SOA and Web Services. SOA Architecture Explaination Transport protocols - communicate between a...
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Transcript of SOA and Web Services. SOA Architecture Explaination Transport protocols - communicate between a...
SOA and Web Services
SOA Architecture
Explaination
• Transport protocols - communicate between a service and a requester.
• Messaging layer - enables the bus to deal with messages
• Description - description of services in terms of functions supported, quality of services of these functions, and supported binding mechanisms.
• Quality of Service - security aspects such as message integrity, confidentiality, reliable transport of messages and various kinds of transactions.
• Components - choreographies and societies of services that cooperate following an agreement protocol to decide on the success of the cooperation at the end of the cooperation.
• Discovery of Services - discovery of services and their descriptions and to agree on a mode of interaction between a requester and a service.
Web Services Architecture
Messaging Layer
• XML, SOAP, and WS-Addressing • SOAP
– exchanges structured and typed information between services.
– designed to reduce the cost and complexity of integrating applications
– Messages can be routed based on the content of the headers and the data inside the message body
– Any software agent that sends or receives messages is called a SOAP node.
– Original Sender, Intermediary and Ultimate Receiver
– SOAP specification defines two built-in roles: Next and Ultimate Receiver.
WS-Addressing
• Provides an interoperable, transport-independent way of identifying message senders and receivers that are associated with message exchange
• Decouples address information from the specific transport used by providing a mechanism to place the target, source, and other important address information directly within the Web service message
• Identify Web services endpoints and to secure end-to-end endpoint identification in messages
WSDL
• Metadata describing Web services• Describe the "functional" characteristics of a Web
service• A WSDL document has two parts: abstract
definitions and concrete descriptions• The abstract section defines SOAP messages in a
language- and platform-independent manner.• The concrete descriptions define site-specific
matters such as serialization.
Discovery Services
• Metadata must be in a form that is discoverable and searchable by users
• Universal Description and Discovery Interface (UDDI) is a widely acknowledged specification of a Web service registry.
• Defines service and supporting protocols for querying service.
• UDDI repositories can be provided in one of three ways:• Public UDDI - Internet-based Web services• Intra Enterprise UDDI - private internal UDDI repository • Inter Enterprise UDDI - shareable between specific
business partners
MetaData Exchange
• WS-MetaDataExchange specification defines protocols that support the dynamic exchange of WS-Policy
• allows a service requester to ask a service provider directly for all or part of its metadata, without the involvement of a third-party registry.
Quality of Service
• WS-Security is the basic building block for secure Web services.
• WS-Security uses existing security models • WS-Trust defines an extensible model for
setting up and verifying trust relationships.• key concept in WS-Trust is a Security Token
Service (STS).• An STS is a distinguished Web service that issues,
exchanges, and validates security token
WS-ReliableMessaging
• Enable Web services to ensure reliable, interoperable exchange of messages
• The specification defines three basic assurances
• In-order delivery - same order in which they were sent.
• At least once delivery - at least one time
• At most once delivery - No duplicate messages