What are the different platforms where we can host WCF service ?
WCF Services can be hosted on following platforms
1. WAS(Windows Activation Service)
2. Self Hosting
3. IIS
Advantage of using a Remote WebService ? When there is a need of using a webservice and only when the
same set of data needs to be accessed by multiple people, or
when a user needs to be able to access the same set of data
from multiple computers. This Remote Web Service is very much
useful.
Description about WCF? WCF (Window Communication Foundation) is a solution for
developers to work in distributing environment. WCF mainly for
make communication between applications. Before WCF, the
technologies to make communication between applications were
ASMX, .NET remoting, and COM+. WCF provides a common platform
for all .NET communication.
WCF is a framework for developing, configuring, exposing, and
hosting services. All service providers were agree on SOAP
concept for making communication between application before
WCF. The idea of WCF is a combination of SOAP and web service.
There are two categories of classes in WCF.
. Service model classes handle configuration and validation.
. Channel layer classes handle things such as communication
and data transformation.
WCF services expose functionality through one or more
endpoints. Clients communicate with the service's endpoint. In
configuring an end points there are three components require.
. Address
. Binding
. Contract
These three components are interrelated.
An address mean an URL.
Binding tells the WCF runtime how your endpoint communicates.
Contracts mean it gives the information of working endpoints.
With the help of XML-based config information we can configure
an end point, programmatically using methods/properties, or
with both XML config files and some coding. WCF includes
multiple usability avenues. For example, we can use WCF out of
the box with little or no coding or elect to build custom
implementations for all aspects of your service.
In making communication channels plays an important role, the
WCF runtime detects the binding for creating the channels. The
main task of channel are receiving and transforming data. Data
goes in one end of the channel, the channel operates on the
data, and new data is dumped out the other end of the channel.
What is Metadata Exchange(MEX) endpoint
Author: Blessy Baby Posted Date: 10/02/2011
Category: WCF Points: 15
Metadata describes the information how to communicate with the
service.cleint can request metdata for learning about the
endpoint and message format.The service does not expose MEX
enpoint, nobody can know the details of service.For knowing
address, binding and contract for the service, service should
expose the mex endpoint. This can be exposed in code or
configuration
What is ABCs in WCF
Author: Blessy Baby Posted Date: 10/02/2011
Category: WCF Points: 15
A- Address: this is the location or endpoint to which messages
send by the clint
B- Binding: This defindes the channel to communicate with the
address eg: basichttpbinding
C- Contact: It defines waht functionality or feature providd
by this endpoint
what are the difference between webservice and WCF service
Author: Blessy Baby Posted Date: 10/02/2011
Category: WCF Points: 15
Web service can access only by the protocol http, but WCf can
access any protocol and any transport type. WCF is flexible.
Same wcf services can access using differnt endpoints.
What are the 4 security features of WCF?
1) Authentication
2) Authorization
3) Integrity
4) Confidentiality
What is WAS?
Author: Jean Paul Posted Date: 24/12/2010
Category: WCF Points: 15
WAS is Windows Process Activation Service.
It is a process activation mechanism implemented in Windows
2008. It can be used to host WCF servuces.
What are the 3 ways to host WCF services?
1. Windows Service
2. IIS Hosting
3. Windows Activation Services (WAS)
What is DataContract and ServiceContract?Explain Data represented by creating DataContract which expose the
data which will be transefered /consumend from the serive
to its clients.
**Operations which is the functions provided by this
service.
To write an operation on WCF,you have to write it as an
interface,This interface contains the "Signature" of the
methods tagged by ServiceContract attribute,and all methods
signature will be impelemtned on this interface tagged with
OperationContract attribute.
and to implement these serivce contract you have to create
a class which implement the interface and the actual
implementation will be on that class.
Code Below show How to create a Service Contract:
[ServiceContract]
Public Interface IEmpOperations
{
[OperationContract]
Decimal Get EmpSal(int EmpId);
}
Class MyEmp: IEmpOperations
{
Decimal Get EmpSal()
{
// Implementation of this method.
}
}
What is meant by EndPoint in WCF?
It's an Interface, it paves a way on how the client should
communicate with the service.
It has three points, they are;
1) Address - defines where the service resides
2) Binding - defines how to communicate
3) Contract - defines what the service does
What are the various ways of hosting a WCF Service?
