Importing multiple streams from Rational ClearCase UCM or base Rational ClearCase

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You can individually import multiple streams from Rational® ClearCase® UCM or base Rational ClearCase. The importer imports file and folder versions into the same components and elements if they are the same in Rational ClearCase source control.

When you create the first synchronization stream to import, the IBM® Engineering Workflow Management (EWM) source control stream is initialized with empty content, and the file versions that are selected by the baselines or the label types are imported and created sequentially.

When you import streams in the order of their dependencies, and you choose the same files and folders to import for every stream, the importer creates a file history in a similar branch structure as the one in the Rational ClearCase system. You should select the component root folder as the synchronization root for each component, and select the same component roots across all related streams. Making these selections helps you plan, which Rational ClearCase streams to import and in which the order.

When the importer adds a new synchronized file or folder, it locates the containing component for the root folder in Rational ClearCase. The importer then locates the component in EWM that is linked to the one in Rational ClearCase. If the component is not in the new synchronization stream, the importer searches for the relevant baseline of the component, adds the baseline to the synchronization stream, and imports the file versions on top of it. Although the importer does not import all the versions, the versions that are imported have similar relationships as in the Rational ClearCase version tree, because the EWM change sets are created on top of the baseline that is created by other import actions (usually from the parent stream). This behavior helps avoid the rapid increase of the EWM repository database size when you import multiple streams, because the change set is always a delta from the previous baseline as opposed to a delta from empty content.

When the importer adds a new synchronized file or folder, and when the importer cannot find the relevant baseline of the component in EWM, the component in the stream is initialized with its initial, empty baseline, and the importer imports files on top of the empty content. This process is the same as when you import the first synchronized stream. You then see disconnected line segments in the History view of EWM after multiple stream are imported. Therefore, it is important to plan the order of the Rational ClearCase streams to import. The importer locates the relevant baseline in the following ways:
  1. It locates the origin of the stream by component (the initial foundation baseline of the UCM stream, or the backstop label type of base Rational ClearCase).
  2. It finds a matching baseline in EWM by name.

The following figure shows an example of a Rational ClearCase UCM stream structure. The horizontal lines represent UCM streams, and the blue or red diamond shapes represent baselines. The branch of the line represents when a child stream is created from the connected baseline. For example, Substream B is created from the BL 3 baseline.

Rational ClearCase stream structure.

When you import all these streams into EWM, use the following order to import the streams:
  1. Main stream A: The importer creates all of the baselines from BL 1 to BL 6.
  2. Substream B: The importer selects BL 3 as initial content for the synchronized stream. BL 3 is created by importing Main stream A. The importer for Substream B creates the baselines from Sub-BL B1 to Sub-BL B3.
  3. Substream C: The importer selects BL 5 as initial content for the synchronized stream. BL 5 is created by importing Main stream A. The importer for Substream C creates the baseline Sub-BL C1.
  4. Substream D: The importer selects Sub-BL B1 as initial content for the synchronized stream. Sub-BL B1 is created by importing Substream B. The importer for Substream D creates the baseline Sub-BL D1.

At the end of multiple import actions, the file versions branch like the preceding figure when you display the history.

You can also manually create a EWM source control snapshot and specify it in the synchronization stream creation wizard as initial content for the synchronization stream. This feature is useful if you import streams selectively and still want to create similar version branching. For example, you might use this feature if you import an integration stream and its grandchild stream, but not the child stream, or when you import streams across multiple UCM projects selectively. The EWM change sets for imported file versions are created on top of specified snapshot, so you can create version branching for files that is similar to what you have in Rational ClearCase.