Clearcase
A Little History
Many of our clients utilize IBM Rational Clearcase for their SCM system of course. Clearcase is the Cadillac of SCM systems. Born in the old Unix workstation company named Apollo and originating from the DSEE project when HP bought out Apollo, engineers on DSEE project didn't want to see their beloved DSEE die so they started a company named Atria.
Atria did well and was soon bought out by another software company, makers of Purify - a software product that helps developers find memory leaks in their code.
Later Rational, purveyors of many software engineering environments and tools, bought PureAtria and for many years it was known simply as Rational Clearcase.
Finally IBM, seeing the wisedom in the Rational Approach, bought out Rational where Clearcase, Multisite, Clearquest and the rest of the Rational suite of tools reside today.
Base Clearcase
Base Clearcase is how Clearcase was originally developed. As such it's a full featured, large, complex and flexible SCM system. Many companies still use Base Clearcase and have build their own set of scripts around Base Clearcase to represent, control enforce policies and automate workflow. IBM Rational saw this and decided to collect the various ways that people use Clearcase to come up with UCM. Still developing software is about as varied as designing snowflakes so UCM does not always fit the environment. As such Base Clearcase is still available and used today.
Unified Change Management (UCM)
Unified Change Management is a layer built on Base Clearcase to provide additional Software Configuration Management features. These changes include integration with ClearQuest to enforce defect and change tracking with code development through the use of activities. This is part of the Rational Unified Process (RUP) which describes the lifecycle of change management for IBM Rational's software development process. It also gives integrators ownership of projects and streams to allow policy and feature management by project leaders and release engineers. UCM removes the ability/requirement that users manage a configuration specification for a view. UCM is used and configured via either CLIs or GUIs.
Multisite
Multisite enables fast, reliable access to software assets across distributed locations. This extends software configuration management across geographically distributed projects through repository replication. This gives you the following benefits:
- Automatic replication and synchronization of Rational Clearcase repositories enables access to current information, regardless of location
- Simplifies administration with an easy-to-use Web-based interface
- Maintains data integrity by resending information in the event of network failure and automatic recovery of repositories in the event of system failure
- Works with Clearquest® Multisite for integrated workflow management and defect and change tracking across multiple locations and time zones
- Scales to support thousands of users, working in dozens of sites, managing terabytes of data