Product Training Program Unit 2 - Dynamic Expressions

Dynamic Expressions

Why Use Expressions? Not all Route configurations will be simple, static content. For configurations to be re-used, a special type of expression will be needed. For configurations to be determined dynamically at runtime, a special type of expression will be needed.

Environment Properties

What is an Environment Property? An Environment Property is a re-usable configuration value defined either globally or per-interface. Environment Properties are referenced by their Keys, or Names, rather than their actual values. They can be thought of as named variables, as they are a similar concept. Environment Properties are very useful for storing settings that differ from development to production machines. Simply changing the property values ensures that every location that uses them will have the correct values.

Transaction Attributes

What are Transaction Attributes? Transaction Attributes are values that are values that are dynamically populated during the execution of a PilotFish Route. Attributes are assigned automatically by many PilotFish modules, and contain metadata on how that module operated. For example, the name of the file picked up by a listener. Attributes can also be assigned manually by Processors during the execution of a Route. Attributes can be used in OGNL Expressions to give components dynamic configurations.

OGNL Expressions

What are OGNL Expressions? OGNL is a special, stripped-down Java syntax that can be used to write complex dynamic expressions that are evaluated at runtime. Any expression possible in the Java language can be done in OGNL, meaning any form of dynamic expression can be populated here. The most common use of OGNL is to use one or more Transaction Attributes to provide dynamic configuration with their values.