Web
Services architecture
The
Web Services architecture is based upon the interactions between
three roles:
- service provider
- service registry
- service requestor.The interactions involve the publish, find and bind operations.
1.
Service provider -
This
is the provider of the web service.
2.
Service requestor
-
This
is any consumer of the web service.
The
requestor utilizes an existing web service by opening a network
connection and sending an XML request.
3.
Service registry
-
This
is a logically centralized directory of services. The registry
provides a central place where developers can publish new services or
find existing ones.
Web
Service Protocol Stack
This
is having four main layers.
1.
Service transport
-
This
layer is responsible for transporting messages between applications.
Currently, this layer includes :
hypertext
transfer protocol (HTTP)
Simple
Mail Transfer Protocol (SMTP)
file
transfer protocol (FTP)
Blocks
Extensible Exchange Protocol (BEEP).
2.
XML messaging
This
layer is responsible for encoding messages in a common XML format so
that messages can be understood at either end.
Currently, this layer includes :
XML-RPC
SOAP.
3.
Service description
This
layer is responsible for describing the public interface to a
specific web service.
Currently, service description is handled via the Web Service Description Language (WSDL).
4.
Service discovery
This
layer is responsible for centralizing services into a common
registry, and providing easy publish/find functionality.
Currently, service discovery is handled via Universal Description, Discovery, and Integration (UDDI).
Service
Transport
The
bottom of the web service protocol stack is service transport. This
layer is responsible for actually transporting XML messages between
two computers.
Currently,
HTTP is the most popular option for service transport.
SOAP
is not tied to any specific transport protocol. In fact, you can use
SOAP via HTTP, SMTP, or FTP. One promising idea is therefore to use
SOAP over BEEP.
