Differences between Web Services and WCF in ASP.NET

This is one of the good WCF interview Question


1. File Format or Extension
Web Service:Web service file extension is .asmx
WCF: WCF service file extension is .svc




2. Hosting 
Web Service:WebService can host in IIS and outside of IIS also. Please refer this Microsoft article for more details.
WCF: WCF service can host in self hosting, IIS, Windows Activation Services(WAS) and Managed Windows Services.



3. Transport Protocols or Binding 
Web Service:HTTP, TCP, Custom
WCF: HTTP, WS-HTTP, TCP, Custom, Named Pipes, MSMQ, P2P(Point to Point) etc



4. Data Transformation 
Web Service:XML serializer
WCF: DataContractSerializer



5. Serialization NameSpace 
Web Service:System.XML.Serialization
WCF: System.RunTime.Serialization



6. WebMethods and DataContract 
Web Service:Uses WebMethods to translate .Net FW types in to XML.

• [WebService] has to be added to the class
• [WebMethod] attribute        represents the method exposed to the client.

WCF: Uses DataContractAttributes and DataMemberAttribute to translate .Net FW types in to XML.

• [ServiceContract] attribute has to be added to the class
• [OperationContract] attribute represents the method exposed to the client.

7. Security 
Web Service:Not much secured as compared to WCF. Can’t protect the data between Server and Client. Using certificates can protect the data but it is complicated. Normally we use UserName/Password.
WCF: More secured than WebServices. WCF does not need IIS to run, it can run as a System Service on the Server, using a command ambient. WCF is a service and not a Web Service.



8. Encoding techniques 
Web Service:XML1.0, MTOM (Message Transmission Optimization Mechanism), DIME (Direct Internet Message Encapsulation)
WCF: XML1.0, MTOM, Binary



9. Supported Operations 
Web Service:One-Way and Request-Response
WCF: One-Way, Request-Response and Duplex



10. Limitations 
Web Service:

• Hash Table cannot be serialized.
• Only public properties/fields can be serialized

WCF: 

• The DataContractSerializer translate the Hash table into the XML.
•  Public/Private properties/fields        can be serialized.

11. Messaging 
Web Service:Uses only SOAP(Simple Object Access Protocol)
WCF: It can send/receive message in any transport protocol message format. By default it uses SOAP for communication.



12. Exception Handling 
Web Service:Unhandled Exceptions returns to the client as SOAP faults.
WCF: Unhandled Exceptions does not return to the client as SOAP faults. A configuration setting is provided to have the unhandled exceptions returned to the Client for the purpose of debugging.



13. Performance 
Web Service:Slower than WCF. The performance measures in terms of xml serialization.
WCF: Better than WebService.