Although implementing a Web Service yourself appears to be a tempting process if you are stuck with a platform that is very out of date or uncommon, you’ll find that you can almost always find a supported Web Services implementation that will be cheaper for you to purchase than to implement yourself. This is true because it will take thousands of developer hours to follow the appropriate standards. There are currently implementations of Web Services that support Fortran, Pascal, or even COBOL, and this probably means you can find an implementation that supports whatever strange platform you come across.
The alternative to adhering to the standards is communicating with the Web Service in a way that ignores the standards. This only works if you write software for an internal project, because external customers expect you to fully comply with all the standards. However, communicating with a Web Service in a nonstandard way may be an easy way for you to access the services you need from an unsupported platform.