.Net Remoting - Interview Questions with Answers

What’s a Windows process?

It’s an application that’s running and has been allocated memory in the system.

What do you mean by a Windows process in regards to memory allocation?

Each process is allocated its own address space typically 4GB in which it can run. No other process can interfere in that address space.
If the process crashes, it dies alone without taking the entire OS or a bunch of other applications down.

What is the relationship between a Process, Application Domain, and Application?

A process is an instance of a running application. An application is an executable in the computer. There can be numerous processes launched of the same application (5 copies of Word running), but 1 process can run just 1 application. Hence, Process is a running instance of the application.

How to decide which to use .NET Remoting or ASP.NET Web Services?

Remoting is a more efficient communication exchange when you can control both ends of the application involved in the communication process. Remoting is excellent in case of intranet application because of the speed.

Web Services provide an open-protocol-based exchange of information. Web Services are best when you need to communicate with an external organization or another (non-.NET) technology applications.

What is the proxy of the server object in .NET Remoting?

Proxy is copy of the server object( a thin layer) that resides on the client side and behaves as if it was the server. It delegate calls to the real server object. This process is also known as marshalling.

What do mean by remotable objects in .NET Remoting?

Remotable objects can be marshalled across the application domains. You can marshal by value, where a deep copy of the object is created and then passed to the receiver. You can also marshal by reference, where just a reference to an existing object is passed.

What are channels in .NET Remoting?

Channels represent the objects that transfer the other serialized objects from one application domain in the same computer or to different computers. A channel must exist before an object can be transferred.

Windows Communication Foundation :Interview Questions with Answers

What is WCF?
Windows Communication Foundation (WCF) is an SDK for developing and deploying services on Windows. WCF provides a runtime environment for services, enabling you to expose CLR types as services, and to consume other services as CLR types.

WCF is part of .NET 3.0 and requires .NET 2.0, so it can only run on systems that support it. WCF is Microsoft's unified programming model for building service-oriented applications with managed code. It extends the .NET Framework to enable developers to build secure and reliable transacted Web services that integrate across platforms and interoperate with existing investments.

Windows Communication Foundation combines and extends the capabilities of existing Microsoft distributed systems technologies, including Enterprise Services, System. Messaging, Microsoft .NET Remoting, ASMX, and WSE to deliver a unified development experience across multiple axes, including distance (cross-process, cross-machine, cross-subnet, cross-intranet, cross-Internet), topologies (farms, fire-walled, content-routed, dynamic), hosts (ASP.NET, EXE, Windows Presentation Foundation, Windows Forms, NT Service, COM+), protocols (TCP, HTTP, cross-process, custom), and security models (SAML, Kerberos, X509, username/password, custom).

What is service and client in perspective of data communication?
A service is a unit of functionality exposed to the world. The client of a service is merely the party consuming the service.

What is endpoint in WCF? or What is three major points in WCF?
Every service must have Address that defines where the service resides, Contract that defines what the service does and a Binding that defines how to communicate with the service.

In WCF the relationship between Address, Contract and Binding is called Endpoint. The Endpoint is the fusion of Address, Contract and Binding.


1. Address : Specifies the location of the service which will be like http://Myserver/MyService.Clients will use this location to communicate with our service.

2. Contract : Specifies the interface between client and the server. It's a simple interface with some attribute.

3. Binding : Specifies how the two parties will communicate in term of transport and encoding and protocols.

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.

1. 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.


2. 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.

3. 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.

4. 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.

5. 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.

6. Federated WS binding :
Offered by the WSFederationHttpBinding class, this is a specialization of the WS binding, offering support for federated security.

7. 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.

8. MSMQ binding :
Offered by the NetMsmqBinding class, this uses MSMQ for transport and is designed to offer support for disconnected queued calls.

9. 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.

What is contracts in WCF?
In WCF, all services expose contracts. The contract is a platform-neutral and standard way of describing what the service does.

WCF defines four types of contracts.

1. Service contracts : Describe which operations the client can perform on the service.

2. 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.

3. Fault contracts : Define which errors are raised by the service, and how the service handles and propagates errors to its clients.

4. 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?
Address is a way of letting client know that where a service is located. In WCF, every service is associated with a unique address. This contains the location of the service and transport schemas. WCF supports following transport schemas

1. HTTP
2. TCP
3. Peer network
4. IPC (Inter-Process Communication over named pipes)
5. MSMQ

The sample address for above transport schema may look like

http://localhost:81
http://localhost:81/MyService
net.tcp://localhost:82/MyService
net.pipe://localhost/MyPipeService
net.msmq://localhost/private/MyMsMqService
net.msmq://localhost/MyMsMqService

What is the difference WCF and Web services?
1. Web services can only be invoked by HTTP. While Service or a WCF component can be invoked by any protocol and any transport type.

