Patent Publication Number: US-7908601-B2

Title: Computer method and apparatus for merging software configurations when a change set spans multiple artifacts

Description:
BACKGROUND OF THE INVENTION 
     A software artifact is a persistent representation of an aspect of a software system. Common examples of software artifacts are files and directories containing the source code of a software system, but other examples of artifact include requirements, end-user documentation, system models, and system tests. A significant state of a software artifact is saved as a version of that artifact, and the sets of versions of a given artifact define the history of that artifact. 
     A software confirmation is a set of software artifact versions, where only one version of a given artifact is elected by a given software configuration. A software change set identifies a logical change to a configuration, and consists of a set of one or more changes to one or more artifacts. An alternative characterization of a software configuration is that is consists of the set of change sets that have resulted in that configuration. The result of merging two software configurations is logically the union of the corresponding two sets of change sets. 
     A logical change set can span multiple artifacts in a configuration, but merge tools operate on one artifact at a time. When a signal artifact is merged during a configuration merge, a user accepts or reflects a change that is part of a particular change set. But when that user subsequently merges another artifact in that configuration containing additional changes which are part of that same change set, the user is given no guidance about how the has previously treated that change set. As a result, he must notice when the is encountering a logically related change, and then either must remember whether he previously accepted or rejected that change or must correctly reconstruct the logic that caused him to accept or reject that change. Since a user usually encounters multiple logical changes in a singe artifact, and since merge decisions are often very complex and require hours (or sometimes days) to resolve, it can be very difficult to recognize logically related merge decisions in a subsequent artifact, and very difficult to remember or to reproduce the logic that led to a particular merge decision. 
     Some domain-specific merge tools (such as tools for a specific language) are designed to operate concurrently on multiple artifacts from that domain. However, these merge tools cannot deal with artifacts from other domains, so the same problem arises when a logical change results in changes to multiple domains. 
     SUMMARY OF THE INVENTION 
     The present invention addresses the shortcomings of the prior art. In particular, the present invention provides a computer method and system in which changes to software artifacts are made in the context of a workspace, and the workspace identifies a change set that identifies the logical change currently being performed to the software configuration of that workspace. When a new version is created, the version-creation tool records in the new version which parts of the new version have been modified, and associates those changes with the current change set of the workspace. The merge tool is enhanced to accept as input a list of accepted and rejected change sets, and returns as output the additional change sets that have been accepted and rejected during the operation of that merge tool. When a merge that involves multiple artifacts is invoked in the workspace, the workspace accumulates the list of change sets that have been accepted and rejected in respective merges of each artifact, and passes the current value of these lists to the merge tool when it is invoked on the next artifact. The individual artifact merges are then made in the context of all previous merge decisions of the subject configuration. 
     In a preferred embodiment, computer apparatus and method for merging software configurations comprise: 
     a workspace providing a work environment in which to perform operations on a subject software configuration; and 
     a merge tool coupled to perform software configuration merges in the workspace. 
     The workspace identifies a change set of current changes being made to the subject software configuration. Preferably the workspace accumulates change sets in a merge of each artifact forming the subject software configuration and passes said accumulated change sets to the merge tool. The merge tool in turn displays or otherwise outputs to the user an indication of the accumulated change sets such that artifact merges by the user are made in the context of substantially all previous merge decisions. 
     Accordingly, the present invention provides a mechanism to merge multiple artifacts into another artifact and/or into a subject software configuration. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing will be apparent from the following more particular description of example embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating embodiments of the present invention. 
         FIG. 1  is a schematic diagram of one embodiment of the present invention. 
         FIG. 2  is a flow diagram of a merge member in the embodiment of  FIG. 1 . 
         FIG. 3  is a schematic view of a computer network environment in which embodiments of the present invention may be employed. 
         FIG. 4  is a block diagram of a computer node of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A description of example embodiments of the invention follows. 
     Illustrated in  FIG. 1  is a configuration management system  11  embodying the present invention. Configuration management system  11  provides a workspace view of a subject software program  13  and various information regarding the subject software program  13 . The software program  13  is formed of one or more artifacts  15 ,  19 ,  21 . Each artifact  15 ,  19 ,  21  has respective versions, e.g., V.1a, V.3, V.1b, etc. Each configuration  22  of a subject software program  13  employs respective versions of the artifacts  15 ,  19 ,  21 . One of the illustrated configurations  22  of subject software program  13  in  FIG. 1  is formed to version V.1a of artifact  15 , version V.3 of artifact  19  and version V.1b of artifact  21 . Other configurations  22  of subject software program  13  use other version of artifacts  15 ,  19 ,  21 . 
     Information regarding the versions of an artifact  15 ,  19 ,  21  is stored in a respective version history table of the artifact  15 ,  19 ,  21 . In particular, change set information (the change set  33  to which a version belongs) is recorded in respective artifact version history table  17 .  FIG. 1  illustrates the one configuration  22  of subject software program  13  having version history table entry  17   a  for artifact  15 , version history table entry  17   b  for artifact  19  and version history table entry  17   n  for artifact  21 . It is understood that the configuration management system  11  stores the foregoing information for each configuration  22  of program  13 . 
