Filter Operator Sample

Contents

Importing This Sample into StreamBase Studio
Sample Location
Running the Filter Sample
How We Created the Filter Sample

This sample uses a Filter operator to pass only trades of 10000 shares or more. The input stream contains the fields Symbol and Volume.

This topic describes Filter.sbapp, the Filter operator sample application.

Importing This Sample into StreamBase Studio

In StreamBase Studio, import this sample with the following steps:

  • From the top menu, click File → Load StreamBase Sample.

  • Select operator from the Applications list.

  • Click OK.

StreamBase Studio creates a single project for all the operator samples.

Sample Location

By default, the sample files are installed in:

  • On Windows: C:\Program Files\StreamBase Systems\StreamBase.n.m\sample\operator

  • On UNIX: /opt/streambase/sample/operator

When you load the sample into StreamBase Studio, Studio copies the sample project's files to your Studio workspace. StreamBase Systems recommends that you use the workspace copy of the sample, especially on UNIX, where you may not have write access to /opt/streambase. In the default installation, the path to this sample in your Studio workspace is: 

UNIX:       
  ~/streambase-studio-n.m-workspace/sample_operator
Windows XP:
  C:\Documents and Settings\username\My Documents\StreamBase Studio n.m Workspace\
      sample_operator
Windows Vista:
  C:\Users\username\Documents\StreamBase Studio n.m Workspace\
      sample_operator

Running the Filter Sample

Running Filter.sbapp in StreamBase Studio

  1. In the Package Explorer, double-click to open the Filter.sbapp application. Make sure the application is the currently active tab in the EventFlow Editor.

  2. Click the Run button. This opens the SB Test/Debug perspective and starts the application.

  3. In the Application Output view, select the StockOut output stream

  4. In the Manual Input view, select the StockIn input stream

  5. Enter intc and 10000 in the Symbol and Volume fields, respectively

  6. Click Send Data, and observe that data appears in the StockOut stream

  7. Enter 9999 in the Volume field.

  8. Click Send Data, and observe no new data appears in the StockOut stream.

  9. When done, press F9 or click the Stop Running Application button.

Running Filter.sbapp in Terminal Windows

This section describes how to run the sample in UNIX terminal windows or Windows command prompt windows. On Windows, be sure to use the StreamBase Command Prompt from the Start menu as described in the Test/Debug Guide, not the default command prompt.

  1. Open three terminal windows on UNIX, or three StreamBase Command Prompts on Windows. In each window, navigate to the directory where the sample is installed, or to your workspace copy of the sample, as described above.

  2. In window 1, type:

    sbd Filter.sbapp

    The window shows notice[StreamBaseServer] listening on port 10000.

  3. In window 2: type:

    sbc dequeue StockOut

    No output is displayed at this point, but the dequeuer is prepared to receive output. This window will eventually show the output of the application.

  4. In window 3, type:

    sbc enqueue StockIn

    The sbc command is now awaiting keyboard input. Then type: intc, 100.

    No output is displayed yet in the dequeue window.

  5. Type:

    intc, 10000

    Observe this line in the dequeue window: intc,10000.

  6. Type:

    intc, 9999

    No further output is displayed yet in the dequeue window.

  7. Type:

    intc, 10001

    Observe this line in the dequeue window: intc,10001.

  8. Type: Ctrl-Z (Windows) or Ctrl-D (UNIX) to stop the sbc command.

  9. In window 3, type the following command to terminate the server and dequeuer:

    sbadmin shutdown

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How We Created the Filter Sample

  1. Launched StreamBase Studio

  2. Created (or subsequently used) the "sample_operator" project.

  3. From the top menu, in the SB Authoring perspective, selected File > New > EventFlow Application. Selected the sample_operator project and entered Filter for the diagram name.

  4. Created an input stream:

    1. Dragged an input stream from the palette to the canvas.

    2. Clicked it on the canvas, which invoked the Input Stream Properties dialog window.

    3. On the General tab, Name: StockIn.

    4. On the Edit Schema tab, added:

      • Field Name: Symbol, Type: string, Size: 5

      • Field Name: Volume, Type: int

  5. Created a Filter operator:

    1. Dragged a Filter operator from the palette to the canvas.

    2. On the General tab, Name: myFilter.

    3. Connected the StockIn input stream to the myFilter operator.

    4. On the Predicate Setting tab, added:

      • Output Port: 1

      • Predicate: Volume >= 10000

  6. Created an output stream:

    • Dragged an output stream from the palette to the canvas.

    • On the General tab, Name: StockOut.

    • Connected the myFilter operator to the StockOut output stream.

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