Interfaces Sample

The Interfaces sample application 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.

The top-level application uses two Extension Point operators that each implement a different StreamBase interface. One Extension Point references two modules, while the other references one module. See This Sample's Files for a description of each interface and module.

This sample illustrates several aspects of Extension Point operators and StreamBase interfaces. There are two related samples that complete the picture on these subjects:

Sample Description
Extension Point Operator Sample This sample uses an Extension Point operator to dispatch tuples based on a user-specified action to one of two modules, which double or triple an integer field within the 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 Dispatch Styles based on a predicate condition.
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.

This Sample's Files

The Interfaces sample includes the following files:

File Purpose
TopLevel.sbapp The top-level application for this sample. The application populates the HistoricalData table on startup from a CSV file.
quote-history.csv A small CSV file used to load data into the HistoricalData table in TopLevel.sbapp.
QuotesToOrders.sbint A StreamBase interface that defines an input and an output stream, and defines named schemas used by those streams.
QuotesToOrdersWithHistoricalData.sbint A StreamBase interface that extends the QuotesToOrders.sbint interface, adding a table schema and placeholder table to the streams and schema definitions imported from QuotesToOrders.sbint.
BuyOrSellHalfQ2O.sbapp A module that implements the streams and schemas defined in the QuotesToOrders.sbint interface. This module determines whether to sell or buy based on the odd or evenness of the incoming price field. It contains a deliberate error in the BuyOrSellHalf Map operator, which will send an order to the UnexpectedOrders stream. Tuples processed by this module have the prefix Half- in their order IDs.
RandomBuyOrSellQ2O.sbapp Another module that implements the streams and schemas defined in the QuotesToOrders.sbint interface. This module determines at random whether to buy or sell. Tuples processed by this module have the prefix Rndm- in their order IDs.
OrderIfBetterThanYesterday.sbapp A module that implements the streams, named schemas, table schema, and placeholder table defined in the QuotesToOrdersWithHistoricalData.sbint interface. This module attempts to match the incoming symbol field against the same field in the HistoricalData table. If a match is found, the module sends a buy order if the incoming quote price is lower than yesterday's low price from the table, or sends a sell order if the incoming price is higher than yesterday's high price. Tuples processed by this module have the prefix Yester- in their order IDs.

Running the Interfaces Sample in StreamBase Studio

  1. In the Package Explorer, open the sample_interfaces project folder.

  2. Double-click to open the TopLevel.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 Manual Input view, select the QuotesIn input stream.

  5. Enter ibm, 119.00, and 2000 in the symbol, price, and volume fields, respectively. (You can enter the stock symbol field in lowercase, because the first Map operator converts that field to uppercase.)

  6. Click Send Data, and observe data like the following in the Application Output view. The first line might be a Buy order in your case, because it is processed by the module that randomizes buy and sell orders.

    Output Stream Fields
    SellOrders Time Output Stream Fields 13:56:38 SellOrders order_id=Rndm-1, symbol=IBM, order_type=sell, price=119.0, volume=2000
    UnexpectedOrder Time Output Stream Fields 13:56:38 UnexpectedOrders order_id=Half-1, symbol=IBM, order_type=sellTYPOHERE, price=119.0, volume=1000
  7. Notice that there is an order on the UnexpectedOrder stream. This is because the sample as shipped contains a deliberate error to force at least one case of unexpected orders. The Filter operator that splits the output into three streams looks for a match in the order_type field of either buy or sell. However, one of the application's modules, BuyOrSellHalfQ2O.sbapp, outputs either buy or sellTYPOHERE, instead of sell.

  8. [Optional] You can choose to stop the sample now to correct the sample's error, then restart it. If so, follow the sub-steps below; if not, continue on with step 9.

    1. Stop the application by pressing F9 or click the Stop Running Application button.

    2. In the Package Explorer, in the sample_interfaces project folder, double-click BuyOrSellHalfQ2O.sbapp to open it.

    3. Double-click the BuyOrSellHalf Map operator to open its Properties view.

    4. In the Properties view, locate the Expression column corresponding to the order_type output field.

    5. Remove TYPOHERE from the expression.

    6. Save BuyOrSellHalfQ2O.sbapp.

    7. Switch back to the TopLevel.sbapp application, save it, and click the Run button to restart it.

    8. Re-enter the same data as before: ibm, 119.00, and 2000.

    9. Click Send Data, and observe that this time, there are two orders on the SellOrders stream:

      Output Stream Fields
      SellOrders Time Output Stream Fields 14:30:59 SellOrders order_id=Rndm-1, symbol=IBM, order_type=sell, price=119.0, volume=2000
      SellOrders Time Output Stream Fields 14:30:59 SellOrders order_id=Half-1, symbol=IBM, order_type=sell, price=119.0, volume=1000

      The prefix on the order_id field (Half- or Rndm-) tells you which sub-module processed the order. The first order was processed by RandomBuyOrSellQ2O.sbapp, while the second order was processed by BuyOrSellHalf.sbapp.

