Stream represents the flow of data in a process flow. Multiple streams are used when the output of an activity needs to be sent to two or more activities in a process flow.
Steps to create multiple streams for an activity
Click the activity in Canvas area from which multiple streams are to be generated and select View Properties
icon in Context Pad to display the Activity Properties panel.- In the Activity Properties panel, go to STREAMS > Output. The existing stream is displayed.
- If you want to delete the existing stream, click Remove
button. Click Yes, when prompted to confirm. To create a new stream, enter the name for the Stream in the Name field and select the consumer from Consumer drop-down list.
Click Visible
button to display the stream in canvas area.Click Add button and name of the Stream is displayed in the Streams list.
If you are creating an error stream, click Error button
.- Repeat steps 4 and 5 to create another stream.
- Click on canvas area to return to the Canvas Area. The created streams are displayed in the canvas area by data objects Artifact.
The Artifacts are only to show the flow of streams therefore it is necessary to add the activities with appropriate flows. If user deletes a stream from the Multiple Stream Dialog box, then the corresponding Artifacts are also deleted. If an Artifact representing a stream is deleted then the stream is also deleted. Web Process Designer confirm with users to delete the underlying stream.
To hide the Artifacts, click data object Artifact and select Hide Stream option.
The Multiple Stream feature can be used in three scenarios:
Creating more than one Stream
When data from one stream is sent to more than one activity, you can create more than one stream. However, more than one stream can be created only with the selected activities. These activities are Mapping Transformation, Custom Plugin, Repeater Service, XML Validator and Decoder.
A Mapping activity does not always generate multiple streams. It is based on the schemas used in the mapping activity.
Creating Error Stream
If a source or target schema is not compliant with the corresponding source or target data, then the process flow execution will generate error records. Sometimes these error records are useful for users and user may want to store them for debugging. In such a case, error stream is created along with data stream. This error stream can be mapped to some other activity for further processing. For example, user may want to store the error records in a File Target. To specify a stream as an error stream, check the Error Stream checkbox in the Multiple Stream Dialog Box. Error stream can be generated for Schema, Database source, Database target, Advanced Database target and XML Validator only.