Microsoft SAX2 COM Implementation
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4/8/2010
As its name states, SAX2 is a simple application programming interface (API) for XML parsers. Microsoft provides a version of this API to use with its parser, the Microsoft® XML Parser (MSXML). This API offers fewer than a dozen interfaces that you can implement to create SAX2 applications for reading and processing XML documents. These interfaces map as closely as possible to the publicly developed, Java language-based SAX2.
Mapping Java Language Interfaces to COM/C++
Implementing the SAX Java language-based interfaces within a COM/C++ environment presents some challenges. In general, the following guidelines are followed.
- Java language conventions are mapped to COM/C++ conventions as closely as possible.
- Errors and abnormal conditions are returned in COM through return codes (HRESULTs). Additional fields provided by derived exception classes, such as the line and position of a parsing error, must be accommodated in the class, which returns specific HRESULT values.
- If a particular class or interface is supposed to be extended, protected members should be made public, because this is the only option in the COM Interface Definition Language (IDL).
- Friendly default members and methods should be made public if used in other classes or interfaces. Otherwise, they might be hidden in the private section of the implementation behind interfaces.
- If it is natural and simplifies development using a COM object, a class from a Java language package can be reduced. However, the reduction of the class must be implemented so that additional classes can be introduced without breaking an existing application.
For a list of the Microsoft SAX2 interfaces, see the SAX2 Reference node in the table of contents.