Redstream Blog » JAXB http://blog.redstream.nl Pragmatic Integrators Mon, 26 Jul 2010 06:09:45 +0000 en hourly 1 http://wordpress.org/?v=4286 Create your own Expression Evaluator in Mule http://blog.redstream.nl/2010/01/02/create-your-own-expression-evaluator-in-mule/ http://blog.redstream.nl/2010/01/02/create-your-own-expression-evaluator-in-mule/#comments Sat, 02 Jan 2010 07:08:31 +0000 Pascal Alma http://blog.redstream.nl/?p=1562 Although there are a lot of evaluators available in Mule CE it is very easy to add your own evaluator. In my case we have a self defined message format that holds some properties in the header of a message (similar to JMS Message, MuleMessage, etc.). To get access to these properties in the Mule config I created a custom evaluator that made this possible. Although there will be other solutions available for this situation, I found this a nice (pragmatic) way to solve it. It also provides a base to start from in case of possible changes in the future.
The XML schema that describes our message looks like:

PLAIN TEXT
XML:
  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <xs:schema xmlns:tns="http://www.redstream.nl/message/v01_0"
  3.            xmlns:xs="http://www.w3.org/2001/XMLSchema"
  4.            targetNamespace="http://www.redstream.nl/message/v01_0"
  5.            elementFormDefault="qualified">
  6.     <xs:element name="message" type="tns:MessageType"/>
  7.     <xs:complexType name="MessageHeaderType">
  8.         <xs:annotation>
  9.             <xs:documentation>The header for a message. Contains all metadata about the message.</xs:documentation>
  10.         </xs:annotation>
  11.         <xs:sequence>
  12.             <xs:element name="messageVersion" type="tns:versionNumberType" minOccurs="1" maxOccurs="1"/>
  13.             <xs:element name="PropertySet" type="tns:PropertySetType" minOccurs="0" maxOccurs="1"/>
  14.         </xs:sequence>
  15.     </xs:complexType>
  16.     <xs:complexType name="MessageType">
  17.         <xs:sequence>
  18.             <xs:element name="MessageHeader" type="tns:MessageHeaderType" minOccurs="1" maxOccurs="1"/>
  19.             <xs:element name="MessageBody" type="tns:MessageBodyType" minOccurs="0" maxOccurs="1"/>
  20.         </xs:sequence>
  21.     </xs:complexType>
  22.     <xs:complexType name="MessageBodyType">
  23.         <xs:sequence>
  24.             <xs:any minOccurs="0" maxOccurs="1"/>
  25.         </xs:sequence>
  26.     </xs:complexType>
  27.     <xs:complexType name="PropertyType">
  28.         <xs:attribute name="key" type="xs:string" use="required"/>
  29.         <xs:attribute name="value" type="xs:string"/>
  30.     </xs:complexType>
  31.     <xs:complexType name="PropertySetType">
  32.         <xs:annotation>
  33.             <xs:documentation>Set of properties</xs:documentation>
  34.         </xs:annotation>
  35.         <xs:sequence>
  36.             <xs:element name="Property" type="tns:PropertyType" minOccurs="0" maxOccurs="unbounded"/>
  37.         </xs:sequence>
  38.     </xs:complexType>
  39.     <xs:simpleType name="versionNumberType">
  40.         <xs:annotation>
  41.             <xs:documentation>Type used to define a Message versionNumber</xs:documentation>
  42.         </xs:annotation>
  43.         <xs:restriction base="xs:string">
  44.             <xs:pattern value="v[0-9]{2}_[0-9]{1}"/>
  45.             <xs:length value="5"/>
  46.         </xs:restriction>
  47.     </xs:simpleType>
  48. </xs:schema>

And example message looks like this:

PLAIN TEXT
XML:
  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <tns:message xsi:schemaLocation="http://www.redstream.nl/message/v01_0 message_v01_0.xsd" xmlns:tns="http://www.redstream.nl/message/v01_0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  3.     <tns:MessageHeader>
  4.         <tns:messageVersion>v01_0</tns:messageVersion>
  5.         <tns:PropertySet>
  6.             <tns:Property key="SOURCE_SYSTEM" value="CRM" />
  7.             <tns:Property key="ENTITY" value="Order" />
  8.             <tns:Property key="VERSION" value="v01_0" />
  9.         </tns:PropertySet>
  10.     </tns:MessageHeader>
  11.     <tns:MessageBody>
  12.             <payload-root>Blablabla</payload-root>
  13.         </tns:MessageBody>
  14. </tns:message>

