[CONF] Apache Camel > Expression

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_expression_ Page edited by Claus Ibsen Changes (4) h2. Expressions Expressions and [Predicates|Predicate] can then be used to create the various [Enterprise Integration Patterns|Enterprise Integration Patterns] in the [DSL] or [Xml Configuration] like the [Recipient List]. To support dynamic rules Camel supports pluggable [_expression_|http://camel.apache.org/maven/current/camel-core/apidocs/org/apache/camel/_expression_.html] strategies using a variety of different [Languages]. Expressions and [Predicates|Predicate] can then be used to create the various [Enterprise Integration Patterns|Enterprise Integration Patterns] in the [DSL] or [Xml Configuration] like the [Recipient List]. h3. API If you are outside of the [DSL] and want to create your own expressions you can either implement the [_expression_ interface|http://camel.apache.org/maven/current/camel-core/apidocs/org/apache/camel/_expression_.html], reuse one of the other builders or try the [ExpressionBuilder class|http://camel.apache.org/maven/current/camel-core/apidocs/org/apache/camel/builder/ExpressionBuilder.html]. h4. _expression_ The API for a Camel _expression_ is defined in the {{org.apache.camel._expression_}} interface as shown: {code} 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); } {code} h4. Predicate The API for a Camel Predicate is defined in the {{org.apache.camel.Predicate}} interface as shown: {code} public interface Predicate { /** * Evaluates the predicate on the message exchange and returns true if this * exchange matches the predicate * * @param exchange the message exchange * @return true if the predicate matches */ boolean matches(Exchange exchange); } {code} h3. _expression_ Languages The following languages are supported out of the box ... Full Content Expressions Expressions and Predicates can then be used to create the various Enterprise Integration Patterns in the DSL or Xml Configuration like the Recipient List. To support dynamic rules Camel supports pluggable _expression_ strategies using a variety of different Languages. API If you are outside of 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); } Predicate The API for a Camel Predicate is defined in the org.apache.camel.Predicate interface as shown: public interface Predicate { /** * Evaluates the predicate on the message exchange and returns true if this * exchange matches the predicate * * @param exchange the message exchange * @return true if the predicate matches */ boolean matches(Exchange exchange); } _expression_ Languages The following languages are supported out of the box Bean Language for using Java for expressions Constant the unified EL from JSP and JSF Header JXPath Mvel OGNL Ref Language Property Scripting Languages such as BeanShell _javascript_ Groovy Python PHP Ruby Simple File Language Spring _expression_ Language SQL Tokenizer XPath XQuery VTD-XML Most of these languages is also supported used as Annotation Based _expression_ Language. Using Expressions in your IDE To use different _expression_ and predicates in your IDE you need to perform a static import of the builder class for the language(s) you wish to use. Language(s) Builder class to import Scripting Languages such as BeanShell, _javascript_, Groovy, PHP, Python and Ruby org.apache.camel.builder.script.ScriptBuilder SQL org.apache.camel.builder.josql.SqlBuilder XPath org.apache.camel.builder.xml.XPathBuilder XQuery org.apache.camel.builder.saxon.XQueryBuilder See Also Predicate Change Notification Preferences View Online | View Changes | Add Comment