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Description

SerialVer4J supports versioning for serialized objects out-of-the-box.

Currently supported formats

• Plain Java Serialization
• Hessian 1 (Deprecated - Better use Hessian 2)
• Hessian 2
• Burlap
• XStream

Note: A good benchmark for JVM Serializers can be found here .

Steps using SerialVer4J

• Classes you want to serialize and deserialize must follow three simple rules:
  1. Make your class Serializable (as you always do)
  2. Give it a unique serialVersionUID (No default UID like 1L!)
  3. Add an instance variable named versionUID that is initialized with the static serialVersionUID.
     Caution: This has to be the first instance field in your class!
• Create a history xml file that contains informations about your archived classes:
  

          <?xml version="1.0" encoding="UTF-8"?>
          <history versionTag="versionUID">  
            <class package="my.test" name="Address">
              <version>
                <serialVersionUID>-7393761964342362874</serialVersionUID>
                <oldClass>my.test.old.address.v1.Address</oldClass>
                <converterClass>my.test.old.address.v1.AddressConverter</converterClass>
              </version>
              <version>
                <serialVersionUID>-2466841694916192299</serialVersionUID>
                <oldClass>my.test.old.address.v2.Address</oldClass>
                <converterClass>my.test.old.address.v2.AddressConverter</converterClass>
              </version>
            </class>
          </history>
      
  

• Serialize your object with one of the supported formats. It's not necessary to use SerialVer4J for this task. You can use any serializer that supports the target format.
• Deserialize the object using SerialVer4J

  Pure Java Example:

          final InputStream in = ... ;
          try {
              // Load the history
              ClassesHistory history = Utils.readFromFile(new File("versions.xml"));
          
              // Create an instance of the deserializer
              VersioningSerializer serializer = new VersioningJavaSerializer(history);
              
              // Returns the current version of the Address object
              Address address = (Address) serializer.deserialize(in);
              
              :
              
          } finally {
              in.close();
          }
      
  

Limitations

Currently only one class (the root class of the serialized object tree) can have an instance variable named versionUID.