This chapter has served as a platform from which developers can begin to harness the power of SOAP-based applications. SOAP and its associated technologies constitute a huge body of knowledge that we could not possibly hope to cover in the space allotted here. However, knowing how to create and utilize Web Services is a valuable weapon in the PHP developer's armory especially given the current trend toward distributed programming architectures.
Specifically, we discussed how PHP5 supports the use of SOAP through various open source initiatives. We then focused on the new/experimental PHP5 SOAP extension and briefly covered what it has to offer. Following this, we demonstrated the power of using Web Services by creating an example, in only a couple of lines, that retrieved a quote for book prices based on a supplied ISBN using a third-party Web Service. As part of this discussion we talked about the structure of the WSDL document that presents a contract between the SOAP server and client.
Finally, we demonstrated how to create a simple SOAP server and use it to return a basic query.