you are new to WCF and takes you step by step through the fundamental http ://noititsojunchawk.tk This tutorial explains the fundamentals of WCF and is conveniently divided below is the step-by-step method for creating a WCF service along with all the. you are new to WCF and takes you step by step through the fundamental concepts of . Using Windows Explorer, move to the Microsoft Press\WCF Step By.
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Windows Communication Foundation: What is it? . Examples. Implementing a WCF Service and utilizing that service requires a few steps to set up. This code. Interoperability with Microsoft‟s Pre-WCF Technologies. .. The move to service -oriented communication has changed software significant step forward. Configuration information we got from the above step has to be added to the client application configuration file. WCF automatically opens the underlying.
This book is very good for beginners. This books covers all the topics in WCF in general. I will recommend this book, for initial stage of learning. Covering the concepts and details necessary to enable you to build connected solutions, this book offers hands-on guidance for creating the Web services you need to implement robust business applications for Windows.
Teach yourself the essentials of Windows Communication Foundation-one step at a time. With this practical tutorial, you get hands-on guidance for creating the Web services you need to implement robust business applications for Windows. This is also a very good book. AfterCall 4. BeforeAndAfterCall Below code show. Followings are the list Release mode available in the ReleaseInstanceMode 1.
This is designed to optimize a method such a Cleanup ReleaseInstanceMode. By default ReleaseInstanceMode property is set to 'None'. None This property means that it will not affect the instance lifetime. AfterCall This property means that it will deactivate the instance after call is made to the method. BeforeCall This property means that it will create new instance before a call is made to the operation. WCF deactivates the instance and calls Dispose before the call is done.
If the instance is already exist. This is designed to optimize a method such as Create ReleaseInstanceMode. It can use data store like SQL database for maintain instance state. BeforeCall and ReleaseInstanceMode. Net 3. AfterCall Explicit Deactivate You can also explicitly deactivate instance using InstanceContext object as shown below.
This has combined effect of using ReleaseInstanceMode. It means that durable services have the capability to restore their own state when they are recycled. This is means that it will create new instance of object before a call and deactivates the instance after call. It is new feature in. Service will send the instanceID to the client. It takes 'CanCreateInstance' and 'CompletesInstance' property to mention on which operation instance state has to be saved and destroyed.
Calling this operation results in creating the serialization and inserting it into the datastore. If the service is shut down or client closes the proxy. Calling this operation results in deleting the persisted instance from the datastore. Even when client is shut down. So when ever client opening the proxy. This serialized instance xml and key will be saved in the database. But in case of Durable service it is still maintained.
When Durable service is created with database as data store. You might think that we can also maintain session using WCF sessions. When a client make a request to the service.
Create interface and decorate with Service and Operation contract. Let us understand more about the durable service by creating Simple Calculator service which persist the instance state in SQL server database. You need to add [Serializable] And [DurableService ] attribute to the service implementation. Select the 'WCF Service' as shown below. Before configuring the database information in the durable service.
In this implementation. Microsoft provides inbuilt sqlPersistance provider. In order to support durable service. To set up the database environment. Create the console client application and name it as DurableServiceClient Step 7: Retrieve and set the context at the client side. Create the Helper class called it as Helper. This helper class is used to Store. Copy and paste the below code to your helper file.
SetContext ctx. Serialize fs. Delete TokenContextFileName. When I call the Subtract and Multiply operation. SaveContext client. Add SetContext client. In the main method. Call to this method will add instance state to the database.
Subtract 2. Multiply 5. Now I have closed the proxy and creating new proxy instance. I was creating the proxy for the service and calling the Add operation. Output of the client application. Serialized XML instance state save in the database is shown below. Attribute maxConcurrentCalls Description Limits the total number of calls that can currently be in progress across all service instances. Performance of the WCF service can be improved by creating proper instance.
The default is Throttling WCF throttling provides some properties that you can use to limit how many instances or sessions are created at the application level. A positive integer that limits the number of sessions a ServiceHost object can accept.
Open ; Operations In classic object or component- oriented programming model offered only single way for client to call a method. Client will issue a call, block while the call was in progress, and continue executing once the method returned.
WCF will support classical Request-Replay model, along with that it also supports One-Way call call and forget operation and callback service to call back the client Three modes of communication between client and service are 1. It means that, when client make a request to the WCF service and client will wait to get response from service till receiveTimeout. After getting the response it will. If service doesn't respond to the service within receiveTimeout, client will receive TimeOutException.
