Documentation for Ice 3.6. The documentation for Ice 3.5 and Ice 3.4 is available in separate spaces.

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Inserting a User Exception in Java

As in the case of Ice objects, a Dynamic Ice application may represent user exceptions in a native format that is not directly compatible with the Ice API. If the application needs to raise such a user exception to the Ice run time, the exception must be wrapped in a subclass of Ice.UserException. The Dynamic Ice API provides a class to simplify this process:


A subclass of UserExceptionWriter is responsible for supplying a communicator to the constructor, and for implementing the following methods:

Extracting a User Exception in Java

An application extracts a user exception by calling one of two versions of the throwException method defined in the InputStream class:


The version without any arguments attempts to locate and throw a Java implementation of the encoded exception using classes generated by the Slice-to-Java compiler.

If your goal is to create an exception in another type system, such as a native PHP exception object, you must call the second version of throwException and pass an implementation of UserExceptionReaderFactory:


As the stream iterates over slices of an exception from most-derived to least-derived, it invokes createAndThrow passing the type ID of each slice, giving the application an opportunity to raise an instance of UserExceptionReader:


Subclasses of UserExceptionReader must implement the abstract functions. In particular, the implementation of read must call InputStream.startException, unmarshal the remaining slices, and then call InputStream.endException.

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