During the lifecycle of a task instance, the task business data is obtained from various sources, serialized, and stored in the My webMethods Server database. For more information about task data serialization, see About Business Data Fields in the Run-time Environment.

When you modify and republish a task type to the runtime, Task Engine overwrites the existing task type. In the same way, the business data definition, associated with a task type is overwritten each time you change and republish the definition.

To ensure that task business data is available at runtime, the changes you make to the task data definition must conform to the structure of the task data, already serialized in the database. For example, when you use an IS document type for task business data, you can modify that document by adding or removing business data fields. After republishing the IS document type, the business data, created before republishing the IS document type will continue to exists, and will be retrievable by Task Engine.

However, certain changes to the data structure will affect how the data is serialized in the My webMethods Server database, and the business data for task instances, queued before the modification of the data definition will not be available at runtime. For example, when you change the type of an existing business data field in an IS document type, the business data for tasks, queued before the change will become unavailable.

My webMethods Server uses Java object serialization when storing task business data to the database. For more information about the limitations of Java object serialization, see the Java Object Serialization Specification.