ClearCase Versus Subversion

							Software Configuration Management:
Under the Hood of Two Leading Tools
Presented by: Andrew Wheeler & Shane Marcus
                   Agenda

 Project Motivation
 CM Tools Investigated
     ClearCase
     Subversion (SVN)

 Comparison
 Future Work
          Project Motivation

 Critical to software projects survival and
  completion
 A means of document control
 CMMI’s demands
 Good SCM decisions can lead to a
  streamlining of the process
 Most popular SCM tools covered
          ClearCase Background

   Initiated from DSEE
       Domain Software Engineering Environment
   Atria Software (Early ’90s)
     Initially Released to UNIX Platforms
     Windows Support Came Later

 Rational – Tool Alignment
 IBM Buyout
    Subversion (SVN) Background

   Shell Scripts Written by Dick Grune
     Resolve Conflicted Code
     Merge Two Files

   Brian Berliner Transformed Scripts (’89)
       CVS was Born
   Subversion – Derived from CVS
       Marketed as a Compelling Replacement to CVS
   Built by CollabNet, Inc.
Comparison Areas
     Differences in Comparison

Comparison Area        ClearCase        Subversion (SVN)
   Networking      Poor (Chatty RPC         Very Good
                      protocol)
     Ease of      Poor (Difficult and     Excellent (< 10
  Deployment          Complex)               Minutes)
Remote Repository     Indirectly            Indirectly
   Replication       (Multisite)        [Add-on or Utility]
    Evaluation        On-line Only        No Limitation
      Cost           $4250 / $5100             Free
                   Related Work

   User Driven Evaluation
       Rose-Hulman Institute of Technology
          Used as repository for course materials and
           collaboration source among professors
          Feedback to students on coursework through SVN
          Collaboration among teams and backup structure
           for students
               Related Work (cont)

   Collaboration and SCM
       COVEN
         Presents key     issues facing current SCM tools
              Branching and Merging
              Revision history and Reverting
              Labeling and Tagging
                Future Work

   Perform study of software projects who
    use SCM tools
     Collect needs through surveys and rate them
      against the features of a given SCM tool
     Collect metrics on how quickly a project can
      setup a repository structure
     Collect metrics on how much time is spent
      performing a given activity with the same
      amount of SLOC changes per SCM tool
     Compare SCM tool usage to staff size
                     Conclusion
   ClearCase vs. Subversion (SVN)
       Feature Sets Nearly the Same
       Proprietary vs. Open Source
       Significant Cost Difference
       Initial Setup Time
   Difficult to Eliminate Biases
   Restricted Evaluation / Training Opportunity
       ClearCase On-line Only Evaluation
       Relied on Work Exposure to Product