Contents
This topic describes AggregateByTime.sbapp, the Aggregate
operator time dimension sample.
This sample demonstrates use of the time-based Aggregate operator. The time-based aggregate uses elapsed time to manage windows. This example uses 2-second windows to compute average price per share of symbols, grouping its computations by stock symbol.
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In the Package Explorer, double-click to open the
AggregateByTime.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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No output is displayed in the Application Output view yet, but the dequeuer is prepared to receive output. This view will eventually show the output of the application.
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In the Feed Simulations view, right click on
AggregateByTime.sbfsand select . -
Observe application output in the Application Output view. The format is similar to the following:
12:06:42 AvgOut stock=MSFT, TimeBasedAverage=26.05,
start_time=2013-12-05 12:06:40.000-0500, end_time=2013-12-05 12:06:42.000-0500,
first_time=2013-12-05 12:06:40.513-0500, last_time=2013-12-05 12:06:41.620-0500, n=4
12:06:44 AvgOut stock=AAPL, TimeBasedAverage=43.95,
start_time=2013-12-05 12:06:42.000-0500, end_time=2013-12-05 12:06:44.000-0500,
first_time=2013-12-05 12:06:42.223-0500, last_time=2013-12-05 12:06:43.725-0500, n=4
Tip
If output rows are too long to see all the data, click a row to display its fields in the Display Fields pane below the table.
Each row is an average for a group. The output fields represent the following, per window:
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Symbol — The stock symbol, used to sort tuples into groups
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Average — Time-based Average price per share, calculated with the aggregate function avg()
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start_time — The time the window opened (its
openval()) -
end_time — The time the window closed (its
closeval()) -
first_time — Time at which the first tuple arrived in the window (
firstval(time)) -
last_time — Time at which the last tuple arrived in the window (
lastval(time)) -
n — The number of tuples over which average price per share was computed (
count())
Averages and times will all vary depending on the rate of input. For example, the first time you run the sample, the first tuple may occur just before the 2-second boundary and the second time it may occur just after the 2-second boundary. The averages will be different because the tuples are seen in different windows.
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When the feed simulation has stopped, you can observe how emission occurs in two seconds (the difference between end_time and start_time is 2.0) regardless of whether the operator continues to receive input. If you run again, speeding up or slowing down the feed simulation, you will see n go down or up, accordingly.
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Click the Manual Input tab, type a string for Symbol and number for PricePerShare, and then hit . After two seconds, you will observe the operator time out and emit output.
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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 AggregateByTime.sbapp -
In window 2, type:
sbc dequeue AvgOutNo 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:
sbfeedsim ResourceFiles\AggregateByTime.sbfsData starts flowing into the application. Observe several lines in the dequeue window, similar to the following:
MSFT,26.05,2007-04-26 13:29:52.000-0400,2007-04-26 13:29:54.000-0400
AAPL,43.95,2007-04-26 13:29:52.000-0400,2007-04-26 13:29:54.000-0400Average, start, and end times all vary depending on where the tuples fall relative to the wall-clock time. For example, the first time you run the sample, the first tuple may occur just before the 2-second boundary and the second time may occur just after the 2-second boundary. The averages will be different because the tuples occur in different windows. The start times and end times will, of course, be different.
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In window 3, type
sbadmin shutdownto terminate the daemon and dequeuer.
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 all 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 the permission problems that can occur when trying to work with the initially installed location of the sample. The default workspace location for this sample is:
studio-workspace/sample_operator
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/operator
See Default Installation
Directories for the location of streambase-install-dir on your system. This location
may require administrator privileges for write access, depending on your platform.