Software Configuration Management

Transcription

1 Software Configuration Management Object-Oriented Software Construction Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit, Kniesel)

2 Outline of the Lecture Software Configuration Management (SCM) Motivation: Why software configuration management? Activities and roles in software configuration management Terminology and Methodology What are Configuration Items, Baselines, etc.? What goes under version control? SCM Approaches Version Control Tools ClearCase Subversion Comparison Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 2

3 Why Software Configuration Management? The problem: Multiple people have to work on software that is changing More than one version of the software has to be supported Released systems Custom configured systems (different functionality) System(s) under development for different machines and operating systems Need for coordination Software Configuration Management manages evolving software systems controls the costs involved in making changes to a system disciplines and techniques of initializing, evaluating and controlling change to software products during and after the software engineering process Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 3

4 Softwar-Development: Difficulties and Problems Analyst Is requirement #462 impl. In current release? How many level 1 bugs Add promotion calculation Bug 849 still exist? Bug 527 New platform New GUI New customer button Bug 98 New web design transaction Bug 179 Bug 251 Bug 348 Project Manager Hopefully I didn t miss a file. Why does this build not work? Does bug #784 still exist? Build 3 Build 2 Build 1 Tester Developer Integrator Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 4

5 SCM Activities Configuration item identification modeling of the system as a set of evolving components Promotion management is the creation of versions for other developers Release management is the creation of versions for the clients and users Branch management is the management of concurrent development Variant management is the management of versions intended to coexist Change management is the handling, approval and tracking of change requests Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 5

6 SCM Roles Configuration Manager Responsible for identifying configuration items. The configuration manager can also be responsible for defining the procedures for creating promotions and releases Change control board member Responsible for approving or rejecting change requests Developer Creates promotions triggered by change requests or the normal activities of development. The developer checks in changes and resolves conflicts Auditor Responsible for the selection and evaluation of promotions for release and for ensuring the consistency and completeness of this release Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 6

7 Terminology and Methodology What are Configuration Items Baselines Versions, Revisions and Releases The usage of the terminology presented here is not strict but varies for different configuration management systems. Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 7

8 Terminology: Configuration Item (CI) An aggregation of hardware and / or software Treated as a single entity in the configuration management process Software configuration items are not only program code segments but all type of documents according to development, e.g. all type of code files drivers for tests analysis or design documents user or developer manuals system configurations (e.g. version of compiler used) In some systems, not only software but also hardware configuration items (CPUs, bus speed frequencies) exist! (Integration with Product Data Management PDM) Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 8

9 Finding Configuration Items (CIs) Large projects typically produce thousands of entities (files, documents,...) which must be uniquely identified. But not every entity needs to be configured all the time. Issues: What: Selection of CIs (What should be managed?) When: When do you start to place an entity under configuration control? Starting too early introduces too much bureaucracy Starting too late introduces chaos Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 9

10 Finding Configuration Items (continued) Selecting the right configuration items is a skill that takes practice Very similar to object modeling Items follows subsystem decomposition Use techniques similar to object modeling for finding CIs An entity naming scheme should be defined so that related documents have related names. Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 10

11 Configuration Identification is similar to Object Identification The project CI The project CI promote() release() Models Subsystems Documents Object Model Dynamic Model RAD ODD.... Database User Interface Code Data Unit Test.... The project Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 11

12 Terminology: Baseline Selected Project state A specification or product formally reviewed and agreed to by responsible management serves as the basis for further development can be changed only through formal change control procedures Examples: Baseline A: The API of a program is completely defined; the bodies of the methods are empty. Baseline B: All data access methods are implemented and tested; programming of the GUI can start. Baseline C: GUI is implemented, test-phase can start. Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 12

13 More on Baselines As systems are developed, a series of baselines is developed, usually after a review (analysis review, design review, code review, system testing, client acceptance,...) Developmental baseline (RAD, SDD, Integration Test,...) Goal: Coordinate engineering activities. Functional baseline (first prototype, alpha release, beta release) Goal: Get first customer experiences with functional system. Product baseline (product) Goal: Coordinate sales and customer support. Many naming schemes for baselines exist (1.0, 6.01a,...) 3 digit scheme: Release (Customer) Version (Developer) Revision (Developer) Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 13