One-Way In One-Way operation mode, client will send a request to the server and does not care whether it is success or failure of service execution. There is no return from the server side, it is one-way communication. Client will be blocked only for a moment till it dispatches its call to service. If any exception thrown by service will not reach the server.
Client can continue to execute its statement, after making one-way call to server. There is no need to wait, till server execute. Sometime when one-way calls reach the service, they may not be dispatched all at once but may instead be queued up on the service side to be dispatched one at a time, according to the service's configured concurrency mode behavior.
If the number of queued messages has exceeded the queue's capacity, the client will be blocked even if it's issued a one-way call. However, once the call is queued, the client will be unblocked and can continue executing, while the service processes the operation in the background. One-way operation can be enabled by setting IsOneWay property to true in Operation contract attribute. Client will be blocked until operation completes.
Suppose If you want to make use of One-way operation in Sessionful service. It will be good practice. This operation should not return any value. In the below example you can find the decalration of the callback contract and it is configured in the ServiceContract attribute. In which.
Defining and configuring a callback contract Callback service can be enabled by using CallbackContract property in the ServiceContract attribute. Callback Service Till now we have seen that the all clients will call the service to get the things done. In the presence of transport session. Client will not be able to make new call using same proxy instance. So all these binding will be used for callback operation. But WCF also provides the service to call the client.
The client must use a proxy that will set up the bidirectional communication and pass the callback endpoint reference to the service. In the earlier part of the tutorial I have mention that InstanceContext is the execution scope of inner most service instance. It provides a constructor that takes the service instance to the host. So client has to expose a callback endpoint to the service to call. Add System. ServiceModel reference to the project Step 3: Create the Callback and Service contract as shown below.
Implementation of the Callback contract will be done on the client side. You need to mention CallbackContract property in theServiceContract attribute. The following code shows the callback method invocation. Service can call the client side callback method using reference e to the client side callback instance. Using that instance we are calling the OnCallback method from client side. Implement the Service contract as shown below. In the below code you will find using OperationContext is used to receive the reference to Callback instance.
Multiple ] public class MyService: If you are calling the Callback method inside the service method. This is because when a client made a call to the service. This application is used to self-host the WCF service. Service will try to access the lock channel. So you can set ConcurrencyMode to Multiple or Reentent so it will release the lock silently.
If you are not using ConcurrencyMode to Multiple or Reentent. Use Duplex binding to support Callback operation. Press key to stop the service. This is the client application which contain Callback implementation. Run the host application Step 9: Create the contractor which will accept InstanceContext as parameter.
ServiceModel and CallbackService as reference to the project Step Create the proxy class as shown below. Use DuplexClientBase to create the proxy.
An event may result from a direct client call. The service firing the event is called the publisher. WriteLine "Callback method is called from client side. In the output. Create the implementation for Callback Contract class MyCallback: Run the client application. Publisher will be blocked. It will not affect the client. Subscriber can be executed in any manner. Net delegates to manage the list of subscribers. These make publishers to put in wait state.
Let us consider the scenario in which you what to publish large volume of event. It may lead Publisher event not to reach other subscriber. Since service has to communicate to the client. Here we are using one operation to subscribe the event and another for firing the event. PerCall ] public class MyPublisher: DoSomethingAndFireEvent operation will fire the event as shown. I am using Operationcontext to get the reference to the client instance and Subscription method is added as event handler to the service event.
Implementation of the Service Contract is shown below. This application will be used to self-host the service. In the Subscription operation. ServiceModel and WcfEventService as reference to the project. WriteLine "Host is running.. This application will act a client which is used to subscribe the event from service. Run the host application as shown below.
Create the console application using visual studio and name it as WcfEventServiceClient as shown below. Implementation of IMyEvents at client side is shown below. This method will be called when service publish the event.
This is true whether it is the client sending a message to the service or the service returning a message to the client. Transfer mode In our normal day today life. If data transfer is taking place through WCF service. WriteLine "Client call operation which will fire the event".
Streamed transfers can improve the scalability of a service by eliminating the requirement for large memory buffers. StreamRequest In this mode of configuration. Subscriber got notification. As a result. Based on the size and other condition of the data transfer. WCF supports two modes for transferring messages Buffer transfer When the client and the service exchange messages.
