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# HDFS File Writer Output Adapter Samples

## About The Samples

The basic adapter sample illustrates the use of the TIBCO StreamBase® File Writer for Apache Hadoop Distributed File System (HDFS) by taking in a tuple and writing one of its fields contents to a file.

The advanced adapter sample illustrates reading from a sample input file multiple times and writing that data back out in various compression formats.

## Initial Setup

You must also open the `FileWriterBasic.sbapp` or the `FileWriterAdvanced.sbapp` file in the `src/main/eventflow/`packageName`` folder. Select the Parameters tab and edit the value to represent both your current HDFS setup and where you would like to store the sample data.

The `SampleIn.txt` file used in the `FileWriterAdvanced.sbapp` sample must be placed on your HDFS file system before this sample can run.

## Importing This Sample into StreamBase Studio

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

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

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

- Select hdfsfilewriter from the Large Data Storage and Analysis category.

- Click OK.

StreamBase Studio creates a single project containing the sample files.

## Running The Basic 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 `FileWriterBasic.sbapp` file and click the Run button. This opens the SB Test/Debug perspective and starts the module.

4. In the Manual Output view, switch the `Stream` to `Data`, then enter a string value such as 'test', and then click Send Data to send a data tuple to be written to the file. Repeat for as many lines as you wish.

5. In the Output Streams view, observe tuples emitted on the `Status` output streams indicating actions performed to the file.

6. In the Manual Output view, switch the `Stream` to `Control`, then enter 'Close' into the `Command` field, and then click Send Data to send a control tuple which will close the current file for writing.

7. Press F9 or click the Terminate EventFlow Fragment button.

8. This demo will have now created a file in your project called `SampleOut.txt` containing the lines of data you submitted.

## Running The Advanced 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 `FileWriterAdvanced.sbapp` file and click the Run button. This opens the SB Test/Debug perspective and starts the module.

4. In the Output Streams view, observe tuples emitted on the `Status` output streams indicating actions performed to the files.

5. Press F9 or click the Terminate EventFlow Fragment button.

6. This demo will have now created multiple files in your project:

   1. `Sample.gz` - This file is a GZip compressed file created from the `SampleIn.txt` file.

   2. `Sample.gz2` - This file is a BZip2 compressed file created from the `SampleIn.txt` file.

   3. `Sample.zip` - This file is a Zip compressed file created from the `SampleIn.txt` file.

   4. `SampleOut.txt` - This file is a un-compressed file created from the `SampleIn.txt` file.

## 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_hdfsfilewriter

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