Metronome Operator Sample

This sample uses a Metronome operator to output the current share price of all stocks every five seconds. The current prices are stored in a query table.

Running Metronome.sbapp in StreamBase Studio

  1. In the Package Explorer, double-click to open the Metronome.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 CurrentPrices stream. Observe a tuple showing every five seconds, with the current time, a null symbol, and a null price. This indicates that no prices are currently known. Once we record some share prices, the nulls will be replaced with actual values.

  4. In the Manual Input view, enter INTC for symbol, and 23.25 for price.

  5. Click Send Data. Within five seconds, look for a tuple on the CurrentPrices output stream, stating that the current price of INTC is 23.25.

  6. Enter MSFT for symbol, and 25.75 for price.

  7. Click Send Data. Within five seconds, look for two tuples emitted on the CurrentPrices output stream. These tuples are repeated every five seconds.

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

Running Metronome.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 Metronome.sbapp

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

  3. In window 2, type:

    sbc dequeue CurrentPrices

    Look for a tuple every five seconds tuple with the current time, a null symbol, and a null price. This indicates that no prices are currently known. Once we record some share prices, the nulls will be replaced with actual values.

  4. In window 3, type:

    sbc enqueue SetPrice

    The sbc command is now waiting for keyboard input. Type:

    INTC, 23.25

    Within five seconds, look for a tuple in the dequeue window, stating that the current price of INTC is 23.25.

  5. In window 3, type:

    MSFT, 25.75

    Within five seconds, look for two tuples emitted in the dequeue window. These tuples are repeated every five seconds.

  6. In window 3, type: Ctrl+Z (Windows) or Ctrl+D (UNIX) to exit the sbc session.

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

    sbadmin shutdown

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Importing This Sample into StreamBase Studio

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

  • From the top menu, click 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.