When more than one input stream is connected to an activity, Stream Selector is used to specify the input stream to be consumed by the activity. To understand the use of Stream Selector, consider the following scenario (see Figure 147).
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In this process flow, you can see that two input streams are passed to the File_Target. The desirable execution sequence is that first File_Source will be executed then File_Target and there after thereafter the Gateway. Now, if the condition specified at the Gateway is satisfied, the process flow will be finished. If the condition specified at Gateway is not satisfied, the control will be passed to the File Source1 and FTP _Source and further to File_Target. Practically, when this process flow will be executed, the File_Target activity will get confused whether to take input from File_Source or from File Source1 FTP_Source. Thus, this process flow will fail.
To avoid such a situation, Stream Selector is used. Streams from File_Source and File Source1 are FTP_Source are passed to the Stream Selector and then from the Stream Selector to the File_Target. The use of Stream Selector is displayed in Figure 148.
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Stream Selector
Stream Selector takes input from the activity , which that has just executed. If the File_Source has executed before the execution of stream selectorthe Stream Selector, it will take input from the File_Source. If File Source1 has the FTP_Source has just executed, it will take input from File Source1the FTP_Source.
Steps to To use a Stream Selector
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- In the Process Designer, in the Repository View panel. Expand the Activities list of the Adeptia Server and select Selector. A list of selector activities is displayed., expand Activities.
- Expand Selector.
Click Stream Selector Service and drag it to the Graph Canvas.
The Stream Selector Service node is displayed in the Graph Canvas area (see Figure 149).
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- Connect the required activities with the Stream Selector Service node (see Figure 150).
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