Compiler (candle)

The Windows Installer XML compiler is exposed by candle.exe. candle is responsible for preprocessing the input .wxs files into valid well-formed XML documents against the WiX schema, wix.xsd. Then, each post-processed source file is compiled into a .wixobj file.

The compilation process is relatively straight forward. The WiX schema lends itself to a simple recursive descent parser. The compiler processes each element in turn creating new symbols, calculating the necessary references and generating the raw data for the .wixobj file.

The second version of candle is not significantly different from the first implementation. Any changes were either made to enable the new symbol/reference linking or based on feedback from customers. Some of the differences between versions include: the new object file format is XML instead of MSI, modularization of primary keys now happens at link time, and binary streams are imported at link time.