Setting Dynamic Queue Name in EOIO Scenarios Using Custom Adapter Module in Advanced Adapter Engine of PI/PO
Intro
During development of scenarios with Quality of Service = Exactly Once In Order and involving polling sender adapter types (e.g. SFTP, File/FTP, JDBC, Mail, REST in polling mode), as well as some other adapter types (REST in push mode), it is required to set queue name / sequence ID dynamically, based on data contained in the processed message. Standard functionality of such adapters provides support for fixed queue name that is specified in configuration of a sender communication channel (which means, all messages processed by this communication channel, will be sequenced using a single queue / serialization context, which is often not acceptable / optimal), but it lacks functionality of setting queue name dynamically at runtime. In order to fulfil such described requirement, commonly used solution is to develop a custom adapter module. The approach is based on overwriting sequence ID of a processed XI message using standard API of Adapter Framework of Advanced Adapter Engine (refer to SAP JavaDocs for class com.sap.engine.interfaces.messaging.api.Message), and setting the required sequence ID (commonly, its value is based on value of some payload element that can be accessed using XPath). A custom adapter module has to be placed before the XI message reaches Messaging System (which translates to adding this custom module before standard adapter module CallSapAdapter is called in the module processing sequence of a communication channel).
In this blog, I’m not going to dive into details of this approach, since it has already been well described by other SCN community members in the past and examples of corresponding adapter modules have been provided and can be found on SCN – here are just few links and references to materials that have good outlook at this approach and its implementation:
- Working with Module Configuration in SAP PI
- Setting Queue Dynamically using Adapter Module
- Adapter module dynamic Queue Name, n xml elements
- Adapter Module Development. Set QoS EOIO with Queue Name based on XPath expression
Observation of many materials which describe this requirement and solution, and some degree of repeated development in this field undertaken by different teams, motivated me for writing this blog, which aim is to prepare an adapter module that is capable of fulfilling majority of requirements raised in the described area and collected from SCN blogs and forums, as well as those originating from projects I was involved in. Intention is to share with the community the adapter module that is generic enough to be re-used in various projects facing similar requirements, and enable reduction of repeated development efforts.
Adapter module configuration
Module name: Custom_AF_Modules/SetSequenceIdBean.
Below is a list of adapter module parameters. Note that only parameter used to specified XPath expression, is mandatory – all others are optional. Majority of optional parameters are used to further customize determined sequence ID and can be combined in order to achieve the required pattern of the determined sequence ID.
| Parameter name | Description | Possible values | Default value / behaviour | Mandatory or optional |
|---|---|---|---|---|
| xpath | XPath expression that shall extract required payload element’s value for dynamic sequence ID | String value containing valid XPath | Mandatory | |
| error.terminate | Terminate execution of the module if sequence ID cannot be set, causing also termination of further message processing by a channel. Not recommended to be disabled if dynamic sequence ID generation is a must | Boolean or Boolean equivalents (case insensitive):
|
true (enabled) | Optional |
| multipleValues.error | Terminate execution of the module if multiple distinct values were extracted from the message payload using specified XPath expression. If disabled, sequence ID is constructed based on the first extracted value. Not recommended to be disabled if unique sequence ID for every distinct object value per message is a must | Boolean or Boolean equivalents (case insensitive):
|
true (enabled) | Optional |
| sequenceId.deleteLeadingCharacter | Delete leading characters from the extracted value for the specified XPath expression | Boolean or Boolean equivalents (case insensitive):
|
false (disabled) | Optional |
| sequenceId.leadingCharacter | Leading character | String value containing 1 character | Optional | |
| sequenceId.replaceInvalidCharacters | Replace all invalid (not alphanumeric) characters from the constructed sequence ID with underscore symbol (‘_’) | Boolean or Boolean equivalents (case insensitive):
|
false (disabled) | Optional |
| sequenceId.truncate | Truncate constructed sequence ID so that its length does not exceed restrictions applicable for sequence ID (which is, 16 characters) – truncation can be either done to trim beginning of the value or its end. If the value retrieved using the specified XPath, is object identifier (e.g. customer number, sales order number, employee ID) that is iteratively increased for every subsequent instance of an object (e.g. sender system uses number range object for it), then truncation from start may be preferable, leaving a value part varying between closely following instances of objects | Below values are accepted (case insensitive), all others are ignored:
|
(disabled) | Optional |
| sequenceId.prefix | Fixed prefix value for a constructed sequence ID, which will be delimited from remaining sequence ID value part with uderscore symbol (‘_’). Shall not normally contain many characters since it may negatively impact overall length of the constructed sequence ID – optimum is 2-3 characters. From perspective of impact on total sequence ID value length, it is not recommended to use prefix and suffix at the same time. Note that if truncation is enabled for start of the value, prefix may become truncated | String value | (disabled) | Optional |
| sequenceId.suffix | Fixed suffix value for a constructed sequence ID, which will be delimited from remaining sequence ID value part with uderscore symbol (‘_’). Shall not normally contain many characters since it may negatively impact overall length of the constructed sequence ID – optimum is 2-3 characters. From perspective of impact on total sequence ID value length, it is not recommended to use prefix and suffix at the same time. Note that if truncation is enabled for end of the value, suffix may become truncated | String value | (disabled) | Optional |
Usage
In all examples below, in the sender communication channel, Quality of Service = Exactly Once In Order was selected and queue name = ‘DEMO’ was provided:
XPath expression is the only mandatory parameter for the developed adapter module – so let me start with the basic configuration involving only that parameter:
Following payload of the incoming message, against which XPath is applied, is used in this example:
As it can be seen, at runtime, the fixed sequence ID (‘DEMO’) was overwritten by the one determined based on the message payload (‘00012345’):
Next example demonstrates combined usage of several additional parameters to fine tune sequence ID determination more precisely:
Following payload of the incoming message, against which XPath is applied, is used in this example:
When executed at runtime, this leads to the following sequence ID determination and overwriting:
To give feeling of impact of various other module parameters, some more examples of determined sequence ID based on module parameterization and message payload, are given in the table below. Please note that for parameters expecting Boolean values, I used various acceptable values (true/false, True/False, yes/no, 1/0) in sake of demonstration of different possible alternatives to provide configuration for them – in scenarios, it is advisable to select consistent value alternatives and use them for all Boolean parameters configuration (e.g. only true or false, only yes or no, etc.) in order to make adapter module configuration more readable.