     Configuration management system  11  enables users to produce and work with (edit, test, redesign, etc.) such different configurations  22  of subject software program  13 . As previously mentioned, each artifact  15 ,  19 ,  21  is a persistent result of work done by a user, typically persisted in a file system such as models and source code. An “activity” is used to track the results of work done by a user. The “change set”  33  of an activity is the set of changes to artifacts  15 ,  19 ,  21  made by the practitioner to perform the activity. A “workspace”  23  is used to define the work environment of a user—to contain the artifacts  15 ,  19 ,  21  required by that user and the activities that track the results of performing those activities. The workspace  23  is said to “accept” the activity change sets that define the current or working configuration  22 ′. 
     Restated, all changes to software artifacts  15 ,  19 ,  21  are made in the context of workspace  23 . The workspace  23  identifies a change set that indicates of provides the logical change currently being performed to a configuration  22 ′ of that workspace. When a new version of an artifact is created, a version creation tool (not shown) records in respective artifact logs  17  the new artifact version. The version creation tool further associates those changes with the current change set  33 ′ of the workspace  23 . A merge tool  25  accepts as input a list  34  of accepted and rejected change sets, and returns as output the additional change sets that have been accepted and rejected during the operation of the merge tool  25  on the working configuration  22 ′ in workspace  23 . When a merge that involves multiple artifacts  15 ′,  19 ′ is invoked in workspace  23 , the workspace accumulates the list  34  of change sets that have been accepted and rejected in the merge of each of the multiple artifacts  15 ′,  19 ′ and passes the current value of this list to the merge tool  25  when it is invoked on the next artifact. The individual artifact merges are then made in the context of all previous merge decisions and the merging of software configurations  22 ′ with a change set that spans multiple artifacts  15 ′,  19 ′ is smoothly accomplished. 
     In a preferred embodiment, when the merge tool  25  processes a first artifact  15 ′ in a working configuration  22 ′ that requires a merge, merge tool  25  is given (receives as input) the versions to merge and the common ancestor of those versions from artifact version logs  17 . The merge-tool  25  uses the change set information  33  recorded in those versions to recognize which changes belong to which change set  33 , and exposes the merge decisions to the end-user in the form of accepting or rejecting a particular change set  33 . The merge-tool  25  then remembers whether the user has accepted or rejected the set of changes belonging to a given change set  33 , so that when the merge-tool  25  returns control to the workspace  23 , the workspace can be annotated by the accepted and rejected change sets  34 . 
     When a subsequent merge of another artifact  19 ′ is invoked in the workspace  23 , the list  34  of accepted and rejected change sets of all previously merged artifacts in the workspace  23  are passed as an argument to the merge tool  25 . The merge tool uses this information to encourage the user to make consistent decisions about accepting or rejecting a given change set  33  (namely, accepting a change if it is part of a change set that has been accepted in a previous merge, and rejecting a change set if it has been rejected in a previous merge). 
     If the system  11  supports change set evolution, a user will be allowed to make inconsistent decisions about accepting or rejecting changes from different artifacts (i.e. reject a change that is part of a change set that was accepted in the merge of another artifact, or accept a change that is part of a change set that was rejected in the merge of another artifact). When the user commits a set of checked-out artifacts  15 ″,  19 ′ containing inconsistent merge decisions, any inconsistencies are resolved by splitting the inconsistently accepted change set  33  into two change sets  33   m ,  33   n  (one containing the changes that were accepted, and the other containing the changes that were rejected). 
     Some versioning systems will allow the user to persist an incompletely merged artifact  15 ,  19 ,  21 , i.e., an artifact which contains merge decisions that the user performing the merge wants to defer until they have seen that change set  33  in the context of the other artifacts that it affects. In this case, in addition to the accepted and rejected change sets, the merge-tool  25  also returns a list  35  of deferred change sets. When the merge-tool  25  is subsequently invoked on another artifact, and returns a change set  33 ′ marked as being accepted or rejected, if there is a previously merged artifact that has deferred that change set (i.e., an incompletely merged artifact), the user is given an opportunity to re-invoke the merge-tool  25  on that previously incompletely merged artifact, so that the change set can be appropriately accepted or rejected in that previously merged (incompletely merged) artifact. When a user attempts to check-in a merged artifact that contains deferred change sets  35  (i.e., an incompletely merged artifact), the invention system  11  issues to the user a warning about the deferred merges, and gives the user an opportunity to re-invoke the merge tool  25  to complete the merge. 
