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6. Class Enhancement > Binary Compatibility

Binary Compatibility

The standard enhancement interface defined by the JDO reference-enhancement contract provides binary compatibility among all enhancers and runtime environments. It requires that:

  • A class enhanced by the reference enhancer is usable with any JDO-compliant runtime environment.

  • A class enhanced by a JDO-compliant vendor’s enhancer is usable by the reference implementation’s runtime environment.

  • A class enhanced by a JDO-compliant vendor’s enhancer is usable by any other JDO-compliant runtime environment.

Furthermore, an enhanced class file can be shared concurrently in a JVM among several coresident JDO implementations.

An implementation’s runtime environment can determine whether a class was enhanced by its own enhancer. If it has, the implementation’s runtime environment can use any implementation-specific enhancements that were placed in the class file. Otherwise, it must use the standard reference-enhancement interface contract. Table 6-1 shows which enhancement interface a JDO runtime environment will use, based on the enhancer used to enhance the class.


  

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