An Introduction to Windows Communication Foundation (WCF)

What Is WCF?

• Hosting For Component and Services
  A WCF Service can be hosted in ASP.NET Runtime, a Windows Service, a COM+ Component or just a Windows Forms application for peer-to-peer computing.
• Declarative Behavior
  Similar to ASP.NET Web Services, attributes can be used for WCF Services, for example, ServiceContract(), OperationContract, DataContract and DataMember.
• Communication Channels
  Similar to .NET Remoting WCF Services are flexible in changing the channels. WCF offers multiple channels to communicate using HTTP, TCP or an IPC channel.
• Security
• Extensibility

Understanding WCF

1. Over an intranet (the same Network/Platform, in other words, .NET application to .NET application)
2. Over the internet (cross-platform maybe ASP.NET to J2EE application)

WCF in Real-Time Scenario

• 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. (A J2EE application supposed to access the application over the WWW.)

Differences between WCF and ASP.NET Web ServicesAtomic Transactions

WCF Communication Model

Know some terms/ Keywords

• ServiceContract
  Service contracts describe the operations supported by a service, the message exchange pattern they use, and the format of each message. 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.
• DataContract
  Data contracts describe how a CLR type maps to a schema. 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.
• DataMember
  Properties or database table columns in the DataContract class that are supposed to be used by WCF Service should be decorated with the DataMember attribute.

WCF Binding Comparisons

1. X = Not Supported
2. X = Not Supported
3. WS-A = WS-Addressing
4. WS-AT = WS-AtomicTransaction
5. OleTx = OleTransactions
6. * Transaction flow is always disabled by default, but when you enable it, these are the default tx protocols
7. * This binding doesn't use a WCF message encoding; instead it lets you choose a pre-WCF serialization format

How to Create a Sample WCF application with VS2008?

1. Open Visual Studio
2. Select "File" -> "New" -> "Project..."
3. From the left panel, select Web node of your language VB.NET/C#.NET
4. Now among the templates you will see "WCF Service Application"
5. Select the same (WCF Service Application)
6. Provide Suitable Name (Say Practice.WCF) and click on the "OK" button.
   
   
   
7. Modify the connection strings section of the web.config file of the WCF Service.
   
   1. <connectionStrings
   2. addname="con"connectionString="Data Source=PRODSK0542;Initial Catalog=WCF;User
   3. Id=sa;Password=Swayam1;" providerName="System.Data.SqlClient"/>
   4. </connectionStrings>
8. By default, Visual Studio will create a Service and an Interface Service1.svc and IService1.cs
9. Add a new class, "RoomReservationRequest.cs" (DataContract)
10. Import the namespace System.Runtime.Serialization; if not imported
11. Create a property with the same data type for each column present in the RoomReservationRequest table. Decorate the "RoomReservationRequest" class with the "[DataContract]" attribute and each property with "[DataMember]".
    
    1. namespace Practice.WCF
    2. {
    3. [DataContract]
    4. publicclassRoomReservationRequest
    5. {
    6. [DataMember]
    7. public int ReservationId
    8. {
    9. get; set;
    10. }
    12. [DataMember]
    13. public int NoOfRooms
    14. {
    15. get; set;
    16. }
    18. [DataMember]
    19. public string TypeOfRoom
    20. {
    21. get; set;
    22. }
    24. [DataMember]
    25. publicDateTime FromDate
    26. {
    27. get; set;
    28. }
    30. [DataMember]
    31. publicDateTime ToDate
    32. {
    33. get; set;
    34. }
    36. [DataMember]
    37. public string ContactPersonName
    38. {
    39. get; set;
    40. }
    42. [DataMember]
    43. public string ContactPersonMail
    44. {
    45. get; set;
    46. }
    48. [DataMember]
    49. public string ContactPersonMob
    50. {
    51. get; set;
    52. }
    54. [DataMember]
    55. public string Comments
    56. {
    57. get; set;
    59. }
    61. [DataMember]
    62. public string Status
    63. {
    64. get; set;
    65. }
    66. }
    67. }
12. Add a new class "RoomReservationData" and write two methods, such as ReserveRoom and GeReservations.
    
