What is the role of WSDL in WCF?
WSDL stands for Web Service Description Language. The WCF service exposes the WSDL document for the clients, to generate proxies and the configuration file. The WSDL file provides the following information for the consumers of the WCF service.
1. Provides the information about the service contract and operations available.
2. Provides the information about all the end points exposed by the WCF service.
3. Provides the information about the messages and types that can be exchanged between the client and the WCF service.
4. WSDL also provides any information about the policies used.
Showing posts with label wcf interview questions. Show all posts
Showing posts with label wcf interview questions. Show all posts
WCF, WPF, Silverlight, LINQ, Azure and EF 4.0 interview question
WCF, WPF, Silverlight, LINQ, Azure and EF 4.0 interview question
- What is SOA, Services and Messages ?
- What is the difference between Service and Component?
- What are basic steps to create a WCF service ?
- What are endpoints, address, contracts and bindings?
- What are various ways of hosting WCF service?
- What is the difference of hosting a WCF service on IIS and Self hosting?
- What is the difference between BasicHttpBinding and WsHttpBinding?
- How can we do debugging and tracing in WCF?
- Can you explain transactions in WCF (theory)?
- How can we self host WCF service ?
- What are the different ways of implementing WCF Security?
- How can we implement SSL security on WCF(Transport Security)?
- How can we implement transport security plus message security in WCF ?
- How can we do WCF instancing ?
- How Can we do WCF Concurency and throttling?
- Can you explain the architecture of Silverlight ?
- What are the basic things needed to make a silverlight application ?
- How can we do transformations in SilverLight ?
- Can you explain animation fundamentals in SilverLight?
- What are the different layout methodologies in SilverLight?
- Can you explain one way , two way and one time bindings?
- How can we consume WCF service in SilverLight?
- How can we connect databases using SilverLight?
- What is LINQ and can you explain same with example?
- Can you explain a simple example of LINQ to SQL?
- How can we define relationships using LINQ to SQL?
- How can we optimize LINQ relationships queries using ‘DataLoadOptions’?
- Can we see a simple example of how we can do CRUD using LINQ to SQL?
- How can we call a stored procedure using LINQ?
- What is the need of WPF when we had GDI, GDI+ and DirectX?
- Can you explain how we can make a simple WPF application?
- Can you explain the three rendering modes i.e. Tier 0 , Tier 1 and Tier 2?
- Can you explain the Architecture of WPF?
- What is Azure?
- Can you explain Azure Costing?
- Can we see a simple Azure sample program?
- What are the different steps to create a simple Worker application?
- Can we understand Blobs in steps, Tables & Queues ?
- Can we see a simple example for Azure tables?
- What is Package and One click deploy(Deployment Part - 1) ?
- What is Web.config transformation (Deployment Part-2)?
- What is MEF and how can we implement the same?
- How is MEF different from DIIOC?
- Can you show us a simple implementation of MEF in Silverlight ?
What is binding and how many types of bindings are there in WCF?
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.
This binding is used when we need to use SOAP over HTTP. This binding
can also be configured to be used as HTTPS. It can be also configured to send data in plain text or
in optimized form like MTOM.
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.
This binding sends binary-encoded SOAP, including support for reliable
message transfer, security, and transactions, directly over TCP. The biggest disadvantage of
NetTcpBinding is that both server and client should be also made in .NET language.
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.
It is same like BasicHttpBinding. In short, it uses SOAP over HTTP. But with
it also supports reliable message transfer, security and transaction. WS-Reliable Messaging,
security with WS-Security, and transactions with WS-Atomic Transaction supports reliable
message.
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.
This binding sends binary-encoded SOAP over MSMQ. This binding can
only be used for WCF-to-WCF communication.
Which specifications does WCF follow?
Which specifications does WCF follow?
WCF supports specifications defined by WS-* specifications. WS-* specifications are defined
together by Microsoft, IBM, SUN and many other big companies so that they can expose there
service through a common protocol. WCF supports all specifications defined we will understand
them one by one.
• Messaging (WS-Addressing):- SOAP is the fundamental protocol for web services. WS
Addressing defines some extra additions to SOAP headers, which makes SOAP free from
underlying transport protocol. One of the good things about Message transmission is MTOM,
also termed as Message Transmission Optimization Mechanism. They optimize transmission
format for SOAP messages in XML-Binary formant using XML optimized packaging (XOP).
Because the data will sent in binary and optimized format, it will give us huge performance
gain.
• Security (WS-Security, WS-Trust, and WS-Secure Conversation): All the three WSdefine
authentication, security, data integrity and privacy features for a service.
• Reliability (WS-Reliable Messaging): This specification ensures end-to-end
communication when we want SOAP messages to be traversed back and forth many times.
• Transactions (WS-Coordination and WS-Atomic Transaction): These two specifications
enable transaction with SOAP messages.
