To address the need for site-specific extensions the App Services Integration iApp has been designed to allow inclusion of custom code. Custom extensions have full access to the runtime environment of the implementation layer allowing both addition of new functionality, or modification of existing functionality. There are 6 specific points at which a user can execute custom code:

• The start of the deployment
• Before creation of the pools
  • Before creation of each pool
  • After creation of each pool
• After creation of the pools
• Before creation of the virtual servers
  • Before creation of each virtual server
  • After creation of each virtual server
• After creation of the virtual servers
• At the end of the deployment

While custom extensions have full access to all variable values passed from the presentation layer during deployment, any new functionality that requires user input should utilize the fields in the ‘Custom Extensions’ section. Three Extension fields are provided with the base template for this purpose. This lab will walk through some of the included Custom Extension samples to provide a general overview of the functionality. Custom Extensions are contained in the custom_extensions.tcl file. This file is automatically included into the template when it is built via the build scripts.

1. Review the comments in the custom_extensions.tcl file to see how it is structured.

2. Monitor the deployment log and modify one of your existing deployments to include the string

   custom_example=1
   

   in the Extensions: Field 1. Do you see the log messages that are generated in the deployment log?