Contents
This sample uses two Heartbeat operators to prevent a Merge operator from starving when either of its inputs stop receiving tuples. Without the Heartbeat operators, the Merge operator would stop outputting tuples as soon as either of its two input streams is inactive, even if it continued to receive tuples on the other input stream.
This sample also demonstrates how to flag the non-heartbeat tuples on an input stream, so that the heartbeat tuples can be filtered out later on.
-
In the Package Explorer, double-click to open the
HeartbeatMerge.sbappapplication. Make sure the application is the currently active tab in the EventFlow Editor. -
Click the
Run button. This opens the SB Test/Debug perspective and starts the application.
-
In the Application Output view, select the
MergedFeedsstream. No output is displayed at this point, but the Output View is prepared to receive output. This view will eventually show the output of the application. -
In the Manual Input view, select the
Feed1input stream. -
Enter
IBMfor symbol,83.17for price, and2005-11-02 12:00:00for time. -
Click Send Data. You should not see any output in the Output View yet. The tuple you just sent is currently buffered in the Merge operator.
-
Select the
Feed2input stream. -
Enter
MSFTfor symbol,24.89for price, and2005-11-02 12:00:30for time. -
Click Send Data. You should now see the IBM tuple in Output View.
-
Wait a few moments. Within 30 seconds, look for the MSFT tuple to appear in the Output View. If this application had not made use of Heartbeat operators, the MSFT tuple would have remained inside the Merge operator until
Feed1received a tuple with a timestamp greater than or equal to 2005-11-02 12:00:30. Instead, the Heartbeat operators continually emit such tuples, thereby preventing the Merge operator from getting stuck. You can see this for yourself by selecting theFeed1WithHeartbeatsoutput stream in the Output View. -
When done, press F9 or click the
Stop Running Application button.
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.
-
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.
-
In window 1, type:
sbd HeartbeatAggregate.sbappThe window shows
notice[StreamBaseServer] listening on port 10000. -
In window 2, type:
sbc dequeue TicCountsNo output is displayed at this point, but the dequeuer is prepared to receive output of the application.
-
In window 3, type:
echo IBM,84.17,2005-11-02 12:00:00 | sbc enqueue Feed1You should not see any output in the dequeuer window yet. The tuple you just sent is currently buffered in the Merge operator.
-
In window 3, type:
echo MSFT,24.89,2005-11-02 12:00:30 | sbc enqueue Feed2Wait a few moments. Within 30 seconds, look for the MSFT tuple to appear in the dequeuer window. If this application had not made use of Heartbeat operators, the MSFT tuple would have remained stuck inside the Merge operator until Feed1 received a tuple with a timestamp greater than or equal to 2005-11-02 12:00:30. Instead, the Heartbeat operators continually emit such tuples, thereby preventing the Merge operator from getting stuck. You can see this for yourself by dequeuing the Feed1WithHeartbeats output stream.
-
In window 2, type: Ctrl+Z (Windows) or Ctrl+D (UNIX) to exit the sbc session.
-
In window 3, type the following command to terminate the server and dequeuer:
sbadmin shutdown
In StreamBase Studio, import this sample with the following steps:
-
From the top menu, click → .
-
Select operator from the Data Constructs and Operators category.
-
Click OK.
StreamBase Studio creates a single project for the operator samples.
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_operatorSee Default Installation Directories for the default 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/operatorSee Default Installation Directories for the default location of studio-workspace on your system.