This chapter takes a high-level look at the technical underpinnings of web services. It’s important to understand these concepts and technologies when trying to debug problems, which in turn, can help you understand the conceptual relationship between different aspects of web services.
A computer network is essentially nothing more than the notion of two or more independent computers “connected” to each other in some fashion. This, liberally applied, can be used to describe two fax machines, two digital phones, a few personal computers (and perhaps a TiVo), or, more generally, a local area network, a wide area network, or even the Internet itself.
There’s a tremendous amount of physical infrastructure behind establishing these connections. Most of us are familiar with both physical and wireless networks (in particular, the 10/100/1000Base-T physical and various 802.11 wireless technologies). Consider the wireless router connected to the switch, connected to the DSL modem, connected to the service provider’s network, and then the various connections that lead to (for example) the local Amazon.com server. It’s hard to say which is more amazing—that a packet ever gets to the destination or that a response finds its way back.
Just sorting out the basic components of a network can be a very conceptually difficult area, so let’s turn to the time honored standby, the International Standard Organization’s Open System Interconnect (OSI) ...