Loop Sample

Introduction

This sample application takes input from a provided feed simulation. It splits incoming trades into smaller trades of qty = split_size and, if necessary, adds an additional trade for the remainder of qty/split_size. The filter operator is a required part of creating a conditional loop.

Arcs usually take their schemas from upstream operators. But the arc that creates the loop in loop.sbapp requires an explicit schema. As a best practice, when possible, re-use the named schema from the incoming stream (in this case, InputStream) for the looping arc's schema.

Running This Sample 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 your Studio workspace copy of the sample.
In window 1, launch StreamBase Server on loop.sbapp:

sbd loop.sbapp
In window 2, dequeue from the running application's output port:

sbc dequeue
In window 3, start the feed simulation:

sbfeedsim loop-feedsim.sbfs
Observe the tuples emitted from the LittleTradesOut stream.
When done, type the following commands in window 3 to terminate the feed simulation, server, and dequeuer:

Ctrl+C (to terminate the feed simulation)

sbadmin shutdown

Importing This Sample into StreamBase Studio

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

From the top menu, select File → Load StreamBase Sample.
Type loop in the search field to narrow the list of choices.
From the Applications category, select loop.
Click OK.

StreamBase Studio creates a project for the sample.

Sample Location

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_loop

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/loop

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.