[WCF] Summaries II

First Part Here

UDDI is a platform-independent directory protocol for describing services and discovering
and integrating business services via the Internet.
-> like a traditional "yellow page"
-> three parts: the white (details of the company and its contact information), yellow (industry categories), and green (technical details that describe the interface via
a WSDL) pages ;

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Service invocation is a general mechanism for sending messages between an entity that requests a service and another entity that provides the service
1. Find the relevant service that exposes the desired functionality.
2. Find out the type and format of the messages that the service would accept.
3. Understand any specific metadata that might be required as part of the message (for
example, for transaction or security).
4. Send the message to the provider with all relevant data and metadata.
5. Process the response message from the service in the appropriate manner

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Life cycle of an XML web service has eight steps:
1. A client connects to the Internet and finds a directory service to use.
2. The client connects to the directory service in order to run a query.
3. The client runs the relevant query against the directory service to find the web service
that offers the desired functionality.
4. The relevant web service vendor is contacted to ensure the service is still valid and is
available.
5. The description language of the relevant web service is retrieved and forwarded to the
client.
6. The client creates a new instance of an XML web service via the proxy class.
7. The runtime on the client serializes the arguments of the service method into a SOAP
message and sends it over the network to the web service.
8. The requested method is executed, which sets the return value including any out
parameters.
-> web services rely on open web standards (such as SOAP, HTTP, and
XML)
-> support message-based communication by default
-> rely on XML Schema for data types

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3 main design goals of WCF:
• Unification of existing technologies
• Interoperability across platforms
• Service-oriented development
-> is reference the System.ServiceModel assembly
-> native messaging protocol is SOAP
-> provide explicit service oriented application development
-> A schema is defined in the XML Schema language, and contracts are defined in WSDL
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A command-line tool called COMSVCConfig.exe lets an existing
COM+ application spit out a WCF stub to interoperate with COM+ applications.

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A component is compiled code.
-> Ease of reusability, maintenance, and lower application costs
-> you can use components to build services

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WCF and SOA



















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Endpoint
= what this service can do, how can it be accessed, and where it is available
-> One service can have multiple endpoints. Each of these endpoints can differ in the address, binding requirements, or contract getting implemented.
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BizTalk Server provides business process orchestration, message transformation, business activity monitoring, and more, through designers and visual tools
-> is responsible for orchestrating WCF services

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Some of the WS-* suite of protocols are HTTP, standards-based XML, SOAP, WSAddressing, and Message Transmission Optimization Mechanism (MTOM).
-> Microsoft has been generous enough to providethe class library on the top of the .NET Framework called WSE that encapsulates the implementations details and provides an easy-to-use API to consume these specifications

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svcTraceViewer.exe
-> WCF has also come up with end-to-end tracing through a trace viewer
-> also with message logging in the XML
files.
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ABCs of WCF = Service endpoints that are the combination of address, binding, and contract
Endpoints either can be defined in the code or can be defined in the configuration file.
The heart of WCF lives inside the System.ServiceModel namespace and the messaging system underneath it.

ABC stands for address, binding, and contract:
• The address specifies where the messages can be sent (or where the service lives).
• The binding describes how to send the messages.
• The contract describes what the messages should contain.
-> ABC = endpoint
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Precedence in WCF:
1. Attributes are applied.
2. The configuration is applied.
3. The code runs.

A WSDL file describes what a service can do, how a service can be accessed, and where the service can be found.