A Quick guide to handling exceptions in BizTalk Orchestrations

• Download Web Service - 16 Kb
• Download BizTalk Solution - 23 Kb

Introduction

Most of us have might have written code to handle exceptions in any programming language. In BizTalk, exceptions are little bit different. This article explains how to handle exceptions and notification mechanism in ports, using some simple scenarios.

Exceptions vs Delivery Notification

The Delivery Notification flag on the Send Port indicates that the orchestration must be NOTIFIED back, in case the message has not been received by the destination. Delivery Notification works only when the Retry Count set to 0. When a message cannot be delivered, a DeliveryNotificationException is raised and the exception needs to be handled by the Orchestration.

Scenario 1 : Sending a Sales Report...

Consider a scenario where a sales report needs to be uploaded to a Web service.

Assumptions

• If the Web service is not responding, it shall be online only after 24 hrs.
• The retry count and interval on the Web Service Port is set to "0".

If the Web service is not responding, an exception is raised, and is handled by sending the message to an Offline folder.

Receive shape - Receives a Sales Report message.     Scope shape - A scope defines a context in BizTalk. A scope is used to set a Transaction Type, in this case, the TransactionType is set to "None". The scope's Synchronized parameter is set to "true".     A Sales Report message is created, so as to tramit it to the web service. Note the properties of the Web Port which are marked in "Red".   Delivery Notification - If a message fails to be delivered on a Port, the "DeliveryFailureException" is generated. Note that "Delivery Notification" is NOT available for Binding property "Specify Now".     There are two kinds of Exceptions handled in this orchestration. DeliveryFailure Exception General Exception   General Exception - In this case, the message which needed to be sent to the Web Service, is written out to an Offline Folder.   Important Note: DeliveryFailure Exception - This exception is not thrown in this scenario, since a Web Service Port is request-response port. This is reason why the exception is handled in the General Exception section.

Event Log messages...

Observe the event log messages...

Scenario 2 : Raising the 'DeliveryFailureException' using a Dummy folder

In this scenario, we create a "Dummy" folder when messages need to be transmitted, and since the Dummy folder does not exist, we handle an exception and send the messages to the Offline folder.

Receive shape - Receives a Sales Report message.       A Sales Report message is created, so as to transmit it to the web service.   Scope shape - A scope defines a context in BizTalk. A scope is used to set a Transaction Type, in this case, the TransactionType is set to "None". The scope's Synchronized parameter is set to "true".     Note the properties of the ReportDummyPort which are marked in "Red".   Delivery Notification - If a message fails to be delivered on a Port, the "DeliveryFailureException" is generated. Note that "Delivery Notification" is NOT available for Binding property "Specify Now".     There are two kinds of Exceptions handled in this orchestration. DeliveryFailure Exception General Exception   A DeliveryFailure Exception is raised by the Port, since the file path specified in the Dummy Port does not exist. The exception handler handles the exception by sending the message into the OfflineFolder. Notice that in this case the DeliveryFailure Exception has been correctly raised.

Event Log messages...

Observe the event log messages...

About the Downloadable Code

• Unzip the Web Service with the folder names into the C:\inetput\wwwroot directory and setup the web service.
  NOTE - Rename the Persist.asmxto Persist2.asmx so as to make it unavailable.
• Unzip the BizTalk project zip file with the folder names in the C:\ drive.
• The folder KeyAndBindings contains the Bindings.xml file, which can be imported after the solution is built and deployed.
• Place the SalesMessage in the In folder and check the Offline folder.

Some Takeaways

1. Set the Synchronized property on the Scope shape to true, in the case you want to handle exceptions.
2. Always select the "WebPortType" created when the "Web Reference" is added to the project, while creating "Web Ports" in the Orchestration.
3. Delivery Notification is not available on Early Bound Ports.

DONT's miss the following references...

1. Acknowledgments and Negative Acknowledgments (Part 1)
2. BizTalk 2004 Delivery Notification and NACK Sample