CHAPTER 8 – XML with PHP 5 – COMMUNICATING WITH XML

Applications currently communicate via the Internet in several ways, most of which you already know. TCP/IP and UDP/IP are used, but are only low-level transport protocols. Communication between systems is difficult because sys- tems store data in memory using different methods. For example, Intel has a different order of data in memory (Little Endian) than PowerPCs (Big Endian). Another major point was that people just wanted a solid cross-platform tech- nology communication system. One solution is RPC (Remote Procedure Calls), but it's not easy to use, and it's implemented differently by Windows than by most UNIX platforms. XML is often the best solution. XML was developed to "promote" interoperability between systems. It allows applications on different systems to communicate using a standard format. XML is ASCII data, so the differences between systems (such as Endianess) is minimized. Other differ- ences, such as date representation, still exist. One platform might specify Wed Dec 25 16:58:40 CET 2002, another just Wed 2002-12-25. XML-RPC and SOAP are both XML-based protocols. SOAP is the broader protocol, designed specifically for communication, and is well-supported.