Java Doc for StoredFormatIds.java in  » Database-DBMS » db-derby-10.2 » org » apache » derby » iapi » services » io » Java Source Code / Java DocumentationJava Source Code and Java Documentation

An important aspect of the format id concept is that it does not impose an implementation on the stored object. Rather, multiple implementations of an object (or interface) may share a format id. One implementation may store (write) an object and another may restore (read) the object. The implication of this is that a format id specifies the following properties of a stored object.

• The interface(s) the stored object must support. Any implementation which reads the object must support these interfaces.
• The format of the stored object. All implementaions which support the format must be able to read and write it.

An object should implement the Formatable inteface to support a stored format. In addition, the module which contains the object should register the object's class with the Monitor (See FormatIdUtil.register.)

When you add a format id to this file, please include the list of interfaces an implementaion must support when it supports the format id. When Cloudscape code reads a stored form it returns an object of a Class which supports the stored form. A reader may cast this object to any interface listed in this file. It is an error for the reader to cast the object to a class or interface not listed in this file.

When you implement a class that supports a format, add a comment that states the name of the class. The first implementation of a format defines the stored form.

This interface defines all the format ids for Cloudscape software. If you define a format id please be sure to declare it in this file. If you remove support for a one please document that the format id is deprecated. Never remove or re-use a format id.