D2 9 Bpb Workflow Distributed Workflow Processing

BPBWorkflow Distributed workflow processing Tomasz Wrzosek PB Polsoft WfMC Forum Poland 2007

Agenda WMS in distributed environments  Architecture & technologies used  Time (control) issues  Fail-over and orphan processes  Dynamic (re)configuration  Q&A  2

Workflow Management Systems FACTS about WMS critical for work efficiency improvement in organizations  pivotal element to coordinate document and work flows  integrate many data sources used in business processes  THUS negligence in the terms of reliability may cause problems  HA supporting mechanisms are very welcome  3

Architecture 4

Architecture 5

Technologies used BPBWF is based on technologies providing required  services and mechanisms as a standard (J2EE) J2EE containers provide  transactional processing (persistence and business layers)  distributed transactions  services delivery (user transactions, JMS, JNDI..)  declarative configuration  availability of API through standard registers  load balancing and fail-over  session management and distribution  6

Time control distributed systems tend to be … distributed  different services deployed on different machines  may operate in different time-zones  question: how to synchronize events from  different parts of the system/application? persistence issues  related time services  time-zones support  timers  deadlines  7

Deadlines defining required finish times (deadlines) for  activities in process deadline paths  what does a particular deadline mean?  “in eight hours”  “within two weeks”  “by this time tomorrow”  solution  pluggable timer services  service basing on “current local time”  8

Time zones what does “current local time” mean?  client time  app server time  database server time  in which TZ should “11:30 a.m. today” be really  interpreted? requirement: synchronization of engines from  different TZ’s solution  providing the same “engine time” for each cluster node  converting client time to engine time  9

Failover – reactivation services orphan processes  clustered (distributed) applications tend to have higher failure rate  than local ones not always possible to restart a failed node  what happens to processes from failed nodes?  get called “orphan processes”...   may be considered to be lost and need to be restarted…  may get forgotten and clutter data base... but also:  may get migrated to another node and reactivated how it works in BPBWF  process and all its activities managed on the same node   cyclic thread looking for orphan processes  running on each node  when found --> process migrated to finder node 10

Rebooting the engine sometimes application/nodes needs to be  restarted all processes get suspended and need to be  reactivated afterwards same algorithm used  each node finds its processes  reactivates them (resumes)  all timers/listeners for these processes are  reactivated too (and executed if needed) => no process gets lost/unfinished  11

Nice to have HA features Dynamic engine (re)configuration  externalization of configuration details into an XML  file switching plugins in runtime (versioning?)  adding new functionality  new plugins  turning on/off system behavior  resetting  default timer values  class loading properties  default engine behavior  12

Nice to have HA features Process migration  altered process definition has to be applied  running processes, started with the previous one  how should the system behave  automatically change all processes to work with new  definition do nothing and start new processes with new definition  allow user (admin) to decide  in BPBW particular processes can be chosen to migrate  activities, deadlines, the process itself are switched to  new definition if possible if not… the process must be finished using old definition  13

Summary WMS in distributed environments  BPBWF design basics  Time control issues  Fail-over and orphan processes  HA features  dynamic (re)configuration  process migration  14

Thank you Tomasz Wrzosek PB Polsoft sp. z o.o. Poznań, Poland www: http://www.pbpolsoft.com.pl email: tomasz.wrzosek@pbpolsoft.com.pl phone: +48508021847 15

D2 9 Bpb Workflow Distributed Workflow Processing

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D2 9 Bpb Workflow Distributed Workflow Processing Presentation Transcript