Transcript Jinaldesai.net – My Thouths And Learnings OVERVIEW OF SOA AND WCF.

Jinaldesai.net – My Thouths And Learnings
OVERVIEW OF SOA AND WCF
AGENDA
Overview of Service Oriented Architecture (SOA)

Overview of WCF

Introducing WCF Contracts
Jinaldesai.net – My Thouths And Learnings

WHAT IS SERVICES?

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Service is unit of logic(functionality).
Example of services are placing airline ticket
order online or viewing an online bank
statement.
Services are loosely coupled.

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Service interface is independent of implementation.
Services are reusable.
Jinaldesai.net – My Thouths And Learnings

SERVICE CHARACTERISTICS


Handles a business process like calculating
insurance quote; or handles relatively technical
task like accessing a database; or provides
business data and technical details like details
needed for constructing GUI.
Service Can access another service for
performing it’s task.
Service is relatively independent of other service
or software.
Jinaldesai.net – My Thouths And Learnings

WHAT IS SOA?

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Service Oriented Architecture is an evolution of
distributed computing.
It comprises of one or more services.
SOA defines how two computing entities, such as
program, interact in such a way as to enable one
entity to perform a unit of work on behalf of
another entity.
Each interaction is independent of any other
interaction or it’s implementation.
Jinaldesai.net – My Thouths And Learnings

SOA KEY CHARACTERISTICS


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SOA services have self-describing interfaces in
platform-independent XML Document(WSDL).
SOA Services communicate with messages formally
defined via XML schema(XSD).
SOA services are maintained in the enterprise by a
registry that acts as a directory listing(UDDI)
Each SOA service has a quality of service(QoS). Key
Qos elements are security requirements, reliable
messaging and other policies regarding who can
invoke services.
Jinaldesai.net – My Thouths And Learnings

STRUCTURE OF SOA
Jinaldesai.net – My Thouths And Learnings
STRUCTURE OF SOA

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The topmost level contains one or more
integration services, each of which controls a flow
of activities such as processing an applicant's
request. Each integration service invokes one or
more business services.
The second level is composed of services that
each fulfill a relatively low-level business task.
The third level data access services handles
relatively technical task of reading from and
writing to data-storage areas such as
databases/message queues.
Jinaldesai.net – My Thouths And Learnings

DISTRIBUTED APPLICATIONS
Jinaldesai.net – My Thouths And Learnings
DISTRIBUTED APPLICATION ON WINDOWS

Microsoft shipped many communication frameworks
to achieve connected system environment.
Disadvantages:
Each framework comes up with a unique programming
model.
 Each of these framework can be used only in windows
platform.

Jinaldesai.net – My Thouths And Learnings

SERVICES COMMUNICATION
™ervices were used to expose the units of
S
functionality via messages.
Jinaldesai.net – My Thouths And Learnings

SOAP AND REST

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XML Messaging using SOAP as the format, enhanced
with the WS-* protocols(can be used with any
transport protocol). Typically used in enterprise.
REST
™

Which operates on resources through a unified
interface(HTTP). Typically used in public facing web
scenarios.
Jinaldesai.net – My Thouths And Learnings
™o make a service available over http can be done
T
by exposing a SOAP based service or using a
REST( non SOAP) based service.
™
SOAP

WHAT IS WCF?
™CF is the Microsoft next generation technology
W
for developing distributed applications.
 WCF has been built to facilitate the development
of service-oriented applications.
 It is a fusion of current distributed system
technologies designed and developed with the
goal of achieving SOA based development.

Jinaldesai.net – My Thouths And Learnings
WHAT IS WCF?

WCF is a programming model that enables
developers to build service solutions that are
reliable and secure, and even transacted.
It simplifies development of connected
applications and offers a unified, simplified, and
manageable distributed system development
approach.
Jinaldesai.net – My Thouths And Learnings

WHAT DOES WCF SOLVE?
Jinaldesai.net – My Thouths And Learnings
WHY HANDLE UNIFICATION?
Jinaldesai.net – My Thouths And Learnings
UNIFICATION OF DISTRIBUTED TECHNOLOGIES
Jinaldesai.net – My Thouths And Learnings
WCF IN .NET FRAMEWORK STACK
Jinaldesai.net – My Thouths And Learnings
WCF ARCHITECTURE
Contracts
 Service Runtime
 Messaging
 Activation and Hosting

Jinaldesai.net – My Thouths And Learnings
At the heart of WCF is a
layered architecture that
supports a lot of the
distributed application
development styles.
 The Layers are:

WCF LAYERS - CONTRACTS
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WCF contracts define the functionality of WCF
services.
They are created in code by service developers,
and are exposed to clients in the service
metadata
The five types of contracts:

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Service Contracts
Operation Contracts
Data Contracts
Message Contracts
Fault Contracts
Jinaldesai.net – My Thouths And Learnings

WCF LAYERS - SERVICE RUNTIME

The Service Runtime layer is the layer that
specifies and manages the behaviors of the
service that occur during service operation, or
service runtime.
Some of them are as follows:
Metadata Behavior: Controls whether or not
metadata is exposed to the outside world.
 Instance Behavior: Drives how many instances of the
service will be available to process messages.
 Transaction Behavior: Enables transacted
operations.

