What are contracts in WCF?
Service contracts
Describe which operations the client can perform on the service.
There are two types of Service Contracts.
ServiceContract - This attribute is used to define the Interface.
OperationContract - This attribute is used to define the method inside Interface.
Data contracts
Define which data types are passed to and from the service. WCF defines implicit contracts for built-in types such as int and string, but we can easily define explicit opt-in data contracts for custom types.
There are two types of Data Contracts.
DataContract - attribute used to define the class
DataMember - attribute used to define the properties.
Fault contracts
Define which errors are raised by the service, and how the service handles and propagates errors to its clients.
Message contracts
Allow the service to interact directly with messages. Message contracts can be typed or untyped, and are useful in interoperability cases and when there is an existing message format we have to comply with.
What is address in WCF and how many types of transport schemas are there in WCF?
WCF supports following transport schemas
HTTP
TCP
Peer network
IPC (Inter-Process Communication over named pipes)
MSMQ
Where we can host WCF services?
1. IIS
2. Self Hosting
3. WAS (Windows Activation Service)
What is binding and how many types of bindings are there in WCF?
A binding defines how an endpoint communicates to the world. A binding defines the transport (such as HTTP or TCP) and the encoding being used (such as text or binary). A binding can contain binding elements that specify details like the security mechanisms used to secure messages, or the message pattern used by an endpoint.
WCF supports nine types of bindings.
Basic binding
Offered by the BasicHttpBinding class, this is designed to expose a WCF service as a legacy ASMX web service, so that old clients can work with new services. When used by the client, this binding enables new WCF clients to work with old ASMX services.
TCP binding
Offered by the NetTcpBinding class, this uses TCP for cross-machine communication on the intranet. It supports a variety of features, including reliability, transactions, and security, and is optimized for WCF-to-WCF communication. As a result, it requires both the client and the service to use WCF.
Peer network binding
Offered by the NetPeerTcpBinding class, this uses peer networking as a transport. The peer network-enabled client and services all subscribe to the same grid and broadcast messages to it.
IPC binding
Offered by the NetNamedPipeBinding class, this uses named pipes as a transport for same-machine communication. It is the most secure binding since it cannot accept calls from outside the machine and it supports a variety of features similar to the TCP binding.
Web Service (WS) binding
Offered by the WSHttpBinding class, this uses HTTP or HTTPS for transport, and is designed to offer a variety of features such as reliability, transactions, and security over the Internet.
Federated WS binding
Offered by the WSFederationHttpBinding class, this is a specialization of the WS binding, offering support for federated security.
Duplex WS binding
Offered by the WSDualHttpBinding class, this is similar to the WS binding except it also supports bidirectional communication from the service to the client.
MSMQ binding
Offered by the NetMsmqBinding class, this uses MSMQ for transport and is designed to offer support for disconnected queued calls.
MSMQ integration binding
Offered by the MsmqIntegrationBinding class, this converts WCF messages to and from MSMQ messages, and is designed to interoperate with legacy MSMQ clients.
webhttp binding
This binding uses for rest full service
What are WCF Service Endpoints? Explain.
For Windows Communication Foundation services to be consumed, it’s necessary that it must be exposed; Clients need information about service to communicate with it. This is where service endpoints play their role.
A WCF service endpoint has three basic elements i.e. Address, Binding and Contract.
Address: It defines "WHERE". Address is the URL that identifies the location of the service.
Binding: It defines "HOW". Binding defines how the service can be accessed.
Contract: It defines "WHAT". Contract identifies what is exposed by the service.
What is the address formats of the WCF transport schemas?
Address format of WCF transport schema always follow
[transport]://[machine or domain][:optional port] format.
for example:
HTTP Address Format
http://localhost:8888
the way to read the above url is
"Using HTTP, go to the machine called localhost, where on port 8888 someone is waiting"
When the port number is not specified, the default port is 80.
TCP Address Format
net.tcp://localhost:8888/MyService
When a port number is not specified, the default port is 808:
net.tcp://localhost/MyService
NOTE: Two HTTP and TCP addresses from the same host can share a port, even on the same machine.
