Contents
This sample uses a Filter operator to pass only trades of 10000 shares or
more. The input stream contains the fields Symbol and Volume.
This topic describes Filter.sbapp, the Filter
operator sample application.
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 Applications list.
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Click OK.
StreamBase Studio creates a single project for all 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
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Launched StreamBase Studio
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Created (or subsequently used) the "sample_operator" project.
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From the top menu, in the Authoring perspective, selected File > New > EventFlow Application. Selected the
sample_operatorproject and enteredFilterfor the diagram name. -
Created an input stream:
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Dragged an input stream from the palette to the canvas.
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Clicked it on the canvas, which invoked the Input Stream Properties dialog window.
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On the General tab, Name:
StockIn -
On the Edit Schema tab, added:
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Field Name:
Symbol, Type:string, Size:5 -
Field Name:
Volume, Type:int
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Created a Filter operator:
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Dragged a Filter operator from the palette to the canvas.
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On the General tab, Name:
myFilter -
Connected the StockIn input stream to the myFilter operator.
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Set up the myFilter operator:
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On the Predicate Setting tab, added:
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Output Port:
1 -
Predicate:
Volume >= 10000
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Created an output stream:
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Dragged an output stream from the palette to the canvas.
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On the General tab, Name:
StockOut -
Connected the myFilter operator to the StockOut output stream.
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In the Package Explorer, double-click to open the
Filter.sbappapplication. Make sure the application is the currently active tab in the EventFlow Editor. -
Click the
Run StreamBase Application (Default Launch)
button. (Not the Run button.) This
opens the Test/Debug perspective and starts the application.
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In the Application Output view, select the StockOut output stream
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In the Manual Input view, select the StockIn input stream
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Enter
intc10000in the Symbol and Volume fields, respectively -
Click , and observe that data appears in the StockOut stream
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Enter
9999in the Volume field. -
Click , and observe no new data appears in the StockOut stream.
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Click → (F9).
Open three terminal windows. In all windows, first change your working directory to where the samples are installed.
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In window 1, type:
sbd Filter.sbappThe window shows
notice[StreamBaseServer] listening on port 10000. -
In window 2: type:
sbc dequeue StockOutNo output is displayed at this point, but the dequeuer is prepared to receive output. This window will eventually show the output of the application.
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In window 3, type:
sbc enqueue StockInThe sbc command is now awaiting keyboard input. Then type:
intc, 100No output is displayed yet in the dequeue window.
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Type:
intc, 10000Observe this line in the dequeue window:
intc,10000 -
Type:
intc, 9999No further output is displayed yet in the dequeue window.
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Type:
intc, 10001Observe this line in the dequeue window:
intc,10001 -
Type: Control-Z (Windows) or Control-D (UNIX). The command will exit.
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In window 3, type:
sbadmin shutdownThe sbadmin shutdown command will terminate the daemon and dequeuer.