Essentials Of Rational Clearcase Module 2: Working With Files Under Source Control

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IBM Software Group

Essentials of Rational ClearCase Module 2: Working with Files Under Source Control

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Objectives Upon completing this module, you should be able to:  Explain the checkout/checkin model  Explain the difference between a reserved and unreserved checkout  Check out/check in files and directories  Define version trees and branches and explain how branches enable parallel development  Edit a view config spec to automatically create a branch

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Typical Workflow: Work on Files

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Checkout/Checkin Model  When a file is under source control, you check it out to work on it  A file is checked out to a view and a modifiable copy is available to work on  A placeholder is created in the version tree as the potential successor version  When you check in the file, a new version is added to the element version tree 4

View Before and After Checking out hello.c

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Types of Checkout  Reserved checkout:  Default checkout  Has exclusive rights to next place on version tree  No checkins can be made on the same branch until the checkout is resolved  Only allowed if no other reserved checkouts exist for the branch

 Unreserved checkout:  Allowed regardless of the status of other checkouts of the version  Before check in, must be merged or discarded if any checkin has taken place 6

Checking Out a File: ClearCase Explorer

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Checking Out a File: Windows Explorer

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Checking Out a File: Command Line Interface Usage: checkout | co [-reserved] [-unreserved pname] [-ptime] [-branch branch-pname | -version] [-c comment | -cfile pname | -cq | -cqe | -nc] pname ...

Example: X:\Hardware\src>cleartool checkout hello.c Checkout comments for “hello.c": Bug fixing . Checked out “hello.c" from version "\main\r2_int\alex_r2\2".

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You MUST end the comment by typing “.” and Enter

Versioning Directories  To change the directory namespace you must create a new directory version  The ClearCase GUI automatically checks out a directory and creates a new version if a change occurs to the directory namespace (some operations will prompt you to check out the directory)  Using the CLI, you must check out/check in a directory to create a new version  To change only file contents but not the directory namespace, you do not need to check out the directory 10

Checking in a New Version  Adds a new version to the version tree  Removes the read/write copy of the file from the view storage area  The checked in version becomes available to users using dynamic views and to snapshot view users upon the next update  Use ClearCase Explorer, Version Tree Browser, Windows Explorer, ClearCase supported IDEs, or the CLI

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Resolving Checkouts

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What Is a Version Tree? A hierarchical representation of an element in which all versions are logically organized.

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Version-extended Names  Each version of an element has a unique identifier  The extended naming symbol denotes a path into the version tree of an element  @@ is the default extended naming symbol

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Viewing Versions of an Element Graphically  ClearCase graphically depicts an element version tree in the Version Tree Browser

Version selected by your view

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What Are View-private Files?  Files that are not under ClearCase source control  Files that reside in the view; other users in other views do not see them  Examples:  Temporary files created during development or testing  Files not yet added to source control  Read/write copies of files checked out of source control

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Branching Enables Parallel Development  Allows different projects to use the same source at the same time  Controls public/private work  Isolates changes  Temporary, such as new features that have not yet been tested  Permanent, such as fixing a bug in a retired release

 Prevents roadblocks — development can proceed during an integration period 17

What Is a Branch Type?  A user-defined name that forms a unique pathname in the version tree  Allows changes across multiple elements to be logically grouped together  Centralizes administrative control of branch names

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Working on Branches  When working on a project team, you will most likely work on element branches other than /main  A view config spec specifies which versions of the element appear in the view  Edit your view config spec to select the correct branches and the correct versions

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The Default View Config Spec  A default config spec is automatically set whenever you create a new view Rule 1 Rule 2

 Rule 1: Select version of element checked out to THIS view  Rule 2: If no version is checked out, select the latest version on /main 20

Editing a View Config Spec  You can edit the config spec to select versions on a branch other than /main Rule 1 Rule 2

 Rule 1: Select version of element checked out to THIS view  Rule 2: If no version is checked out, select the latest version on the r2_int branch 21

Editing a Config Spec to Create Branches  A view config spec can use the –mkbranch clause to create branches automatically upon checkout:

 Rule 3 is interpreted as:  Select the version of the element with the R1 label  During checkout , automatically create the r2_int branch from the version labeled R1  Check out the 0 (zero) version on the r2_int branch 22

Creating a New Branch Automatically Change your config spec to create a branch when you check out elements that have an R1 label.

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Creating a New Branch Automatically (cont.)

Before checkout into view with the config spec using the auto mkbranch rule

After checkout; notice that checkout created the r2_int branch

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Module Review  How does ClearCase protect files from being modified inadvertently?  What happens when you check out a file?  What is the difference between a reserved and an unreserved checkout?  When do you need to create a new version of a directory?  What happens when you check in a file?  What is a version tree?  What is a view default config spec? 25

Module Lab  In this lab, you perform the following tasks:  Edit a config spec to automatically create branches  View an element version tree  Check out/check in files  Create a view-private file

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