Step 2: Extract Notification Type from Notification Message

Time to complete: 5 minutes

Objective: In this step, you add an expression shape to extract the type of notification received from the SQL Server database.

Prerequisites

You must have completed Step 1: Add Orchestration Shapes to Receive Notification.

To extract the notification type from the notification message

1. Add a variable to the BizTalk orchestration you created in Step 1: Add Orchestration Shapes to Receive Notification.

   1. From the Orchestration View, right-click Variables, and then click New Variable.

   2. Right-click the new variable, Variable_1, and click Properties Window. Set the following properties for the variable.

      Set this property	To this value
      Identifier	NotificationType
      Type	System.String

2. Add an Expression shape to the BizTalk orchestration. From the orchestration Toolbox, drag the Expression shape to the orchestration design surface, and drop it after the Receive shape

   Within the Expression shape, you will add an xpath query to extract the type of notification message received from SQL Server. Before creating an xpath query, let us look at the format of a notification message. A typical notification message resembles the following:

   <Notification xmlns="http://schemas.microsoft.com/Sql/2008/05/Notification/">  
     <Info>Insert</Info>   
     <Source>Data</Source>   
     <Type>Change</Type>   
   </Notification>  
   

3. As you see, the information about the type of the notification is available within the <info> tag, within the parent <Notification> tag. So, add the following xpath query within the Expression shape:

   NotificationType = xpath(NotifyReceive,"string(/*[local-name()='Notification']/*[local-name()='Info']/text())");  
   

   Here, NotificationType is the variable you created to store the value extracted by the xpath query. NotifyReceive is the message you created in Step 2: Create Messages for BizTalk Orchestrations to receive notification messages.

4. The following figure shows the in-progress orchestration with the Expression shape included.

   

What did I just do?

In this step, you added an Expression shape to extract the kind of notification received from the SQL Server database.

Next Steps

You add a Decide shape to filter for Insert notifications, as described in Step 3: Add a Filter for Insert Notifications.

See Also

Step 1: Add Orchestration Shapes to Receive Notification
Step 3: Add a Filter for Insert Notifications
Lesson 2: Receive and Filter Notifications