Expressions

Expressions and Predicates can then be used to create the various Enterprise Integration Patterns in the DSL like with the Recipient List EIP.

To support dynamic rules Camel supports pluggable Expression strategies using a variety of different Languages.

Expression API

If you are outside the DSL and want to create your own expressions you can either implement the Expression interface, reuse one of the other builders or try the ExpressionBuilder class.

Expression

The API for a Camel Expression is defined in the org.apache.camel.Expression interface as shown:

public interface Expression {

    /**
     * Returns the value of the expression on the given exchange
     *
     * @param exchange the message exchange on which to evaluate the expression
     * @param type the expected type of the evaluation result
     * @return the value of the expression
     */
    <T> T evaluate(Exchange exchange, Class<T> type);
}