Helper Applications
update June 22, 2015

For technical details on how Helper Applications are implemented in BIRCH, go to HelperAppsTechnical.html

Rationale: BioLegato uses a variety of helper applications to display output from programs. For example, if output is text, a text editor is called. If the output is PDF, a PDF viewer (eg. Adobe Reader) is called. If output is a web page, a web browser (eg. Firefox) is called.

Because the choice of helper programs varies from system to system and platform to platform, the BIRCH installer checks to see which programs are actually on your system when BIRCH is installed, and chooses a default viewer for each type of file.

Customizing Helper Applications: You can customize the choice of Helper Applications using the BIRCH Admin Tool. From the BIRCH Launcher choose File --> birchadmin to launch the Administration Tool.

Alternatively, you can launch the Administration tool from the command line by typing 'birchadmin'.

In the Adminstration Tool, choose Edit --> BLHelper

Note that for each type of file, there is a pull-down menu from which you can choose from a variety of programs for a given task. Of the possible choices, only those actually on your system will appear in the menu. The Test button tries to run the program using a sample file. When you are satisfied, with a choice, click on Save to apply your change.

Example: Changing the default PDF viewer

On Linux systems, the default PDF viewer is Evince. To change that choice to Adobe Reader, choose Adobe Reader.

Make sure to test your choice by clicking on the Test button. If a sample PDF file appears on the screen, then your new choice works.

Finally, Click on Save to save your change.

Example: Using custom commands

For each of the major platforms (eg. Mac OSX, Linux), BLHelper has a list of programs known to be available for that platform. However, if a program is not seen in the menu, you can still launch it using a Custom Command. For example, on Mac OSX, to tell BioLegato to use the Opera web browser, to to the Web Browser line and set 'Custom command'. Type the command to execute Opera in the white box.
Make sure to Test your command, and then Save it to apply the change.

This example illustrates a point specific for MacOSX. On OSX, most desktop applications are packaged as Apps. For example, Opera would be found in a folder called /Applications/  Apps are run using the open command with the -a option. Thus, the command to run is 'open -a Opera'.

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