Why Is Software Difficult to Build?

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

4
Other Processes

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

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

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

8
Meeting Types

• Issues Meetings
• Regularly schedule meeting (ie. open in
  everyones 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

9
Relationship with Dev Process
10
Configuration Management Process
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 (contd)

• 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

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

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
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

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

20
CM Mechanisms

• Configuration identification and baselining
• Version control
• Access control
• These are the main mechanisms, there are others
  like
• naming conventions,
• directory structure,

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

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

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

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

26
CM Process

• Defines the activities for controlling changes
• Main phases
• CM Planning
• Executing the CM process
• CM audits

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

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

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

30
Requirements Change Management Process
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

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

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

35
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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

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 (contd)

• 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 (contd)

• 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 (contd)

• 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 (contd)

• 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 (contd)

• 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

44
Examples

• Collegiate Project Services http//www.collegiatep
  roject.com/articles/PreliminaryChangeManagementPla
  n.pdf
• Eclipse http//www.eclipse.org/epf/process/change
  _request_faq.php