IPC Address Format
net.pipe://localhost/MyPipe
We can only open a named pipe once per machine, and therefore it is not possible for two named pipe addresses to share a pipe name on the same machine.
MSMQ Address Format
net.msmq://localhost/private/MyService
net.msmq://localhost/MyService
What Message Exchange Patterns (MEPs) supported by WCF? Explain each of them briefly.
1. Request/Response 2. One Way 3. Duplex
Request/Response
It’s the default pattern. In this pattern, a response message will always be generated to consumer when the operation is called, even with the void return type. In this scenario, response will have empty SOAP body.
One Way
In some cases, we are interested to send a message to service in order to execute certain business functionality but not interested in receiving anything back. OneWay MEP will work in such scenarios. If we want queued message delivery, OneWay is the only available option.
Duplex
The Duplex MEP is basically a two-way message channel. In some cases, we want to send a message to service to initiate some longer-running processing and require a notification back from service in order to confirm that the requested process has been completed.
Please explain briefly different Instance Modes in WCF?
WCF will bind an incoming message request to a particular service instance, so the available modes are:
Per Call: instance created for each call, most efficient in term of memory but need to maintain session.
Per Session: Instance created for a complete session of a user. Session is maintained.
Single: Only one instance created for all clients/users and shared among all.Least efficient in terms of memory.
What are different elements of WCF Srevices Client configuration file?
WCF Services client configuration file contains endpoint, address, binding and contract. A sample client config file looks like
<system.serviceModel>
<client>
<endpoint name = "MyEndpoint"
address = "http://localhost:8000/MyService/"
binding = "wsHttpBinding"
contract = "IMyContract"
/>
</client>
</system.serviceModel>
How to configure Reliability while communicating with WCF Services?
Reliability can be configured in the client config file by adding reliableSession under binding tag.
<system.serviceModel>
<services>
<service name = "MyService">
<endpoint
address = "net.tcp://localhost:8888/MyService"
binding = "netTcpBinding"
bindingConfiguration = "ReliableCommunication"
contract = "IMyContract"
/>
</service>
</services>
<bindings>
<netTcpBinding>
<binding name = "ReliableCommunication">
<reliableSession enabled = "true"/>
</binding>
</netTcpBinding>
</bindings>
</system.serviceModel>
Reliability is supported by following bindings only
NetTcpBinding
WSHttpBinding
WSFederationHttpBinding
WSDualHttpBinding
How to set the timeout property for the WCF Service client call?
The timeout property can be set for the WCF Service client call using binding tag.
<client>
<endpoint
...
binding = "wsHttpBinding"
bindingConfiguration = "LongTimeout"
...
/>
</client>
<bindings>
<wsHttpBinding>
<binding name = "LongTimeout" sendTimeout = "00:04:00"/>
</wsHttpBinding>
</bindings>
Please explain different modes of security in WCF? Or Explain the difference between Transport and Message Level Security.
In Windows Communication Foundation, we can configure to use security at different levels
a. Transport Level security means providing security at the transport layer itself. When dealing with security at Transport level, we are concerned about integrity, privacy and authentication of message as it travels along the physical wire. It depends on the binding being used that how WCF makes it secure because most of the bindings have built-in security.
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<netTcpBinding>
<binding name="netTcpTransportBinding">
<security mode="Transport">
<Transport clientCredentialType="Windows" />
</security>
</binding>
</netTcpBinding>
b. Message Level Security For Tranport level security, we actually ensure the transport that is being used should be secured but in message level security, we actually secure the message. We encrypt the message before transporting it.
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<wsHttpBinding>
<binding name="wsHttpMessageBinding">
<security mode="Message">
<Message clientCredentialType="UserName" />
</security>
</binding>
</wsHttpBinding>
It totally depends upon the requirements but we can use a mixed security mode also as follows:
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<basicHttpBinding>
<binding name="basicHttp">
<security mode="TransportWithMessageCredential">
<Transport />
<Message clientCredentialType="UserName" />
</security>
</binding>
</basicHttpBinding>
Service contracts
Describe which operations the client can perform on the service.
