Goals of BPM Architecture
Since this architecture is being built on top of J2EE platform, all the best practices for J2EE enterprise applications holds true and not repeated in this article. Common best practices like robust OO design, extensibility, scalability, reusability and maintainability are precursors for a good BPMS architecture.
Process Data
The process data which are defined and carried by the process should be light weight as far as possible. For instance, if an employee detail is needed for the process, it is advisable to have a key for employee record and fetch the aggregate details whenever necessary. This would avoid the heavy data flow across the process and also no obsolete data would be retained in the BPM system, thereby BPM can avoid the expensive sync up calls between different applications.
Integration
Integration is the nerve center of any BPMS architecture. Since BPMS itself is tied to a product, integration layer should be a separate component outside the BPMS deployable artifact. Even better the integration layer can be deployed as services. This would pave way for future SOA interactions. Also, any business logic changes in the external systems wouldn’t affect the BPM layer, there by increasing scalability and maintainability of the BPM application.
Integration Layer
It’s imperative that BPM should interact with lot of other external systems. It is desirable to have a separate integration layer rather than clubbing all the integration logic and external calls into BPM adapters itself. The external calls can be wrapped as a separate artifact or even better can be deployed as a separate application in stand-alone server. As the BPMS application grows the number of external calls will increase proportionately. If this is the case, having integration layer as a separate server will be much more scalable. The additional responsibilities for integration layer would be orchestration, data transformation, presentation layer support etc.
BPM Process Data in Presentation Layer
There is a need to present the process data in applications external to BPMS. Applications external to BPMS may not be in the same platform as the BPMS product. So the process data in BPMS have to be exposed as services. A process task might be presented in an external portal / may be in a mobile application. BPM architecture should be scalable enough to support the presentation of BPM process data as services.
Process as Service
A lot of BPM products provide capability to expose the process as a service itself. The service thus exposed should be checked for WS-1 compatibility or the latest interoperability standards. If not, it is better to have a custom developed service which would invoke the corresponding process. The in-house developed service will have more advantages in terms of flexibility, re-usability and maintainability.
Process Versioning
It is quite often that a deployed process undergoes some changes after ever release. How to make sure that any subsequent deployments would not break the in-flight instances of previous versions of the process? Well the solution for this problem cannot be addressed with one aspect. The issue of in-flight instances continues to haunt many successful programs. In-flight instance management should be dealt at an architecture and process design level. This is definitely a broader topic and the solution differs from product to product, and this calls for a separate post.
Application Data Model
There is a need to segregate the data model of the BPM product with the BPM application data. The data model of the application has to be separate from BPM product schema. Sometimes, BPM artifact data like process id, process data names have to be referred in the BPM application code. So there is a need to persist BPM process data along with the application data in application schema. Hard-coding of artifact names should be avoided in the application code and these have to be configured from a database. For instance, if process name is referred in application code, then it is advisable to have a database table with all process names and a reference from the application code can be fetched from the database table.
Source - http://bpmstech.blogspot.com/2011/05/best-practices-for-bpms-design-and_16.html
Business Process Management (BPM) software and services empower organizations of all sizes to not only meet but exceed their customers' expectations, not only react to, but anticipate shifts in their marketplace, and all of this while keeping costs under control. It takes a process aware organization to achieve this level of agility and IBM has both the tools and the know-how to transform you into one.
Friday, July 5, 2013
Exception handling in BPM by Prasanna CS, Senior BPM Consultant
Exception handling is one of the prime aspects of software design which attributes to the robustness of the application. Exception handling gains more significance in BPM space, since exceptions had to be dealt both at a system level and at a business level. Bruce Silver has added one more dimension to exception handling in BPM, in his article, wherein exceptions had to be dealt at the process modeling itself.
