Web Services by iFour Technolab Pvt. Ltd.

 Introduction to Web Service
 SOAP (Simple Object Access Protocol)
 WSDL (Web Service Description Language)
 WSDL Components
 WCF (Windows Communication Foundation)
 Advantages of WCF
 Difference between WCF and Web service
 WCF Service Components
 Address
 Binding
 Contract
 REST
 WEB API
INDEX
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 An application that is designed to interact directly with other applications over the
internet
 In simple sense, Web Services are means for interacting with objects over the Internet
 The Web service consumers are able to invoke method calls on remote objects by using
SOAP and HTTP over the Web
 It is language independent and Web Services communicate by using standard web
protocols and data formats, such as
 HTTP
 XML
 SOAP
Introduction to Web Service

Flow
Introduction to Web Service (Cont.)

 Advantage:
 Web Service messages are formatted as XML, a standard way for communication
between two incompatible system. And this message is sent via HTTP, so that they can
reach to any machine on the internet without being blocked by firewall
Introduction to Web Service (Cont.)

 SOAP - Simple Object Access Protocol
 REST - Representation State Transfer
Three ways we can develop web service
 ASMX Web Service (SOAP)
 WCF (SOAP /REST)
 ASP.NET Web API ( REST)
Types of Web service

SOAP-REST Web service Communication Flow
Web service request and response flow

Web service Communication Flow
Web service request and response flow Cont.

 Remote function calls that invokes method and executes them on Remote machine and
translate the object communication into XML format
 In short, SOAP are way by which method calls are translate into XML format and sent via
HTTP
SOAP (Simple Object Access Protocol)

 SOAP and XML created the solution for the problem that developers were facing before
 Standard XML based protocol that communicated over HTTP
 SOAP is message format for sending messaged between applications using XML. It is
independent of technology, platform and is extensible too
 SOAP and XML to give us connectivity between applications
SOAP (Cont.)

 A Standard by which a web service can tell clients what messages it accepts and which
results it will return
 Contains every detail regarding using web service and Method and Properties provided by
web service and URLs from which those methods can be accessed and Data Types used
 The operations and messages are described abstractly, and then bound to a concrete
network protocol and message format to define an endpoint
 Related concrete endpoints are combined into abstract endpoints (services)
 It is extensible to allow description of endpoints and their messages regardless of what
message formats or network protocols are used to communicate, however, the only
bindings described in this document describe how to use WSDL in conjunction with SOAP
WSDL (Web Service Description Language)

WSDL Components

WSDL 1.1 Term WSDL 2.0 Term Description
Service Service
Contains a set of system functions
that have been exposed to the
Web-based protocols
Port Endpoint
Defines the address or connection
point to a Web service. It is
typically represented by a simple
HTTP URL string
Binding Binding
Specifies the interface and defines
the SOAP binding style
(RPC/Document) and transport
(SOAP Protocol). The binding
section also defines the operations
WSDL Components (Cont.)

PortType
Interfa
ce
Defines a Web service, the operations that can be performed, and the messages that are
used to perform the operation
Operation
Operat
ion
Defines the SOAP actions and the way the message is encoded, for example, "literal." An
operation is like a method or function call in a traditional programming language
Message n/a
Typically, a message corresponds to an operation. The message contains the information
needed to perform the operation. Each message is made up of one or more logical parts.
Each part is associated with a message-typing attribute
The message name attribute provides a unique name among all messages. The part
name attribute provides a unique name among all the parts of the enclosing message.
Parts are a description of the logical content of a message. In RPC binding, a binding may
reference the name of a part in order to specify binding-specific information about the
part
Types Types
Describes the data. The XML Schema language (also known as XSD) is used (inline or
referenced) for this purpose
WSDL Components (Cont.)

 Programming platform and runtime system for building, configuring and deploying
network-distributed services
 Latest service oriented technology, Interoperability is the fundamental characteristics of
WCF
 Unified programming model provided in .NET Framework 3.0
 Combined feature of Web Service, Remoting, MSMQ and COM+
 Provides a common platform for all .NET communication
WCF (Windows Communication Foundation)

 Interoperable with other services when compared to .NET Remoting where the client and
service have to be .NET
 Provide better reliability and security in compared to ASMX web services.
 No need to make much change in code for implementing the security model and changing
the binding. Small changes in the configuration will make our requirements
 Integrated logging mechanism, changing the configuration file settings will provide this
functionality
Advantages of WCF

Features Web Service WCF
Hosting It can be hosted in IIS
It can be hosted in IIS, windows activation service, Self-hosting, Windows
service
Programming
[WebService] attribute has to be added to
the class
[ServiceContract] attribute has to be added to the class
Model
[WebMethod] attribute represents the
method exposed to client
[OperationContract] attribute represents the method exposed to client
Operation
One-way, Request- Response are the
different operations supported in web
service
One-Way, Request-Response, Duplex are different type of operations
supported in WCF
XML
System.Xml.serialization name space is
used for serialization
System.Runtime.Serialization namespace is used for serialization
Encoding
XML 1.0, MTOM(Message Transmission
Optimization Mechanism), DIME, Custom
XML 1.0, MTOM, Binary, Custom
Transports
Can be accessed through HTTP, TCP,
Custom
Can be accessed through HTTP, TCP, Named pipes, MSMQ,P2P, Custom
Protocols Security Security, Reliable messaging, Transactions
Difference between WCF and Web service