There are two types of Service Contracts.
ServiceContract - This attribute is used to define the Interface.
OperationContract - This attribute is used to define the method inside Interface.
Data contracts
Define which data types are passed to and from the service. WCF defines implicit contracts for built-in types such as int and string, but we can easily define explicit opt-in data contracts for custom types.
There are two types of Data Contracts.
DataContract - attribute used to define the class
DataMember - attribute used to define the properties.
Fault contracts
Define which errors are raised by the service, and how the service handles and propagates errors to its clients.
Message contracts
Allow the service to interact directly with messages. Message contracts can be typed or untyped, and are useful in interoperability cases and when there is an existing message format we have to comply with.
What is address in WCF and how many types of transport schemas are there in WCF?
WCF supports following transport schemas
HTTP
TCP
Peer network
IPC (Inter-Process Communication over named pipes)
MSMQ
Where we can host WCF services?
1. IIS
2. Self Hosting
3. WAS (Windows Activation Service)
What is binding and how many types of bindings are there in WCF?
A binding defines how an endpoint communicates to the world. A binding defines the transport (such as HTTP or TCP) and the encoding being used (such as text or binary). A binding can contain binding elements that specify details like the security mechanisms used to secure messages, or the message pattern used by an endpoint.
WCF supports nine types of bindings.
Basic binding
Offered by the BasicHttpBinding class, this is designed to expose a WCF service as a legacy ASMX web service, so that old clients can work with new services. When used by the client, this binding enables new WCF clients to work with old ASMX services.
TCP binding
Offered by the NetTcpBinding class, this uses TCP for cross-machine communication on the intranet. It supports a variety of features, including reliability, transactions, and security, and is optimized for WCF-to-WCF communication. As a result, it requires both the client and the service to use WCF.
Peer network binding
Offered by the NetPeerTcpBinding class, this uses peer networking as a transport. The peer network-enabled client and services all subscribe to the same grid and broadcast messages to it.
IPC binding
Offered by the NetNamedPipeBinding class, this uses named pipes as a transport for same-machine communication. It is the most secure binding since it cannot accept calls from outside the machine and it supports a variety of features similar to the TCP binding.
Web Service (WS) binding
Offered by the WSHttpBinding class, this uses HTTP or HTTPS for transport, and is designed to offer a variety of features such as reliability, transactions, and security over the Internet.
Federated WS binding
Offered by the WSFederationHttpBinding class, this is a specialization of the WS binding, offering support for federated security.
Duplex WS binding
Offered by the WSDualHttpBinding class, this is similar to the WS binding except it also supports bidirectional communication from the service to the client.
MSMQ binding
Offered by the NetMsmqBinding class, this uses MSMQ for transport and is designed to offer support for disconnected queued calls.
MSMQ integration binding
Offered by the MsmqIntegrationBinding class, this converts WCF messages to and from MSMQ messages, and is designed to interoperate with legacy MSMQ clients.
webhttp binding
This binding uses for rest full service
What are WCF Service Endpoints? Explain.
For Windows Communication Foundation services to be consumed, it’s necessary that it must be exposed; Clients need information about service to communicate with it. This is where service endpoints play their role.
A WCF service endpoint has three basic elements i.e. Address, Binding and Contract.
Address: It defines "WHERE". Address is the URL that identifies the location of the service.
Binding: It defines "HOW". Binding defines how the service can be accessed.
Contract: It defines "WHAT". Contract identifies what is exposed by the service.
What is the address formats of the WCF transport schemas?
Address format of WCF transport schema always follow
[transport]://[machine or domain][:optional port] format.
for example:
HTTP Address Format
http://localhost:8888
the way to read the above url is
"Using HTTP, go to the machine called localhost, where on port 8888 someone is waiting"
When the port number is not specified, the default port is 80.
TCP Address Format
net.tcp://localhost:8888/MyService
When a port number is not specified, the default port is 808:
net.tcp://localhost/MyService
NOTE: Two HTTP and TCP addresses from the same host can share a port, even on the same machine.
