Broker System Messages

Service Broker uses three system message types to communicate status and error information

from Service Broker.

Most of the messages in a Service Broker conversation are the application-defined messages

used to communicate between services. Each message must comply with a message-type

format that was defined by a

statement. The set of message types

allowed for a conversation is defined by the contract specified in the

statement.

In addition to the application-defined message types specified in the contract, any

conversation can also receive messages that use one of three system-defined message types.

Service Broker uses these message types to report errors and the status of dialogs. Every

application must contain logic to handle Error messages and End Dialog messages. If the

application sets a conversation timer on a dialog conversation, the application must contain

logic to handle Dialog Timer messages. Service Broker provides these message types to every

service, whether they appear in the contract for the service or not. For more information, see

Handle Service Broker error messages.

When a remote service ends a dialog with an error or the local broker detects an unrecoverable

error in a dialog, the local broker creates an Error Message. Error messages are of message

type. Error messages are validated as

well-formed XML.

The XML document that is contained in an error message uses the namespace. The root element of the document has the

local name

, and contains an element named

and an element named. The

element holds an integer value. The

element holds the human-readable text of

the message.

For example, an error message generated by a service that processes expense reports might

contain the following XML (reformatted for readability):

CREATE MESSAGE TYPE
BEGIN DIALOG
CONVERSATION https://schemas.microsoft.com/SQL/ServiceBroker/Error https://schemas.microsoft.com/SQL/ServiceBroker