Download Web Services The General Web Services Architecture

Web Services
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Problem with .NET remoting and other middleware standards
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Solution
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The Web services standard is more high level and flexible than
other standards and therefore has wide industry support
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They are not compatible with each other
Define a higher level standard, in this case, Web services
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Supports a service oriented architecture
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The base protocols are SOAP over HTTP over TCP/IP
Define standard XML based ways of representing services, publishing
them, discovering them, and learning their specification
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Stateless, although it is still possible to use session cookies
Web services support in .NET
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ASP.NET – basic support, only RPC style communication
WSE – extended support, including security and messaging
The General Web Services Architecture
UDDI
UDDI
SOAP
SOAP
Web
Web
Server
Server
SOAP
Web
Web Service
Service
Any
Any Client
Client
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Main Web Services Components
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Simple Object Access Protocol (SOAP)
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Web Service Description Language (WSDL)
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An extendible XML based standard for describing service
Includes the capabilities of an IDL + semantic description of the
service
DISCO
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Extendible XML based RPC protocol
Serialization standard (XSD)
A simple protocol for publishing available services
Universal Description, Discovery and Integration (UDDI)
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A yellow pages directory for services
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Support both semantic and syntactic description of services
Supports discovery
Web Services Operation in Practice
Find a Service
http://www.uddi.org
Link to DISCO or WSDL document
UDDI
Discovery
Web
Service
Consumer
http://yourservice.com
HTML or XML with a link to WSDL
How do we talk? (WSDL)
Web
Service
http://yourservice.com?WSDL
XML with service descriptions
Let me talk to you (SOAP)
http://yourservice.com/svc1
XML/SOAP BODY
DesignDesign-Time or Dynamic
Runtime
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UDDI Data Structures
Business:
Business: Information
Information about
about the
the
entity
entity who
who offers
offers aa service
service
tModel:
tModel: Descriptions
Descriptions of
of specifications
specifications
for
for services
services
Name,
Name, contact,
contact, description
description
and
and categorization
categorization of
of the
the provider
provider
Pointer
Pointer to
to aa WSDL
WSDL file
file
Service:
Service: Descriptive
Descriptive information
information
about
about aa particular
particular family
family of
of technical
technical
offerings
offerings
Name,
Name, description
description and
and
categorization
categorization of
of the
the service
service
Binding:
Binding: Technical
Technical information
information
about
about aa service
service entry
entry point
point
Access
Access point(s)
point(s) for
for the
the service
service
WSDL Documents
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Types
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Message
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Operation
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Port Type
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A container for data type definitions using some type system (such as XSD).
An abstract, typed definition of the data being communicated.
An abstract description of an action supported by the service.
An abstract set of operations supported by one or more endpoints.
By default: One-way, Request-response, Solicit-response, and Notification
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Binding
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Port
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A concrete protocol and data format specification for a particular port type.
A single endpoint defined as a combination of a binding and a network
address.
Service
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A collection of related endpoints.
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SOAP Elements
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Envelope (mandatory)
– Top element of the XML document representing the message
Header (optional)
– Determines how a recipient of a SOAP message should
process the message
– Adds features to the SOAP message such as authentication,
transaction management, message routes, etc…
Body (mandatory)
– Exchanges information intended for the recipient of the
message.
– Typical use is for RPC calls and error reporting.
POST /HelloWorld/Hello.asmx HTTP/1.1
Host: localhost
Content-Type: text/xml; charset=utf-8
Content-Length: length
SOAPAction: "http://tempuri.org/Add"
<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope …>
<soap:Header>
<AuthHeader xmlns="http://tempuri.org/">
<Username>avi</Username>
<Password>xM76w@</Password>
</AuthHeader>
</soap:Header>
<soap:Body>
<Add xmlns="http://tempuri.org/">
<a>23</a>
<b>44</b>
</Add>
</soap:Body>
</soap:Envelope>
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SOAP Faults
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Used to carry error and/or status information within a SOAP
message
Appears within the SOAP body
Defines the following:
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faultcode (mandatory)
Faultstring (mandatory)
faultactor (optional)
Detail
<SOAP:Fault>
<faultcode>SOAP:Server</faultcode>
<faultstring>Internal Application Error</faultstring>
<detail xmlns:f=“http://www.a.com/CalculatorFault”>
<f:errorCode>794634</f:errorCode>
<f:errorMsg>Divide by zero</f:errorMsg>
</detail>
</SOAP:Fault>
Web Services Enhancement
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Core WSE functionality implemented as input and output filters
Output
Filters
Client
Server
Input
Filters
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Input
Filters
Output
Filters
The use of IO filters is encapsulated by the pipeline class
Pipeline can be extended with custom filters
Pipeline can be configured per-proxy or per-process
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Server Integration
HttpContext.Current
Input Filter
HttpHttpRequest
Output Filter
Input Filter
Output Filter
Input Filter
Output Filter
WebServicesExtension
HttpHttpContext
SoapSoapContext
Web Service
HttpHttpResponse
SoapSoapContext
Pipeline
ResponseSoapContext.Current
RequestSoapContext.Current
Proxy Integration
RequestSoapContext
Output Filter
Input Filter
SoapWebSoapWebResponse
Output Filter
ProxyClass
Input Filter
WebServicesWebServicesClientProtocol
Output Filter
SoapWebSoapWebRequest
Input Filter
SoapContext
Pipeline
SoapContext
ResponseSoapContext
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