Services vs. Distributed Objects

Even after fairly large implementations of web services and wide spread adoption of services, services still compared with distributed objects. This entry is dedicated to highlight differences between services and distributed objects.

1. Distributed objects are designed to operate in corporate intranet environment while services are for internet.

2. Distributed objects boasts object’s life cycle which can be summarized as:
a. Upon request, a factory instantiates the object;
b. The consumer who requested the instantiation performs operations on the object instance; and
c. Later, either the consumer releases the instance or the runtime system garbage-collects it.

A special case is the singleton object, which does not go through this cycle. In both the cases, the object is identified through a reference that can be passed between processes to provide a access mechanism for it. Objects often contain references to other objects, and distributed object technology comes with exhaustive reference-handling techniques to manage objects’ lifecycle.
Service does not feature object like lifecycle, factory, garbage collection, etc.
3. The flow of information among distributed objects is very closed and only understood by objects of same type (say RMI, DCOM, CORBA, etc). But in services information exchange is done using XML or some derivative of XML.