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Why Is Software Difficult to Build?

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Presentation on theme: "Why Is Software Difficult to Build?"— Presentation transcript:

1 Why Is Software Difficult to Build?
Lack of control Lack of monitoring Lack of traceability Uncontrolled changes

2 Conflicts in Team Software Development
Simultaneous updates – how to prevent one person from undoing the changes of another Shared and common code – how to notify everyone who needs to know about a change Versions – how to make changes to all affected versions when needed

3 Other Software Processes
With a focus on: Configuration management Change management Other Software Processes Other Processes

4 Other Processes Development Process is the central process around which others revolve Methods for other processes often influenced by the dev process Other Processes

5 Other Processes In the context of Dev Processes

6 Monitoring and control
Aspect of project management process Lasts for the duration of the project and covers the development process Monitors all key parameters like cost, schedule, risks Takes corrective actions when needed Needs information on the dev process – provided by metrics Other Processes

7 Communication Facilitation
Realistically no plan covers everything! Additional decisions are made during development Documents should be updated and communicated Typical environment Multiple teams Multiple user groups Multiple disciplines Multiple locations In many setting PM is center of communication hub Planning and content meetings Other Processes

8 Meeting Types Issues Meetings QA Meetings
Regularly schedule meeting (ie. open in everyone’s schedule) Issues gathered the day before and distributed Issue initiator indicates required attendance QA Meetings Planning Discussion with business Discussion with developers Regular Review of open tickets Other Processes

9 Relationship with Dev Process
Other Processes

10 Configuration Management Process
Other Processes

11 Software Configuration Management Basics
Identification – identifying software configuration items in a baseline Control – controlling the release of a product and changes to it throughout its lifecycle Status Accounting – recording and reporting of the status of components and changes Auditing and Reviewing – Validating the completeness of a product and that SCM procedures are being followed

12 SCM Definitions Baseline – One or more software configuration items that have been formally reviewed and agreed upon and serve as a basis for further development Software Configuration Item – A collection of software elements treated as a unit for the purposes of SCM Configuration – A collection of all the elements of a baseline and a description of how they fit together

13 SCM Definitions (cont’d)
Configuration Control Board – Group with the responsibility for reviewing and approving changes to baselines Software – All of the code, specifications, plans, descriptions, processes, and documents associated with a software development effort Version – A specific instance of a baseline or configuration item

14 Background A software project produces many items - programs, documents, data, manuals, … All of these can be changed easily – need to keep track state of items Software Configuration Management (SCM) Systematically control the changes Focus on changes during normal evolution (req changes will be handled separately) CM requires discipline as well as tools Other Processes

15 Background SCM often independent of dev process
Dev process looks at macro picture, but not on changes to individual items/files As items are produced during dev they are brought under SCM SCM controls only the products of the development process Other Processes

16 Examples of Configuration Items
Product concept specification Software project plans Software requirements specifications Software design descriptions Source code Database descriptions SCM procedures Software release processes Software test documents User documentation Maintenance documentation

17 SCM Process and Dev process
Other Processes

18 Need for CM CM needed to deliver product to the client
What files should comprise the product? What versions of these files? How to combine these to make the product? Just for this, versioning is needed, and state of different items has to be tracked There are other functions of CM also Other Processes

19 Functionality Needed Capture current state of programs
Capture latest version of a program Undo a change and revert back to a specified version Prevent unauthorized changes Gather all sources, documents, and other information for the current system Other Processes

20 CM Mechanisms Configuration identification and baselining
Version control Access control These are the main mechanisms, there are others like naming conventions, directory structure,… Other Processes

21 Configuration Items Sw consists of many items/artifacts
In CM some identified items are placed under CM control Changes to these are then tracked Periodically, system is built using these items and baselines are established Baseline – logical state of the system and all its items; is a reference point Other Processes

22 Version Control Allows different projects to use the same source files at the same time Isolates work that is not ready to be shared by the rest of the project Isolates work that should never be shared Allows software engineers to continue development along a branch even when a line of development is frozen

