Mobile Objects

Mobile objects, sometimes called mobile agents, are bits of code that can move to another execution site (presumably on a different machine) under their own programmatic control, where they can then efficiently interact with the local environment. Commercial instantiations of this technology include Aglets from IBM, Concordia from Mitsubishi, and Voyager from ObjectSpace.

For certain types of problems, the mobile object paradigm offers advantages over more traditional distributed object approaches. These advantages include

• Network bandwidth: for some database queries or electronic commerce applications, it is more efficient to perform tests on data by bringing the tests to the data than by bringing large amounts of data to the testing program.
• Parallelism: mobile agents can be spawned in parallel to accomplish many tasks at once.

Disadvantages (or inconveniences) of the mobile agent approach are that

• In a fashion similar to that of DOOP programming, an agent developer must programmatically specify where to go and how to interact with the target environment.
• There is generally little coordination support to encourage interactions among multiple (mobile) participants.
• Agents must be written in the programming language supported by the execution environment, whereas many other distributed technologies support heterogeneous communities of components, written in diverse programming languages.