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AggregateRequest node
Use the AggregateRequest node to record the fact that request messages have been sent. This node also collects information that helps the AggregateReply node to construct the compound response message.
This topic contains the following sections:
Purpose
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 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. The aggregation information that is added to the message Environment by the AggregateControl node must not be changed.
- 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. The information that is added to the message Environment by the AggregateRequest node must be preserved, 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 AggregateRequest node is contained in the Routing drawer of the palette, and is represented in the WebSphere® Message Broker Toolkit by the following icon:
Using this node in a message flow
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Terminals and properties
When you have put an instance of the AggregateRequest node into a message flow, you can configure it; see Configuring a message flow node. The properties of the node are displayed in the Properties view. All mandatory properties for which you must enter a value (those that do not have a default value defined) are marked with an asterisk.
The AggregateRequest node terminals are described in the following table.
Terminal | Description |
---|---|
In | The input terminal that accepts messages sent as part of an aggregate request. |
Out | The output terminal to which the input message is routed when processing completes successfully. |
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 AggregateRequest node Description properties are described in the following table.
Property | M | C | Default | Description |
---|---|---|---|---|
Node name | No | No | The node type (AggregateRequest) | 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 AggregateRequest node Basic property is described in the following table.
Property | M | C | Default | Description |
---|---|---|---|---|
Folder Name | Yes | No | The name that is used as a folder in the AggregateReply node's compound message to store the reply to this request. You must enter a value for this property, but the value does not need to be unique. |
Property | M | C | Default | Description |
---|---|---|---|---|
Events | No | No | None | Events that you have defined for the node are
displayed on this tab. By default, no monitoring events are defined
on any node in a message flow. Use Add, Edit,
and Delete to create, change or delete monitoring
events for the node; see Configuring monitoring event sources using monitoring properties for details. You can enable and disable events that are shown here by selecting or clearing the Enabled check box. |