1. A computer-implemented method for designing and compiling custom runtime components that provide improved processing of certain types of messages that comprise data objects serialized for transmission from one system to another, the method comprising: in a graphical user interface, receiving design-time input from a user for characterizing logical structure and physical structure of a particular message type in serialized form; based on said design-time input, creating metadata in markup language format that characterizes the logical structure and physical structure of the particular message type in serialized form; based on the metadata, automatically generating source code for de novo creation of custom runtime components comprising newly created custom source code that is highly optimized for runtime processing of said particular message type; and compiling the source code to create said custom runtime components for deployment in a runtime environment, so that at runtime, messages of the particular message type are processed with said custom runtime components in a manner that is highly optimized for the particular message type.