why is software difficult to build?

Why Is Software Difficult to Build?

Lack of control Lack of monitoring Lack of traceability Uncontrolled changes

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

Other Processes 3

With a focus on: Configuration management

Change management

Other Processes

Development Process is the central process around which others revolve

Methods for other processes often influenced by the dev process

Other Processes 4

Other Processes In the context of Dev Processes

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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 6

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 7

Meeting Types Issues 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 ticketsOther Processes 8

Relationship with Dev Process

Other Processes 9

Other Processes 10

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

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

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

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 14

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 15

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

SCM Process and Dev process

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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 18

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

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CM Mechanisms

Configuration identification and baselining

Version control Access control

These are the main mechanisms, there are others like naming conventions, directory structure,…

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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 21

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

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

solutionOther Processes 23

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

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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

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CM Process

Defines the activities for controlling changes

Main phases CM Planning Executing the CM process CM audits

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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 27

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 28

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 29

Other Processes 30

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 31

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

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 33

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 34

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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 36

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

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

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

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

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

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

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 43

Examples

Collegiate Project Services http://www.collegiateproject.com/articles/PreliminaryChangeManagementPlan.pdf

Eclipse: http://www.eclipse.org/epf/process/change_request_faq.php

Other Processes 44