What is SOAP and RESTFul Webservice

SOAP

Simple Object Access Protocol (SOAP) standard an XML language defining a message architecture and message formats, is used by Web services it contain a description of the operations. WSDL is an XML-based language for describing Web services and how to access them. will run on SMTP,HTTP,FTP etc. Requires middleware support, well defined mechanisam to define services like WSDL+XSD, WS-Policy SOAP will return XML based data

REST  Representational State Transfer (RESTful) web services. they are second generation Web Services. RESTful web services, communicate via HTTP than SOAP-based services and do not require XML messages or WSDL service-API definitions. for REST no middleware is required only HTTP support is needed.WADL Standard, REST can return XML, plain text, JSON, HTML etc

Difference between WCF and Web API and WCF REST and Web Service

The .Net framework has a number of technologies that allow you to create HTTP services such as Web Service, WCF and now Web API. There are a lot of articles over the internet which may describe to whom you should use. Now a days, you have a lot of choices to build HTTP services on .NET framework. In this article, I would like to share my opinion with you over Web Service, WCF and now Web API. For more information about Web API refers What is Web API and why to use it ?.

Web Service

• It is based on SOAP and return data in XML form.
• It support only HTTP protocol.
• It is not open source but can be consumed by any client that understands xml.
• It can be hosted only on IIS.

WCF

• It is also based on SOAP and return data in XML form.
• It is the evolution of the web service(ASMX) and support various protocols like TCP, HTTP, HTTPS, Named Pipes, MSMQ.
• The main issue with WCF is, its tedious and extensive configuration.
• It is not open source but can be consumed by any client that understands xml.
• It can be hosted with in the applicaion or on IIS or using window service.

WCF Rest

• To use WCF as WCF Rest service you have to enable webHttpBindings.
• It support HTTP GET and POST verbs by [WebGet] and [WebInvoke] attributes respectively.
• To enable other HTTP verbs you have to do some configuration in IIS to accept request of that particular verb on .svc files
• Passing data through parameters using a WebGet needs configuration. The UriTemplate must be specified
• It support XML, JSON and ATOM data format.

Web API

• This is the new framework for building HTTP services with easy and simple way.
• Web API is open source an ideal platform for building REST-ful services over the .NET Framework.
• Unlike WCF Rest service, it use the full featues of HTTP (like URIs, request/response headers, caching, versioning, various content formats)
• It also supports the MVC features such as routing, controllers, action results, filter, model binders, IOC container or dependency injection, unit testing that makes it more simple and robust.
• It can be hosted with in the application or on IIS.
• It is light weight architecture and good for devices which have limited bandwidth like smart phones.
• Responses are formatted by Web API’s MediaTypeFormatter into JSON, XML or whatever format you want to add as a MediaTypeFormatter.

To whom choose between WCF or WEB API

• Choose WCF when you want to create a service that should support special scenarios such as one way messaging, message queues, duplex communication etc.
• Choose WCF when you want to create a service that can use fast transport channels when available, such as TCP, Named Pipes, or maybe even UDP (in WCF 4.5), and you also want to support HTTP when all other transport channels are unavailable.
• Choose Web API when you want to create a resource-oriented services over HTTP that can use the full features of HTTP (like URIs, request/response headers, caching, versioning, various content formats).
• Choose Web API when you want to expose your service to a broad range of clients including browsers, mobiles, iphone and tablets.

Web Services Platform Elements,Why Web Services?

Web Services have three basic platform elements: SOAP, WSDL and UDDI.

SOAP?

SOAP is an XML-based protocol to let applications exchange information over HTTP. Or more simple: SOAP is a protocol for accessing a Web Service.

• SOAP stands for Simple Object Access Protocol
• SOAP is a communication protocol
• SOAP is a format for sending messages
 • SOAP is designed to communicate via Internet
 • SOAP is platform independent
 • SOAP is language independent
• SOAP is based on XML
• SOAP is simple and extensible
• SOAP allows you to get around firewalls
 • SOAP is a W3C standard

WSDL?

WSDL is an XML-based language for locating and describing Web services.
• WSDL stands for Web Services Description Language
• WSDL is based on XML
• WSDL is used to describe Web services
• WSDL is used to locate Web services
• WSDL is a W3C standard

UDDI?

 UDDI is a directory service where companies can register and search for Web services.

• UDDI stands for Universal Description, Discovery and Integration
 • UDDI is a directory for storing information about web services
• UDDI is a directory of web service interfaces described by WSDL
 • UDDI communicates via SOAP
 • UDDI is built into the Microsoft .NET platform

Introduction to Web Services

Web Services can convert your applications into Web-applications.
Web Services are published, found, and used through the Web. 

What You Should Already Know

Before you continue, you should have a basic understanding of the following:
• HTML
 • XML

What are Web Services?
• Web services are application components
• Web services communicate using open protocols
• Web services are self-contained and self-describing
• Web services can be discovered using UDDI
• Web services can be used by other applications
 • XML is the basis for Web services

How Does it Work? 
The basic Web services platform is XML + HTTP. XML provides a language which can be used between different platforms and programming languages and still express complex messages and functions. The HTTP protocol is the most used Internet protocol. Web services platform elements:
• SOAP (Simple Object Access Protocol)
• UDDI (Universal Description, Discovery and Integration)
 • WSDL (Web Services Description Language)