14 Version vs. Revision vs. Release Version: An initial release or re-release of a configuration item Associated with a complete compilation or recompilation of the item. Different versions have different functionality. Revision: Change to a version that corrects only errors in the design/code Does not affect the documented functionality. Release: The formal distribution of an approved version or revision. Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 14

15 SCM: The Fundament of the Development Process Analysis Design Implementation Test Maintenance Software Configuration Management Collect and Manage Information to create, maintain, and extend Software Source code Binaries Documentation HTML/XML files Bitmaps & JPEGs cgi, java scripts Requirements Models Test scripts Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 15

16 Basic SCM-Approaches: General Scenario Developmentand SCM-Tools Developer Files Working Environment Repository Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 16

17 SCM-Approach: "Vault Model" Developmenttools Copies of Source-Files Working Environment Developer SCM-Tools Problems Development tools can not directly access the repository many private versions outside the repository no central control of private copies by the SCM system (no global locking) possible data loss by concurrent updates (lost changes) Repository Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 17

18 SCM-Approaches: "Standard Repository" Development- Tools Developer... API Idea All development tools directly access the repository via a given interface (API describes a "standard") Problems All tools must be adapted to this standard... every time the standard is modified / extended Repository Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 18

19 SCM-Approach: "Virtual File System" (VFS) Developer Development- Tools / / VFS VFS real file system virtuel file system Idea Intercept all I/O - operations of the operating system (open, read, write) and bypass them to the repository Advantages transparence, because the repository is shown as a regular directory tree seamless integration with existing standard software user does not have to change his mode of operation Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 19

20 ClearCase Architecture Applications with file access Multiversion File System File system of Windows / UNIX ClearCase MVFS non-versioned files ClearCase VOB Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 20

21 ClearCase Virtual File System src VOB foo.h foo.c emacs make gcc grep eclipse src foo.c foo.h User space applications Versioned Object Base (VOB) Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 21

22 ClearCase Virtual File System src VOB foo.h foo.c emacs make gcc grep eclipse WIN DOWS / UNIX M V F S src foo.c foo.h User space applications Versioned Object Base (VOB) Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 22

23 ClearCase VOB (Versioned Object Base) Safe Repository based on object-oriented database only accessible by ClearCase 0 Stores all versioned files Source code Directories bugfix Release 1 develop Binaries Who did what, when, why? Concurrent file access Arbitrary many VOBs in the network with arbitrary many files Release 2 Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 23

24 SCM: The Fundament of the Development Process Analysis Design Implementation Test Maintenance Software Configuration Management Version Control Build Build Management Workspace Management Workspace Management Process Control Process Control Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 24

25 Workspace Management (1) Setup and maintenance of a personal working environment set of needed objects Sources, Binaries, for a certain task bug fixing, development of a new functionality or an extension Approaches unconstrained: no well-defined working environment needed hierarchical sub-environments: existing application areas can be copied and changed locally change sets: Original version of an object + set of changes of this object rule-based environments: needed objects are defined via rules Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 25

26 Workspace Management: Hierarchical Sub-Environments Principle copy - modify - merge parent 1 child 4 = parent 2 child 1 child 2 child 3 child 5 child 6 Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 26

27 Workspace Management: Change Sets Grouping of changes that base on each other e.g. bug fixes often used for the organization of on development line at the end of a development process the cumulated changes are released as a new version (patch bundles, service release / pack) Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 27

28 Workspace Management: Rule-Based Workspaces Principle: rule-based selection of objects / versions Static rule evaluation Evaluation of the rules at the start of work selected versions are copied in the the private working environment the user must explicitly start the synchronization at the end of his work Dynamic rule evaluation Evaluation of the rules at object access time Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 28

29 Views in ClearCase All objects in the vob are read-only A developer must explicitly initiate a check-out command to be able to change an object The object is copied into the private memory area, but is accessible through the same path and name The check-in command updates the object version in the VOB and deletes the local version Only the developer who initated the check-out command is allowed the checking the new object version variation: unreserved check-out : first check-in wins; all others have to merge Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 30

30 ClearCase Workspace Management: Views View Transparent working on different releases of the same project Show version 2.20 Some kind of filter Work in real-time Direct access to the whole dataset Downloads are only initiated if necessary Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 31

31 ClearCase Views: Private Storage View Local copy enables working without network access Synchronization with database happens automatically Merging happens automatically Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 32

