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# Once Input Adapter Sample

## Introduction

This sample demonstrates the TIBCO StreamBase® Once Input Adapter, an input adapter that starts up and sends a single tuple as its output.

## Importing This Sample into StreamBase Studio

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

- From the top-level menu, click File → Load StreamBase Sample.

- Enter `once` to narrow the list of options.

- Select Once input adapter from the StreamBase Standard Adapters category.

- Click OK.

StreamBase Studio creates a single project containing the sample files.

## Running This Sample in StreamBase Studio

1. In the Project Explorer view, open the sample you just loaded.

   If you see red marks on a project folder, wait a moment for the project to load its features.

   If the red marks do not resolve themselves after a minute, select the project, right-click, and select Maven → Update Project from the context menu.

2. Open the `src/main/eventflow/`packageName`` folder.

3. Open the `Once.sbapp` file and click the Run button. This opens the SB Test/Debug perspective and starts the module.

4. The Output Streams view shows the timestamp tuple that is sent on startup as output.

5. When done, press F9 or click the Terminate EventFlow Fragment button.

## About This Sample and Terminal Windows

The Once adapter cannot be demonstrated using terminal windows, because it sends its single tuple as soon as the application starts in StreamBase Server. By the time we might be able to start a dequeue session to see the output on `OutputStream1`, the single tuple event has already occurred.

## 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 permission problems. The default workspace location for this sample is:

    studio-workspace/sample_adapter_embedded_once

See Default Installation Directories for the default location of `studio-workspace` on your system.