  9. Enter similar data, but this time use an even number for the price field: ibm, 120.00, and 2000.

  10. Click Send Data, and observe data like the following in the Application Output view. Remember that your results may vary because of processing by the module that randomizes buy and sell orders.

    Output Stream Fields
    SellOrders Time Output Stream Fields 14:33:24 SellOrders order_id=Rndm-2, symbol=IBM, order_type=sell, price=120.0, volume=3000
    BuyOrders Time Output Stream Fields 14:33:24 BuyOrders order_id=Half-2, symbol=IBM, order_type=buy, price=120.0, volume=1500
    BuyOrders Time Output Stream Fields 14:33:24 BuyOrders order_id=Yester-1, symbol=IBM, order_type=buy, price=120.0, volume=3000
  11. Continue entering data in the Manual Input view to see the results. Keep in mind the following points:

    • The BuyOrSellHalf.sbapp module is set up to process quotes with even prices as buy orders, and odd prices as odd prices as sell orders.

    • The OrderIfBetterThanYesterday.sbapp module only gets involved if the symbol you input is found in the HistoricalData table, and the price meets certain criteria. The HistoricalData table is loaded from the quote-history.csv file. Open that CSV file to determine the symbols and prices listed. To see this module in action, enter a price above the number in the first column of the CSV file, or below the number in the third column.

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

Running the Interfaces Sample 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, type:

    sbd TopLevel.sbapp

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

  3. In window 2: type:

    sbc dequeue

    No output is displayed at this point, but the dequeuer is prepared to receive output. This window will eventually show the output of all three streams of the top-level application.

  4. In window 3, type:

    sbc enqueue QuotesIn

    The sbc command is now awaiting keyboard input.

  5. In windows 3, type the following. (You can enter the stock symbol field in lowercase, because the first Map operator in TopLevel.sbapp converts that field to uppercase.)

    ibm, 119.00, 2000

    Observe lines like the following in window 2. The prefix for the second field (Half- or Rndm-) tells you which sub-module processed the order. The first line might be a Buy order in your case, because it is processed by the module that randomizes buy and sell orders.

    SellOrders,Rndm-1,IBM,sell,119,2000
    UnexpectedOrders,Half-1,IBM,sellTYPOHERE,119,1000
  6. [Optional] Stop the application in order to fix the sample's error, then restart the application.

    1. In window 3, type Ctrl+C to end the sbc session, then type:

      sbadmin shutdown

    2. In Studio, open the BuyOrSellHalfQ2O.sbapp application to correct its deliberate error, as described in step 8 of the previous section.

    3. Repeat steps 2, 3, and 4 of this procedure. In window 3, type the same data as step 5:

      ibm, 119.00, 2000

      This time, observe a different set of output lines in window 2.

  7. In window 3, type another entry:

    ibm, 120.00, 3000

    Observe lines like the following in window 2. Your results may vary because of processing by the module that randomizes buy and sell orders.

    BuyOrders,Half-2,IBM,buy,120,1500
    BuyOrders,Yester-1,IBM,buy,120,3000
    SellOrders,Rndm-2,IBM,sell,120,3000
  8. Continue entering data in window 3. Keep in mind the following points:

    • The BuyOrSellHalf.sbapp module is set up to process quotes with even prices as buy orders, and odd prices as odd prices as sell orders.

    • The OrderIfBetterThanYesterday.sbapp module only gets involved if the symbol you input is found in the HistoricalData table, and the price meets certain criteria. The HistoricalData table is loaded from the quote-history.csv file. Open that CSV file to determine the symbols and prices listed. To see this module in action, enter a price above the number in the first column of the CSV file, or below the number in the third column.

  9. In window 3, type: Ctrl+C to exit the sbc session.

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

    sbadmin shutdown

Back to Top ^

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 interfaces from the Applications category.

  • Click OK.

StreamBase Studio creates a single project for all 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_interfaces

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/interfaces

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