If you want to transfer large message. Run the client application and you see the when event is fired from the service. Stream transfer When client and Service exchange message using Streaming transfer mode. In this mode of configuration. NetworkStream are derived from it. Streaming Client and Service exchange message using Streaming transfer mode.
Net stream class for Streaming the message. Stream and it's subclass can be used for streaming. Stream the data. Stream in base class for streaming. Send and accept requests in streaming mode. TransferMode property should be set according to the desired streaming mode in the bindings.
Stream and MemoryStream are serializable and it will support streaming 3. FileStream is non serializable. So you can increase the message size using maxReceivedMessageSize attribute in the binding element as shown below.
Send and accept requests in buffered mode. With all of these bindings streaming is disabled by default. Transaction Resources Transactional programming requires working with a resource that is capable of participating in a transaction. While doing singe operation. Below figure gives idea about transaction. Productivity penalty has to be payee for all effort required for handcrafting the recovery logic 4.
In addition. Solution Best way to maintain system consistence and handling error-recovery challenge is to use transactions. Recovery Challenge Let us discuss more on challenge we will phased and how to recover from it. Such resources have been around in one form or another for decades. Transaction encounters an error and rollback to Consistence State A from intermediate state. These operations might success or fail. Transaction that execute successfully and transfer the system from consistence state A to B.
Transactions fail to either in commit or abort. Consider a system maintained in consistent state. It provides way to logically group single piece of work and execute them as a single unit. WCF allows client applications to create transactions and to propagate transactions across service boundaries. We are not considering about sub operation which are failed. Some resources support auto-enlisting. We mainly consider about the success operation.
Performance will be decreased because you need to execute huge amount of code. This act is called enlisting. Because we have to recover all these state to its previous consistence state. When transaction completes. Transaction Properties Transaction can be said as pure and successful only if meets four characteristics.
Durable transactions must survive failures. In which service starts and manage the transaction. Resources participating in the transaction should be locked and it should not be access by other third party. Any network failure or machine crash also increases the complexity for managing the transaction.
Now the questions arise that which service will begin the transaction?
Which service will take responsibility of committing the transaction? How would one service know what the rest of the service feels about the transaction? Service could also be deployed in different machine and site. WCF come up with distributed transaction using two way committed protocol and dedicated transaction manager.
Client itself will act as service or client. If service disallows at binding level. This enables service to participate in a client transaction and it includes multiple services in same transaction. TransactionFlow can be enabled only at the operation level not at the service level.
FaultException will be thrown when client disable at its binding. Transaction Mode This article explains about the how to configure the service and client transaction mode in WCF service. Allowed in the operation contract 3.
Transaction Protocols As a developer we no need to concern about transaction protocols and transaction manager used by WCF. Set TransactionFlowOption. Basically there are three different kinds of transaction protocols used by WCF. WCF itself will take care of what kind of transaction protocols should be used for different situation.
NotAllowed in the operation contract 3. This seeing ensures that the service always has a transaction. This setting ensures service does not use transaction 1. Mandatory in the operation contract 3.
Allowed ] bool AddEmployee int id. This attribute is used to enable the service transaction when the client transaction is not available. Modify the service application to throw exception explicitly after successfully insert statement execution and check the transaction behavior. Create the Employee WCF service to allow client user to insert employee detail 2. TransactionFlowOption take three set of values. Run the client application to successfully insert the employee detail 5.
WCF transaction was explained with below employee service 1. Create the Employee service that allows the addition of new employee details in DB. Create the client application by consuming the Employee Service and insert the employee details 4. Decorate the operation contract with TransactionFlow attribute for enabling the transaction.
Enable the transaction from server side by setting proper attributes 3. Update the service endpoint to enable transactions for wsHttpBinding by setting the transactionFlow attribute to true. It is required to set the transaction at the service contract level as mention in Step 1. Create a new console application from add Employee service as ServiceReference Step 5: Create a new proxy object for the employee service and call the AddEmployee method.
AddEmployee 1. WriteLine "Error while adding employee details". Output shows the employee detail is added successfully and DB also shows the new entry is made Step 6: Now everything works fine. WriteLine "Employee details add successfully". WriteLine ex.
Run the client application and check the output. WCF RIA service will generate the code at the client side related to the service and domain entities declared at the server side. DB is not updated. It solves the major problem while developing business application like decoupling the resource access. RIA service client will be updated with business rule and entity present at the server side. Result clearly says that even insert statement is executed successfully and error is thrown after insert statement.
