21 September, 2009

.Net Framework 3.0 FAQ

What is an operation contract?
An operation contract defines the parameters and return type of an operation. When creating an interface that defines the service contract, you signify an operation contract by applying the OperationContractAttribute attribute to each method definition that is part of the contract. The operations can be modeled as taking a single message and returning a single message, or as taking a set of types and returning a type. In the latter case, the system will determine the format for the messages that need to be exchanged for that operation.


What is a message contract?
A message contact describes the format of a message. For example, it declares whether message elements should go in headers versus the body, what level of security should be applied to what elements of the message, and so on.


What is a fault contract?
A fault contract can be associated with a service operation to denote errors that can be returned to the caller. An operation can have zero or more faults associated with it. These errors are SOAP faults that are modeled as exceptions in the programming model.


In Terms of WCF, what do you understand by metadata of a service
The metadata of a service describes the characteristics of the service that an external entity needs to understand to communicate with the service. Metadata can be consumed by the Service Model Metadata Utility Tool ( Svcutil.exe) to generate a WCF client and accompanying configuration that a client application can use to interact with the service.

The metadata exposed by the service includes XML schema documents, which define the data contract of the service, and WSDL documents, which describe the methods of the service.


What is password fatigue?
As the use of internet increases, as increases the danger of online identity theft, fraud, and privacy. Users must track a growing number of accounts and passwords. This burden results in "password fatigue," and that results in less secure practices, such as reusing the same account names and passwords at many sites.


What are activities in WWF?
Activities are the elemental unit of a workflow. They are added to a workflow programmatically in a manner similar to adding XML DOM child nodes to a root node. When all the activities in a given flow path are finished running, the workflow instance is completed.

An activity can perform a single action, such as writing a value to a database, or it can be a composite activity and consist of a set of activities. Activities have two types of behavior: runtime and design time. The runtime behavior specifies the actions upon execution. The design time behavior controls the appearance of the activity and its interaction while being displayed within the designer.

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