How the ALE Module works

When processing application events, the ALE Module acts as a server to the SAP application. In this capacity, the ALE Module receives events that the SAP application "pushes", or sends, to the connector. When processing requests, the ALE Module receives business object requests from the integration broker and sends them to the SAP application.

This section documents the following processes:

Initialization and termination

The init() method opens an RFC connection to the SAP R/3 application through the SAP Gateway. If the connector fails to initialize, it terminates the connection using the terminate() method. The connector terminates by disconnecting from the SAP Gateway.

When processing application events or business object requests, the connector's initialization process does the following:

  1. Registers with the SAP Gateway the Program ID specified in the RfcProgramID connector configuration property. For information on setting the Program ID as a TCP/IP port see Registering the RFC Server Module with the SAP gateway.
  2. Opens an MQSeries session to the queues configured for the connector.
  3. Verifies that the required MQSeries queues for event and request processing have been created. If they have not been created, terminates the connector.

For more information, see Configuring the ALE Module.

Because the connector supports multi-threading, when the ALE Module processes requests from the integration broker, it does not use the module's init() method to create a connection handle. Instead, it uses the vision connector framework's connection pool of such handles.

Important:
When you use this module to process application events, connector polling is required to properly initialize the module (to install the RFC functions on the server), and for it to properly manage errors. Therefore, do not set the value of the PollFrequency property to key or to no. Do not allow the SAP application to trigger events to the connector until you have verified that the connector's log displays the installation of the required RFC functions.

Business object processing

The ALE Module's processing of WebSphere business objects for SAP is initiated either through event processing or request processing.

This section describes:

Note:
When business object data is returned from SAP's Java Connector (jCO) API, the ALE Module receives values for DATS and TIMS fields in the following formats: YYYY-MM-DD (the hyphens are included) for the DATS data element, and HH:mm:ss (the colons are included) for the TIMS data element. The capitalized HH denotes 24-hour time, and not 12-hour time. When processing events, the ALE Module changes these formats to fit the 8-character and 6-character maximum size of their corresponding business object attributes. The connector shortens the length of the value by removing the hyphens from the date data and the colons from the time data.

Event processing

Two RFC-enabled functions in an SAP application initiate all event processing for the ALE Module. The ALE's business object handler for event processing supports the functions idoc_inbound_asynchronous and inbound_idoc_process.

When processing events, this business object handler persistently stores the business objects in an MQSeries queue. The connector maintains the Transaction IDs (TIDs) associated with the RFC call to guarantee that each piece of data is delivered once and only once.

Important:
A single RFC call can send the data for one or more IDocs. Therefore, an MQSeries queue may contain a JMS-MQ message that represents multiple IDocs, each of which represents a business object. Each RFC call is associated with a single TID.

This section describes the following:

Processing events in the MQSeries queue

Figure 19 illustrates how the ALE Module processes the MQSeries queue.

Figure 19. Business object event processing


Business-object event processing for the ALE Module executes in the following manner:

  1. An RFC function pushes event data to the SAP Gateway, where a listener thread picks up events. The thread checks the TID associated with the event to determine whether a JMS-MQ message exists for the TID (that is, whether the TID has been sent previously):
  2. The listener thread instantiates the ALE event-processing business object handler, which retrieves the RFC-interface data from the SAP Gateway.
  3. The business object handler formats each transaction into a JMS-MQ message, which it stores persistently in the queue specified by the SAPALE_Wip_Queue configuration property.

    Each JMS-MQ message represents a single RFC call. Each RFC call can represent one or more business objects associated with a single TID. The connector stores the TID in the message's CorrelationID property, sets the TidStatus to CREATED, and sets the IDocProcessStatus to unknown. The connector uses the message body to store IDoc data.

  4. After each transaction completes, the connector changes the value of TidStatus and sends a confirmation back to SAP indicating that the transaction is complete. After SAP receives the confirmation, it removes the TID and its associated data from the SAP application.

