Guaranteed Delivery for EMS Messages

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Chapter 3 Configuring the Adapter : Guaranteed Delivery for EMS Messages

Guaranteed Delivery for EMS Messages

This section describes the setup required for guaranteed delivery for EMS messages using durable subscribers.

Guaranteed delivery and receipt of EMS messages is enabled by sending persistent messages over topics to durable subscribers. For this purpose, only the transferTypes of BlockModeSFT and RecordMode with EMS are used.

Durable subscribers to a topic cause published messages to be saved while the durable subscriber is offline. Also, subscribers to a topic that are connected to a fault-tolerant server receive messages from the secondary server after a failover

Follow these steps to achieve guaranteed delivery:

1.

Set the deliveryMode="persistent" for the Publisher.

Persistent messages published to a topic are written to disk only if that topic has at least one durable subscriber or one subscriber with a fault-tolerant connection to the EMS server.

2.

Set the publishDestinationType="TOPIC" for the Publisher

Similarly, for the subscriber, set the subscribeDestinationName="TOPIC".

3.

Set the SubscriberName="sub1"

Here, sub1 is an identifier of your choice.

A new SubscriberName ID is required so that the EMS server can identify which consumer clients requires which messages resent after a failure. This Subscribername ID is created dynamically when the Subscriber is started. These durable subscriber Subscriber IDs can also be created with the aid of the EMS Administration Tool or through configuration files on the server. This first implementation of durable subscriber support in the adapter does not have any mechanism to remove a durable subscriber through the Subscriber; the EMS Administration tool is used.

4.

Optional specify which EMS_ACK_TYPE acknowledgement for the Subscriber to use.

5.

If the endPublishDestinationName parameter is specified in the Publisher, it must equal the same value as publishDestinationName. Similarly, the value of the subscribeDestinationName parameter and publishDestinationName must equal the value of the generateFileSubjectName parameter. in the Subscriber.