July 30, 2023

cMessageRouter – Docs for ESB ESB 7.x

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cMessageRouter

Creates different channels for each filtered message type according to specified
conditions so that messages can later on be treated more accurately in each new
channel.

cMessageRouter Standard properties

These properties are used to configure cMessageRouter running in the Standard Job framework.

The Standard
cMessageRouter component belongs to the Routing family.

Usage

Usage rule

cMessageRouter is used as a
middle component in a Route. It can only have one input channel but
multiple output channels. Messages can be outputted through either a
When, Otherwise or Route
types of connection.
Connections Row / Route: Select this link to pass on all
the messages to the next component.

Trigger / When: Select the
When link and click the
Component view.

In the Type list, select the type of language you will
use to declare your condition from none,
bean, constant,
correlation, el,
groovy, header,
javaScript, sql,
jsonpath, jxpath,
mvel, ognl,
php, property,
python, ruby,
simple, Spel,
sql, xpath, and
xquery.

Append endChoice(): If the When
link is followed by a cMessageFilter or
cLoadBalancer and so on, there will be a compile
error. This is because once there is such a component there, the flow type will
change from choice() to loadbalance(), which can not be followed by a
When or Otherwise link. Select
this check box to change the flow type back from loadbalance() to choice().

In the Condition field, type in the condition that will
be used to filter the messages.

All the messages that do not match this condition are retrieved with the
Otherwise link to a different channel or dropped if
an Otherwise link does not present.

Note:

There can be more than one When link in a Route.

 

Trigger / Otherwise: This link
automatically retrieves the messages that do not match the
When conditions.

Note:

There can be only one Otherwise link, which is
optional, in a Route.

Limitation

It is recommended not to put any message handling after the
When or the Otherwise link. Always use a Mock/Direct
endpoint to replace them and make a new Route to handle the
messages.

Routing messages according to a criterion

This scenario applies only to Talend Open Studio for ESB, Talend Data Services Platform and Talend Data Fabric.

In this use case, we route XML messages that are sent from the sending endpoint according to a defined criterion: those XML files in which the value of the city node is Paris are sent to a folder named Paris_only, and other messages are sent to a folder named Other_cities.

cMessageRouter_1.png

Of
the four XML files used in this scenario, Message_1.xml and Message_4.xml
contain the city name of Paris. The following is an
example:

Dropping and linking the components

  1. From the Connectivity folder of the Palette, drop three cFile and four cMessagingEndpoint components onto the design workspace, and
    label them Sender, Receiver_Paris, and Receiver_Others, directParis, directOthers, directParisRoute, and directOthersRoute respectively to better identify their
    roles.
  2. From the Routing folder, drop a cMessageRouter component onto the design
    workspace, and label it Message_router.
  3. From the Miscellaneous folder, drop two cLog components onto the design workspace, and label them Monitor_Paris and Monitor_Others respectively.
  4. Right-click the cFile component labeled
    Sender, select Row > Route from the
    contextual menu and click the cMessageRouter component.
  5. Right-click the cMessageRouter component, select Trigger > When from the contextual menu and click the cMessagingEndpoint component labeled directParis. This endpoint will retrieve the messages that meet the defined criterion.
  6. Right-click the cMessageRouter component, select Trigger > Otherwise from the contextual menu and click the cMessagingEndpoint component labeled directOthers. This endpoint will collect all the messages that do not meet the filter criterion.
  7. Right-click the cMessagingEndpoint component labeled directParis, select Row > Route from the contextual menu and click the cFile component labeled Receiver_Paris. Repeat this operation to link the component labeled Receiver_Paris to Monitor_Paris, directOthersRoute to Receiver_Others, and Receiver_Others to Monitor_Others respectively using the Row > Route connection.

Configuring the components and connections

The cMessageRouter component does not have any
property as it filters and routes the messages from one endpoint to others based on
the conditions set in its When
connection(s).

  1. Double-click the cFile component labeled
    Sender to open its Basic settings view in the Component tab.

    cMessageRouter_2.png

  2. In the Path field, specify the file path to message source.

    From the Encoding list, select the encoding type of your message files. Leave the other parameters as they are.
  3. In the design workspace, click the When
    connection you created and click the Component view to define a filter against which messages
    will be routed.

    cMessageRouter_3.png

  4. In the Type list, select xpath because the format of the messages used is XML.

    In the Condition field, type in "/person[city='Paris']" to retrieve only those messages in which the value of the city node is Paris.
  5. Double-click the cMessagingEndpoint component labeled directParis to open its Basic settings view in the Component tab.

    cMessageRouter_4.png

  6. In the URI field, enter the endpoint URI, for example, “direct:Paris” to receive the filtered message.
  7. Repeat these steps to set the endpoint URI of the cMessagingEndpoint components labeled directOthers as “direct:Others”. Set the endpoint URIs of the cMessagingEndpoint components labeled directParisRoute and directOthersRoute as “direct:Paris” and “direct:Others” respectively.
  8. Double-click the cFile component labeled Receiver_Paris to open its Basic settings view in the Component tab, and specify the path for the messages meeting the filter criterion in the Path field.

    cMessageRouter_5.png

    Repeat this step to define the path for all the other messages from the sender in the cFile component labeled Receiver_Others.
  9. Double-click the cLog component labeled Monitor_Paris to open its Basic settings view in the Component tab.

    cMessageRouter_6.png

  10. Select INFO in the Level list. Select the Specify output log message option and enter the following code in the Message field to display the filename of the message sent to the specified directory.

    Repeat this step to customize the message in the cLog component labeled Monitor_Others to display the filename of the message sent to the specified directory.
  11. Press Ctrl+S to save your Route.

Viewing code and executing the Route

  1. Click the Code tab at the bottom of the
    design workspace to have a look at the generated code.

    cMessageRouter_7.png

    As shown in the code, the messages are routed according to conditions initialized with the .choice() piece of code. The filter you defined is initialized with the .when() piece of code, and the non filtered messages are routed through the .otherwise() piece of code.
  2. Click the Run button in the Run view or press F6 to execute your Route.

    RESULT: The files containing “Paris” are sent to a folder named Paris_only, and the other messages are sent in a folder called Other_cities.
    cMessageRouter_8.png

Document get from Talend https://help.talend.com
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Docs 7.x
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