Messaging Solutions in a Linux Environment

252 Messaging Solutions in a Linux Environment

1. Click Selection in the top-center of Figure 7-41 on page 250.

2. Right-click a starting node and select Create Connection.

3. A dialog box appears that lists the node’s output terminals. Select an output

terminal (which becomes the origin of the connection), and click OK to return

to the editor view.

4. To complete the connection, position the mouse pointer over the desired

destination input terminal of the target node and click that node.

The message flow with all the nodes connected is shown in Figure 7-43.

Figure 7-43 Nodes connected to each other

Alternative views

An alternative way of looking at the connections between nodes is the Outline

view, shown in Figure 7-44 on page 253.

Chapter 7. Implementing highly available brokers 253

Figure 7-44 Outline view of the connected nodes

To see a neater view of the message flow, right-click any place in the message

flow editor and select Manhattan Layout. The resulting formatting change to the

message flow is shown in Figure 7-45.

Figure 7-45 Message flow in Manhattan layout

254 Messaging Solutions in a Linux Environment

The default names of the nodes do not clarify the intended function. Therefore,

naming the nodes appropriately might help you to quickly understand a message

flow. Right-click any node and select Rename.

Figure 7-46 Rename node for functionality

Figure 7-47 shows the message flow with the nodes renamed to reflect the

intended functionality.

Figure 7-47 Message flow after renaming nodes

Setting node properties

Several properties needs to be set on the nodes in this message flow. The

properties of a node are accessed by right-clicking on a node and selecting

Properties.

Chapter 7. Implementing highly available brokers 255

Properties of the MQInput node

The input of this message flow are the messages generated by the message

generation application. This message is a delimited message that does not carry

any header to detail the type or format of the message. Such a header, called

MQRFH2, would limit the amount of information to be provided in the MQInput

node. Since this header is not required, the message flow developer has to

provide these details so that the broker knows how to handle any incoming

message.

1. To set the properties of the MQInput node, right-click the node and select

Properties (see Figure 7-48). In the section Basic, provide the name of the

input queue, which is cq in our scenario.

Figure 7-48 TDSInput Node properties

2. Select the Default section and provide details about the incoming messages,

as shown in Figure 7-49 on page 256. In this window, we specify the Message

Domain, which is MRM. Next, select the message set from the drop-down list.

Note that the identifier is unique to our environment. The field Message Type

should be set to the name of the message as defined in the message set,

which is ResourceUsage. The Message Type tells the broker what the logical

format of the message is. The Message Format field, selected from a

drop-down list, provides the name of the physical format of the message.

Here the Message format is TDS1.

256 Messaging Solutions in a Linux Environment

Figure 7-49 TDSInput node default property

Properties of the Trace node

The Trace node is one way to debug a message flow and to obtain information at

runtime about the processing of a message. The output of a Trace node can be

redirected to a file on the file system, or to an operating system specific logging

mechanism or to the user trace. The user trace is a broker trace that can be

activated and deactivated at runtime.

Trace records generated by the Trace node can include any text, date and time

information and also portions or the complete parsed message.

You can identify parts of the message to be written to the trace record, specifying

the full field identifiers enclosed within the characters ${ and }. If you want to

record the entire message, specify ${Root}, as shown in Figure 7-50 on

page 257.