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8/6/2019 Lnt Cc Presentation

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2nd July 2007 | 1 | Sanjay MishraConfidential L&T Infotech

Configuration Management with

ClearCase


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Confidential L&T Infotech

What is meant by Software Configuration

Management (SCM)?

Managing the changings to the Software

Its covers the tools and processes used to control,

co-ordinate and track code, requirements,

documentation problems, change requests, design,

tools, compilers, libraries, patches, changes made tothem and who makes the changes.


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SCM Tools

Clearcase PVCS (Perforce Version Control System)

CVS (Concurrent Version Control System)

VSS (Visual Source Safe) CM Synergy

Subversion


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What is ClearCase?


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ClearCase is

Version management tool for all types of files and

directories

- records all actions

- reports history

- accurate reproduction of every release

Available both in Unix and Windows NT environments

Two user interfaces- command line: cleartool

- graphical: xclearcase


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Comparing Clearcase with VSS

Attributes Visual Source Safe Clearcase

Platform

dependencies

Works over network shares,thereby slowing responsetimes. Limited to Microsoftplat forms only

PlatformIndependent

Scalabilityand

performance

Microsoft recommends thatVSS databases not exceed 3to 5 GB, for performanceand stability reasons

Underlyingarchitecture andMVFS can slowresponse times.

Installation Inbuilt with Microsoft VisualStudio

Requires preinstall planning& investment inhardware andinfrastructure.


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Contd..

Attributes Visual Source Safe Clearcase

Distributeddevelopment

Doesnt offer a scalabledistributed developmentsolution

Achieved throughMultisite

Branching and

merging

Limited support for

branching and relatedoperations. Branchingrelationships arentmaintained.

Clearcase branching

automatically tracksthe history of allbranching operations

Cost ofownership

Available throughMicrosoft.

Can be high, due tolicensing,infra structure, andadministration costs


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History of Clearcase

ClearCase was developed by Atria Software andfirst released in 1992 on Unix and later on

Windows. Atria later merged with Rational

Software, which was purchased by IBM . IBM

continues to develop and market ClearCase.


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Different Phases of Clearcase

1. Version Control2. Workspace Management

3. Build Management

4. Process Control

5. Multisite Environment


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ClearCase Servers

ClearCase is a Client/Server style package. For

example, all VOB information is kept on a Server

called a VOB Server. The user's ClearCase client

system requests information from theserver

which is sent to the user's machine

The following are the various types of servers

that a ClearCase site might have.


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VOB Server

The machine that contains the VOB storage area isthe VOB server. Therein maybe one or more VOB

servers depending upon the speed of the system,the number of users, and most important of all,your budget. The ClearCase Administrator's Manualhas some important information on setting up the

size and number of your VOBs, and the power ofyour VOB server.


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View Server

The Set of views (Workspace for developers) stored in

one particular server is called as View server

License Server If your site has a dedicated license server machine

that serves licenses for a variety of software, then

this system could serve as the License Server Since the License Server is a very low CPU intensive

server which is usually placed upon the same

machine that serves as the VOB server.

Clearcase uses the floating type license


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Registry Server

The Registry can be thought of as the "Table ofContents" to ClearCase's Vobs and Views.

The ClearCase VOB Registry links the VOB Tags (themount points of the VOBs on the ClearCase user'smachine) to the directories where the VOBs areactually stored.

The ClearCase View Registry links the View Tags (thename of the view) to the directories where the View

is actually stored. It is recommended that a single Registry be used.


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Advantages of ClearCase

Can handle projects that:

a) Consists from a lot of developers.

b) Go on for a very long time.

Security

Versatile (multi-purpose) lots of possibilities and

capabilities.

Traceability


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Advantages cont.

Supported by multiple OS

Windows, Unix (Solaris, AIX, ), Linux.

Can be accessed from client on one OS to a

server on another OS.

Enables real parallel development - work on multiple

versions of the same source file concurrently.


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Disadvantages

High price

Too versatile

one can never learn all capabilities.