IPC Address Format
net.pipe://localhost/MyPipe
We can only open a named pipe once per machine, and therefore it is not possible for two named pipe addresses to share a pipe name on the same machine.
MSMQ Address Format
net.msmq://localhost/private/MyService
net.msmq://localhost/MyService
What Message Exchange Patterns (MEPs) supported by WCF? Explain each of them briefly.
1. Request/Response 2. One Way 3. Duplex
Request/Response
It’s the default pattern. In this pattern, a response message will always be generated to consumer when the operation is called, even with the void return type. In this scenario, response will have empty SOAP body.
One Way
In some cases, we are interested to send a message to service in order to execute certain business functionality but not interested in receiving anything back. OneWay MEP will work in such scenarios. If we want queued message delivery, OneWay is the only available option.
Duplex
The Duplex MEP is basically a two-way message channel. In some cases, we want to send a message to service to initiate some longer-running processing and require a notification back from service in order to confirm that the requested process has been completed.
Please explain briefly different Instance Modes in WCF?
WCF will bind an incoming message request to a particular service instance, so the available modes are:
Per Call: instance created for each call, most efficient in term of memory but need to maintain session.
Per Session: Instance created for a complete session of a user. Session is maintained.
Single: Only one instance created for all clients/users and shared among all.Least efficient in terms of memory.
What are different elements of WCF Srevices Client configuration file?
WCF Services client configuration file contains endpoint, address, binding and contract. A sample client config file looks like
<system.serviceModel>
<client>
<endpoint name = "MyEndpoint"
address = "http://localhost:8000/MyService/"
binding = "wsHttpBinding"
contract = "IMyContract"
/>
</client>
</system.serviceModel>
How to configure Reliability while communicating with WCF Services?
Reliability can be configured in the client config file by adding reliableSession under binding tag.
<system.serviceModel>
<services>
<service name = "MyService">
<endpoint
address = "net.tcp://localhost:8888/MyService"
binding = "netTcpBinding"
bindingConfiguration = "ReliableCommunication"
contract = "IMyContract"
/>
</service>
</services>
<bindings>
<netTcpBinding>
<binding name = "ReliableCommunication">
<reliableSession enabled = "true"/>
</binding>
</netTcpBinding>
</bindings>
</system.serviceModel>
Reliability is supported by following bindings only
NetTcpBinding
WSHttpBinding
WSFederationHttpBinding
WSDualHttpBinding
How to set the timeout property for the WCF Service client call?
The timeout property can be set for the WCF Service client call using binding tag.
<client>
<endpoint
...
binding = "wsHttpBinding"
bindingConfiguration = "LongTimeout"
...
/>
</client>
<bindings>
<wsHttpBinding>
<binding name = "LongTimeout" sendTimeout = "00:04:00"/>
</wsHttpBinding>
</bindings>
Please explain different modes of security in WCF? Or Explain the difference between Transport and Message Level Security.
In Windows Communication Foundation, we can configure to use security at different levels
a. Transport Level security means providing security at the transport layer itself. When dealing with security at Transport level, we are concerned about integrity, privacy and authentication of message as it travels along the physical wire. It depends on the binding being used that how WCF makes it secure because most of the bindings have built-in security.
Collapse | Copy Code
<netTcpBinding>
<binding name="netTcpTransportBinding">
<security mode="Transport">
<Transport clientCredentialType="Windows" />
</security>
</binding>
</netTcpBinding>
b. Message Level Security For Tranport level security, we actually ensure the transport that is being used should be secured but in message level security, we actually secure the message. We encrypt the message before transporting it.
Collapse | Copy Code
<wsHttpBinding>
<binding name="wsHttpMessageBinding">
<security mode="Message">
<Message clientCredentialType="UserName" />
</security>
</binding>
</wsHttpBinding>
It totally depends upon the requirements but we can use a mixed security mode also as follows:
Collapse | Copy Code
<basicHttpBinding>
<binding name="basicHttp">
<security mode="TransportWithMessageCredential">
<Transport />
<Message clientCredentialType="UserName" />
</security>
</binding>
</basicHttpBinding>
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