23 Version and access control
Key issues in CM Done primarily on source code through source code control systems, which also provide access control Allows older versions to be preserved and hence can undo changes Examples: CVS – Original open source system (1986) Subversion – Open source CVS replacement (1999) Microsoft Visual SourceSafe (VSS) – targeted for smaller dev projects IBM Rational ClearCase – Industrial strength solution Other Processes

24 Version and Access Control
When programmer developing code – is in private area When code is made available to others, it goes in an access-controlled library For making changes to an item in library, it has to be checked out Changes made by checking-in the item – versioning is automatically done Final system is built from the library Other Processes

25 Version/Access Control
Generally both version and access control done through CM tools Tools limit access to specified people - formal check in, check out procedures Automatic versioning done when a changed file is checked-in Check-in, check-out control may be restricted to a few people in a project Require successful compile/build cycle Other Processes

26 CM Process Defines the activities for controlling changes Main phases
CM Planning Executing the CM process CM audits Other Processes

27 CM Planning Identify items to be placed under CM
Define library structure for CM Define change control procedures Define access control, baselining, reconciliation, procedures Define release procedure Other Processes

28 CM Audit During project execution CM procedures have to be followed (e.g. moving items between directories, naming, following change procedures, …) Process audit has to be done CM audit can also check if items are where they should be Other Processes

29 Summary – CM CM is about managing the different items in the product, and changes in them Developing a CM plan at the start is the key to successful to CM CM procedures have to be followed; audits have to be performed Requires discipline and tools Other Processes

30 Requirements Change Management Process
Other Processes

31 Background Requirements change at any time during the development
Changes impact the work products and the various configuration items Uncontrolled changes can have a huge adverse impact on project in cost/sched Changes have to be allowed, but in a controlled manner Other Processes

32 Change Control Proposed changes to baselines must have some level of review The impact of proposed changes must be identified and understood. When appropriate the approval of the CCB, key managers and project members must be obtained Approved changes must be properly implemented After changes are made all affected parties must be notified

33 A Change Mgmt Process Log the changes
Perform impact analysis on the work products and items Estimate impact on effort and schedule Review impact with stakeholders Rework the work products/items Other Processes

34 Changes Change often triggered by change request
Change req log keeps a record of requests Impact analysis for a change request involves identifying the changes needed to diff items, and the nature of change The impact of changes on the project is reviewed to decide whether to go ahead Cumulative changes also often tracked Other Processes

35 http://www. marinebiodiversity

36 Baseline CM Recall: A baseline is one or more software configuration items that have been formally reviewed and agreed upon and serve as a basis for further development Other Processes

37 Baseline Management What baselines are required to be defined and managed? Typically aligned with major milestones Applies to documents as well as code How is the current software configuration defined? A snapshot of everything the product has produced at some point in time

38 Baseline Management (cont’d)
Who must approve changes to baselines? Usually the Change Control Board (CCB) How and when are baselines created and physically controlled? Through the use of document control systems, code control tools, and procedures to prevent the making of unapproved changes

39 Baseline Management (cont’d)
How are people informed of changes? The CCB disseminates change information How are baselines verified? By reviews, inspections, and the testing of code Are baselines tied to project milestones? Many are, but during coding many may not be

40 Baseline Management (cont’d)
What information is required to process a change to a baseline? A description of the proposed changes Reasons for making the changes List of other items affected by the changes What tools, resources, and training are required to perform baseline change assessment? File comparison tools to identify changes Resources and training depend on size and complexity of project

41 Baseline Management (cont’d)
How are unauthorized changes to source code prevented, detected, and corrected? No way to prevent unauthorized changes Provide software engineers with training A commercial available SCM systems provide adequate protection Unauthorized changes should be caught during assessment procedures

42 Baseline Management (cont’d)
What tools, resources, and training are required to perform baseline management? A fully featured SCM tool On large projects a separate SCM group may be needed SCM training is required for all involved in the process

43 For your project: Should have a configuration management process defined Change management procedures Any changes to the baseline documents should be documented and include a formal change management request Other Processes

44 Examples Collegiate Project Services eliminaryChangeManagementPlan.pdf Eclipse: equest_faq.php Other Processes

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