.  
       FIG. 12  is a flowchart illustrating operation of a traceability application in accordance with exemplary aspects of the present invention.  FIG. 13  is a flowchart illustrating the operation of querying traceability links in accordance with exemplary aspects of the present invention. It will be understood that each block of the flowchart illustrations, and combinations of blocks in the flowchart illustrations, can be implemented by computer program instructions. These computer program instructions may be provided to a processor or other programmable data processing apparatus to produce a machine, such that the instructions which execute on the processor or other programmable data processing apparatus create means for implementing the functions specified in the flowchart block or blocks. These computer program instructions may also be stored in a computer-readable memory, transmission medium, or storage medium that can direct a processor or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory, transmission medium, or storage medium produce an article of manufacture including instruction means which implement the functions specified in the flowchart block or blocks.  
      Accordingly, blocks of the flowchart illustrations support combinations of means for performing the specified functions, combinations of steps for performing the specified functions and computer usable program code for performing the specified functions. It will also be understood that each block of the flowchart illustrations, and combinations of blocks in the flowchart illustrations, can be implemented by special purpose hardware-based computer systems which perform the specified functions or steps, or by combinations of special purpose hardware and computer instructions.  
      With particular reference to  FIG. 12 , operation of a traceability application is illustrated. Operation begins and an administrator creates a model for traceability links (block  1202 ). The traceability application determines whether the administrator makes a request to manage traceability types (block  1204 ). If the administrator requests to manage traceability types, the traceability application allows the administrator to modify the model for traceability links (block  1206 ). Thereafter, operation proceeds to block  1208 . If the administrator does not request to manage traceability types in block  1204 , operation proceeds directly to block  1208 .  
      In block  1208 , the traceability application determines whether a request is received from a traceability tool user. A request in block  1208  may be a create request, an update request, a delete request, or a query request. If a create request is received, the traceability application creates a new traceability link according to information in the request (block  1210 ) and operation returns to block  1204  to determine whether the administrator request to manage traceability types. If an update request is received, the traceability application updates a traceability link according to information in the request (block  1212 ) and operation returns to block  1204  to determine whether the administrator request to manage traceability types. If a delete request is received, the traceability application deletes a traceability link according to information in the request (block  1214 ) and operation returns to block  1204  to determine whether the administrator request to manage traceability types.  
      If a query request is received in block  1208 , the traceability application queries traceability links according to information in the request (block  1216 ) and operation returns to block  1204  to determine whether the administrator request to manage traceability types. Operation of querying traceability links is described in further detail with reference to  FIG. 13  below.  
      If the traceability application does not receive a request form a traceability tool user in block  1208 , the traceability application determines whether an exit condition exists (block  1218 ). An exit condition may exist, for example, if the traceability application exits. If an exit condition exists, operation ends; otherwise, operation returns to block  1204  to determine whether the administrator requests to manage traceability types.  
      With reference now to  FIG. 13 , operation of querying traceability links is illustrated. Operation begins and the traceability application receives a query (block  1302 ). The traceability application then matches matching traceability links (block  1304 ) and presents the results to the requester (bock  1306 ).  
      Next, the traceability application determines whether a traceability link is selected (block  1308 ). If a traceability link is selected, such as by clicking on a traceability link in the display with a mouse, for example, the traceability application presents traceability link properties (block  1310 ). Thereafter, operation returns to block  1308  to determine whether a traceability link is selected.  
      If a traceability link is not selected in block  1308 , the traceability application determines whether an artifact is selected (block  1312 ). If an artifact is selected, such as by double-clicking a traceability link in the display with a mouse, for example, the traceability application presents artifact properties and linked artifacts (block  1314 ). Thereafter, operation returns to block  1308  to determine whether a traceability link is selected.  
      If an artifact is not selected in block  1308 , the traceability application determines whether an exit condition exists (block  1316 ). An exit condition may exist, for example, if the traceability application exits or if the traceability tool user submits another request or query. If an exit condition exists, operation ends returning to the operation shown in  FIG. 12 ; otherwise, operation returns to block  1308  to determine whether a traceability link is selected.  
      Thus, the present invention solves the disadvantages of the prior art by providing a model based traceability framework in an integrated development environment. The model based framework is embeddable, or deployable, in any application or plugin within the integrated development environment. A database provides scalable persistence of the model and traceability links created using the model. The framework comprises an underlying model that is created by an administrator through a table schema. Tools using the framework allow the creation and management of traceability links, which may be created during code generation or manually through a user interface. The tools allow a user to query traceability links by ID, URI/UREF, traceability type, and who/what/when criteria, for example.  
      An administrator manages the model by creating and maintaining artifact information, traceability link types, and traceability link information in tables. Traceability link types may include, for example, artifact-to-artifact links, model-to-model links, model-to-code links, and artifact-to-model/code links. A traceability tool, which may a standalone application or a plugin to an existing tool, allows users to create, update, and delete traceability links. The traceability tool may also allow users to query traceability links. In addition, the traceability tool may mark links as suspect.  
      The invention can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment containing both hardware and software elements. In a preferred embodiment, the invention is implemented in software, which includes but is not limited to firmware, resident software, microcode, etc.  
      Furthermore, the invention can take the form of a computer program product accessible from a computer-usable or computer-readable medium providing program code for use by or in connection with a computer or any instruction execution system. For the purposes of this description, a computer-usable or computer readable medium can be any apparatus that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.  
      The medium can be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system (or apparatus or device) or a propagation medium. Examples of a computer-readable medium include a semiconductor or solid state memory, magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk and an optical disk. Current examples of optical disks include compact disk—read only memory (CD-ROM), compact disk—read/write (CD-R/W) and DVD.  
      A data processing system suitable for storing and/or executing program code will include at least one processor coupled directly or indirectly to memory elements through a system bus. The memory elements can include local memory employed during actual execution of the program code, bulk storage, and cache memories which provide temporary storage of at least some program code in order to reduce the number of times code must be retrieved from bulk storage during execution.  
      Input/output or I/O devices (including but not limited to keyboards, displays, pointing devices, etc.) can be coupled to the system either directly or through intervening I/O controllers.  
      Network adapters may also be coupled to the system to enable the data processing system to become coupled to other data processing systems or remote printers or storage devices through intervening private or public networks. Modems, cable modem and Ethernet cards are just a few of the currently available types of network adapters.  
      The description of the present invention has been presented for purposes of illustration and description, and is not intended 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.