Web services Architecture and its characteristics

 Every framework needs some sort of architecture to make sure the entire framework works as desired, similarly, in web services. The Web Services Architecture consists of three distinct roles as given below :

1. Provider – The provider creates the web service and makes it available to client application who want to use it.
2. Requestor – A requestor is nothing but the client application that needs to contact a web service. The client application can be a .Net, Java, or any other language based application which looks for some sort of functionality via a web service.
3. Broker – The broker is nothing but the application which provides access to the UDDI. The UDDI, as discussed in the earlier topic enables the client application to locate the web service.

The diagram below showcases how the Service provider, the Service requestor and Service registry interact with each other.

1. Publish – A provider informs the broker (service registry) about the existence of the web service by using the broker’s publish interface to make the service accessible to clients
2. Find – The requestor consults the broker to locate a published web service
3. Bind – With the information it gained from the broker(service registry) about the web service, the requestor is able to bind, or invoke, the web service.

Web service Characteristics

Web services have the following special behavioral characteristics:

1. They are XML-Based – Web Services uses XML to represent the data at the representation and data transportation layers. Using XML eliminates any networking, operating system, or platform sort of dependency since XML is the common language understood by all.
2. Loosely Coupled – Loosely coupled means that the client and the web service are not bound to each other, which means that even if the web service changes over time, it should not change the way the client calls the web service. Adopting a loosely coupled architecture tends to make software systems more manageable and allows simpler integration between different systems.
3. Synchronous or Asynchronous functionality – Synchronicity refers to the binding of the client to the execution of the service. In synchronous operations, the client will actually wait for the web service to complete an operation. An example of this is probably a scenario wherein a database read and write operation are being performed. If data is read from one database and subsequently written to another, then the operations have to be done in a sequential manner. Asynchronous operations allow a client to invoke a service and then execute other functions in parallel. This is one of the common and probably the most preferred techniques for ensuring that other services are not stopped when a particular operation is being carried out.
4. Ability to support Remote Procedure Calls (RPCs) – Web services enable clients to invoke procedures, functions, and methods on remote objects using an XML-based protocol. Remote procedures expose input and output parameters that a web service must support.
5. Supports Document Exchange – One of the key benefits of XML is its generic way of representing not only data but also complex documents. These documents can be as simple as representing a current address, or they can be as complex as representing an entire book.