AggregateControl node

This topic contains the following sections:

Purpose

Use the AggregateControl node to mark the beginning of a fan-out of requests that are part of an aggregation.

Aggregation is an extension of the request/reply application model. It combines the generation and fan-out of a number of related requests with the fan-in of the corresponding replies, and compiles those replies into a single aggregated reply message.

The aggregation function is provided by the following three nodes:

  • The AggregateControl node marks the beginning of a fan-out of requests that are part of an aggregation. It sends a control message that is used by the AggregateReply node to match the different requests that have been made. The information that is propagated from the Control terminal includes the broker identifier, the aggregate name property, and the timeout property. You must not change the aggregation information that is added to the message Environment by the AggregateControl node.
  • The AggregateRequest node records the fact that the request messages have been sent. It also collects information that helps the AggregateReply node to construct the aggregated reply message. You must preserve the information that is added to the message Environment by the AggregateRequest, otherwise the aggregation fails.
  • The AggregateReply node marks the end of an aggregation fan-in. It collects replies and combines them into a single aggregated reply message.

The AggregateControl node is represented in the workbench by the following icon:

AggregateControl node icon

Using this node in a message flow

Look at the following samples to see how to use this node:

Configuring the AggregateControl node

When you have put an instance of the AggregateControl node into a message flow, you can configure it. To display its properties, either double-click the node, or right-click the node and click Properties.

All mandatory properties for which you must enter a value (those that do not have a default value defined) are marked with an asterisk.

This node creates the LocalEnvironment.ComIbmAggregateControlNode folder. This folder and the fields within it are for internal use by WebSphere Message Broker and you should not rely on their existence or values when developing your message flows.

The following steps describe how to configure the AggregateControl node:

  1. Optional: On the Description tab, enter a short description, a long description, or both. You can also change the name of the node on this tab.
  2. On the Basic tab:
    1. Enter a value for the Aggregate Name. This name is used to associate the fan-out message flow with the fan-in message flow. This value must be contextually unique within a broker. This property is mandatory; you must enter a value.
    2. Enter a Timeout value in seconds. The default value is zero; if you accept this default value, the timeout is disabled for fan-outs from this node (that is, it waits for replies indefinitely). If not all responses are received, the message flow continues to wait, and does not complete. Set a value greater than zero to ensure that the message flow can complete, even if not all responses are received. Refer to the AggregateReply node for further information about timeouts.

Terminals and properties

The AggregateControl node terminals are described in the following table.

Terminal Description
In The input terminal that accepts a message for processing by the node.
Out The output terminal to which the original message is routed when processing completes successfully.
Control The output terminal to which a control message is routed. The control message is sent to a corresponding AggregateReply node.

The Control terminal is deprecated in Version 6.0; to use connections from the Control terminal, see Using control messages in aggregation flows.

The following tables describe the node properties. The column headed M indicates whether the property is mandatory (marked with an asterisk if you must enter a value when no default is defined); the column headed C indicates whether the property is configurable (you can change the value when you add the message flow to the bar file to deploy it).

The AggregateControl node Description properties are described in the following table:

Property M C Default Description
Node name No No The node type The name of the node.
Short Description No No   A brief description of the node.
Long Description No No   Text that describes the purpose of the node in the message flow.

The AggregateControl node Basic properties are described in the following table:

Property M C Default Description
Aggregate Name Yes Yes   A name that used to associate the fan-out message flow with the fan-in message flow.
Timeout (sec) Yes No 0 The amount of time, in seconds, that it waits for replies to arrive at the fan-in.

On z/OS, if the Timeout property is not set to zero, set the queue manager parameter EXPRYINT to 5.