• Metadata (WS-Policy and WS-Metadata exchange): WSDL is a implementation of WSMetadata
Exchange protocol. WS-Policy defines more dynamic features of a service, which
cannot be expressed by WSDL.
WCF follows WS-* specifications other
languages like JAVA , C++ can also exploit features like Messaging , Security , Reliability and
transactions written in C# or VB.NET. This is the biggest achievement of WCF to integrate the
above features with other languages.
WCF supports specifications defined by WS-* specifications. WS-* specifications are defined
together by Microsoft, IBM, SUN and many other big companies so that they can expose there
service through a common protocol. WCF supports all specifications defined we will understand
them one by one.
• Messaging (WS-Addressing):- SOAP is the fundamental protocol for web services. WS
Addressing defines some extra additions to SOAP headers, which makes SOAP free from
underlying transport protocol. One of the good things about Message transmission is MTOM,
also termed as Message Transmission Optimization Mechanism. They optimize transmission
format for SOAP messages in XML-Binary formant using XML optimized packaging (XOP).
Because the data will sent in binary and optimized format, it will give us huge performance
gain.
• Security (WS-Security, WS-Trust, and WS-Secure Conversation): All the three WSdefine
authentication, security, data integrity and privacy features for a service.
• Reliability (WS-Reliable Messaging): This specification ensures end-to-end
communication when we want SOAP messages to be traversed back and forth many times.
• Transactions (WS-Coordination and WS-Atomic Transaction): These two specifications
enable transaction with SOAP messages.
• Metadata (WS-Policy and WS-Metadata exchange): WSDL is a implementation of WSMetadata
Exchange protocol. WS-Policy defines more dynamic features of a service, which
cannot be expressed by WSDL.
WCF follows WS-* specifications other
languages like JAVA , C++ can also exploit features like Messaging , Security , Reliability and
transactions written in C# or VB.NET. This is the biggest achievement of WCF to integrate the
above features with other languages.
What are the advantages of hosting WCF Services in IIS as compared to self-hosting?
What are the advantages of hosting WCF Services in IIS as compared to self-hosting?
There are two main advantages of using IIS over self-hosting:-
Automatic activation
IIS provides automatic activation that means the service is not necessary to be running in
advance. When any message is received by the service it then launches and fulfills the request.
But in case of self hosting the service should always be running.
Process recycling
If IIS finds that a service is not healthy that means if it has memory leaks etc, IIS recycles the
process. For every browser instance, a
worker process is spawned and the request is serviced. When the browser disconnects the worker,
process stops and you loose all information. IIS also restarts the worker process. By default, the
worker process is recycled at around 120 minutes. So why does IIS recycle. By restarting the
worker process it ensures any bad code or memory leak do not cause issue to the whole system.
In case of self-hosting both the above features, you will need to code yourself. Lot of work
right!!.
There are two main advantages of using IIS over self-hosting:-
Automatic activation
IIS provides automatic activation that means the service is not necessary to be running in
advance. When any message is received by the service it then launches and fulfills the request.
But in case of self hosting the service should always be running.
Process recycling
If IIS finds that a service is not healthy that means if it has memory leaks etc, IIS recycles the
process. For every browser instance, a
worker process is spawned and the request is serviced. When the browser disconnects the worker,
process stops and you loose all information. IIS also restarts the worker process. By default, the
worker process is recycled at around 120 minutes. So why does IIS recycle. By restarting the
worker process it ensures any bad code or memory leak do not cause issue to the whole system.
In case of self-hosting both the above features, you will need to code yourself. Lot of work
right!!.
What are the various ways of hosting a WCF service?
What are the various ways of hosting a WCF service?
There are three major ways to host a WCF service:-
• Self-hosting the service in his own application domain. This we have already covered in
the first section. The service comes in to existence when you create the object of Service
Host class and the service closes when you call the Close of the Service Host class.
• Host in application domain or process provided by IIS Server.
• Host in Application domain and process provided by WAS (Windows Activation
Service) Server.
There are three major ways to host a WCF service:-
• Self-hosting the service in his own application domain. This we have already covered in
the first section. The service comes in to existence when you create the object of Service
Host class and the service closes when you call the Close of the Service Host class.
• Host in application domain or process provided by IIS Server.
• Host in Application domain and process provided by WAS (Windows Activation
Service) Server.
Which are the various programming approaches for WCF?/What is one-way operation?
Which are the various programming approaches for WCF?/What is one-way operation?
IsOneWay equal to true ensures that the client does not have to wait for the response. So methods
marked by IsOneWay to true should always return void. In this, the caller does not get anything
IsOneWay equal to true ensures that the client does not have to wait for the response. So methods
marked by IsOneWay to true should always return void. In this, the caller does not get anything
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