Web Services
A Web
Service is programmable application logic accessible via standard Web
protocols. One of these Web protocols is the Simple Object Access Protocol
(SOAP). SOAP is a W3C submitted note (as of May 2000) that uses standards based
technologies (XML for data description and HTTP for transport) to encode and
transmit application data.Consumers of a Web Service do not need to know anything about the platform, object model, or programming language used to implement the service; they only need to understand how to send and receive SOAP messages (HTTP and XML).
Soap Message
A
SOAP message consists of several elements, most notably an envelope. The
envelope encapsulates the data transmitted within the SOAP message. Below is a
simple SOAP message complete with HTTP headers:
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)
What
is SOAP?
SOAP
is an XML-based protocol to let applications exchange information over HTTP.SOAP are remote function calls that invokes method and execute them on Remote machine and translate the object communication into XML format.
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
What
is WSDL?
WSDL
is an XML-based language for locating and describing Web services.
·
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.
·
WSDL contains every details regarding using web service
o Method and Properties
provided by web service
o URLs from which those
method can be accessed.
o Data Types used.
o Communication Protocol
used.
·
What is Discovery or
.Disco Files?
o Discovery files are used
to group common services together on a web server.
o 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.
o
.Disco File (static)
§ .Disco File contains
§ URL for the WSDL
§ URL for the documentation
§ URL to which SOAP
messages should be sent.
§ A static discovery file
is an XML document that contains links to
other resources that describe web services.
o
.VsDisco File (dynamic)
§ A dynamic discovery files
are dynamic discovery document that are automatically generated by VS.Net
during the development phase of a web service.
·
What is difference
between Disco and UDDI?
o Disco is Microsoft's
Standard format for discovery documents which contains information about Web
Services, while UDDI is a multi-vendor standard for discovery documents which
contains information about Web Services.
·
What is Web Service
Discovery Tool (disco.exe) ?
o The Web Services
Discovery Tool (disco.exe) can retrieve discovery information from a server
that exposes a web service.
·
What is Proxy Class?
o A proxy class is code
that looks exactly like the class it meant to represent; however the proxy
class doesn't contain any of theapplication logic. Instead, the proxy
class contains marshalling and transport logic.
o A proxy class object
allows a client to access a web service as if it were a local COM object.
o The Proxy must be on the
computer that has the web application.
·
What is Web Service
Description Language Tool (wsdl.exe)?
o This tool can take a WSDL
file and generate a corresponding proxy class that you can use to invoke the
web service.
o Alternate of generating
Proxy class through WSDL.exe is you can use web reference. Web Reference automatically generate a proxy classes for a web service by
setting a web reference to point to the web service.
o Advantage of using Web Reference as compare to using WSDL.exe
Tool is you can update changes
done in web service class easily by updating web reference, which is more
tedious task with WSDL.exe tool.
·
Testing a Web Service?
o You can test web service
without building an entire client application.
§ With Asp.net you can
simply run the application and test the method by entering valid input
paramters.
§ You can also use .Net Web
Service Studio Tool comes from Microsoft.
- 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
What
is 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
1.
WEB METHOD
2.
XML
3.
HTTP
PROTOCOL
4.
SOAP
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