When a message is received, IIS starts the service and controls its lifetime. Instancing A service has an instancing model. There are three instancing models: "single," in which a single CLR object services all the clients; "per call," in which a new CLR object is created to handle each client call; and "per session," in which a set of CLR objects is created, one for each separate session. The choice of an instancing model depends on the application requirements and the expected usage pattern of the service.
Client application A program that exchanges messages with one or more endpoints. It is important to note that a single application can be both a client and a service. Channel A concrete implementation of a binding element. The binding represents the configuration, and the channel is the implementation associated with that configuration. Therefore, there is a channel associated with each binding element. Channels stack on top of each other to create the concrete implementation of the binding: the channel stack.
WCF client A client-application construct that exposes the service operations as methods in the. Any application can host a WCF client, including an application that hosts a service. Therefore, it is possible to create a service that includes WCF clients of other services. Metadata In a service, describes the characteristics of the service that an external entity needs to understand to communicate 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. When enabled, metadata for the service is automatically generated by WCF by inspecting the service and its endpoints. To publish metadata from a service, you must explicitly enable the metadata behavior. Security In WCF, includes confidentiality encryption of messages to prevent eavesdropping , integrity the means for detection of tampering with the message , authentication the means for validation of servers and clients , and authorization the control of access to resources.
Transport security mode Specifies that confidentiality, integrity, and authentication are provided by the transport layer mechanisms such as HTTPS. When using a transport like HTTPS, this mode has the advantage of being efficient in its performance, and well understood because of its prevalence on the Internet.
The disadvantage is that this kind of security is applied separately on each hop in the communication path, making the communication susceptible to a "man in the middle" attack. Message security mode Specifies that security is provided by implementing one or more of the security specifications, such as the specification named Web Services Security: SOAP Message Security. Each message contains the necessary mechanisms to provide security during its transit, and to enable the receivers to detect tampering and to decrypt the messages.
In this sense, the security is encapsulated within every message, providing end-to-end security across multiple hops. Because security information becomes part of the message, it is also possible to include multiple kinds of credentials with the message these are referred to as claims. This approach also has the advantage of enabling the message to travel securely over any transport, including multiple transports between its origin and destination.
The disadvantage of this approach is the complexity of the cryptographic mechanisms employed, resulting in performance implications. Transport with message credential security mode Specifies the use of the transport layer to provide confidentiality, authentication, and integrity of the messages, while each of the messages can contain multiple credentials claims required by the receivers of the message. Skip to main content.
The following picture shows the limitation of. NET Web Services as well. Apart from its own features software should be capable of the following: Communication with software already running within the hotel's network for help desk purposes. NET Windows Forms application. Communication with software already running for the Tourism Office for booking of rooms. Of course we are supposed to implement the application using Microsoft.
NET Technology. Now, since we know that in order to communicate with another. NET application within the same network. NET Remoting is the best option.
But based on our requirements our application should be capable of interaction with another J2EE application over the WWW. So we can't use. NET Remoting. The System. DataContract and System. Serialization assembly can be added for. NET types to indicate that instances of the type are to be serialized into XML, and which specific fields or properties of the type are to be serialized.
NET objects. The following example describes what is meant by "Atomic Transactions". Consider that Bank A and Bank B want to interact with someone's account at the same time. When one of them finishes the other one will find there is not enough money to finish the transaction. This scenario is common for computer systems and you can see it many times in memory management, IO operations and database interactions. Atomic transactions are a way to avoid this problem. They simply lock on a transaction and do not allow any other transaction to interact with the resource.
If anything fails during the Atomic transaction then everything will return to the state before the transaction started. Endpoints are nothing but the locations defined by a service through which a message can be sent and received. The service may have multiple end points. The service contract may be an interface or class for generating a service description.
A service must implement at least one service contract. An interface or class to be exposed as a service should be decorated with ServiceContractAttribute. OperationContract Methods in the interface or class that are supposed to be exposed as a service should be decorated with OperationContractAttribute. A data contract may be understood as a class or interface that is mapped to a database and is supposed to be exploited by a WCF Service. This class or interface needs to be decorated with DataContract attribute.
Click OK to start the installation. In the Select Features window, expand. What is HTTP activation feature? What is http activation feature? On the task pane on the left, click Turn Windows features on or off. How to activate Windows Communication Foundation in Windows 10?
There are other patterns such as a one-way message in which a single endpoint sends a message without any expectation of a reply. A more complex pattern is the duplex exchange pattern where two endpoints establish a connection and send data back and forth, similar to an instant messaging program.
For more information about how to implement different message exchange patterns using WCF see Contracts. This metadata can be used to automatically generate and configure clients for accessing WCF services. For more information, see Metadata. Because WCF is built using the. NET Framework, it also includes code-friendly methods of supplying the contracts you want to enforce.
One of the universal types of contracts is the data contract. In essence, as you code your service using Visual C or Visual Basic, the easiest way to handle data is by creating classes that represent a data entity with properties that belong to the data entity. WCF includes a comprehensive system for working with data in this easy manner. Once you have created the classes that represent data, your service automatically generates the metadata that allows clients to comply with the data types you have designed.
For more information, see Using Data Contracts. Messages can be encrypted to protect privacy and you can require users to authenticate themselves before being allowed to receive messages. For more information, see Security.
Messages can be sent on any of several built-in transport protocols and encodings. These messages can be encoded as text or using an optimized binary format.
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