A2Z about web Service (What will be next)
This article will explain you everything about Web Services in .Net, so lets get started with Web Service.
What is Web Service?
A. Web Service is an application that is designed to interact directly with other applications over the Internet. In simple sense, Web Services are means for interacting with objects over the Internet.
B. Web Service is
1. Language Independent
2. Protocol Independent
3. Platform Independent
4. It assumes stateless service architecture.
Origin of Web Service or How Web Service comes into existence?
As I have mention before that Web Service is nothing but means for Interacting with objects over the Internet.
1. Initially Object - Oriented Language comes which allow us to interact with two objects within same application.
2. Than comes Component Object Model (COM) which allows to interact two objects on the same computer, but in different applications.
3. Than comes Distributed Component Object Model (DCOM) which allows to interact two objects on different computers, but within same local network.
4. Finally the web services, which allows two object to interact Internet. That is it allows interacting between two objects on different computers and even not within same local network.
5. In NEXT articles, we will see what next after Web service; I think you got it what next.
How Web Service communicates:
Web Services communicate by using standard web protocols and data formats, such as
A. HTTP
B. XML
C. SOAP
What are the advantages of using Web Service?
A. Web Service messages are formatted as XML, a standard way for communication between two incompatible systems.
B. The message is sent via HTTP, so that they can reach to any machine on the Internet without being blocked by firewall.
Web Services Related Terms:
A. SOAP
SOAP is remote function calls that invoke method and execute them on Remote machine and translate the object communication into XML format. In short, SOAP is way by which method calls are translate into XML format and sent via HTTP.
B. WSDL
1. WSDL stands for Web Service Description Language, a standard by which a web service can tell clients what messages it accepts and which results it will return.
2. WSDL contains every details regarding using web service
a. Method and Properties provided by web service
b. URLs from which those method can be accessed.
c. Data Types used.
d. Communication Protocol used
C. UDDI
UDDI allows you to find web services by connecting to a directory.
D. Discovery or .Disco
1. Discovery files are used to group common services together on a web server.
2. Discovery files .Disco and .VsDisco are XML based files that contains link in the form of URLs to resources that provides discovery information for a web service.
3. .Disco File contains
a. URL for the WSDL
b. URL for the documentation
c. URL to which SOAP messages should be sent.
4. A static discovery file is an XML document that contains links to other resources that describe web services
E. Proxy Class
1. A proxy class is code that looks exactly like the class it meant to represent; however the proxy class doesn't contain any of the application logic. Instead, the proxy class contains marshalling and transport logic.
2. A proxy class object allows a client to access a web service as if it were a local COM object.
3. The Proxy must be on the computer that has the web application
Few interesting thing about Web Service in .Net :
1. Each Response from web service is a new object, with a new state.
2. Web Service are asynchronous because the request object from the client application and the response object from the web service are unique SOAP envelopes that do not require shared connection.
3. This allows client application and the web service to continue processing while the interaction is ongoing.