To get access to the 'Property' elements in the message-header via an 'evaluator expression' I created the following Java class based on the info given here:

PLAIN TEXT
JAVA:
  1. package nl.redstream.evaluator;
  2.  
  3. import nl.redstream.cdm.util.JaxbUtil;
  4. import java.util.List;
  5. import javax.xml.bind.JAXBException;
  6. import nl.redstream.message.v01_0.Message;
  7. import nl.redstream.message.v01_0.PropertySetType;
  8. import nl.redstream.message.v01_0.PropertyType;
  9. import org.apache.log4j.Logger;
  10. import org.mule.api.MuleMessage;
  11. import org.mule.api.expression.ExpressionEvaluator;
  12. import org.mule.api.expression.RequiredValueException;
  13. import org.mule.config.i18n.CoreMessages;
  14.  
  15. /**
  16. *
  17. * @author pascal
  18. */
  19. public class CdmMessageEvaluator implements ExpressionEvaluator {
  20.  
  21.     public static final String NAME = "cdm-msg-property";
  22.    
  23.     protected static Logger logger = Logger.getLogger(CdmMessageEvaluator.class);
  24.  
  25.     public Object evaluate(String expression, MuleMessage msg) {
  26.         Object result = null;
  27.  
  28.         boolean required;
  29.  
  30.         //Is the header optional? the '*' denotes optional
  31.         if (expression.endsWith("*")) {
  32.             expression = expression.substring(expression.length() - 1);
  33.             required = false;
  34.         } else {
  35.             required = true;
  36.         }
  37.  
  38.         Message cdmMsg = null;
  39.         //Look up the property on the message
  40.         if (msg.getPayload() instanceof Message)
  41.         {
  42.             cdmMsg = (Message) msg.getPayload();
  43.         } else if (msg.getPayload() instanceof String)
  44.         {
  45.             try {
  46.                 // Apparantly we are getting the message as an XML String
  47.                 // So use jaxb to create a Object of it
  48.                 cdmMsg =
  49.                         JaxbUtil.unmarshal(Message.class,
  50.                         msg.getPayload().toString());
  51.             } catch (JAXBException ex) {
  52.                 throw new UnsupportedOperationException("Unexpected String input received (not a Ship Message)");
  53.             }
  54.  
  55.         } else {
  56.             // It's not an expected payload. Fail this operation.
  57.              throw new UnsupportedOperationException("Unexpected inputtype received: " + msg.getPayload().getClass().getName());
  58.         }
  59.  
  60.         result = getProperty(cdmMsg.getMessageHeader().getPropertySet(),expression.toUpperCase());
  61.  
  62.         if (result == null && required) {
  63.             throw new RequiredValueException(CoreMessages.expressionEvaluatorReturnedNull(NAME, expression));
  64.         }
  65.         return result;
  66.     }
  67.  
  68.     public String getName() {
  69.         return NAME;
  70.     }
  71.  
  72.     public void setName(String name) {
  73.         throw new UnsupportedOperationException("setName");
  74.     }
  75.  
  76.     private String getProperty(PropertySetType propertySet, String property)
  77.     {
  78.         List<PropertyType> props = propertySet.getProperties();
  79.  
  80.         String value = null;
  81.         for (PropertyType prop: props) {
  82.              if (prop.getKey().toUpperCase().equals(property))
  83.              {
  84.                  value = prop.getValue();
  85.                  break;
  86.              }
  87.         }
  88.         return value;
  89.     }
  90. }

I think the code is fairly straightforward. In the method 'evaluate' I receive the payload of the MuleMessage and I check to see if the payload is a JAXBObject of the type Message. If it is a String I assume I receive the XML message as payload and transform the String to the expected JAXB object myself (see this post for more details about this subject).
When I have access to the JAXBObject I simply question the properties of the message for the property name that is supplied with the expression. If a value is found this is returned by the expression.
To make use of this evaluator I 'bootstrapped' it with the Mule application. This can simply be done by adding the file 'registry-bootstrap.properties' to your classpath in the folder 'META-INF/services/org/mule/config' (as explained here). In this file I put:

PLAIN TEXT
CODE:
  1. object.1=nl.redstream.evaluator.CdmMessageEvaluator

And that's it. To make use of this evaluator I have in my Mule config:

PLAIN TEXT
XML:
  1. <expression-recipient-list-router evaluator="custom" custom-evaluator="cdm-msg-property" expression="ADDR_LIST" transformer-refs="JaxbObjectToCdmXml">

This will take the property 'ADDR_LIST' out of my Message and use it as outbound Endpoint, but I will explain that in another post.