Complex support

must have very good - full time - administrator.


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Basic Concepts

VOB Versioned Object Base

A Permanent read only data repository that

stores the files, directories and metadata

under the version controlled data

The whole database consists of several

VOBs


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VIEW A working area for an individual developer to access the VOB

Used to select the version of an element

Used to access for one or more VOBs without interfering others

Temporary storage area

Allows multiple views for each user


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Basic Concepts (cont.)

CONFIG SPECConfiguration Specification

- A set of ordered rules used to select at most

one version of each element and determines which

version of an element are visible in view.

ELEMENT- A file or directory under the source control ,

stored in a clearcase VOB such as files, directories,

binary file objects, libraries, etc


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METADATATypes:

1. Label type

2. Attribute type

3. Hyperlink type4. Branch type

5. Eltype type

6. Trigger type

- can be connected to a specific version of an

element, or to a branch, or to the entire element


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vob1 vob2

CONFIG SPECs

VIEWs

vob

3

Kalles view Annas view Test groups view Peters view

elements

VOBs


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Default Config Spec:

element * CHECKEDOUT

element * /main/LATEST

- a rule per line

- rules are processed from top to bottom; if no

matching version of an element was not found for

the first rule, the system tries to find a version that

matches the second rule etc.


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Files in Version Tree Browser Window

x.cc z.ccy.cc w.cc

/main /main /main /main

CHECKEDOUT

0

1

2

3

0

1

2

3

5

4

0

1

2

3

4

0

1

2

3

4


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Versions that match with Default Config Spec

0

1

2

3

4

x.cc

5

z.ccy.cc w.c

c


4

0

1

2

3

0

1

2

3

4

0

1

2

3


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Labelling

x.cc z.ccy.cc w.cc


REL1 REL1

REL1

REL1

4

0

1

2

3

0

1

2

3

4

0

1

2

3

5

4

0

1

2

3


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Example of Config Spec for LabelREL1:

element * REL1

element * /main/LATEST


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Versions that match using the Config Spec for REL1


REL1 REL1

REL1

REL1

x.cc z.ccy.cc w.c

c

4

0

1

2

3

0

1

2

3

5

4

0

1

2

3

4

0

1

2

3


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Branching

0

rel1_corr

1

x.cc z.ccy.cc w.cc


REL1 REL1

REL1

REL1

4

0

1

2

3

0

1

2

3

4

0

1

2

3

5

4

0

1

2

3

0

1

rel1_corr


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Example of Branch Config Spec

element * CHECKEDOUT

element * /main/rel1_corr/LATEST

element * REL1 -mkbranch rel1_corr element * /main/LATEST


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Versions that match using the Branch Config Spec

x.cc z.c

c

y.cc w.c

c

0

rel1_corr

1

x.cc z.ccy.cc w.cc


REL1 REL1

REL1

REL1

4

0

1

2

3

0

1

2

3

4

0

1

2

3

5

4

0

1

2

3

0

1

rel1_cor

r


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Basic Actions for an Element

Checkout

- a new editable version is created- only one person can edit the file at the same time

Checkin

- the version that was created by checkout commandis saved to the VOB and is then visible to the other

views

- the element changes to write-protected mode

Uncheckout- undo operation for checkout

Example click here


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Types of VOBS

Private Vob Public Vob

It will create by default We have to mention the

keyword public in the tag

Password not required Registry password required

Need to create directory to

mount (Access point)

Automatically mount

Only owner/root can mount

the Vob

Anyone can mount the vob


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Types of Views

Dynamic Snapshot

Works based on

clearcase network

Works without CCase

network also.

MVFS (Multi Version

File System)

CCFS Support

(Clearcase File System)Slow Fast

Fast immediate

updates

Periodic (manual)

updates are requiredto see file updates

Derived objects sharing No such facility


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Other Utilities

Clearmake

- ClearCase variant of the Unix make utility

MultiSite

- same VOB is used concurrently at several different

locations


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Thats about basics in ClearCase!

Lets try how it works in practise


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Thank You!!

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