Chapter 27. Python

Overview

Python is a remarkably powerful dynamic programming language that is used in a wide variety of application domains. Python is often compared to Tcl, Perl, Ruby, Scheme or Java. The Python support is part of the camel-script module.

Adding the script module

To use Python in your routes you need to add a dependency on camel-script to your project as shown in Example 27.1, “Adding the camel-script dependency”.

Example 27.1. Adding the camel-script dependency

<!-- Maven POM File -->
...
<dependencies>
  ...
  <dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-script</artifactId>
    <version>${camel-version}</version>
  </dependency>
  ...
</dependencies>

Static import

To use the python() static method in your application code, include the following import statement in your Java source files: 
import static org.apache.camel.builder.camel.script.ScriptBuilder.*;

Built-in attributes

Table 27.1, “Python attributes” lists the built-in attributes that are accessible when using Python.

Table 27.1. Python attributes

AttributeTypeValue
contextorg.apache.camel.CamelContextThe Camel Context
exchangeorg.apache.camel.ExchangeThe current Exchange
requestorg.apache.camel.MessageThe IN message
responseorg.apache.camel.MessageThe OUT message
propertiesorg.apache.camel.builder.script.PropertiesFunctionFunction with a resolve method to make it easier to use the properties component inside scripts.
The attributes all set at ENGINE_SCOPE.

Example

Example 27.2, “Route using Python” shows a route that uses Python.

Example 27.2. Route using Python

<camelContext>
  <route>
    <from uri="direct:start"/>
    <choice>
      <when>
        <langauge langauge="python">if request.headers.get('user') = 'admin'</langauge>
        <to uri="seda:adminQueue"/>
      </when>
      <otherwise>
        <to uri="seda:regularQueue"/>
      </otherwise>
    </choice>
  </route>
</camelContext>

Using the properties component

To access a property value from the properties component, invoke the resolve method on the built-in properties attribute, as follows: 
.setHeader("myHeader").python("properties.resolve(PropKey)")
Where PropKey is the key of the property you want to resolve, where the key value is of String type.
For more details about the properties component, see Properties in the Apache Camel Component Reference Guide.