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| <h1>Fragments</h1> | |
| <p>A plug-in <b> fragment</b> is used to provide additional | |
| plug-in functionality to an existing plug-in after it has been installed. Fragments are ideal for shipping features like language or | |
| maintenance packs | |
| that typically trail the initial products for a few months. Another | |
| frequent use of fragments is to deliver OS or windowing system-specific | |
| features. When a | |
| fragment is | |
| detected by the platform and its target plug-in is found, the function in | |
| the fragment is "merged" with the original function in the target | |
| plug-in. If you query the plug-in registry, you will see the features | |
| defined in a fragment as if they were contributed by the original plug-in.</p> | |
| <p>While this merging mechanism is good from a runtime point of view, | |
| developers need to view | |
| fragments as separate entities while working on them. Fragment development is | |
| often done by different teams, on a different schedule, sometimes even on | |
| different operating systems from the original plug-in.</p> | |
| <p>PDE provides full support for fragment development. Fragments can be viewed as | |
| "limited plug-ins." They have all of the capability of regular | |
| plug-ins but have no concept of life-cycle. Fragments have no top-level class | |
| with "startup" and "shutdown" methods.</p> | |
| <p>The PDE concept of workspace and external plug-ins turns out to work quite | |
| nicely when developing a fragment. You can work on a fragment whose target is an external plug-in. | |
| Since external plug-ins cannot be changed inside the workbench, the environment | |
| inherently supports the fact that the fragment should be developed without | |
| modifying its target plug-in. </p> | |
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