The significance of exception handling at a process modeling step cannot be ignored. There is a need to handle ACID transactions in BPM, with a business solution and it has to be captured in the model with business semantics. For instance, a classic example of flight, hotel and rental car booking when deemed as a single atomic transaction cannot always be dealt at a system level. If flight booking and hotel booking are two different applications in two different domains (if flight carrier and hotel are different companies), then system transactions cannot be propagated and even if it seems to be possible, system level locks for transaction may not be possible to be obtained since the whole transaction may exceed beyond days to complete. The ideal way to deal with this situation is to have three distinct transactions as business process and even if one fails the other transactions must be canceled using a business process. If flight booking has been confirmed and if hotel booking transaction fails, then flight booking should also be canceled, wherein flight cancellation must be modeled as a separate business process.
It becomes imperative for a BPM solution to handle system level exceptions gracefully. Since process instances can span across business days, in case of system exceptions the process state has to be persisted and should be able to recover from the state where it was left. This may not be possible always for each and every process instance. Sometimes there is a good chance that a process instance may get into an irrecoverable state. In such scenarios, it may not be desirable for the users to create a new process instance altogether. The alternatives for irrecoverable instances due to system exceptions are few, and one probable solution could be to create a new process instance and associate the application process data with the new instance, and programmatically navigate process the instance to the workflow step where it failed.
Another alternative is to create an exception business process. Any system level exception occurring in any of the application business process would trigger the exception business process, which would notify the user about the exception. Also exception process can notify a repair/admin team about the exception. Having a repair queue of exceptions can help the repair/admin team to get first hand information about the exception without the need for notification from the business users about what had happened. Also, irrecoverable process instances can be dealt internally within the IT team, without burdening the business users.
In my opinion, a BPM solution should handle both business and system exceptions. Handling every exception at a process model level would clutter the process diagram with fine grained details defeating the very purpose of a business process diagram. The need for hour is a finer distinction between business and system exceptions should be made even before a process is set to get modeled. A business exception may not look like an exception at all from a BPMN perspective, since most of the business exception would be handled by a new business process altogether, instead of the intermediate handler event.
Source - http://bpmstech.blogspot.com/2011/05/exception-handling-in-bpm.html
The significance of exception handling at a process modeling step cannot be ignored. There is a need to handle ACID transactions in BPM, with a business solution and it has to be captured in the model with business semantics. For instance, a classic example of flight, hotel and rental car booking when deemed as a single atomic transaction cannot always be dealt at a system level. If flight booking and hotel booking are two different applications in two different domains (if flight carrier and hotel are different companies), then system transactions cannot be propagated and even if it seems to be possible, system level locks for transaction may not be possible to be obtained since the whole transaction may exceed beyond days to complete. The ideal way to deal with this situation is to have three distinct transactions as business process and even if one fails the other transactions must be canceled using a business process. If flight booking has been confirmed and if hotel booking transaction fails, then flight booking should also be canceled, wherein flight cancellation must be modeled as a separate business process.
It becomes imperative for a BPM solution to handle system level exceptions gracefully. Since process instances can span across business days, in case of system exceptions the process state has to be persisted and should be able to recover from the state where it was left. This may not be possible always for each and every process instance. Sometimes there is a good chance that a process instance may get into an irrecoverable state. In such scenarios, it may not be desirable for the users to create a new process instance altogether. The alternatives for irrecoverable instances due to system exceptions are few, and one probable solution could be to create a new process instance and associate the application process data with the new instance, and programmatically navigate process the instance to the workflow step where it failed.
Another alternative is to create an exception business process. Any system level exception occurring in any of the application business process would trigger the exception business process, which would notify the user about the exception. Also exception process can notify a repair/admin team about the exception. Having a repair queue of exceptions can help the repair/admin team to get first hand information about the exception without the need for notification from the business users about what had happened. Also, irrecoverable process instances can be dealt internally within the IT team, without burdening the business users.
In my opinion, a BPM solution should handle both business and system exceptions. Handling every exception at a process model level would clutter the process diagram with fine grained details defeating the very purpose of a business process diagram. The need for hour is a finer distinction between business and system exceptions should be made even before a process is set to get modeled. A business exception may not look like an exception at all from a BPMN perspective, since most of the business exception would be handled by a new business process altogether, instead of the intermediate handler event.
Source - http://bpmstech.blogspot.com/2011/05/exception-handling-in-bpm.html
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