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2nd July 2007 | 1 | Sanjay MishraConfidential L&T Infotech
Configuration Management with
ClearCase
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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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Basic Concepts (cont.)
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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Basic Concepts (cont.)
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
/main /main /main /main
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
/main /main /main /main
REL1 REL1
REL1
REL1
4
0
1
2
3
0
1
2
3
4
0
1
2
3
5
4
0
1
2
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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
/main /main /main /main
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
/main /main /main /main
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
/main /main /main /main
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!!