Author: Alwyn Duraisingh.M Posted Date: 28/09/2010
Category: WCF Points: 10
There are three ways available through which we can host the
WCF Service, They are;
1) Using Internet Information Server(IIS)
2) Self hosting
3) Windows Activation Service (WAS)
what are the advantages of WCF service over Web Service?
Author: Alwyn Duraisingh.M Posted Date: 28/09/2010
Category: WCF Points: 10
1) WCF service supports both the HTTP and TCP Protocol
2) The reliability is more
3) It has a greater flexibility.
What is the utility name to test WCF services? WcfTestClient.exe
It resides in the folder
drive:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE
What is the application utility name to view logs in WCF?
eventvwr.exe
What is service and client in perspective of data
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?
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.
What is Transport and Message Reliability?
Transport reliability (such as the one offered by TCP) offers
point-to-point guaranteed delivery at the network packet
level, as well as guarantees the order of the packets.
Transport reliability is not resilient to dropping network
connections and a variety of other communication problems.
Message reliability deals with reliability at the message
level independent of how many packets are required to deliver
the message. Message reliability provides for end-to-end
guaranteed delivery and order of messages, regardless of how
many intermediaries are involved, and how many network hops
are required to deliver the message from the client to the
service.
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 the Advantage of WCF?
Advantages:-
------------
1. WCF is interoperable with other services when compared to
.Net Remoting,where the client and service have to be .Net.
2. WCF services provide better reliability and security in
compared to ASMX web services.
3. In WCF, there is no need to make much change in code for
implementing the security model and changing the binding.
Small changes in the configuration will make your
requirements.
4. WCF has integrated logging mechanism, changing the
configuration file settings will provide this functionality.
In other technology developer has to write the code.
Whether webservices support data reader? No
Which contract is used to documented the view for error
occurred in the service to client in wcf? Fault Contract is used to documented the view for error
occurred in the service to client in wcf
Which namespace is used to access WCF service? System.ServiceModel
What is UDDI?
UDDI stands for Universal Description, Discovery and
Integration.
It is a platform independent XML based registry that made the
process of finding web services easier.
What is a SOA Service?
SOA is Service Oriented Architecture. SOA service is the
encapsulation of a high level business concept. A SOA service
is composed of three parts.
1. A service class implementing the service to be provided.
2. An environment to host the service.
3. One or more endpoints to which clients will connect.
Which format is used When sending and retrieving a DataSet
from an XML Web service?
DiffGram format
What is a Messaging Protocol in webservice?
The format of messages exchanged between Web Services clients
and Web Services should be vendor neutral and should not carry
details about the technology used to implement the service.
Also, the message format should allow for extensions and
different bindings to specific transport protocols. SOAP and
ebXML Transport are specifications which fulfill these
requirements. We expect that the W3C XML Protocol Working
Group defines a successor standard
Can you give an example of when it would be appropriate to use
a web service as opposed to a non-serviced .NET component?
o Communicating through a Firewall When building a distributed
application with 100s/1000s of users spread over multiple
locations, there is always the problem of communicating
between client and server because of firewalls and proxy
servers. Exposing your middle tier components as Web Services
and invoking the directly from a Windows UI is a very valid
option.
o Application Integration When integrating applications
written in various languages and running on disparate systems.
Or even applications running on the same platform that have
been written by separate vendors.
o Business-to-Business Integration This is an enabler for B2B
intergtation which allows one to expose vital business
processes to authorized supplier and customers. An example
would be exposing electronic ordering and invoicing, allowing
customers to send you purchase orders and suppliers to send
you invoices electronically.
o Software Reuse This takes place at multiple levels. Code
Reuse at the Source code level or binary componet-based
resuse. The limiting factor here is that you can reuse the
code but not the data behind it. Webservice overcome this
limitation. A scenario could be when you are building an app
that aggregates the functionality of serveral other
Applicatons. Each of these functions could be performed by
individual apps, but there is value in perhaps combining the
the multiple apps to present a unifiend view in a Portal or
Intranet.
o When not to use Web Services: Single machine Applicatons
When the apps are running on the same machine and need to
communicate with each other use a native API. You also have
the options of using component technologies such as COM or
.NET Componets as there is very little overhead.
o Homogeneous Applications on a LAN If you have Win32 or
Winforms apps that want to communicate to their server
counterpart. It is much more efficient to use DCOM in the case
of Win32 apps and .NET Remoting in the case of .NET Apps.
