Configuration Management and Distributed Software Engineering

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Configuration Management and Distributed Software
Engineering

• Jon A. Preston
• Dr. Xiaolin Hu
• CSc8350 Spring 2005

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Agenda

• SE Coordination and collaboration
• CM Artifact management
• IDE Integrating CMS/CSCW
• Code visualization techniques
• Open-systems architecture

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Collaboration/Coordination

• Software engineering involves coordinating
  multiple developers, architects, testers,
  designers, and managers
• Net-centric computing dominates
• Resultant distributed nature of SE projects
• Leverage geography to achieve SE shifts

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Configuration Management

• Principally involves artifact management and
  coordination
• Allow maximum concurrency
• Minimize collisions (lost and/or replicated work)
• Recent study (2001)
• 12.5 of all changes to a file occur within 24
  hours
• 16 parallel versions to be merged

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Configuration Management
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Optimistic vs. Pessimistic

• Two approaches to CM
• Optimistic
• High concurrency (hopefully disjoint)
• Must deal with possible merge
• Pessimistic
• Low concurrency
• Avoids the merge problem
• Users can check out read only and edit

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Pessimistic Coordination
Checkout denied until A is checked in
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Optimistic Coordination
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Distributed Configuration Management

• Network-centric computing
• Distributed file system
• Distribute artifacts among many machines
• Coordinate among machines (lookup, etc.)
• Can offer replication services (reliability,
  performance)
• Must then deal with replicating locks and changes

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Distributed CM
Files A-I
User 1
Locks file C
Locks file T
Files J-Q
User 2
Locks file J
Locks file Z

Files R-Z
User N
Locks file L
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Distributed CM with Replication
Files A-I
User 1
Locks file C
Locks file T
Files J-Q
User 2
Locks file J
Files R-Z
Locks file Z

User N
Locks file L
Files R-Z
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Distributed CM with Replication
Files A-I
User 1
Locks file C
Locks file T
Files J-Q
User 2
Locks file J
Files R-Z
Updates file Z

User N
Locks file L
Updates file Z
Files R-Z
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Structure of Software Systems

• Highly structured code blocks
• Hierarchical trees/graphs
• Reuse leads to interdependencies
• Can auto-detect such structures and
  interdependencies

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Fine-grain Differentials
Version n
Version n1
Edited code block
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Collaborative IDE and Versioning

• Locking (pessimistic CM) doesnt scale
• Highly-structured nature of software code helpful
• Supports wait-free collaboration
• Must deal with collisions/merging
• Evolution graph (branching and merging) presented

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Collaborative Editing in Jazz

• Plug in for Eclipse (Java IDE)
• Shows Rear View Window of other users
• Connects with IM, email, and screen sharing
• Lightweight collaboration

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Microsofts Integrated Approach

• Visual Studio 2005 Team System
• Integrates architecture, design, development,
  testing, and oversight/tracking
• Includes communication hooks

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Visual Studio 2005 Team System
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Test Integration and Coverage
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Code Visualization

• Augur
• Extends SeeSoft
• Allows for an aggregate view of distributed
  software development
• Colors indicate users as well as structure of
  code and age of change
• Multiple views
• Presented at ICSE04

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SeeSoft
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Augur Visualizing Source Code
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Augur Visualizing Source Code
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Open-systems Architecture

• Current research in CSCW
• Web-based systems
• Change tracking in Office
• Web-services
• Access remotely
• Subscriber pattern for notification
• Middleware
• Update legacy CMS with new functionality

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Core Functionality

• Optimistic check out
• Pessimistic check out
• Check in
• Subscribe and unsubscribe
• Publish lists
• Artifacts (and state)
• Users (contact information, presence, etc.)
• Subscriptions

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Open-systems Architecture
Notification (Email, IM, etc.)

CVS
Fine-grain middleware
Network
VSS
Doc Editor
Connection middleware
Fine-grain middleware
Web Services-Provided Core Functionality


CMS
Connection middleware
IDE
Fine-grain middleware
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Conclusion

• Traditional CM does not scale well
• Pessimistic locking inhibits concurrency
• Fine-grain locking a possible solution
• Integration of CSCW and IDE critical
• Visualization techniques useful
• Track changes over time
• Provide meta-view of structure
• Open-systems architecture is promising