    1. namespace Practice.WCF
    2. {
    3. internalclassRoomReservationData
    4. {
    5. private string connectionString =ConfigurationManager.ConnectionStrings["con"].ConnectionString;
    6. internal bool ReserveRoom(RoomReservationRequest roomReservationReq)
    7. {
    8. SqlConnection connection = GetConnection();
    9. string sqlCommand ="INSERT INTO RoomReservationRequest(NoOfRooms, TypeOfRoom, FromDate, ToDate, ContactPersonName, " +
    10. "ContactPersonMail, ContactPersonMob, Comments, Status) VALUES (" +
    11. "@NoOfRooms, @TypeOfRoom, @FromDate, @ToDate, @ContactPersonName, " +
    12. "@ContactPersonMail, @ContactPersonMob, @Comments, @Status)";
    14. SqlCommand command = connection.CreateCommand();
    15. command.CommandText = sqlCommand;
    16. command.Parameters.Add("@NoOfRooms", System.Data.SqlDbType.Int);
    17. command.Parameters.Add("@TypeOfRoom", System.Data.SqlDbType.NVarChar, 20);
    18. command.Parameters.Add("@FromDate", System.Data.SqlDbType.DateTime );
    19. command.Parameters.Add("@ToDate", System.Data.SqlDbType.DateTime);
    20. command.Parameters.Add("@ContactPersonName", System.Data.SqlDbType.NVarChar, 50);
    21. command.Parameters.Add("@ContactPersonMail", System.Data.SqlDbType.NVarChar, 50);
    22. command.Parameters.Add("@ContactPersonMob", System.Data.SqlDbType.NVarChar, 20);
    23. command.Parameters.Add("@Comments", System.Data.SqlDbType.NVarChar, 200);
    24. command.Parameters.Add("@Status", System.Data.SqlDbType.NVarChar, 200);
    26. command.Parameters["@NoOfRooms"].Value = roomReservationReq.NoOfRooms;
    27. command.Parameters["@TypeOfRoom"].Value = roomReservationReq.TypeOfRoom;
    28. command.Parameters["@FromDate"].Value = roomReservationReq.FromDate;
    29. command.Parameters["@ToDate"].Value = roomReservationReq.ToDate;
    30. command.Parameters["@ContactPersonName"].Value = roomReservationReq.ContactPersonName;
    31. command.Parameters["@ContactPersonMail"].Value = roomReservationReq.ContactPersonMail;
    32. command.Parameters["@ContactPersonMob"].Value = roomReservationReq.ContactPersonMob;
    33. command.Parameters["@Comments"].Value = roomReservationReq.Comments;
    34. command.Parameters["@Status"].Value = roomReservationReq.Status;
    36. int rowsEffected =0;
    37. try
    38. {
    39. rowsEffected = command.ExecuteNonQuery();
    40. }
    41. finally
    42. {
    43. if (connection !=null)
    44. {
    45. connection.Close();
    46. connection.Dispose();
    47. }
    48. }
    50. return rowsEffected > 0;
    51. }
    53. internalRoomReservationRequest[] GetReservations(DateTime fromDate, DateTime toDate)
    54. {
    55. List<RoomReservationRequest> reservedRooms = newList<RoomReservationRequest>();
    56. SqlConnection connection = GetConnection();
    57. SqlCommand command = connection.CreateCommand();
    59. command.CommandText ="SELECT ReservationId, NoOfRooms, TypeOfRoom, FromDate" +
    60. ",ToDate, ContactPersonName, ContactPersonMail, ContactPersonMob, Comments, Status "+
    61. "FROM RoomReservationRequest "+
    62. "WHERE FromDate > @FromDate AND ToDate<@ToDate";
    64. command.Parameters.Add("@FromDate", System.Data.SqlDbType.DateTime);
    65. command.Parameters.Add("@ToDate", System.Data.SqlDbType.DateTime);
    67. command.Parameters["@FromDate"].Value = fromDate;
    68. command.Parameters["@ToDate"].Value = toDate;
    70. SqlDataReader reader =null;
    72. try
    73. {
    74. reader = command.ExecuteReader(CommandBehavior.CloseConnection);
    75. while (reader.Read())
    76. {
    77. RoomReservationRequest roomReservationRequest = newRoomReservationRequest();
    78. roomReservationRequest.ReservationId =Convert.ToInt16(reader[0]);
    79. roomReservationRequest.NoOfRooms =Convert.ToInt16(reader[1]);
    80. roomReservationRequest.TypeOfRoom = reader[2].ToString();
    81. roomReservationRequest.FromDate =Convert.ToDateTime(reader[3]);
    82. roomReservationRequest.ToDate =Convert.ToDateTime(reader[4]);
    83. roomReservationRequest.ContactPersonName = reader[5].ToString();
    84. roomReservationRequest.ContactPersonMail = reader[6].ToString();
    85. roomReservationRequest.ContactPersonMob = reader[7].ToString();
    86. roomReservationRequest.Comments = reader[8].ToString();
    87. roomReservationRequest.Status = reader[9].ToString();
    89. reservedRooms.Add(roomReservationRequest);
    90. }
    91. }
    92. finally
    93. {
    94. if (reader !=null)
    95. {
    96. reader.Close();
    97. reader.Dispose();
    98. }
    100. if (connection != null)
    101. {
    102. connection.Close();
    103. connection.Dispose();
    104. }
    105. }
    106. return reservedRooms.ToArray();
    108. privateSqlConnection GetConnection()
    109. {
    110. SqlConnection connection = newSqlConnection(connectionString);
    111. try
    112. {
    113. connection.Open();
    114. }
    115. finally
    116. {
    117. }
    118. return connection;
    119. }
    120. }
    121. }
13. Declare two methods for the interface IService1, such as ReserveRoom and GetReservations.
    
