Accessing Message Send Control

The message send control can be accessed in one of two ways:

  1. Through the Status Page:
  2. Through the Administration page

The Message Send Control page

This page configures the message sending policy for an outgoing interface. An outgoing interface will deliver messages to the remote interface sequentially, in the order they are queued.

If the outgoing interface fails to respond, or returns an error, the outgoing interface can either retry sending the message or can discard the message, depending on the configuration.

What happens to the message depends on the nature of the receiving application, the reason the message either failed to return or returned an error, and the response that was returned, if any.

There is some ambiguity in HL7 regarding the meaning of error, reject, and the circumstances in which they are returned. The Control/Query chapter of the HL7 standard provides conflicting advice on the subject.

By default, HL7Connect will adopt the following policy:

If the message is to be resent, the outgoing interface will attempt to resend it indefinitely, and all other messages will wait for that message to be sent.

Modifying the Message Send Controls

The policy outlined above will not suit all systems, so the message send controls can be modified using the parameters outlined below:

General Sending Control

Sending Message Cache Count controls the number of messages read from the outgoing interface queue at once. The default is 100, so up to 100 messages will be loaded, ready to send to the remote system when the queue is read. The database queue will not be read again, until all messages have been sent, or the interface is restarted.

When there are small numbers in the queue, this setting is not relevant. However, if an interface falls many thousands of messages behind, the delay period while preloading the messages may be a problem. The higher the cache count, the higher the total throughput.

Resending control

Parameters can be configured to control the behaviour of the interface when handling failed/no response messages.

Field    Description
Retry Count    The number of times to try before no more attempts are made to send the message.

0 means that the interface will continue to try to send the message indefinitely. The first try at sending the message is generally done before consulting this setting, so the retry count can be set to "1" to not attempt to resend the message after the initial send.

Other messages wait    If selected, the interface will delay all other messages, until the original message has been sent.

If not selected, then the other messages will be sent and resending of the current failed message will be tried again at another time.

This will result in messages arriving at the remote system out of order, but will prevent other messages being delayed by a message that is unacceptable.

Wait Period    The number of seconds before resending the message has a default of 30 seconds
Notification    If desired, a notification can be sent when a message fails more than a nominated number of times
Notification Count    The number of errors that will occur before sending a notification

© Kestral Computing P/L 2000-2015. HL7Connect v2.00-063 generated on 30-Nov 2015
Keywords: Sending, Message Sending Control, Response, Messages / Handling Rejected Messages, Messages / Resending, Notifications, Rejected Messages, Resending Messages, Timeouts