Provided are a method for parsing a bit stream including multiple data formats, and an apparatus and computer program including a set of parsers and parser-selection and invocation capabilities for handling parsing of multiple data formats. A first parser is selected and invoked to handle a first formatted component of the bit stream, and this selected parser selects and invokes a next parser which is capable of handling a differently formatted next component of the bit stream. This is differentiated from systems which rely on a single generic parser or a single high-level parser selection process, and is especially advantageous when parsing messages to enable message processing in systems in which a message can include multiple different, nested data formats.