32 ClearCase Views simple way manage many tasks foo.h src foo.c Fast and simple switching between different tasks dynamic sharing of tasks control over private and public activities src src foo.h foo.c foo.h Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 33

33 ClearCase Workspace Management Multi Site Parallel Development Parallel development with geographic separated project teams Automatic updates and copies of the VOBs with or without network access Only one team has "mastership" Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 34

34 ClearCase Workspace Management 2 3 Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 35

35 SCM: The Fundament of the Development Process Analysis Design Implementation Test Maintenance Software Configuration Management Version Control Build Build Management Workspace Management Workspace Management Process Control Process Control Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 36

36 Version Control (1): Branching Branching Graph Model Representation of the most important development lines and change sets symbolic names for better comprehension and simpler references every branch has additional administrative annotations new_gui 1 2 arc.c V V1_maintenance V1.1 V bug=239 bug=248 bug=267 bug=268 bug=301 symbolic name reference to a branch point V2 18 comments... Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 37

37 ClearCase Versions Control: Branching Automatic branching, when ever necessary Every member has an isolated working environment Release different working environments for different tasks \development 1 \bugfix Allows parallel and thorough development Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 38

38 Version Control (2): Merging Problem merging happens automatically, if shared acestor exists of two files is known Version A... x=0... basis version... x= x=1... Version B experimental results... x=?... in approx. 90% of all cases the merging can is done without user interaction approx. 1% of all merges was erroneous, most of these were detected becaus of syntax errors Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 39

39 Versioning of folders /usr/src/proj /usr/src/proj gui_src gui_doc gui schedule src doc schedule arc.c zbuf.c plan.doc arc.c zbuf.c plan.doc Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 41

40 Version Control (3): Possible Extensions Labels symbolic names Attributes additional comments arc.c 1 2 (hyperlink) design_for change_req=218 (attribute) arc.doc 1 2 RLS1 Hyperlinks relationships RLS1 (label) 3 3 RLS2 triggers 7 ECA-rules Change Sets Annotations (on code level) Namespaces... Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 42

41 ClearCase Baselining minicalc.dsw h minicalc.h c minicalc.cpp rc minicalc.rc Release 1 Release 1 Release 1 Release Release Release Release 2 4 Release 2 A global label can be assigned to every version in a release (e.g. release 1) Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 43

42 SCM: The Fundament of the Development Process Analysis Design Implementation Test Maintenance Software Configuration Management Version Control Build Build Management Workspace Management Workspace Management Process Control Process Control Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 44

43 Build Management (1) Management of all information necessary for the reproducible creation of derived objects necessary data: correct versions of all source files and other derived objects names and versions of all used tools all parameter adjustments resulting properties of build management derived objects can be used by different users at the same time (binary sharing) only the essential operations for the creation of a derived object must be carried out (minimal rebuilding) a bill-of-materials list can automatically created which lists all needed components Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 45

44 Build Management (2) Problems with conventional tools the "normal" make tool does not support binary sharing insufficient BOM list prevents binary sharing, because it can not be decided if really "everything" related to the object is identical minimal rebuilding requires analysis of dependencies for which specialized solutions (incremental compilers) exist, but no solution which can be generalized to an inhomogeneous build process Solution in ClearCase The VFS tracks all I/O accesses by the compilers and other tools and thereby collects and logs all directly and indirectly referenced objects clearmake is responsible for this task integrated into IDEs (e.g. Eclipse, WebSphere Studio) Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 46

45 Build Management: Solution with ClearCase audit on clearmake invoke build script audit off additional information /bin/cc -g parse.c view Config Config Record Record File System I/O Audit HP/UX HP/UX /bin/cc -g parse.c /bin/cc -g parse.c Bill-of-material associated with new derived objects VOB repository Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 47

46 ClearCase Build And Release Management Build Auditing Reproduce build with the help of bill of material lists VOB Server Hosts Build Maintenance Automatic detection of dependencies HP DEC Sun HP Build Avoidance Enables the sharing of "derived objects" between developers Sun SGI IBM NT Build Performance Enables parallel and distributed builds Builds may be distributed Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 48

