Extension Point Operator Sample

This sample uses an Extension Point operator to dispatch tuples to one of two sub-modules, based on a user-specified action at runtime. The sub-modules simply double or triple an integer field within the incoming tuple. If no action is specified, the tuple is sent to both modules.

This sample illustrates StreamBase interfaces used with the Extension Point operator, and illustrates the dispatch of tuples to one of two modules based on an expression that evaluates to the identifier of one of the modules. This sample also illustrates the use of a PNG image file to provide the Extension Point operator with a custom icon.

There are two related samples that complete the picture on the subject of Extension Point operators and StreamBase interfaces:

Sample Description
Interfaces Sample Demonstrates how to use StreamBase interfaces to enforce a set of stream and schema definitions, and to use different implementations of the same interface for different purposes.
Extension Point Deployment Sample This sample is a variation of the Extension Point operator sample to illustrate the use of StreamBase deployment files. The StreamBase interface in this sample specifies externally defined modules. Two example .sbdeploy files are provided, which you use to run this sample.

First run and understand the current sample, then turn to the deployment file variation.

This Sample's Files

The Extension Point sample is composed of following files:

File Purpose
ExtensionPoint.sbapp The top-level application for this sample. Its input stream accepts an integer value and a string field, action, that determines what to do with the integer. The recognized values for action are double, triple, and null.
The following files are located in the Modules subdirectory of the operator project directory.
Multiplier.sbint A StreamBase interface that defines two input streams and one output stream, and defines named schemas used by those streams.
Doubler.sbapp A module that implements the streams and schemas defined in the Multiplier.sbint interface. This module doubles its input value, and appends as a list(string) the StreamBase path through this module.
Tripler.sbapp Another module that implements the Multiplier.sbint interface. This module performs the same actions as Doubler.sbapp except that it triples its input value.

Open ExtensionPoint.sbapp in Studio and look at the Properties view for the Extension Point operator named Multiply. The Concurrency tab is entirely responsible for directing input tuples to one or both of the referenced modules, either Doubler.sbapp or Tripler.sbapp:

  • If a tuple enters input port 2, the dispatch style is Broadcast, which means the tuple is sent to both modules.

  • If a tuple enters input port 1, the dispatch style is Name. In this case, the expression lower(action) must resolve to the identifier of one of the two modules ("double" or "triple") as defined in the Modules tab.

Running ExtensionPoint.sbapp in StreamBase Studio

  1. In the Package Explorer view, open the sample_operator project folder.

  2. Double-click to open the ExtensionPoint.sbapp application. Make sure the application is the currently active tab in the EventFlow Editor.

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

  4. In the Application Output view, select the Output output stream. No output is displayed at this point.

  5. In the Manual Input view, select the Input input stream

  6. Enter the following field values:

    Field Enter this value
    value 2
    action double
  7. Click Send Data, and a tuple arrives in the Application Output view. Select the new tuple and observe this data below the output stream table:

    value=2, action=double, newValue=4, path=[Entering port 1 for Name dispatch,Doubler.sbapp]
  8. In the Manual Input view, enter the following field values:

    Field Enter this value
    value 2
    action triple
  9. Click Send Data, and a tuple arrives in the Application Output view. Select the new tuple and observe this data below the output stream table:

    value=2, action=triple, newValue=6, path=[Entering port 1 for Name dispatch,Tripler.sbapp]
  10. In the Manual Input view, enter the following field values:

    Field Enter this value
    value 3
    action null
  11. Click Send Data, and two tuples arrive in the Application Output view. Select the new tuples and observe this data below the output stream table:

    value=3, action=null, newValue=6, path=[Entering port 2 for Broadcast dispatch,Doubler.sbapp]
    value=3, action=null, newValue=9, path=[Entering port 2 for Broadcast dispatch,Tripler.sbapp]
  12. When done, press F9 or click the Stop Running Application button.

Running ExtensionPoint.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 your workspace copy of the sample, as described above.

  2. In window 1, start StreamBase Server running the Extension Point sample application. You must specify the provided server configuration file so that the application can locate the interface file and modules in the Modules folder. Enter:

    sbd -f op-samples.sbconf ExtensionPoint.sbapp
  3. In window 2, type:

    sbc deq Output

    No output is displayed at this point, but the dequeuer is prepared to receive output.

  4. In window 3, type:

    sbc enq Input

    The sbc command in window 3 now waits for keyboard input. Type:

    2, double
    2, triple
    3, null

    Look for output lines like the following in window 2:

    2,double,4,"[Entering port 1 for Name dispatch,Doubler.sbapp]"
    2,triple,6,"[Entering port 1 for Name dispatch,Tripler.sbapp]"
    3,null,6,"[Entering port 2 for Broadcast dispatch,Doubler.sbapp]"
    3,null,9,"[Entering port 2 for Broadcast dispatch,Tripler.sbapp]"
  5. In window 3, type: Ctrl+C to exit the sbc session.

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

    sbadmin shutdown

Importing This Sample into StreamBase Studio

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

  • From the top menu, select FileLoad StreamBase Sample.

  • Select operator from the Data Constructs and Operators category.

  • Click OK.

StreamBase Studio creates a single project for the operator samples.

Sample Location

When you load the sample into StreamBase Studio, Studio copies the sample project's files to your Studio workspace, which is normally part of your home directory, with full access rights.

Important

Load this sample in StreamBase Studio, and thereafter use the Studio workspace copy of the sample to run and test it, even when running from the command prompt.

Using the workspace copy of the sample avoids permission problems. The default workspace location for this sample is:

studio-workspace/sample_operator

See Default Installation Directories for the location of studio-workspace on your system.

In the default TIBCO StreamBase installation, this sample's files are initially installed in:

streambase-install-dir/sample/operator

See Default Installation Directories for the default location of studio-workspace on your system.