Main problem developer are facing while developing the n-tier RIA application will be coordinating the application logic between middle tier and presentation tier.
It is mainly used in RIA applications like Silverlight. Because all the code execution is comes under the transaction so failure in any module of code will revert back all code execution. WCF RIA service will allow developer to write the set of service code and this server code will be available to the client side without manually duplicate that programming logic.
AJAX client. A domain service class must be marked with the EnableClientAccessAttribute attribute to make the service available to the client project.
RIA Services generates the corresponding classes for the client project. RIA service exposes the data from server side to client side using Domain service. Domain service contains set of business related data operation and it is exposed as WCF service. When the EnableClientAccessAttribute attribute is applied to a domain service.
RIA service framework implements the each domain service as WCF service to access the data as business entity. Problems solved in RIA Service 3. Since entity objects used in domain service are serializable and so it can be access across different layer 4.
To have best performance of the RIA application. Client" fig: Asynchronous call — Asynch service call are supported in Domain service by using WCF infrastructure 3. This problem is solved by auto generating the code at the client side while recompiling the project. Handling large data and data across different tier — Large amount of data can be access and filter using IQueryable object.
DomainContext class available inside the name space "System. Validation — Entity can be validated based using adding attribute to the class members Example: This is the data class which will return list of Employee and update the employee list Data Model class: Add code to return the Employee list Domain Service class: Create methods containing your application logic.
Create domain service class. By right click project file and select Add new item. To expose the Employee related operation to the client side. Compile the solution — After compilation RIA service will generate the application logic at the client side using DomainContext object.
Domain Context class at client: Update emp. Enable show all files option for the solution and view the auto generated code. View the DomainContext class are created at the client side. DataGrid x: Add DataGrid to Main. Run the application and see the output as shown below.
It became very popular because of it behavior. Other operations like POST. Download Souce: This Restful service will be consumed using client console application. Data Model class: This sample explains about the creating the RESTful service to create and updating the resource information available at the sever side. Remove existing. Interface and Implementation: Employee GetEmployee int Id.
OperationContract and DataContract as shown below. IEmployeeService As it is mention in introduction section of RESTful service. Add newEmp. Method exposed at the server side can be call using url. This service can be hosted as normal WCF service by creating the ServiceHost object and adding endpoint with different binding. Update newEmp. Allowed ] Delete System. ToInt32 empId. Just type the url in the web browser to read all the employee details. Endpoints Console. By hosting the restful service with WebServiceHost host class will automatically set the binding and other configuration setting..
We can access the RESTful service using browser. WriteLine "ASP. In the below code you can see that I have only mention url for the hosting. In the above interface declaration.
For this example we are using console application for hosting service. Now we have completed with service implementation project. Below code first read the employee details from the server and add new employee and once again it read the employee details to confirm the added resource. Now we can start with client application. If we need to get specific employee details. For this example we can create a console application to read the employee information and add new employee to the server resource.
Format "EmpID: Below code shows how to configure the JSON response format. Below sample is the ASP. Date Verification of caller will be referring as service authentication.
This will make sure that communication channel between client and service is secured. Types Of Authentication 2. Transfer Security Mode 3. Transport Security Protection Level 4. Click on File: After that, the following window will be appear.
After that, we specify the name of this library to be Calc which we can define in the Name Section. And then we click on the OK Button.
Step 2: When we click on the Ok Button, the Calc. In the Solution Explorer, we delete the following files, since we want to create the service from the start.
Here we name it ICalcService. And then we write the following code. Step 5: Now we declare as an interface not a class so we change the code like this. After that we add another class. Code using System. After that we add another class: It is an actual service implementation class. Now we look at the code: Code public class CalcService: Now we add the ServiceBeahvior like this: Single ] It specifies the behavior of our service and InstanceContextMode.
Now we write the following code in it. Single ] public class CalcService: Single means it creates a single instace of our service. CalcService in the Configuration option: After that we click on the Name Option: After that we select the Calc. After that the following window will be appear. Step 8: Now we run the program. Here we click on Contart and again select the Calc..
And then we click on Empty Name. When we click on Add the following window will be appear: Here we enter values for n1 and n2 and click on the Invoke Button. The result will appear as: After that we click on Add or any other function.