 A WCF Service is composed of three components :
 Service Class - It implements some service as a set of methods
 Host Environment - It can be a Console application or a Windows Service or a Windows Forms
application or IIS as in case of the normal .asmx web service in .NET
 Endpoints - All communications with the WCF service will happen via the endpoints. The
endpoint is composed of 3 parts (collectively called as ABC's of endpoint) as defines below:
 Address
 Binding
 Contract
WCF Service Components

 The endpoints specify an Address that defines where the endpoint is hosted
 It’s basically url
 Example:
http://localhost/WCFServiceSample/Service.svc
Address

 The endpoints also define a binding that specifies how a client will communicate with the
service and the address where the endpoint is hosted
 Different Bindings supported by WCF:
Binding
Binding Description
BasicHttpBinding
Basic Web service communication. No security by
default
WSHttpBinding
Web services with WS-* support. Supports
transactions
WSDualHttpBinding
Web services with duplex contract and transaction
support

WSFederationHttpBinding Web services with federated security. Supports transactions
MsmqIntegrationBinding Communication directly with MSMQ applications. Supports transactions
NetMsmqBinding
Communication between WCF applications by using queuing. Supports
transactions
NetNamedPipeBinding
Communication between WCF applications on same computer. Supports
duplex contracts and transactions
NetPeerTcpBinding
Communication between computers across peer-to-peer services.
Supports duplex contracts
NetTcpBinding
Communication between WCF applications across computers. Supports
duplex contracts and transactions
BasicHttpBinding Basic Web service communication. No security by default
WSHttpBinding Web services with WS-* support. Supports transactions
Binding (Cont.)

 The endpoints specify a Contract that defines which methods of the Service class will be
accessible via the endpoint; each endpoint may expose a different set of methods
 Different contracts in WCF:
 Service Contract
 It describe the operation that service can provide. For E.g., A Service provide to know the temperature of
the city based on the zip code, this service is called as Service contract
 It will be created using Service and Operational Contract attribute
 Message Contract
 Default SOAP message format is provided by the WCF runtime for communication between Client and
service
 If it is not meeting requirements then we can create our own message format. This can be achieved by
using Message Contract attribute
Contract

Data Contract
 It describes the custom data type which is exposed to the client. This defines the data types,
which are passed to and from service
 Data types like int, string are identified by the client because it is already mention in XML
schema definition language document, but custom created class or data types cannot be
identified by the client e.g. Employee data type
 By using Data Contract we can make client to be aware of Employee data type that are
returning or passing parameter to the method
Fault Contract
 Suppose the service we consumed is not working in the client application. we want to know the
real cause of the problem. How we can know the error? For this we are having Fault Contract
 Fault Contract provides documented view for error occurred in the service to client. This helps
us to easy identity, what error has occurred
Contract (Cont.)

 REST stands for ‘Representational State Transfer’ and it is an architectural pattern for
creating an API that uses HTTP as its underlying communication method
 Almost every device that is connected to the internet already uses HTTP, it is the base protocol
that the internet is built on which is why it makes such a great platform for an API
 HTTP is a request and response system, a calling client sends a request to an endpoint and the
endpoint responds
 The client and endpoint can be anything but a typical example is a browser accessing a web server
or an app accessing and API
REST

 There are several key implementation details with HTTP that you should be aware of:
 Resources - REST uses addressable resources to define the structure of the API. These are the
URLs you use to get to pages on the web
 Example: ‘http://www.microsoft.com/Surface-Pro-3’ is a resource
 Request Verbs - A browser typically issues a GET verb to instruct the endpoint it wants to get
data, however there are many other verbs available including things like POST, PUT and DELETE
 Request Headers - Additional instructions that are sent with the request. These might define
what type of response is required or authorization details
 Request Body - Data that is sent with the request
 Example: A POST (creation of a new item) will required some data which is typically sent as the
request body in the format of JSON or XML
 Response Body - Main body of the response. If the request was to a web server, this might be a
full HTML page, if it was to an API, this might be a JSON or XML document
 Response Status codes - These codes are issues with the response and give the client details on
the status of the request
REST (Cont.)
ASP.NET Software Development Companies India

 The term API stands for ‘Application Programming Interface’
 In the world of web development the term ‘API’ is synonymous with online web services
which client apps can use to retrieve and update data
 These online services have had several names/formats over the years such as SOAP,
however the current popular choice is to create a REST (or RESTful) API
WEB API

 http://www.tutorialspoint.com/webservices/
 http://www.w3schools.com/xml/xml_services.asp
 http://www.c-sharpcorner.com/uploadfile/00a8b7/web-service/
 https://www.tutorialspoint.com/asp.net/asp.net_web_services.htm
References

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