Tuesday, 1 July 2014

What is Service
A service is a program that performs a task and that a client application can communicate with through well-defined messages. To call a Web or WCF service, the client passes it a message, which consists of XML. The message will typically include a request for the service to perform an action, such as retrieve or update the inventory information for a product. If the service returns data to the client, it passes back a message, also consisting of XML. 

The client and the service need to agree on what the XML will look like. The most common message format is Simple Object Access Protocol (SOAP). SOAP defines the format of XML request and reply messages and how clients and services encode the data in the messages. 

What is Difference Between Object Oriented and Service Oriented
In object-oriented programming, objects are tightly coupled. To call the Inventory component, a client application creates an instance of the component and therefore, controls its lifetime. In a service-oriented application, services and clients are loosely coupled. To call the Inventory service, a client does not instantiate an instance of a component. It simply passes a message to the service and may receive a message in return. 

Service-oriented applications are loosely coupled. All communication occurs through messages. SOAP defines the format of messages. Contracts define the contents of messages. A service will publish a contract that specifies what methods clients can call, what arguments those methods take and what, if anything, the methods return. The contract can also specify security requirements and whether a transaction is required.

Why Use Windows Communication Foundation?

WCF provides a number of benefits over ASP.NET Web Services, including:
  • Support for sending messages using not only HTTP, but also TCP and other network protocols.
  • The ability to switch message protocols with minimal effort.
  • Support for hosting services on hosts other than a Web server.
  • Built-in support for the latest Web services standards (SOAP 1.2 and WS-*) and the ability to easily support new ones.
  • Support for security, transactions and reliability.
  • Support for sending messages using formats other than SOAP, such as Representational State Transfer (REST). 

What is Serialization

Serialization is the process of converting an object into a stream of bytes in order to store the object or transmit it to memory, a database, or a file. Its main purpose is to save the state of an object in order to be able to recreate it when needed. The reverse process is called deserialization.
  The object is serialized to a stream, which carries not just the data, but information about the object's type, such as its version, culture, and assembly name. From that stream, it can be stored in a database, a file, or memory.

Uses of Serailization
Serialization allows the developer to save the state of an object and recreate it as needed, providing storage of objects as well as data exchange. Through serialization, a developer can perform actions like sending the object to a remote application by means of a Web Service, passing an object from one domain to another, passing an object through a firewall as an XML string, or maintaining security or user-specific information across applications.
Types of Serialization
Binary Serialization
Binary serialization is used for serializing an object which uses network steams, or convert a WCF object type and store in the file system. Binary serialization is used to get data back from a network stream and other types without any loss. The binary object can be serialized to disk, memory, network, etc. The class public and private members are serialized and restored back as the original value in the deserialization process. This process is used to store large object values in persistence storage or to send them through a network and restore back when required. 

The serialization process is useful when a large object has to be stored in persistence storage. The object oriented class hierarchy may involve complexity for storing and retrieving values. This process is useful for resolving complexities automatically. The Common Language Runtime will manage the object reference and circular references between classes automatically.

Binary serialization uses binary format for understanding communication between .NET Framework applications. It saves metadata information along with an object. It helps for restructuring the object when it deserializes an object from persistence storage. A binary formatter is faster than other serialization formatters. It can serialize generic and non-generic collections. This serialization supports serializing private and public members. 

XML And Soap Serialization

The XmlSerializer class is derived directly from the Object base class. XML serialization does not include type information. XML serialization serializes only public fields and properties of the object into an XML stream that confirms with the specific XSD language. 

he System.Xml.Serialization namespace has all the classes and interfaces for serializing and deserializing values. SOAP serialization confirms to the SOAP specification. Web applications can use the XmlSerializer class to create XML and send across applications. XML serialization converts only public fields and properties of an object into the XML stream.

Serializer in WCF

Basically their are two Serializer in WCF
1- DataContactSerializer
2- NetDataContactSerializer

 Dat­a­Con­tract­Se­ri­al­izer does not include the CLR type infor­ma­tion in the seri­al­ized XML, which allows for loose cou­pling between the client and server because they don’t have to share the same CLR types.
How­ever, this also means you often have to re-create the same types on the client, though Visual Stu­dio han­dles most of this for you when you add a new ser­vice ref­er­ence to your project. How­ever, rather than dese­ri­al­iz­ing the orig­i­nal type, mes­sages are dese­ri­al­ized into a new, but iden­ti­cal CLR type on the client.

While Dat­a­Con­tract­Se­ri­al­izer is used by WCF by default, there is another seri­al­izer which you can use if you wish to share the same CLR types between the client and server – the Net­Dat­a­Con­tract­Se­ri­al­izer. The Net­Dat­a­Con­tract­Se­ri­al­izer dif­fers from the Dat­a­Con­tract­Se­ri­al­izer in that it includes the CLR type infor­ma­tion in the seri­al­ized XML and can only be used if the same CLR types are seri­al­ized and dese­ri­al­ized at both ends.
You can use the Net­Dat­a­Con­tract­Se­ri­al­izer on any type which are marked with the Dat­a­Con­trac­tAt­tribute or Seri­al­iz­ableAt­tribute, or types that imple­ment the ISe­ri­al­iz­able interface.

Here is the DataContractSerializer version of the Person data
<Customer xmlns="http://www.contoso.com" xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
And here is the version from the NetDataContractSerializer
<Customer z:Id="1" z:Type="NetDCS.Person" z:Assembly="NetDCS, Version=, Culture=neutral, PublicKeyToken=null" xmlns="http://www.contoso.com" xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns:z="http://schemas.microsoft.com/2003/10/Serialization/">
  <FirstName z:Id="2">Zighetti</FirstName>
  <LastName z:Id="3">Barbara</LastName>

No comments:

Post a Comment