ALE interface inbound processing, WebSphere Adapter for SAP Software

IBM BPM, V8.0.1, All platforms > Authoring services in Integration Designer > Services and service-related functions > Access external services with adapters > Configure and using adapters > IBM WebSphere Adapters > SAP Software > SAP interfaces > ALE interfaces
Inbound processing for the ALE interfaces

The adapter supports inbound processing (from the SAP server to the adapter) for the ALE interface.

When you configure a module for the ALE interface, you can indicate whether the IDocs are sent as a packet. In addition, you can specify whether IDocs are sent parsed or unparsed. You make these selections on the Configuration Properties window of the external service wizard. The selections you make are reflected in the application-specific information for the IDoc business object.
The following list describes the sequence of processing actions that result from an inbound request using the ALE interface.

The adapter starts event listeners to the SAP server.
Whenever an event occurs in SAP, the event is sent to the adapter by way of the event listeners.
The adapter converts the event into a business object before sending it to the endpoint.

The adapter uses the event recovery mechanism to track and recover events in case of abrupt termination. The event recovery mechanism uses a data source for persisting the event state.
If you have selected split IDocs and SAP is sending packet IDocs, the adapter delivers each IDoc inside the packet as an individual event to the end point. During recovery, the SAP system has to resubmit the whole packet. The adapter only delivers IDocs which have not been delivered in previous attempts from the packet.
The adapter is able to listen to and deliver events from multiple SAP systems using multiple activation specs.
The adapter is also able to deliver events to multiple endpoints. You enable delivery to multiple endpoints by configuring multiple activation specifications.

If the endpoints subscribe to the same events from the same SAP system, all properties in the individual activation specifications must be identical.
Endpoints that subscribe to different activation specifications receive events that match the criteria for the activation specification.

Define a separate activation specification for each endpoint to which events need to be delivered, except when the adapter delivers events only to those endpoints that are active.
When multiple endpoints subscribe to the same events from the same event store, the adapter assures event delivery to active endpoints only. Any endpoints that are inactive do not receive the event. If there are multiple endpoints and any one endpoint is not active, the message is skipped for that endpoint and the adapter delivers the event only to the active endpoints. If all the endpoints are inactive, the event is rolled back, and the event needs to be resubmitted from SAP.
The following table provides an overview of the differences between the ALE interface and the ALE pass-through IDoc interface for inbound processing.

differences between the ALE interface and the ALE pass-through IDoc interface
Interface When to use SplitIDoc = true SplitIDoc = false Parsed IDoc = true Parsed IDoc = false
ALE inbound This interface converts the raw incoming IDocs to business objects, which are readily consumable by the client at the endpoint. On receiving the IDoc packet from SAP, the adapter converts the IDocs to business objects, one by one, before sending each one to the endpoint. On receiving the IDoc packet from SAP, the adapter converts the IDocs in the packet as one business object before sending it to the endpoint. The incoming IDoc is parsed for both control record and data record. The individual segments in the IDoc are read and parsed to convert into business objects. The incoming IDoc is only partially parsed (the control record of the IDoc is parsed but the data record is not). The client at the endpoint is responsible for parsing the data record.
ALE pass-through IDoc This interface wraps the raw incoming IDoc in a business object before delivering it to the client at the endpoint.
The client is responsible for parsing the raw IDoc.
On receiving the IDoc packet from SAP, the adapter wraps each raw IDoc within a business object before sending the objects, one by one, to the endpoint. On receiving the IDoc packet from SAP, the adapter wraps the raw IDoc packet in a business object before sending it to the endpoint. This attribute is not applicable to the ALE pass-through IDoc. This attribute is not applicable to the ALE pass- through IDoc interface. (Neither the control record nor the data record of the IDoc is parsed.

Event error handling
WebSphere Adapter for SAP Software provides error handling for inbound ALE events by logging the errors and attempting to restart the event listener.
Event recovery

You can configure the adapter for ALE inbound processing so that it supports event recovery in case of abrupt termination. When event recovery is specified, the adapter persists the event state in an event recovery table that resides on a data source. Event recovery is not enabled by default; you must specify it by enabling once-only delivery of events during adapter configuration.
Event processing for parsed IDocs
An inbound event can contain a single IDoc or multiple IDocs, with each IDoc corresponding to a single business object. The multiple IDocs are sent by the SAP server to the adapter in the form of an IDoc packet. During adapter configuration, you can specify whether the packet can be split into individual IDocs or whether it must be sent as one object (non-split).
Event processing for unparsed IDocs
Unparsed IDocs are passed through, with no conversion of the data (that is, the adapter does not parse the data part of the IDoc). The direct exchange of IDocs in the adapter enables high-performance, asynchronous interaction with SAP, because the parsing and serializing of the IDoc occurs outside the adapter. The consumer of the IDoc parses the IDoc.
IDoc status updates
To monitor IDoc processing, you can configure the adapter to update the IDoc status. When the adapter configuration property ALEUpdateStatus is set to true (indicating that an audit trail is required for all message types), the adapter updates the IDoc status of ALE business objects that are retrieved from the SAP server. After the event is sent to the message endpoint, the adapter updates the status of the IDoc in SAP to indicate whether the processing succeeded or failed. Monitoring of IDocs applies only to inbound processing (when the IDoc is sent from the SAP server to the adapter).

The ALE interfaces

Interface	When to use	SplitIDoc = true	SplitIDoc = false	Parsed IDoc = true	Parsed IDoc = false
ALE inbound	This interface converts the raw incoming IDocs to business objects, which are readily consumable by the client at the endpoint.	On receiving the IDoc packet from SAP, the adapter converts the IDocs to business objects, one by one, before sending each one to the endpoint.	On receiving the IDoc packet from SAP, the adapter converts the IDocs in the packet as one business object before sending it to the endpoint.	The incoming IDoc is parsed for both control record and data record. The individual segments in the IDoc are read and parsed to convert into business objects.	The incoming IDoc is only partially parsed (the control record of the IDoc is parsed but the data record is not). The client at the endpoint is responsible for parsing the data record.
ALE pass-through IDoc	This interface wraps the raw incoming IDoc in a business object before delivering it to the client at the endpoint. The client is responsible for parsing the raw IDoc.	On receiving the IDoc packet from SAP, the adapter wraps each raw IDoc within a business object before sending the objects, one by one, to the endpoint.	On receiving the IDoc packet from SAP, the adapter wraps the raw IDoc packet in a business object before sending it to the endpoint.	This attribute is not applicable to the ALE pass-through IDoc.	This attribute is not applicable to the ALE pass- through IDoc interface. (Neither the control record nor the data record of the IDoc is parsed.