Web Services can convert your applications into Web-applications. Web Services are published, found, and used through the Web.
What are Web Services?
Web services are application components and can communicate using open protocols which are self-contained and self-describing. It can be discovered using UDDI and can be used by other applications. XML is the basis for Web services. The basic Web services platform is XML + HTTP. The HTTP protocol is the most used Internet protocol. XML provides a language which can be used between different platforms and programming languages and still express complex messages and functions. The Web Services platform is a simple, interoperable, messaging framework. It still misses many important features like security and routing. But, these features will be available as soon as SOAP becomes more advanced.
The concepts behind Web Services are remarkably simple, and we'll be taking a deeper look at what's involved. Then, with a little help from our good friend PHP, we can set up our Web Service.
The first thing to understand about Web Services is they're not really anything new. If we ever used an RSS Feed to take news from another Website and place it on your own, you've already got a good idea of how Web Services work. Web Services are about exchanging data between a server and a client, using a standard XML format to "package" requests and data so that both systems can "understand" each other. The server and the client could both be Web servers, or any other electronic device you care to think of.
Some of the Web services platform elements we use:
- SOAP (Simple Object Access Protocol)
- UDDI (Universal Description, Discovery and Integration)
- WSDL (Web Services Description Language)
Why We USE Web Services?
Hopefully, Web services can make it much easier for applications to communicate.
Web Services are about exchanging data between a server and a client, using a standard XML format to "package" requests and data so that both systems can "understand" each other. The server and the client could both be Web servers, or any other electronic device you care to think of.
Network-wise, data exchange in a Web Service typically happens via TCP port 80, using standard HTTP protocol POSTs. Put another way, Web Services operate in basically the same way your browser does when it POSTs an HTML form to a site, and receives a Web page in response. The only real difference is that, instead of HTML, Web Services use XML. And this means Web Services can be available anywhere on the Internet, passing through firewalls the same way viewing a Web page does. The data exchange happens at the packaging layer.
On top of the data exchange, you also need information that describes the interface (or Application Program Interface - API) to the service. This makes the Web Service useful to the rest of the Internet, allowing other developers to develop programs that can access your Web Service. This is called the description layer, and the WSDL (Web Service Description Language) standard that will make this happen is under development.