Pickling State in the Java System

The JavarMlsystem (hereafter referred to simply as "Java") inherently supports the transmission of stateless computation in the form of object classes. In this paper we address the related task of capturing the state of a Java object in a serialized form for the purposes of transmission or storage, to be used later in reconstituting an equivalent object. This is accomplished by a mechanism known as pickling [Binel et al. 1987; Binell et al. 1994; Herlihy & Liskov 19821. Pickling is the process of creating a serialized representation of objects. Pickling defines the serialized form to include meta information that identifies the type of each object and the relationships between objects within a stream. Values and types are serialized with enough information to insure that the equivalent typed object and the objects to which it refers can be recreated. Unpickling is the complementary process of recreating objects from the serialized representation. Pickling and unpickling extract from the Java Virtual machine, at runtime, any meta information needed to pickle the fields of objects. Class specific methods are only required to customize the pickling process. l. Java and other Java-based names and logos are trademarks of Sun Microsystems, Inc., and refer to Sun's family of Java-branded products and services@ 1997 The USEND( Association, Computing Systems, Vol. 9 . No. 4 . Fall 1996 291