Project-X Runtime Architecture

As mentioned in the previous sections, an Integration Flow in Project-X receives messages through Ingress Connectors. When an Ingress Connector is registered by an Integration Flow, a transport listener that implements the intended transport protocol of that connector is initialized and started by Project-X. Depending on their configuration similarities, multiple ingress connectors of an Ultra Project can share the same underlying transport listener to receive messages.

Once a message is received by a transport listener, it creates a Message object with the received data, setting the payload, headers and any other related information. Then this message object is enclosed in a Message Context object which bears the contextual information regarding the message.

After the Message Context is built, transport listener will handover it to the Message Receiver, with two consumer methods, one to be invoked on the successful completion of the message flow and other to be invoked on the failure of the message flow. In addition to these, In-Out type transport listeners will provide another consumer method to be invoked on the submission of a response.

Once a Message Context is received from a transport listener to the Message Receiver, first the receiver will check whether an Ingress Connector has been already selected by the transport listener to handle the message. If not, the message receiver will select the suitable Ingress Connector based on the received message.

Then if the message is a request-response type message, the Message Receiver will set a Response Timeout value to the Message Context. If the selected Ingress Connector has a Response Timeout value specified, it will be used or if not, the global Response Timeout value (which is specified in the org.adroitlogic.x.core.IntegrationPlatform bean on the conf/server.xml file) will be used.

Finally the Message Receiver will register the provided consumer methods with the Message Context, set few other internally used properties and handover the message context (with the selected Ingress Connector) to the Integration Platform.

When the Message Receiver provided a Message Context to the Integration Platform, it will set the information such as the current scope parameters, exchange pattern, transactional information, etc and dispatch the Message Context to the previously selected Ingress Connector through the customized executor service of Project-X which is known as the Scale-First Executor Service.

The selected Ingress Connector receives the Message Context through Scale-First Executor service and after performing any connector specific operations, the Message Context will be passed to the processing element connected to the "Processor" outport of the Ingress Connector which will be the first processing element of the Integration Flow.

After the Ingress Connector, the Message Context is sent through a series of Processing Elements. Each of these Processing Elements will perform a specific processing operation on the Message Context and handover the resulting Message Context to one or more processing elements.

Before executing any processing, every Processing Element will check whether the received Message Context is not expired and not marked as completed. If any one of these conditions failed, the processing of that Message Context will be aborted there onwards. In the event of expiration, the Message Context will be marked as Exceptionally Completed with a Timeout Exception.

An Egress Connector can be used to send the processed Message to an external system or endpoint. An Egress Connector receives a Message Context just as a regular processing element and first validates that the Message Context is neither expired nor already completed. Then if there is a Connector Operation element connected, the Message Context will be handed over to it and the resulting Message Context will be sent-out to the desired endpoint using the underlying transport sender.

But depending on whether it is one-directional or bi-directional, this sending-out behaviour of an Egress Connector varies.

If the Ingress Connector that received the message is a request-response type Ingress Connector, a response can be sent by connecting the last processing element of the response path to the "Input" port of the Ingress Connector. Then the current content of the message will be sent as the response content and the message flow will be completed successfully.