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What are the advantages & disadvantages of using Rational ClearCase Bridge versus Rational ClearCase Version Importer?

Robert Gormally (611) | asked Jun 04 '14, 5:47 a.m.
retagged Jun 04 '14, 9:00 a.m. by Masabumi koinuma (46115)
Our team is currently utilising ClearCase UCM for source control on a large project, and we are in the process of migrating to RTC for project lifecycle management.

We are trying to determine whether to migrate our (large) codebase from our existing UCM repository into RTC using ClearCase Version Importer, or to integrate with it using ClearCase Bridge.

What are the advantages & disadvantages of using Rational ClearCase Bridge versus Rational ClearCase Version Importer?

If we decide to use a Bridge, what functionality/features of RTC will not be available to us?

Thanks for your help!

2 answers

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Geoffrey Clemm (30.0k23035) | answered Jun 04 '14, 8:15 a.m.
edited Jun 04 '14, 10:01 p.m.
With the ClearCase Bridge, you are continuing to use ClearCase for versioning, and are using RTC for change request management, task management, and planning.   With the ClearCase importer (either the Version Importer or the Baseline Importer), you are using RTC for versioning as well, and only using ClearCase for occasional access to archived versioned information that was not imported into RTC.

Robert Gormally commented Jun 04 '14, 8:25 a.m.

Thanks Geoffrey!

Are there any features of RTC/Jazz that will be unavailable to us if we continue to use UCM for source control?

For example, will it be possible to start Jazz Team Builds from within RTC if our source is in UCM?

Masabumi koinuma commented Jun 04 '14, 11:46 a.m.

There is no technical limitation that makes any RTC features unavailable while you use ClearCase Bridge, as far as I know. You can use Jazz Team Build while you continue to use ClearCase UCM. This video may help you:

In terms of Version Importer, I DO recommend to use Version Importer for UCM as well because the Baseline Importer does not import any UCM metadata either. You can specify an option of the Version Importer to essentially do the same as what you can do by the Baseline Importer.

Robert Gormally commented Jun 04 '14, 11:58 a.m.

Thanks Masabumi!

I believe that RTC allows administrators to finely control what actions a user can perform via SCM, for example, what streams a user can flow their changes to.

Is such fine grained control possible only for code using the Jazz SCM?

Masabumi koinuma commented Jun 04 '14, 4:49 p.m.

Oh, if you compare ClearCase and RTC SCM, you'd find many differences. You may find a summary of the change in one slide of the enablement session recording:
Webinar: Importing Version History to RTC

Robert Gormally commented Jun 05 '14, 4:35 a.m.

Ah yes, I see on slide 4 that Process Integration is specific to RTC SCM.

On slide 11, it infers that ClearCase is preferable to RTC SCM for 'Very large development projects'. I realise it is difficult to give a single figure - above what approximate size would it be better to use a Bridge rather than importing the UCM project into RTC?

Masabumi koinuma commented Jun 05 '14, 1:20 p.m.

There's no simple answer for you about large deployments because it really depends on your CC or RTC deployments ( machines, network topology, database, etc.). I'd say CC and RTC has different approach to scale to large deployment, and CC has longer history of supporting large deployments successfully.

Like Georg mentions below, the bridge is a way to use RTC in a complimentary fashion, and easy to deploy for existing CC deployments. If the user community is happy with CC, there'd be no reason to 'force' them to switch SCM from CC to RTC.

If you're more interested in consolidating servers to single solution ( as opposed to deploy/maintain both CC and RTC), and developers are not using CC's unique capability, migration to RTC can be an option for you but it requires more planning/execution work than the bridge.

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Georg Kellner (825375100) | answered Jun 05 '14, 10:41 a.m.
Hi Robert,

configuring the bridge is easily done (I would say an hour the first time, every additional project/component will take minutes), while doing a migration from one SCM system to an other can take weeks, based on the repository size, team size, complexity of development environment and so on.

So what is the goal?
If it is the integration (UCM) ChangeSet - RTC task, the bridge would be the solution.
If you have problems with CC UCM, which can be solved with RTC SCM (I remember some refactoring issues in CC), a migration can make sense.

Regarding size of a project in UCM:
In UCM you can use rootless components containing rooted components, and also rootless components, based on rootless components.
I know projects having:
rootless "system" component containing
rootless "sub-system" component containing
rootless "component" component containing
rooted "module" component
Such combinations are not possible in RTC afaik.

greetings georg.

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