    If the AleUpdateStatus configuration property evaluates to true, the connector updates the status of the IDoc in SAP. If it retrieves a packet of IDocs, it updates the status of all IDocs in the packet. For more information, see Updating the IDoc status in SAP.

  5. The connector moves the JMS-MQ message from the Wip queue to the queue specified by the SAPALE_Event_Queue configuration property.
  6. The ALE Module's polling thread picks up the event message from the Event queue.
  7. The connector instantiates an ALE data handler that will convert the data in the message body to business objects for posting to the integration broker..
  8. The connector attempts to post each business object to the integration broker. If the integration broker is WebSphere Interchange Server, the connector first checks if there are subscriptions for the business object. After processing all the business objects in the message body, the message's IDocProcessingStatus and BOProcessingStatus are updated and the message is moved to the queue specified by the SAPALE_Archive_Queue property. For more information on IDocProcessingStatus see, "Creating archive messages" and on BOProcessingStatus see, "Structure of JMS-MQ message for event and archive processing".

The Ale module uses FIFO (First In, First Out) to maintain the processing order when reading the messages from the Event queue.

Important:
Connector polling is required for this module to manage errors properly when it processes application events. Therefore, do not set the value of the connector's PollFrequency property to key or to no. Do not allow the SAP application to trigger events to the connector until you have verified that the connector's log displays the installation of the required RFC functions.

Structure of JMS-MQ message for event and archive processing

Table 23 describes the structure of the message that the connector sends to the Event and Archive queues.

Table 23. Structure of JMS-MQ message for event and archive processing

Property name Description
CorrelationId The JMS message header property--the connector sets the value of this property from the Transaction ID (TID) sent by SAP
TidStatus The JMS message header property that maintains the status of the TID
IDocProcessStatus The JMS message header property that maintains the status of the IDoc object during event processing
BOProcessingStatus The JMS message header property that maintains the status of all IDocs in the message using the following format, <CID> :: <IDoc sequence number><Status symbol>. Possible status symbols are S for Success, F for fail and U for unsubscribed. For example "<CID> :: 0S, 1F, 2U" means the first IDoc was successful, second failed, and third was unsubscribed for CorrelationId = <CID>.

Table 24 describes the possible values for the IDocProcessStatus property after an event is moved to the Archive queue.

Table 24. Archive queue values for the IDocProcessStatus message property

IDocProcessStatus property value Event status Description
success Success All business objects in the message have been posted with no errors.
partial Partial success One or more but not all business objects in the message have been posted with an error. If the integration broker is WebSphere Interchange Server, one or more but not all business objects in the message have been posted with an error or are unsubscribed.
unsubscribed Unsubscribed If the integration broker is WebSphere Interchange Server, all business objects in the message are unsubscribed.
fail Fail All business objects in the message have been posted with an error.

Creating archive messages

When the message is moved from the Event queue to the Archive queue, the IDocProcessingStatus and BOProcessingStatus are updated. The message body remains unchanged.

For example, assume the connector processes an event message with four IDocs, each of which it transforms or attempts to transform into a business object, with the results illustrated in Table 25:

Table 25. Archive message creation

Status of IDoc or business object Resulting archive message
Successfully transforms the first IDoc, and posts the business object to the integration broker The IDocProcessStatus is updated to success and the BOProcessingStatus is <CID> :: 0S
Fails to transform the second IDoc into a business object The IDocProcessStatus is updated to partial and the BOProcessingStatus is <CID> :: 0S, 1F
Successfully transforms the third IDoc, and posts the business object to the integration broker The IDocProcessStatus is set to partial and the BOProcessingStatus is <CID> :: 0S, 1F, 2S
Successfully transforms the fourth IDoc, but the business object created is not subscribed in the integration broker
  • The IDocProcessStatus is set to partial and the BOProcessingStatus is <CID> :: 0S, 1F, 2S, 3U
  • After processing the last IDoc, moves the message from the Event queue to the Archive queue and gives it IDocProcessStatus of partial and BOProcessingStatus of <CID> :: 0S, 1F, 2S, 3U

