Contents
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.
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In the Package Explorer, double-click to open the
Metronome.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.
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In the Application Output view, select the
CurrentPricesstream. 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. -
In the Manual Input view, select the
SetPriceinput stream -
Enter
INTCfor symbol, and23.25for price. -
Click Send Data. Within five seconds, look for a tuple on the
CurrentPricesoutput stream, stating that the current price of INTC is 23.25. -
Enter
MSFTfor symbol, and25.75for price. -
Click Send Data. Within five seconds, look for two tuples emitted on the
CurrentPricesoutput stream. These tuples are repeated every five seconds. -
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.
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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.
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In window 1, type:
sbd Metronome.sbappThe window shows
notice[StreamBaseServer] listening on port 10000. -
In window 2, type:
sbc dequeue CurrentPricesLook 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.
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In window 3, type:
sbc enqueue SetPriceThe sbc command is now waiting for keyboard input. Type:
INTC, 23.25Within five seconds, look for a tuple in the dequeue window, stating that the current price of INTC is 23.25.
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In window 3, type:
MSFT, 25.75Within five seconds, look for two tuples emitted in the dequeue window. These tuples are repeated every five seconds.
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In window 3, type: Ctrl+Z (Windows) or Ctrl+D (UNIX) to exit the sbc session.
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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:
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From the top menu, click → .
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Select operator from the Data Constructs and Operators category.
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Click OK.
StreamBase Studio creates a single project for the operator samples.
By default, the sample files are installed in:
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On Windows:
C:\Program Files\StreamBase Systems\StreamBase.n.m\sample\operator -
On UNIX:
/opt/streambase/sample/operator
When you load the sample into StreamBase Studio, Studio copies the sample project's
files to your Studio workspace. StreamBase Systems recommends that you use the
workspace copy of the sample, especially on UNIX, where you may not have write access
to /opt/streambase. In the default installation, the
path to this sample in your Studio workspace is:
UNIX: ~/streambase-studio-n.m-workspace/sample_operator Windows XP: C:\Documents and Settings\username\My Documents\StreamBase Studion.mWorkspace\ sample_operator Windows 7 and Windows Vista: C:\Users\username\Documents\StreamBase Studion.mWorkspace\ sample_operator