This section explains, through an example scenario, how the Selective Consumer EIP can be implemented using WSO2 ESB. The following topics are covered:
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This example scenario demonstrates how a specific receiver only processes messages that are pre-filtered based on certain criteria. We have an Axis2 server as the consumer. The consumer criteria is specified through an XML schema validation, which is stored as a local entry in the registry. We use the Validate mediator to check whether the messages that are sent to the ESB match the criteria of the schema. The Axis2 server can consume the message only if the message meets the validation criteria.
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- Download and install WSO2 ESB from http://wso2.com/products/enterprise-service-bus. For a list of prerequisites and step-by-step installation instructions, refer to Getting Started Installation Guide in the WSO2 ESB documentation.
- Start the sample Axis2 server. For instructions, refer to the section Setting Up the ESB Samples Setup - Starting Sample Back-End Servicesthe Axis2 server in the WSO2 ESB documentation.
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Simulating the sample scenario
Send the following request using a SOAP client like SoapUI.
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Let's investigate the elements of the ESB configuration in detail. The line numbers below refer to the ESB configuration shown above.
- localEntry [line 2 in ESB config] - A local registry entry with key
selective_criteriais used to define the XML schema used for validation inside the main sequence. - validate [line 33] in ESB config] - This mediator is used to define the portion of a message used for validation. In this example, no source attribute is specified using an XPath expression, so the ESB performs the validation on the first child element of the SOAP body.
- scehma [line 34 in ESB config] - Defines which schema to use for validation. In this example, the local registry entry definition in line 2 is used.
- on-fail [line 35 in ESB config] - Defines the action to take on failure of a validation. In this example, a fault is created and the message is dropped.