    1. namespace Practice.WCF
    2. {
    3. [ServiceContract]
    4. publicinterfaceIService1
    5. {
    6. [OperationContract]
    7. bool ReserveRoom(RoomReservationRequest reservationRequest);
    9. [OperationContract]
    10. RoomReservationRequest[] GetReservations(DateTime fromDate, DateTime toDate);
    11. }
    12. }
14. Implement the Interface ISErvice1 in the Service1.svc.cs file. Create an instance of the class "RoomReservationData" that we implemented in Step 12 and use it in the implemented methods.
    
    1. namespace Practice.WCF
    2. {
    3. publicclassService1 :IService1
    4. {
    6. #region IService1 Members
    7. privateRoomReservationData roomReservationData = newRoomReservationData();
    8. public bool ReserveRoom(RoomReservationRequest reservationRequest)
    9. {
    10. return roomReservationData.ReserveRoom(reservationRequest);
    11. }
    13. public RoomReservationRequest[] GetReservations(DateTime fromDate, DateTime toDate)
    14. {
    15. return roomReservationData.GetReservations(fromDate, toDate);
    16. }
    17. #endregion
    18. }
    19. }
15. Now we are done with the implementation of WCF Service. Set the Service1 as the Startup page. Run your WCF application. The following screen should be the result.
    
    
    
16. Publish the WCF Service.
    
    • To publish the service, right-click on "Practice.WCF.csproj" and select "Publish".
      
      
      
    • Enter the location where you need to publish/host the service.
      
      
      
    • Click on the "Publish" button to publish the site.
      
17. You may check the published WCF Service by typing the URL into browser,
    
    for example, http://localhost/wcf/Service1.svc: a page the same as in Step 14 will appear.

How to Consume the WCF Service?

• Open the command prompt and go to the location where svcutil.exe is placed. You may find it at the following location: "C:\Program Files\Microsoft SDKs\Windows\v6.0A\bin".
• Write the following command and press the Enter key to generate the Class/Config files.
  
  
  
• This will generate the Service1.cs and output.config files at the same location where svcutil.exe is placed, in other words "C:\Program Files\Microsoft SDKs\Windows\v6.0A\bin".
• The class generated and the config file we need to include into our client application for consuming the service.

1. Open Visual Studio
2. Select "File" -> "New" -> "Project..."
3. Select "Windows Forms application"
4. Create a Form similar to the following:
   
   
   
5. Include the class generated by Step iii of Section 8.1
6. Right-click on the project and select the option "Add Service Reference".
   
   
   
7. Enter the URL/ Address where the service is hosted and click the "Go" button to find the service. You may see the Services Methods/Logic exposed by WCF Service
   
   
   
8. Click "OK" to add the service.
9. Double-click the "Room Reservation Enquiry" button to write the logic. Ensure that you have imported the
   
   1. private void btnEnquiry_Click(object sender, EventArgs e)
   2. {
   3. Service1Client client = newService1Client();
   4. RoomReservationRequest[] reservationEnquiry =null;
   5. reservationEnquiry = client.GetReservations(dateFromDate.Value, dateToDate.Value);
   6. if (reservationEnquiry.Length > 0)
   7. {
   8. gvReservationData.DataSource = reservationEnquiry;
   9. gvReservationData.Visible = true;
   10. }
   11. else
   12. {
   13. gvReservationData.Visible = false;
   14. lblMessage.Text = "Sorry data not available.";
   15. }
   16. }
10. When we added the reference of the Service to the client project, one configuration file would also have been added to the application, in other words App.Config. Replace the <system.serviceModel> node of this file by the <system.serviceModel> node of the output.config file generated into "Step- 3" of "Section 7.1".
11. Run the client application. Enter the "From Date" and "To Date" then click the "Enquiry" button to test the application.

1. DBBackup.zip
2. Source.zip

1. WCFService
2. WCFClient

• Open the directory WCFService.
• Double-click the "Practice.WCF.sln" file to open the solution.
• Modify the web.config file of the Service as suggested in Step-7 of Section-8.2.
• Publish the service as suggested in Step-16 of Section-8.2.

• Open the WCFClient directory.
• Double-click the "HelpDeskService.sln" file to open the solution.
• Run the solution.
• Select the dates and hit the "Enquiry" button.