What Is SOAP Web Services
What Is SOAP ?
If you using ajax programing for devlop your application i recomendation are you using SOAP, SOAP is a simple XML (Extensible Markup Languagebased) protocol to let applications exchange information over HTTP.
Why Using SOAP ?
It is Very important for application develop to allow Internet communication between programs or client and server.
Ajax applications communicate using Remote Procedure Calls (RPC) between objects like DCOM and CORBA, but Hypertext Transfer Protocol HTTP was not designed for this. RPC represents a compatibility and security problem, firewalls and proxy servers will normally block this kind on your traffic.
SOAP is a better way to communicate between applications is over HTTP, because HTTP is supported by all Internet browsers and servers like firefox, IE, Opera etc. SOAP was created to accomplish this.
SOAP provides a way to communicate between applications running on different operating systems like windows and linux, with different platform and programming languages.
About SOAP ?
this web services stuff sounds pretty cool, but how does it work? Well, interestingly enough, it works in a similar fashion to your typical client/server relationship. You’re used to using a web browser to interact with a server in order to retrieve requested web pages. Web services works in quite a similar way; the only thing that changes is what constitutes a client and a server.
When a developer creates a web service, what he is actually doing is creating a set of functions that can be called remotely. The client code then connects to this URL and invokes one or more methods. Additionally, the client code can also get a list of the available functions (including details of the input parameters and returned data). For example, the PayPal SOAP (Simple Object Access Protocol) API provides a method you can execute called DoDirectPayment. If you ran a website that used PayPal to process customer transactions, you might call this method, passing in the customer’s details and credit card number. The PayPal web server would then return data, indicating the status of the transaction (such as whether it succeeded or failed).
SOAP is a protocol that allows remote procedures to be executed. All requests to and responses from a SOAP web service use XML. By using the SOAP library built into PHP, the requests can easily be generated and responses can easily be interpreted.
Although in this example the developer connects directly to a third-party API (i.e., PayPal’s API), in this chapter we are going to look at creating our own web service, as well as connecting to this service to use that data in a small Ajax application. There are several different standards available that can be used for web services—such as SOAP and REST (Representational State Transfer). We will be using SOAP in this chapter, and we will be using the SOAP library that comes with PHP 5.