| Module parameterization | Incoming message payload | Determined sequence ID / error | Comments |
|---|---|---|---|
| (no module parameterization provided) |
|
ModuleException: One or several required adapter module parameters are missing or incorrect | Mandatory parameter ‘xpath’ is missing |
| error.terminate = 0 |
|
DEMO | Mandatory parameter ‘xpath’ is missing, but termination on error is disabled, so channel default configuration (fixed queue name) is used |
| xpath = /GenericObjects/ID |
|
ModuleException: Failure while attempting to set sequence ID | Application of the specified XPath to message payload didn’t yield to extraction of any value |
| xpath = /GenericObjects/Object/ID |
|
00012345 | |
| xpath = /GenericObjects/Object/ID |
|
ModuleException: Failure while attempting to set sequence ID | Constructed sequence ID length is larger than acceptable limit (16 characters) |
|
xpath = /GenericObjects/Object/ID error.terminate = False |
|
DEMO | Constructed sequence ID length is larger than acceptable limit (16 characters), but termination on error is disabled, so channel default configuration (fixed queue name) is used |
| xpath = /GenericObjects/Object/ID |
|
ModuleException: Failure while attempting to set sequence ID | Multiple different (distinct) values were retrieved from the message’s payload using specified XPath |
|
xpath = /GenericObjects/Object/ID multipleValues.error = no |
|
00012345 | Multiple different (distinct) values were retrieved from the message’s payload using specified XPath, but termination for such cases is disabled, so the first of those values was used when constructing sequence ID |
|
xpath = /GenericObjects/Object/ID sequenceId.deleteLeadingCharacter = true sequenceId.leadingCharacter = 0 |
|
12345 | |
|
xpath = /GenericObjects/Object/ID sequenceId.deleteLeadingCharacter = true sequenceId.leadingCharacter = 00 |
|
00012345 | Leading characters were not deleted, because incorrect value was specified in parameter ‘sequenceId.leadingCharacter’ (multiple characters instead of an expected one leading character) |
|
xpath = /GenericObjects/Object/ID sequenceId.deleteLeadingCharacter = true |
|
00012345 | Leading characters were not deleted, because leading character was not specified was not specified (parameter ‘sequenceId.leadingCharacter’ missing) |
|
xpath = /GenericObjects/Object/ID sequenceId.truncate = start |
|
00012345 | Determined sequence ID value is already less than 16 characters long, so its truncation is not required and was skipped |
|
xpath = /GenericObjects/Object/ID sequenceId.truncate = end |
|
TEST_OBJECT_1234 | |
|
xpath = /GenericObjects/Object/ID sequenceId.truncate = begin |
|
ModuleException: Failure while attempting to set sequence ID | Incorrect value specified for parameter ‘sequenceId.truncate’ (only ‘start’ and ‘end’ are valid values) |
|
xpath = /GenericObjects/Object/ID sequenceId.replaceInvalidCharacters = true |
|
TEST_OBJECT_01 | |
|
xpath = /GenericObjects/Object/ID sequenceId.prefix = v |
|
V_00012345 | |
|
xpath = /GenericObjects/Object/ID sequenceId.suffix = r2 |
|
00012345_R2 | |
|
xpath = /GenericObjects/Object/ID sequenceId.deleteLeadingCharacter = yes sequenceId.leadingCharacter = 0 sequenceId.prefix = v sequenceId.suffix = r2 sequenceId.truncate = start |
|
5_TEST_OBJECT_R2 | Even though set initially, prefix, as well as part of the original value retrieved using XPath expression, are truncated, because truncation from start was enabled and constructed sequence ID value after deleting leading symbols and adding prefix and suffix turned to be longer than 16 characters |
Source code and deployable
Source code of the adapter module and corresponding accompanying development artifacts are available at
GitHub repository for SetSequenceIdBean
Compiled and built latest version of the adapter module, assembled into deployable EAR file, is available at
Latest release of SetSequenceIdBean
The adapter module has been compiled in compliance to JDK 1.6, and has been successfully tested in PO 7.31 and PO 7.4 systems.
Outro
I will highly appreciate your feedback left in comments to this blog and encourage you sharing ideas about demanded, but yet missing functionality of this adapter module. This will help a lot on the way of enriching future versions of the module with new features based on your suggestions, and increasing module’s re-usability.
New NetWeaver Information at SAP.com
Very Helpfull