2. Second web services are not flexible. But Services are flexible. If you make a new version of the service then you need to just expose a new end point. So services are agile and which is a very practical approach looking at the current business trends.

How can we host a service on two different protocols on a single server?
Let’s first understand what this question actually means. Let’s say we have made a service and we want to host this service using HTTP as well as TCP.

You must be wondering why to ever host services on two different types of protocol. When we host a service it’s consumed by multiple types of client and it’s very much possible that they have there own protocol of communication. A good service has the capability to downgrade or upgrade its protocol according the client who is consuming him.

Let’s do a small sample in which we will host the ServiceGetCost on TCP and HTTP protocol.

Once we are done the server side coding its time to see make a client by which we can switch between the protocols and see the results. Below is the code snippet of the client side for multi-protocol hosting

How does WCF work?
Follows the 'software as a service' model, where all units of functionality are defined as services.

A WCF Service is a program that exposes a collection of Endpoints. Each Endpoint is a portal (connection) for communication with either clients (applications) or other services.

Enables greater design flexibility and extensibility of distributed systems architectures.

A WCF application is represented as a collection of services with multiple entry points for communications.

What are the main components of WCF?

1.Service: The working logic or offering, implemented using any .Net Language(C).

2.Host: The environment where the service is parked. E.g. exe, process, windows service

3.Endpoints: The way a service is exposed to outside world.

Explain transactions in WCF.
Transactions in WCF allow several components to concurrently participate in an operation. Transactions are a group of operations that are atomic, consistent, isolated and durable. WCF has features that allow distributed transactions. Application config file can be used for setting transaction timeouts.

What are different isolation levels provided in WCF?
The different isolation levels:

1. READ UNCOMMITTED: - An uncommitted transaction can be read. This transaction can be rolled back later.

2. READ COMMITTED :- Will not read data of a transaction that has not been committed yet

3. REPEATABLE READ: - Locks placed on all data and another transaction cannot read.

4. SERIALIZABLE:- Does not allow other transactions to insert or update data until the transaction is complete.

Explain transactions in WCF.
Transactions in WCF allow several components to concurrently participate in an operation. Transactions are a group of operations that are atomic, consistent, isolated and durable. WCF has features that allow distributed transactions. Application config file can be used for setting transaction timeouts.

How do I serialize entities using WCF?
LINQ to SQL supports serialization as XML via WCF by generating WCF serialization attributes and special serialization specific logic during code-generation. You can turn on this feature in the designer by setting serialization mode to ‘Unidirectional’. Note this is not a general solution for serialization as unidirectional mode may be insufficient for many use cases.

What is End point ?
Every service must have Address that defines where the service resides, Contract that defines what the service does and a Binding that defines how to communicate with the service. In WCF the relationship between Address, Contract and Binding is called Endpoint.

The Endpoint is the fusion of Address, Contract and Binding.

Story : Perfectness

A man and his girlfriend were married. It was a large celebration. All of their friends and family came to see the lovely ceremony and to partake of the festivities and celebrations. A wonderful time was had by all.

The bride was gorgeous in her white wedding gown and the groom was very dashing in his black tuxedo. Everyone could tell that! The love they had for each other was true.

A few months later, the wife comes to the husband with a proposal: “I read in a magazine, a while ago, about how we can strengthen our marriage.” She offered.

“Each of us will write a list of the things that we find a bit annoying with the other person. Then, we can talk about how we can fix them together and make our lives happier together.”

The husband agreed, so each of them went to a separate room in the house and thought of the things that annoyed them about the other. They thought about this question for the rest of the day and wrote down what they came up with.

The next morning, at the breakfast table, they decided that they would go over their lists.

“I’ll start,” offered the husband. He took out his list. It had many items on it enough to fill three pages, in fact. As he started reading the list of the little annoyances, he noticed that tears were starting to appear in his wife’s eyes.

“What’s wrong?” he asked. “Nothing” the wife replied, “keep reading your lists.”

The husband continued to read until he had read all three pages to his wife. He neatly placed his list on the table and folded his hands over top of it.

“Now, you read your list and then we’ll talk about the things on both of our lists.” He said happily.

Quietly the wife stated, “I don’t have anything on my list. I think that you are perfect, the way that you are. I don’t want you to change anything for me. You are lovely and wonderful and I wouldn’t want to try and change anything about you.”

The husband, touched by her honesty and the depth of her love and acceptance for him, turned his head and wept.

In life, there are enough times when we are disappointed, depressed and annoyed. We don’t really have to go looking for them. We have a wonderful world that is full of beauty, light and promise.

Why waste time in this world looking for the bad, disappointing or annoying when we can look around us, and see the wondrous things before us?

Lessons to learn from this: I believe that WE ARE HAPPIEST when we see and praise the good and try our best to forget the bad. Nobody’s perfect but we can find perfectness in them to change the way we see them.