]]> http://blog.redstream.nl/2010/01/02/create-your-own-expression-evaluator-in-mule/feed/ 1 Mule2, CXF and serializable classes http://blog.redstream.nl/2009/07/01/mule2-cxf-and-serializable-classes/ http://blog.redstream.nl/2009/07/01/mule2-cxf-and-serializable-classes/#comments Wed, 01 Jul 2009 19:25:17 +0000 Pascal Alma http://www.pascalalma.net/?p=890 This post is one of the series of posts about issues that occurred when we were using Mule2 in a real life project. As I wrote in my last post we were using CXF to call a webservice with Mule. After the issues we ran into as described in that article, we ended up with the folowing issue. The generated classes that are used for the XML to Java mapping has to be serializable. This is possible by using a binding file when generating the classes with Maven as described in the documentation here.
However, I haven't been able to do this in my situation. And according to this post I am not the only one. So to keep the project moving I decided to make use of Metro JAX-WS instead of CXF, since this CXF thing had cost us enough of our precious time. With the Metro implementation we had it running in no time without any unexpected issues.

]]> http://blog.redstream.nl/2009/07/01/mule2-cxf-and-serializable-classes/feed/ 2 Mule2 and the IllegalArgumentException http://blog.redstream.nl/2009/06/24/mule2-and-the-illegalargumentexception/ http://blog.redstream.nl/2009/06/24/mule2-and-the-illegalargumentexception/#comments Wed, 24 Jun 2009 19:47:20 +0000 Pascal Alma http://www.pascalalma.net/?p=863 This is the first of a series of short posts about issues we had when using Mule2 in a real project. The first issue I want to mention is the IllegalArgumentException. When we first ran into this exception we hadn't really a clue where to look for the solution. After some investigation it appeared that the exception is raised when a components operation is called with the wrong type of argument.
Most likely this error:

Root Exception stack trace:
java.lang.IllegalArgumentException: argument type mismatch
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.mule.transport.cxf.CxfMessageDispatcher.doSendWithProxy(CxfMessageDispatcher.java:176)
...

will occur if you forget to use a translator or the translator you configured doesn't work as expected as was the case in our situation. We are receiving an XML file as a JMS message and wanted to translate this XML file to a Java object that we used as argument in our component. For the XML to Java translation we were relying on the default xml-to-object-translator. However we only got it working by using a custom translator that is using Jaxb2 for the translation as I described here.

]]> http://blog.redstream.nl/2009/06/24/mule2-and-the-illegalargumentexception/feed/ 0 Generating JAXB2 with Maven2 http://blog.redstream.nl/2009/04/10/generating-jaxb2-with-maven2/ http://blog.redstream.nl/2009/04/10/generating-jaxb2-with-maven2/#comments Fri, 10 Apr 2009 20:09:15 +0000 Pascal Alma http://www.pascalalma.net/?p=740 I have blogged before about how to generate JAXB binding classes based on your WSDL file, this time I wanted to generate JAXB classes based on just XSD files. Although I expected this to be simple, it took me quite some time to get it right, so I decided to give this item its own post :-)
I have got the following schema 'customer.xsd' that I want to bind to Java classes:

PLAIN TEXT
XML:
  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
  3.     targetNamespace="http://www.pascalalma.net/schema/customer"
  4.     xmlns:tns="http://www.pascalalma.net/schema/customer"
  5.     elementFormDefault="qualified">
  6.  
  7.     <xsd:element name="customer">
  8.         <xsd:complexType>
  9.             <xsd:sequence>
  10.                 <xsd:element name="id" type="tns:idType" />
  11.                 <xsd:element name="name"  type="tns:nameType" />
  12.                 <xsd:element name="address" type="tns:addressType" />
  13.             </xsd:sequence>
  14.         </xsd:complexType>
  15.     </xsd:element>
  16.     <xsd:simpleType name="idType">
  17.         <xsd:restriction base="xsd:positiveInteger">
  18.             <xsd:minInclusive value="1"/>
  19.             <xsd:maxInclusive value="9999999999"/>
  20.         </xsd:restriction>
  21.     </xsd:simpleType>
  22.     <xsd:simpleType name="nameType">
  23.         <xsd:restriction base="xsd:string">
  24.             <xsd:minLength value="1"/>
  25.             <xsd:maxLength value="128"/>
  26.         </xsd:restriction>
  27.     </xsd:simpleType>
  28.     <xsd:simpleType name="addressType">
  29.         <xsd:restriction base="xsd:string">
  30.             <xsd:minLength value="1"/>
  31.             <xsd:maxLength value="255"/>
  32.         </xsd:restriction>
  33.     </xsd:simpleType>
  34. </xsd:schema>

I have added this schema to my /main/resources/ directory in my Maven project. The generated JAXB objects will be used in an EJB class called 'CustomerLogger'. The class looks like:

PLAIN TEXT
JAVA:
  1. package net.pascalalma.services;
  2.  
  3. import javax.ejb.Stateless;
  4. import net.pascalalma.schema.customer.Customer;
  5.  
  6. /**
  7. *
  8. * @author pascal
  9. */
  10. @Stateless
  11. public class CustomerLogger implements CustomerLoggerRemote {
  12.  
  13.     public void log(Customer cust)
  14.     {
  15.         System.out.println("################################");
  16.  
  17.         System.out.println("# Name:" + cust.getName());
  18.         System.out.println("# Address + " +cust.getAddress());
  19.  
  20.         System.out.println("################################");
  21.     }
  22. }

and the corresponding interface:

PLAIN TEXT
JAVA:
  1. package net.pascalalma.services;
  2.  
  3. import javax.ejb.Remote;
  4. import net.pascalalma.schema.customer.Customer;
  5.  
  6. /**
  7. *
  8. * @author pascal
  9. */
  11. public interface CustomerLoggerRemote {
  12.  
  13.     void log(Customer cust);
  14. }

I also created a test class that tests the JAXB marshalling and unmarshallig (only for this case, I don't think you normally want to test that) and the CustommerLogger EJB class. It looks like this:

PLAIN TEXT
JAVA:
  1. package net.pascalalma.services;
  2.  
  3. import java.io.StringReader;
  4. import java.io.StringWriter;
  5. import java.io.Writer;
  6. import javax.xml.bind.JAXBContext;
  7. import javax.xml.bind.JAXBElement;
  8. import javax.xml.bind.JAXBException;
  9. import javax.xml.bind.Marshaller;
  10. import javax.xml.bind.Unmarshaller;
  11. import javax.xml.transform.Source;
  12. import javax.xml.transform.stream.StreamSource;
  13. import net.pascalalma.schema.customer.Customer;
  14.  
  15. import net.pascalalma.schema.customer.ObjectFactory;
  16. import org.junit.After;
  17. import org.junit.Before;
  18. import org.junit.Test;
  19.  
  20. /**
  21. *
  22. * @author pascal
  23. */
  24. public class CustomerLoggerTest extends EJBTestBase {
  25.  
  26.     private CustomerLoggerRemote cl = null;
  27.  
  28.     @Before
  29.     public void setUpTest() throws Exception {
  30.         cl = (CustomerLoggerRemote) context.lookup("CustomerLoggerRemote");
  31.     }
  32.  
  33.     @After
  34.     public void tearDownTest()
  35.             throws Exception {
  36.         cl = null;
  37.     }
  38.  
  39.     @Test
  40.     public void logTest() throws Exception {
  41.  
  42.         cl.log(getTestCustomerObject());
  43.  
  44.     }
  45.  
  46.     @Test
  47.     public void unmarshalTest() throws JAXBException {
  48.         JAXBContext jaxbContext = JAXBContext.newInstance(Customer.class);
  49.         Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
  50.  
  51.         Source ss = new StreamSource(new StringReader(getTestCustomerXml()));
  52.  
  53.         JAXBElement<customer> root = unmarshaller.unmarshal(ss, Customer.class);
  54.  
  55.         Customer c1 = root.getValue();
  56.  
  57.         assert c1 != null;
  58.         assert c1.getId() == getTestCustomerObject().getId();
  59.         assert c1.getName().equals(getTestCustomerObject().getName());
  60.         assert c1.getAddress().equals(getTestCustomerObject().getAddress());
  61.     }
  62.  
  63.     @Test
  64.     public void marshallTest() throws JAXBException {
  65.         JAXBContext jaxbContext = JAXBContext.newInstance(Customer.class);
  66.         Marshaller m = jaxbContext.createMarshaller();
  67.  
  68.  
  69.         Writer sw = new StringWriter();
  70.  
  71.         m.marshal(getTestCustomerObject(), sw);
  72.  
  73.         String result = sw.toString();
  74.  
  75.         assert result.length()> 0;
  76.         assert result.indexOf("Palma IT")> 0;
  77.         assert result.indexOf("Papendrecht")> 0;
  78.     }
  79.     private String getTestCustomerXml() {
  80.         return "<customer xmlns=\"http://www.pascalalma.net/schema/customer\">\n" +
  81.                 "\t<id>1</id>\n" +
  82.                 "\t<name>Palma IT</name>\n" +
  83.                 "\t<address>Papendrecht, Holland</address>\n" +
  84.                 "</customer>\n";
  85.     }
  86.  
  87.     private Customer getTestCustomerObject() {
  88.         ObjectFactory of = new ObjectFactory();
  89.  
  90.         Customer ct = of.createCustomer();
  91.         ct.setId(1);
  92.         ct.setAddress("Papendrecht, Holland");
  93.         ct.setName("Palma IT");
  94.  
  95.         return ct;
  96.     }
  97. }

