Overview

In this section:

iWay Service Manager horizontal scaling through reverse invocation allows a message received by one Service Manager configuration to be processed on another configuration. Configurations are expected to be on separate machines, but this is not a requirement. Messages can be distributed over an arbitrary number of associated configurations to balance workload and provide for high availability of processing services.

Messages are received at a receiving engine (the iWay Proxy) and executed at an execution engine. Each message arriving at the iWay Proxy is assigned to a named service. This assignment can be configured in a fixed manner based on the receiving listener or it can be assigned using the full services of Service Manager intelligent routing services. Regardless of how the assignment is made, the receiving engine locates an execution engine offering the named service, and passes the message to that engine for execution.

Processing engines connect to the receiving engine on a secure, reverse channel. This enables the receiving engine to be located across a firewall, enabling execution to be carried on in a secure environment not open to outside, unauthorized access.

This is also referred to as Reverse Invocation because the execution engine connects to the receiving engine rather than the receiving engine connecting to the execution engine to pass a document.


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The Proxy Service

Messages arrive at the proxy through any of the supported Service Manager protocols. Each protocol is managed by a listener. The listener is configured to pass the message to a relay service, which selects an attached execution service and passes the message to the selected engine for execution. All other Service Manager capabilities are supported. For example, intelligent routing can examine the incoming message to select the appropriate relay service for execution.


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The Execution Service

The execution engine accepts relayed messages, executes them, and returns the result to the relay service, which in turn relays the result back to the configured emitter(s). Usually, ancillary emit operations are performed on the execution engines, though this is not required.

An execution engine is configured with one or more gateway listeners. A gateway is a named service that attaches to the attach point of a receiving engine. There must be one gateway for each service name offered, at each receiving engine attach point.


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The Reverse Invocation Process

This section depicts the reverse invocation process in a step-by-step fashion. In this depiction, Service Manager is deployed to two locations, one within the enterprise and one in the demilitarized zone (DMZ).

  1. The iWay Proxy, or Receiving Engine, starts with the RVIAttach listener waiting for connections to be initiated from the Execution engine, as shown in the following image.

  2. The connection is initiated by the Gateway listener configured on the execution engine located in the enterprise, behind the firewall. A service name is defined in the gateway listener configuration, as shown in the following image.

  3. After the connection is established, it is added to a pool of connections and can be referenced by the service name, as shown in the following image.

  4. When a partner connects to the event listener defined on the iWay Proxy, the message is routed to the execution engine through the relay service that is added to the event listener. The relay service is configured with the service name defined in the gateway listener configuration, as shown in the following image.

  5. After the connection between the iWay Proxy and the execution engine is established, messages pass securely through the configuration, as shown in the following image.

  6. Multiple channels can be configured in the same way. Gateway listeners configured on the execution engine can spawn services that the iWay Proxy can use to pass data to the configured gateway listeners, as shown in the following image.


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A Sample Scenario

As an example of a Reverse Invocation scenario in which the payload is an EDI document, an AS2 message is routed over the public Internet. The message must be processed securely within the enterprise, where security certificates reside. The iWay Proxy server receives the message securely within the DMZ and passes it back for secure processing to an iWay Service Manager located inside the enterprise that acts as the Execution engine.

The following diagrams depict the process:

  1. The Execution engine initiates a connection with the Receiving Engine (iWay Proxy).

  2. The session is established.

  3. The trading partner initiates a connection with the iWay Proxy (the receiving engine).

  4. The connection is established, and the iWay Proxy manages connectivity between the trading partner and the internal processes hosted by the Execution engine.

From the perspective of a trading partner, a secure connection is established, and information can safely pass through the firewall for secure processing.


iWay Software