Updating the IDoc status in SAP

To cause the connector to update a standard SAP status code after the ALE Module has retrieved an IDoc for event processing, you must:

If AleUpdateStatus evaluates to true, the connector sends the ALEAUD IDoc to SAP with status code information and, optionally, descriptive text. The ALEAUD IDoc calls the IDOC_INPUT_ALEAUD function module. The connector supports sending the following status codes to this function module:

In both of the cases above, the business integration system does not send further status codes that would indicate further processing.

For information on setting the connector-specific configuration properties that are required to return IDoc status, see:

For information on setting the connector-specific configuration properties that are optional to return IDoc status, see:

Request processing

The vision connector framework uses the value of the verb AppSpecificInfo property of the top-level business object to instantiate the ALE request-processing business object handler. The doVerbFor() method in the request-processing business object handler initiates all business object requests.

The business object handler converts the business object data into two tables that represent the IDoc format and its meta-data component, the control record. Once the data is in IDoc format, the business object handler makes an RFC call to the appropriate SAP function module: either idoc_inbound_asynchronous or inbound_idoc_process. Because ALE is asynchronous, the connector does not wait for a return response.

Important:
By default, parent wrapper business objects generated by SAPODA contain a TransactionId attribute. A value in this attribute causes the connector to manage TIDs when processing service call requests. If you do not want TID management for request processing, do not set a value for this attribute. For more information, see Parent wrapper business object.
Note:
The value of the TransactionId attribute must be a unique identifier. The value is not the equivalent of a TID in the SAP application. These values are stored in a table within the JMS_MQ message in the queue specified by the SAPtid_Queue configuration property.

If the TransactionId attribute does not have a value, the ALE Module sends the request directly to SAP. If the TransactionId attribute has a value, the ALE Module does the following:

  1. The connector checks whether the JMS-MQ message in the queue specified by the SAPtid_Queue configuration property has this value.
  2. The connector converts the business object to RFC tables and makes an RFC call to SAP.
  3. After SAP acknowledges receipt of the RFC call, the connector removes the key from the table, archives the key, and returns a success status to the integration broker.

Archiving

After successfully processing a service call request, the corresponding entry in the table of the JMS-MQ message in the SAPtid_Queue is removed and archived to a directory. A file is created in the \ale\request sub-directory for WINNT or /ale/request for Unix systems. The ale sub-directory is located in the directory where the adapter is started. The entry that has been removed from the table will be used to create the new file. The file name will have the following format: <ObjectID>_<TID><timestamp>.executed where ObjectID is the value from the TransactionId attribute, TID is the transaction ID from SAP, and timestamp is the time stamp of when the file was created.

The adapter itself manages the deletion of these archive files using the connector configuration property ArchiveDays. The value in the connector configuration property, ArchiveDays, determines the amount of days these archived files will persist in the ale\request sub-directory. Any files older than the number of days specified in ArchiveDays will be deleted. If this property is not configured, the default value for ArchiveDays is seven days. These archive files can also managed manually by deleting the files yourself.

Resubmission of Failed Requests

For all failed requests indicated by the integration broker, check whether an archive file has been created for the request. If the archive file exists for the Object ID in the request then do not resubmit the request from the integration broker. Resubmit the request if there is no archive file for that ObjectID. Ensure the ArchiveDays connector configuration property is set to a value that will allow for verification of resubmitted requests.

Columns in the table of the JMS MQSeries message for request processing

Table 26 describes the columns of the JMS-MQSeries message that the connector gets from the SAPtid_Queue:

Table 26. Columns of JMS-MQ message for request processing

Column name Description
ObjectID The value that is in the TransactionID attribute of the requested business object. This value is used as the key for the table
TID The transaction ID obtained from SAP
TidStatus Status of the transaction

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