47 ClearCase Build And Release Management Build Auditing Reproducibility of build by bill-of-materials lists foo.h foo.c Target Target foo.o foo.o built built on on host host falcon falcon by by arthur arthur Reference Reference Time Time 4-June-2001, 4-June-2001, 1:30:42 1:30:42 View View was was falcon:/home/falcon/arthur/myview falcon:/home/falcon/arthur/myview Build Build Script: Script: cc cc -g -g -o -o foo foo foo.c foo.c New New Build Build bin foo.o project src foo.c foo.h V I E W foo.c foo.o Private Storage User arthur Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 49

48 ClearCase Build And Release Management Build Avoidance foo.h foo.o foo.c Developer share derived objects Target Target foo.o foo.o built built on on host host falcon falcon by by ford ford Reference Reference Time Time 5-June-2001, 5-June-2001, 9:14:42 9:14:42 View View was was falcon:/home/falcon/ford/myview falcon:/home/falcon/ford/myview Build Build Script: Script: cc cc -g -g -o -o foo foo foo.c foo.c New New Build Build bin foo.o project src foo.c foo.h V I E W foo.c foo.o Private Storage User ford No need to recompile foo.c Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 50

49 SCM: The Fundament of the Development Process Analysis Design Implementation Test Maintenance Software Configuration Management Version Control Build Build Management Workspace Management Workspace Management Process Control Process Control Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 52

50 Process Control Development process encompasses analysis, design, implementation and maintenance of a software product SCM is just a part of this process Identification of problems Isolation of Problems, Definition of procedures Creation of time tables Organization of (automatic) testing measurement of software properties tools to automate the development processes: workflow manager action-response concept working on a task may influence or start other tasks Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 53

51 Solution: Unified Change Management Activity Activity Activity Activities Activities which are defined to to organize the work done in in the project Artefacts Artefacts files which are created / / changed in in the project Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 54

52 UCM: Connection between Activities and Artifacts ClearQuest: Activities Management of activities Rational ClearCase Management of artifacts Request Priority Owner Special Promo 1 Terry Bug Sandy Add GUI button 2 Kim Change Set Special Promo a.html c.xml b.jpg V5 V3 V8 Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 55

53 ClearCase Summary Version Control Full Full Branching & Labeling All All File File System Elements Directories Graphical Merge Merge & Compare Conversion Utilities Utilities Build Build Management makefile compatible Automatic Dependency Mgmt Mgmt Build Build Auditing --Config Config Records Parallel, Distributed Building Binary Binary Sharing Workspace Management Rule-based Configurations Dynamic Evaluation Transparent Access Access Scalable Fully Fully Distributed Process Control Attributes Hyperlinks Pre-Event, Post-Event Triggers Locks Locks & Permissions Completely Customizable Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 57

54 Subversion Alternative for Version Control Open-source tool for software versioning 'real' rename, move, copy (in contrast to CVS) directories, renaming and file metadata is versioned atomic commits robust network layer (WebDAV DeltaV) based on DBMS (BerkleyDB) or file-based repository Branches / tags in constant time clean text / binary handling concept for user and access rights Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 58

55 Subversion Architeture for a VFS cmd line client dev tools integration file system integration gui client Client Interface Client Library Repository Access dav svn Apache mod_dav mod_dav_svn Internet mod_svn svnserve Repository Interface Subversion Repository Berkeley DB Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 59

56 VFS Open-Source Solution Apache + Subversion + WebDAV Clients Linux: davfs2 file system driver Windows: Novell Netdrive Branch/Versions directly visible Restrictions Synchronization of changes Only support for auto-versioning no view support Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 60

57 ClearCase Summary ClearCase Pros Industrial strength Excellent merge tools Good GUI on Windows Proven reliability Scales up well ClearCase Cons Heavyweight server and client Very steep learning curve for users All merges are server based Merges over high latency links are slow Very expensive Weak GUI on Unix platforms Server communication is RPC based so anything over a high latency link is slow High administration overhead Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 61

58 Subversion Summary Subversion Pros Widespread IDE support,editor and file system / tool integrations Eclipse: Windows Explorer: lightweight server and client Quick learning curve for users (many similarities with cvs) Fast and efficient on the network Flexible architecture Low administration overhead Subversion Cons Merge tracking is currently completely manual Weak support for checking out part of a repository (Views) supports only version control Transparent work on the repository is limited No sharing of derived objects Armin B. Cremers, Sascha Alda & Tobias Rho (based on Bruegge & Dutoit) ObjectOriented Software Construction 62