Introduction to Types of Web Services
In this article, we will discuss on the Types of Web Services. The most important web service is REST and SOAP. Some of the well-known web services which use markup languages are Web template, JSON-WSP, JSON-RPC, WSDL, WSCL, WSFL, WS-Metadata Exchange, and XINS.
REST and SOAP are the two popular types of Web Services used extensively in the world. REST means Representational State Transfer and SOAP means Simple Object Access Protocol. SOAP is completely a protocol meanwhile REST is actually an architectural style. SOAP can’t use REST as it is a protocol whereas REST can use SOAP web services because it is a concept. SOAP uses service interfaces to expose business logic whereas REST uses URI to expose business logic.
What is Web Service?
A web service is a consistent medium to help in the efficient communication between a client and a server application over the network. It is a software module and is particularly designed to perform a set of tasks. The client requests the server to invoke a series of web services and in response, the server hosts the web services. The requests are made through remote procedure calls (RPC). The most important element of a web service is the data that is transferred between the client and the server which is in the .xml format. This format is clearly understood by many programming languages. Precisely, applications (though written in different programming languages) communicate with each other in XML. Therefore it provides a common platform for programmers to co-ordinate and work.
Web Services procure many advantages – reducing the cost of communication, exposing the business functionality on the network, having a standardized protocol that is understood by everyone, building interoperability among the various applications, and creating a service for a specific task. A web service has service-oriented architecture and makes a combination of both internal and external services to any organization. It is capable of producing and providing the required service for the client.
Types of Web Services
At a technical level, web services can be implemented in different ways. Below mentioned are the two types of web services.
SOAP
Originally developed by Microsoft it is also known as a transport-independent messaging protocol. It transfers XML data as SOAP messages. Each message has an XML document. The document follows a particular pattern. It uses HTML and SMTP for transmission of messages. SOAP web services have a standard for security and address. They are hard-coded and are generated without the use of a repository. SOAP features a built-in error handling system. The responses to the requests contain error information which helps you to track and rectify the errors.
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SOAP works very well when it is in distributed enterprise settings. It has the benefit of automation when used with a few language products. The only major drawback is that it uses WSDL (Web Services Description Language) to discover the service and has no other alternative mechanism.
A SOAP message contains the following elements:
- An <Envelope> which contains the start and the end of the message. This is the root element. It includes the ‘header’ and the ‘body’.
- The header contains the attributes which are used to process the message.
- The body includes the XML data that needs to be sent out.
- A Fault which provides error messages when processing data.
REST
Representation State Transfer (REST) appeals to developers as it has a simpler interface than SOAP. It is an architectural style (each URL represents individual object). It provides communication and connectivity between the devices and the internet for API-based tasks. REST allows different data formats like HTML, JSON, XML etc. Compared to SOAP, it consumes less bandwidth and resources. The web services can be written in any programming language and it can be used on any platform. It can also use SOAP web services but SOAP cannot use REST web services.
REST web services provide flexibility to the applications which are built with the different programming languages and the platforms to communicate efficiently with each other. Now everything is consistently moving to the cloud. Therefore, all cloud-based architectures are developed and work on REST web services principle.
The key elements of REST implementation are:
- Resources: It commands the webserver to provide details that are demanded.
- Request Verbs: These describe whatever you want to do with the particular resource (demanded details)
- Request Headers: Additional instructions sent with the request, they define the type of request required.
- Request Body: The Request Body has the necessary details of the particular resource which is necessary to be added to the server.
- Response Body: This is the main body of the response received.
- Response Status Codes: These are the general codes and are returned together with the responses which are received from the webserver.
Architecture of Web Service
Every framework needs some sort of architecture to ensure that the complete framework works or functions as desired. There are three distinct roles in the architecture of web services:
- Service Provider: The Provider is the one who creates the web service and makes it totally available to the client application who wants to use it for their specific purposes.
- Service Requestor: It is the client application that is needed to contact the web service. The client application may be .Net, Java or any other programming language based application that looks out for a particular kind of functionality through a web service.
- Service Broker: This is the application that provides access to the UDDI (Universal Description, Discovery, and Integration) and this is what provides a repository on which the various WSDL files may be hosted.
All three elements of the architecture of web services help to find, bind and publish the web service.
Conclusion
Modern web services have now completely changed the digital scenario with the help of evolving system integration along with interoperability. They offer a level of functionality that is modern and also less complex. All this only comes to say that the web services and their demand is multiplying with the growing digitalization in all the fields of commerce and business. Their relevance and importance cannot be taken for granted and needs to be agreed upon to understand the functionality of technology and its uses.
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