Gather Operator Sample

Contents

Running Gather.sbapp in StreamBase Studio
Running Gather.sbapp in Terminal Windows
Importing This Sample into StreamBase Studio
Sample Location

The Gather.sbapp sample application uses a Gather operator to generate an alarm (a true value) for trades of 10,000 shares or more for a stock whose price is $200 or greater. The input stream contains the fields Symbol,Volume, and Price.

Note

This is a very simple example which might be better done using a single Map operator, but it is instructive. For an example that truly requires a Gather operator, see the Compliance sample application.

Running Gather.sbapp in StreamBase Studio

In the Package Explorer, double-click to open the Gather.sbapp application. 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 BigTradeAlarm output stream. No output is displayed at this point, but the dequeuer is prepared to receive output. This view will eventually show the output of the application.
In the Manual Input view, select the TradesIn input stream.
Enter intc, 10000, and 201 in the Symbol, Volume, and Price fields, respectively
Click Send Data, and observe this data appears in the BigTradeAlarm stream:
```
BigTradeAlarm=true
```
Enter intc, 10000, and 199 in the Symbol, Volume, and Price fields, respectively
Click Send Data, and observe this data appears in the BigTradeAlarm stream:
```
BigTradeAlarm=false
```
Enter intc, 1000, and 201 in the Symbol, Volume, and Price fields, respectively
Click Send Data, and observe this data appears in the BigTradeAlarm stream:
```
BigTradeAlarm=false
```
Enter intc, 1000, and 187 in the Symbol, Volume, and Price fields, respectively
Click Send Data, and observe this data appears in the BigTradeAlarm stream:
```
BigTradeAlarm=false
```
When done, press F9 or click the Stop Running Application button.

Running Gather.sbapp 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.

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 Gather.sbapp

The window shows notice[StreamBaseServer] listening on port 10000.
In window 2: type:

sbc dequeue BigTradeAlarm

No output is displayed at this point, but the dequeuer is prepared to receive output. This window will eventually show the output of the application.
In window 3, type:

sbc enqueue TradesIn

The sbc command is now awaiting keyboard input. Then type: intc, 10000, 201

Observe this line in the dequeue window: true
Type:

intc, 10000, 199.

Observe this line in the dequeue window: false
Type:

intc, 1000, 201.

Observe this line in the dequeue window: false
Type:

intc, 1000, 187.

Observe this line in the dequeue window: false
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

Importing This Sample into StreamBase Studio

In StreamBase Studio, import this sample with the following steps:

From the top menu, click File → Load StreamBase Sample.
Select operator from the Data Constructs and Operators category.
Click OK.

StreamBase Studio creates a single project for all the operator samples.

Sample Location

By default, the sample files are installed in:

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 Studio n.m Workspace\
      sample_operator
Windows 7 and Windows Vista:
  C:\Users\username\Documents\StreamBase Studio n.m Workspace\
      sample_operator