Jinaldesai.net – My Thouths And Learnings

WCF LAYERS - MESSAGING


The messaging layer defines what formats and
data exchange patterns can be used during
service communication.
Client applications can be developed to access
this layer and control messaging details and
work directly with messages and channels.
Some of the Channels and components are as
follows:

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
HTTP Channel
TCP Channel
MSMQ Channel
Jinaldesai.net – My Thouths And Learnings

WCF LAYERS – ACTIVATION & HOSTING

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In its final form, a service is a program. Like other
programs, a service must be run in an executable.
This is known as a self-hosted service.
Services can also be hosted, or run in an executable
managed by an external agent, such as IIS or
Windows Activation Service (WAS). WAS enables
WCF applications to be activated automatically when
deployed on a computer running WAS.
Services can also be manually run as executable (.exe
files). A service can also be run automatically as a
Windows service. COM+ components can also be
hosted as WCF services.
Jinaldesai.net – My Thouths And Learnings

WCF SERVICE FROM THE OUTSIDE
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A service is a collection of
one or more endpoints.
A service must have at least
one endpoint.
An endpoint is the
component of the service
that communicates with the
client and provides the
service operations.
Each endpoint has its very
own address, which makes it
distinguishable from the
other endpoints on the
service.
Jinaldesai.net – My Thouths And Learnings

WCF SERVICE FROM THE INSIDE
Jinaldesai.net – My Thouths And Learnings

WCF CONTRACTS – SERVICE CONTRACTS

A service contract defines the operations that a
service supports, and maps to a portType in Web
Service Description Language (WSDL).
Service contracts are implemented as .NET
Framework interfaces that are annotated with
the ServiceContract attribute.
[ServiceContract]
public interface IBookOrder { … }
Jinaldesai.net – My Thouths And Learnings

WCF CONTRACTS – OPERATION CONTRACTS

Operation contracts define the individual
operations that a service supports and map to
operations in WSDL.
Operations are defined by adding methods to a
Service Contract interface that is annotated with
the OperationContract attribute.
[OperationContract]
void SomeOperation();
Jinaldesai.net – My Thouths And Learnings

WCF CONTRACTS – DATA CONTRACTS

A data contract is a formal agreement between a service and a
client that abstractly describes the data to be exchanged.
Data contract can be explicit or implicit.

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Simple type such as int, string etc has an implicit data contract.
User defined object are explicit or Complex type, for which you have to
define a Data contract using [DataContract] and [DataMember]
attribute.
[DataContract]
Class Employee
{
[DataMember]
public string FirstName { get; set; }
[DataMember]
public string LastName { get; set; }
}
Jinaldesai.net – My Thouths And Learnings

WCF CONTRACTS – MESSAGE CONTRACTS


Message: Message is the packet of data which contains
important information. WCF uses these messages to
transfer information from Source to destination.
Message Pattern: It describes how the programs will
exchange message with each other. It can be Simplex – one
way communication, Request/Reply – two way
communication but at a time only one can send a message
and Duplex – two way communication both source and
destination can send message simultaneously.
In most of the cases WCF will automatically take care of
message, but at some point developer will also require
control over the SOAP message format. In that case WCF
provides Message Contract to customize the message as per
requirement.
Jinaldesai.net – My Thouths And Learnings

WCF CONTRACTS – MESSAGE CONTRACTS

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The most common scenario for this is inserting
custom SOAP headers. Another common scenario is to
define security properties for the message’s headers
and body, that is, to decide whether these elements
are digitally signed and encrypted.
WCF supports either RPC(Remote Procedure Call) or
Message style operation model.
In the RPC model, you can develop operation with Ref
and out parameter. WCF will automatically create
the message for operation at run time.
In Message style operation WCF allows to customize
the message header and define the security for header
and body of the message.
Jinaldesai.net – My Thouths And Learnings

WCF CONTRACTS – MESSAGE CONTRACTS
Defining Message Contracts: Message contract can be
applied to type using MessageContract attribute. Custom
header and body can be included to message using
MessageHeader and MessageBodyMember attribute.
[MessageContract]
public class EmployeeDetails
{
[MessageHeader]
public string EmpID;
[MessageBodyMember]
public string Name;
[MessageBodyMember]
public string Designation;
}
Jinaldesai.net – My Thouths And Learnings

WCF CONTRACTS – FAULT CONTRACTS


By default when we throw any exception from service,
it will not reach the client side.
WCF provides the option to handle and convey the
error message to client from service using SOAP
Fault contract.
SOAP faults are message types that are included in
the metadata for a service operation and, therefore,
create a fault contract that clients can use to make
their operation more interactive. In addition, because
SOAP faults are expressed to clients in XML
form, they are highly interoperable.
Jinaldesai.net – My Thouths And Learnings

WCF CONTRACTS – FAULT CONTRACTS
[ServiceContract()]
public interface IService
{
[OperationContract]
[FaultContract
MyFaultException
{
private string _reason;
[DataMember]
public string Reason
{
get { return _reason; }
set { _reason = value; }
}
(typeof(MyFaultExcept
ion))]
string GetMessage();
}
[DataContract]
public class
}
Jinaldesai.net – My Thouths And Learnings
Fault Contract Example:
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THANKS