Bug 351641

Description Rüdiger Herrmann 2011-07-09 15:46:14 EDT

A serialVersionUID is there to indicate the version of the _serialized form_ of the class in which it is declared. If the serialVersionUID is missing for a serializable class, one is generated. Everywhere its is recommended to use explicit serialVersionUIDs (e.g. in Effective Java 1nd ed., Bloch, p 223).

The generated version is affected by the class's name, the names of the interfaces it implements, and all of its public and protected members. Thus, even a small cange like a convenience method may change the generated version.

As long as they are only used to enable transparent session failover (bug 341761), I tend to omit explicit serialVersionUIDs for serializable classes for these reasons:
* the serialized form is stored for a 'short' term only. Currently, I can hardly imagine that in between serialization and deserialization, a new applications is deployed (and with it the version of the serialized form changes)
* maintaining an explicit serialVersionUID is hard. Each programmer that adds or removes fields from a serializable class must take the serial version into account. We have no quality assurance for this and establishing on is considerable work.
* many serialVersionUID declarations make the source code harder to read

If we decide to omit explicit versions, we would have to state (e.g. in SerializableCompatibility) somewhere that the serializability of classes in RWT isn't meant for general purpose use.