       FIG. 2  provides a flow diagram of the operations of merge tool/means  25  and workspace  23 . As a first step  39 , invention system  11  initializes workspace  23  including initializing accepted/rejected change set list  34 , deferred change set list  35  and other supporting data elements for a current work session. Next at  41 , upon creation of a new version of an artifact, system  11  records changes in respective version history logs  17 . Also system  11  associates the recorded changes with a current working change set  33 ′ in workspace  23 . When the merge tool  25  is invoked for subject artifacts in working configuration  22 ′, step  43  provides input to merge tool  25 . The input includes the change set  33  being considered, the list  34  of previously accepted and rejected change sets and list  35  of previously deferred change sets. In response to user decision (acceptance/rejection of changes in the change sets  33 ) for the subject artifact, merge tool  25  receives and remembers the acceptance/rejection of this change set in change set list  34 . 
     At step  47  workspace  23  accumulates lists  33 ,  33 ′ of change sets that have been accepted and rejected in the merges of each of the multiple subject artifacts  15 ′,  19 ′. Similarly at step  49  the workspace  23  accumulates deferred change sets  35 . 
     In a subsequent merge of another artifact into working software configuration  22 ′, step  45  is again invoked via lop  46 . If a previously incompletely merged artifact of working configuration  22 ′ has a deferred change set  35 , then at step  57  workspace  23  enables the end user to re-invoke the merge tool  25  on that artifact. Loop  48  back to step  45  similarly enables merging of another artifact into working software configuration  22 ′ as needed/desired. 
       FIG. 3  illustrates a computer network or similar digital processing environment in which the present invention may be implemented. 
     Client computer(s)/devices  50  and server computer(s)  60  provide processing, storage, and input/output devices executing application programs and the like. Client computer(s)/devices  50  can also be linked through communications network  70  to other computing devices, including other client devices/processes  50  and server computer(s)  60 . Communications network  70  can be part of a remote access network, a global network (e.g., the Internet), a worldwide collection of computers. Local area or Wide area networks, and gateways that currently use respective protocols (TCP/IP, Bluetooth, etc.) to communicate with one another. Other electronic device/computer network architectures are suitable. 
       FIG. 4  is a diagram of the internal structure of a computer (e.g., client processor/device  50  or server computers  60 ) in the computer system of  FIG. 3 . Each computer  50 ,  60  contains system bus  79 , where a bus is a set of hardware lines used for data transfer among the components of a computer or processing system. Bus  79  is essentially a shared conduit that connects different elements of a computer system (e.g., processor, disk storage, memory, input/output ports, network ports, etc.) that enables the transfer of information between the elements. Attached to system bus  79  is I/O device interface  82  for connecting various input and output devices (e.g., keyboard, mouse, displays, printers, speakers, etc.) to the computer  50 ,  60 . Network interface  86  allows the computer to connect to various other devices attached to a network (e.g., network  70  of  FIG. 3 ). Memory  90  provides volatile storage for computer software instructions  92  and data  94  used to implement an embodiment of the present invention (e.g., artifact history logs/tables  17 , merge tool/means  25 , workspace  23 , working change sets  33 ′, list  34  of accepted/rejected change sets and deferred change sets  35  detailed above). Disk storage  95  provides non-volatile storage for computer software instructions  92  and data  94  used to implement an embodiment of the present invention. Central processor unit  84  is also attached to system bus  79  and provides for the execution of computer instructions. 
     In one embodiment, the processor routines  92  and data  94  are a computer program product (generally referenced  92 ), including a computer readable medium (e.g., a storage medium such as one or more DVD-ROM&#39;s, CD-ROM&#39;s, disketts, tapes, etc.) that provides at least a portion of the software instructions for the invention system. Computer program product  92  can be installed by any suitable software installation procedure, as is well known in the art. In another embodiment, at least a portion of the software instructions may also be downloaded over a cable, communication and/or wireless connection. In other embodiments, the invention programs are a computer program propagated signal product  107  embodied on a propagated signal on a propagation medium (e.g., a radio wave, an infrared wave, a laser wave, a sound wave, or an electrical wave propagated over a global network such as the Internet, or other networks(s)). Such carrier medium or signals provide at least a portion of the software instructions for the present invention routines/program  92 . 
     In alternate embodiments, the propagated signal is an analog carrier wave or digital signal carried on the propagated medium. For example, the propagated signal may be a digitized signal propagated over a global network (e.g., the Internet), a telecommunications network, or other network. In one embodiment, the propagated signal is a signal that is transmitted over the propagation medium over a period of time, such as the instructions for a software application sent in packets over a network over a period of milliseconds, seconds, minutes, or longer. In another embodiment, the computer readable medium of computer program product  92  is a propagation medium that the computer system  50  may receive and read, such as by receiving the propagation medium and identifying a propagated signal embodied in the propagation medium, as described above for computer program propagated signal product. 
     Generally speaking, the term “carrier medium” or transient carrier encompasses the foregoing transient signals, propagated signals, propagated medium, storage medium and the like. 
     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 compute 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 electronics, 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. 
     While this invention has been particularly shown and described with references to example embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.