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IBM developerWorks: Introduction to Bonobo: Bonobo & ORBit

Sep 09, 2001, 16:03 (4 Talkback[s])
(Other stories by Michael Meeks)
"Large-scale software is hard to write in a monolithic fashion. Inevitably, designs are broken into subparts and layers to make the software more manageable and tractable to parallel-team development and debugging. Also inevitably, however, there are problems at the interfaces: Often the interfaces are not well specified, and often they are subject to change. Another problem is that large applications tend to be split into modules that require hard build-time linkage together, whether as separate source modules or as libraries. Furthermore, large pieces of software have often evolved into huge unwieldy beasts that become impossible to maintain or extend.

Component software is one solution to this traditional problem. Component software is not monolithic in the least; on the contrary, it is minimalist. In Bonobo we use the OMG's IDL (Interface Definition Language) to codify the contract between components, providing an easy-to-understand overview of a component's external obligations. Bonobo also allows out-of-process components. This means that a huge piece of software can be pulled in as a component or automated without any nightmarish symbol mismatches. At the same time, it allows many bugs in a complex multi-component system to be easily isolated to a certain component. Similarly, this out-of-processes operation makes the stability of a multi-component system a constant: that of the container, rather than scaling linearly with the number of components (assuming that the container can sensibly handle subcomponent failure).

Using Bonobo also solves one of the tricky problems in Free Software that is also one of its strengths: diversity. Often in the Free world (and in the non-Free world as well, for that matter), people cease maintaining projects due to time pressure, and replacements are rewritten from scratch. Or again, competing projects, such as CD player applications, arise. Allowing these applications to share the same Bonobo interfaces makes it easy to provide functional replacements, and tracing the entry points allows you to better understand an old application."

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