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Essentials of Rational ClearCase Module 3: Merging to and from the Integration Workspace

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Objectives Upon completing this module, you should be able to:  Explain how ClearCase merges versions of elements  Merge work to and from the integration area  Resolve merge conflicts using the Diff Merge tool

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Typical Developer ClearCase Workflow

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Merging Overview  Merging is the process by which ClearCase propagates changes from one branch to another  A merge combines the contents of two or more files or directories into a new version of a file or directory  After a merge, development can continue on both branches  Future merges have no restriction in either frequency or direction  ClearCase includes automated merge facilities for handling most merge scenarios 4

Element Types and Merging  Every file in a VOB is associated with an element type  ClearCase uses element types to categorize and manage elements  Not all ClearCase element types can be merged

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Integrating Parallel Development: Merging Policies

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How ClearCase Merges Files and Directories

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Merge Algebra

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Types of Merges

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Merging Versions in ClearCase In ClearCase, you can merge in one of three ways: Merge Manager Version Tree Browser

Command Line Interface

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Merging Using the Version Tree Browser Scenario: For element hello.c, merge v1 on /pat_2 with v3 on /r2_int

1 Select the “from”version, and then click Tools > Merge to.

2 When the cursor changes to resemble a target, click the “to” version.

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Merging Using the Version Tree Browser (cont.) 4 Click OK to confirm the merge.

3 Click Yes to perform the merge.

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Merging Using the Version Tree Browser (cont.)  If there are no conflicting changes, the merge proceeds automatically  As a result of the merge, ClearCase:

5 Check in the file to complete the merge.

 Copies the checked out file to file.contrib  Places the results of the merge in the checked-out version of the file  Records the merge in the VOB database 13

Merging with the Merge Manager  The Merge Manager provides a graphical interface for locating files to be merged and for performing the merge  Start > Programs > Rational > ClearCase > Merge Manager

1 To start a new session, click New.

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Merging with the Merge Manager (cont.) 2 Select the view to which you are merging.

3 Select the specific elements that you want to merge.

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Merging with the Merge Manager (cont.) 4 Choose a method for selecting the version of each element to merge.

Merge from LATEST element on a selected branch Merge from elements according to a specified label Use a ClearCase query language statement to select the “from” versions Merge elements selected by a particular view

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Merging with the Merge Manager (cont.) 5 Provide additional information needed for the merge, then click Finish.

6 Confirm the merge criteria, then click Find.

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Merging with the Merge Manager (cont.) 7 Click Yes to verify the merge elements.

8 Click OK to start the merge.

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Non-Automatic Merges: The Diff Merge Tool Merge results pane

Base contributor: The original version

Contributor 1: The version that you are delivering FROM

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Contributor 2: The version that you are delivering TO

Using Diff Merge to Resolve Differences

Navigational Buttons: Use to move between merge points.

Merge Buttons: Click to move changes from the first, second, or third contributor pane to the merge results pane.

Red arrow: Indicates where a manual merge is needed.

Difference Indicators: Signify that content was added, removed, or changed. 20

Merging Directories  A directory merge:  Can process two or more versions of the same directory element  Results in a new directory version that reflects the contents of all the contributors  Cannot process two different directory elements

 To perform a directory merge:  Make sure the config spec selects the target version  Make sure all contributor versions are checked in  Check out the target version of the directory  Perform the merge immediately without making any other changes to the checked-out version 21

Merging Directories (cont.) Resolving changes for directories in the Merge Tool is the same as with files but with filenames instead of text.

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Module Review  How does the ClearCase merge algorithm work?  What element types can be merged? What element types cannot be merged?  What are the three types of merges that the ClearCase merge tool identifies? How does it handle each merge type?  When merging versions, how does ClearCase automatically resolve conflicts between contributors?  What is the Merge Manager? Why would you use it? 23

Module Lab  In this lab, you will perform the following tasks:  Merge using the Version Tree Browser  Merge using the Merge Manager  Resolve merge conflicts using the Diff Merge tool

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