Web services are standards defined for data exchange over the Web. This is not to say that web services will be exposed to the Internet, just that there is an agreed-upon set of "web standards" that many products support. When deciding which standard to adopt, the most important thing to consider is often the advice of technical staff.
They may recommend to you, in order, a standard that is easiest to implement, has the broadest technical support for the product, and is most likely to work well in your environment. In order to have a successful SOA implementation that will stand the test of time and continue to scale in the future, all three of these factors are extremely important. Interoperability is extremely important.
WS-I
The Web Services Interoperability Organization (WS-I) specializes in developing best practices for Web standards to ensure interoperability across different operating systems, platforms, or programming languages. WS-I is responsible for defining best practice documents such as Web services security and Web services processing technical specifications. This documentation helps developers and businesses conform to practices that others are using to ensure user operability.
WS-I also publishes technical specifications, test suites, and samples on how to deploy these protocols. In fact, WS-I is a governing body formed by many organizations such as Microsoft and IBM, and its mission is to promote interoperable Web services.
Agreement of use
Web services rely on protocols to ensure that communication is meaningful. The content of data sent between services must be previously agreed to ensure that both parties know what content is received. SOAP is an example of the most widely used protocol when exchanging data. SOAP uses the XML programming language, allowing both parties to decode what is being sent and format the information sent back and forth.
illustrate
We'll cover some architecture soon and also refer to some web service protocols. It is important not to confuse these two things. So let’s briefly introduce it below.
Software architectures such as REST and RPC are not protocols. They are methods that specify how the agreement is to be implemented.
WSDL (Web Services Description Language) is a language used to describe a specific Web service in a formatted way so that applications can parse the service. WSDL itself does not provide any functionality in the form of Web services interactions.
The protocols themselves, such as SOAP, XML-RPC or DCOM, define exactly how messages are delivered and how a program understands the data it receives.
There are two main types of architectures in SOA: the RPC family of protocols and the Representational State Transfer (REST) approach.
RPC
The remote procedure call (RPC) method allows programmers to call resources of a remote system just like "calling" local resources when programming on a system. The disadvantage of RPC-style services is that people tend to use them as if they were familiar with the programming language on the specific platform. It's even easy to call a remote procedure if it's the same as the local procedure.
This logic violates the concept of "loose coupling". The concept of loose coupling actually means that the remote process should not depend on any specific operating system or programming language.
SOAP is the successor protocol to XML-RPC and is just a remote procedure call that contains its information in XML. SOAP uses the HTTP protocol to send data, which is nice and simple, however, it does have some disadvantages. Despite this, most web services these days still use the HTTP protocol for communication since they are built using the SOAP protocol.
REST
The Representational State Transfer (REST) approach is fundamentally different from remote procedure calls because it works at a different level. A REST call looks like any other web request over the HTTP protocol, while an RPC call looks like a standard function call. The focus of REST is to operate with stable resources rather than individual messages, resulting in a more standard and widely understood way of interacting, much like the HTTP protocol itself. REST handles transferring chunks of simple data, while RPC transfers complex processes.
Should REST or RPC be used?
The question of whether to use REST is certainly a good one. It seems like the way of the future. However, your SOA needs to be integrated into every piece of software you currently use. The adoption of REST has been slow, mainly due to web service support. Although a REST system can use WSDL to describe a SOAP message over HTTP, there is not enough support to actually use it. For example, Apache doesn't even support the methods required to use REST without installing the plug-in module.
There are other standards that are not part of the Web services family. But, as you might expect, these standards don't have widespread support. Jini, WCF and CORBA are some examples. When a vendor offers you a product that only supports one of the above technologies, you want to run away, not walk away. Web services are now widely supported. The use of Web services will only grow. SOA itself is said to be new, unstable and risky. However, these risks can largely be mitigated when you choose an appropriate Web services standard that has broad technical support.
Finally, sticking to old-school SOAP over some type of RPC-style system is currently a viable mechanism for building SOA using Web services. If you do this, you significantly reduce your chances of vendor lock-in.