First Application Sample

About This Sample

This sample, firstapp.sbapp, demonstrates a StreamBase application with one notable characteristic: it is easy to create. You may have already created it yourself, if you performed the tutorial in the Getting Started Guide.

The application is modest in functionality, but building it teaches you some important fundamentals including:

  • The general design process of defining input streams, schemas, operators, and output streams

  • Adding and connecting components in an EventFlow

  • Typechecking operators to ensure that streaming data can flow through the application without errors

  • Features of the SB Authoring and SB Test/Debug perspectives

  • Running the application in StreamBase Studio

  • Creating a feed simulator to enqueue test data automatically to the running application

Importing This Sample into StreamBase Studio

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

  • From the top menu, select FileLoad StreamBase Sample.

  • Type fir narrow the list of options.

  • Select firstapp from the Applications category.

  • Click OK.

StreamBase Studio creates a project for the sample.

Running firstapp.sbapp in StreamBase Studio

To start this sample:

  1. In the Project Explorer, open the sample you just loaded.

  2. Open the src/main/eventflow folder.

  3. Open the package folder (most samples contain a single package folder. Open the top-level package folder if your sample contains more than one folder).

  4. Open the named application file and click the Run button. This opens the SB Test/Debug perspective and starts the application.

    If you see red marks, wait a moment for the project in Studio to load its features.

    If red marks do not resolve themselves in a moment, select the project and right-click MavenUpdate Project from the context menu.

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

The server is ready to receive input. See the following sections to manually enqueue data into this sample. For additional enqueuing instructions, see the Getting Started Guide.

Enqueuing Data Manually

To enqueue data manually in Studio:

  1. Open the Manual Input view.

  2. In the Application Output view, make sure that the Output stream option is set to All streams.

  3. Enter IBM in the symbol field, and 10000 in the quantity field.

  4. Click Send Data to send this tuple to the application.

  5. Observe the output in the Application Output view:

    Because the quantity satisfies the Filter predicate, your tuple is passed through on the BigTrades stream.

  6. Enter 100 in the quantity field and click Send Data again.

  7. Observe that this time, your output appears in the AllTheRest output stream.

    Why? Because the quantity is below the predicate's threshold of 10000.

  8. Enter different values above and below the threshold, and see how your application responds. Try entering a nonvalid quantity like alpha.

Enqueuing Data Using a Feed Simulation

To enqueue test data using any of the three feed simulations:

  1. Open the Feed Simulations view.

  2. In the Feed Simulations view, select a feed simulation.

  3. Click Run.

    The Application Input view displays generated tuples enqueued from your Feed Simulation. At the same time, the Application Output view begins displaying tuples on the two output streams.

  4. If you chose firstapp-enum.sbfs, let it run for five or ten seconds, then click Stop (otherwise it runs continuously). The other two feed simulators run to completion, but feel free to stop them when you have enough data.

    Note that stopping the feed simulation does not stop the application.

  5. Observe the results in the Application Input and Application Output views. (If necessary, resize the views so that you can see their contents clearly.)

    Tip

    Click a row to display its field summary below the list, as shown in the next figure.

    You should see trades values that are both above and below the threshold of 10000 that was set in your Filter operator.

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

This Sample's Files

In addition to the application, the installed First Sample includes two additional feed simulations. Thus, there are three simulations in total, each demonstrating a different way of modeling test data:

firstapp-enum.sbfs

Also featured in the tutorial, generates values from a list of symbols and quantities, in random order. The enumeration also specifies the weights of the quantities.

firstapp-trace1.sbfs

Uses an external comma-separated value data file, firstapp-trace1.csv, to explicitly list the order and values of tuples.

firstapp-trace2.sbfs

Uses values specified in another external comma-separated value data file, firstapp-trace2.csv, and also uses relative timestamps to control the rate of enqueuing.

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_firstapp

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