Next is setting up the correct plugin in your pom like this:

PLAIN TEXT
XML:
  1. <plugin>
  2.   <groupId>org.jvnet.jaxb2.maven2</groupId>
  3.   <artifactId>maven-jaxb2-plugin</artifactId>
  4.   <executions>
  5.     <execution>
  6.       <goals>
  7.         <goal>generate</goal>
  8.       </goals>
  9.     </execution>
  10.   </executions>
  11.   <configuration>
  12.     <schemaDirectory>src/main/resources/schemas</schemaDirectory>
  13.     <readOnly>true</readOnly>
  14.     <removeOldOutput>true</removeOldOutput>
  15.     <verbose>false</verbose>
  16.     <extension>true</extension>
  17.     <bindingIncludes>
  18.        <bindingInclude>jaxb-bindings.xml</bindingInclude>
  19.     </bindingIncludes>
  20.   </configuration>
  21. </plugin>

As you can see I am reffering to a specific binding file to be used: 'jaxb-bindings.xml'. This file is used to make the generated objects 'serializable' (I described similar situation here). The complete pom can be found here.

If all this is in place you can test your setup by performing
mvn clean install.
Here is my complete project structure:

While putting up this project I ran into several issues:

  • First make sure you have the right plugin

    • You should be using this one for JAXB2 and not this one which is for JAXB.

  • Second please note the differences in including JAXB binding file

    • As I set before I did the same thing before using JAXWS plugin, but the syntax of including the binding file and the content of the binding file is a little different in this case, so make sure you are aware of that. I wasn't and it took some time to figure it all out.

  • Last issue had to do with my xsd syntax

    • Originally I had the following syntax in my XSD file:

    PLAIN TEXT
    XML:
    1. ...
    2.  <xsd:element name="customer" type="tns:customerType" />
    3.     <xsd:complexType name="customerType">
    4.         <xsd:sequence>
    5.             <xsd:element name="id" type="tns:idType" />
    6.             <xsd:element name="name"  type="tns:nameType" />
    7.             <xsd:element name="address" type="tns:addressType" />
    8.         </xsd:sequence>
    9.     </xsd:complexType>
    10. ...

    But that caused the following exception:

    com.sun.istack.SAXException2: unable to marshal type "net.pascalalma.schema.customer.CustomerType" as an element because it is missing an @XmlRootElement annotation

    The cause for this issue is described here and it made me to redefine my xsd in the one I showed at top of this post.

]]> http://blog.redstream.nl/2009/04/10/generating-jaxb2-with-maven2/feed/ 2