Copyright © Choreology Ltd. March 2002 Choreology® The Interplays of Commerce OASIS Business Transaction Protocol: Multi-party Coordination for Commercial Collaborations March 2002

Choreology® The Interplays of Commerce 2 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Goals Inter-organizational multi-party coordination Targetting Web Services, but not only WS Accommodate Long-running Transactions

Choreology® The Interplays of Commerce 3 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Requirements Coordination of autonomous parties  Relationships are governed by contracts, rather than the dictates of a central design authority Drop less ACID  Multiple possible successful outcomes to a transaction  Relaxed isolation, volatile results Interoperation  Using XML, over multiple communications protocols Discontinuous service  Work unit lifespans exceed sub-system MTBFs

Choreology® The Interplays of Commerce 4 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 The key BTP roles Application Client sideService side Protocol Client Initiator/Terminator Service Transaction Decider (Composer or Coordinator) Participant Enroller Factory

Choreology® The Interplays of Commerce 5 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Ask Factory to Create top coordinator Application Client sideService side Protocol Client Initiator/Terminator Service CoordinatorParticipant Enroller Factory BEGIN / BEGUN&CONTEXT creates

Choreology® The Interplays of Commerce 6 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Send Application Message with CONTEXT Application Client sideService side Protocol Client Initiator/Terminator Service CoordinatorParticipant Enroller Factory CONTEXT

Choreology® The Interplays of Commerce 7 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Service creates and causes ENROL of Participant Application Client sideService side Protocol Client Initiator/Terminator Service CoordinatorParticipant Factory Enroller creates ENROL / ENROLLED

Choreology® The Interplays of Commerce 8 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Send Application Reply with CONTEXT_REPLY Application Client sideService side Protocol Client Initiator/Terminator Service CoordinatorParticipant Enroller Factory CONTEXT_REPLY

Choreology® The Interplays of Commerce 9 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 CONFIRM_TRANSACTION Application Client sideService side Protocol Client Initiator/Terminator Service CoordinatorParticipant Factory Enroller CONFIRM_TRANSACTION

Choreology® The Interplays of Commerce 10 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Two-phase Confirmation: PREPARE phase Application Client sideService side Protocol Client Initiator/Terminator Service CoordinatorParticipant Factory Enroller PREPARE / PREPARED

Choreology® The Interplays of Commerce 11 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Two-phase Confirmation: Outcome phase Application Client sideService side Protocol Client Initiator/Terminator Service CoordinatorParticipant Factory Enroller CONFIRM / CONFIRMED

Choreology® The Interplays of Commerce 12 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 TRANSACTION_CONFIRMED Reply Application Client sideService side Protocol Client Initiator/Terminator Service CoordinatorParticipant Factory Enroller TRANSACTION_CONFIRMED

Choreology® The Interplays of Commerce 13 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Cancellation Example showed CONFIRM/CONFIRMED Terminating application can also issue CANCEL_TRANSACTION  Or the CONFIRM_TRANSACTION can fail, leading to TRANSACTION_CANCELLED  CANCEL/CANCELLED exchange with Participant

Choreology® The Interplays of Commerce 14 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Service and Participant: Provisional effect and Counter-effect  Forward Operations create a provisional effect …  … and durably record information needed by Participant  Participant uses log to perform final effect or to counter-effect A (provisional ) finalise A counter A Log of A Participant Service CONFIRM CANCEL Service sideClient side

Choreology® The Interplays of Commerce 15 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Provisional, final and counter effects Provisional effect  Apparently – the application’s forward operation  Really – just do what is needed to do either final or counter  Do something, log (persist) information for final or counter Final effect – action on CONFIRM  Final effect is action on CONFIRM  Complete the operation so it did happen  Use the information in the log, discard log Counter effect – action on CANCEL  Counter-effect is action on CANCEL  Make it that the application did not happen (or unhappened)  Use the information in the log, discard the log  May be perfect or have side effects

Choreology® The Interplays of Commerce 16 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March PC  ACID Example #1: Compensation strategy  Provisional Effect includes committed database updates or message enqueues  E.g. debit credit card account  Final effect is no-op  Counter-effect involves compensatory action  E.g. contra-credit credit card  In whole or in part depending on business contract Example #2: XA RM  Provisional Effect posits but does not commit database updates or MQPUTs  Final effect  invoke xa_commit  Throw away RM undo logs  Counter-effect is to invoke xa_rollback  Process RM undo logs

Choreology® The Interplays of Commerce 17 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Service decides what a Participant covers  Service can combine provisional effects into one Participant  Single confirm or cancel signal  Application specific  Service had the right to create and enrol two participants A B finalAB counterAB Operation Group Log of A, B Participant Service CONFIRM CANCEL Service sideClient side

Choreology® The Interplays of Commerce 18 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Superior-Inferior Relationship - outcome Superior Inferior PREPARE CONFIRM CANCEL PREPARED CONFIRMED CANCELLED Composer Coordinator Sub-composer Sub-coordinator Sub-composer Sub-coordinator Participant

Choreology® The Interplays of Commerce 19 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Transaction Tree - 1 Superior [e.g. Coordinator] Inferior [Participant] Inferior [Participant] Inferior [Participant]

Choreology® The Interplays of Commerce 20 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Transaction Tree - 2 Superior [e.g. Coordinator] Inferior [Participant] Inferior [Participant] Inferior [Participant] Inferior/Superior [e.g. Sub-coordinator]

Choreology® The Interplays of Commerce 21 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Transaction Tree - 3 Superior [Composer] Inferior [Participant] Inferior [Participant] Inferior [Participant] Inferior/Superior [e.g. Sub-coordinators]

Choreology® The Interplays of Commerce 22 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Coordination Hub: control and outcome relationships Application Client Service Protocol Client Initiator/Terminator Service Participant Factory Enroller Coordination Hub Transaction Decider (Composer or Coordinator) control outcome

Choreology® The Interplays of Commerce 23 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Cohesions: The Concept Superior Composer Inferior Participant Shipping Atom  Inferiors Participants ServicesBuyer Goods Atom  Inferior Coordinators Superior Cohesion Terminator #1 #2

Choreology® The Interplays of Commerce 24 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Cohesions: PREPARE both Atoms Superior Composer Inferior Participant Inferiors Participants ServicesBuyer Inferior Coordinators Superior Cohesion Terminator P P PREPARE #1 #2 PREPARE_INFERIORS #1, #2 Shipping Atom  Goods Atom 

Choreology® The Interplays of Commerce 25 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Cohesions: both are PREPARED Superior Composer Inferior Participant Inferiors Participants ServicesBuyer Inferior Coordinators Superior Cohesion Terminator INFERIOR_ STATUSES #1 P’d #2 P’d P’d PREPARED Shipping Atom  Goods Atom  #1 #2

Choreology® The Interplays of Commerce 26 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Cohesions: CONFIRM #1 (  CANCEL #2) Superior Composer Inferior Participant Inferiors Participants ServicesBuyer Inferior Coordinators Superior Cohesion Terminator CONFIRM CANCEL CONFIRM CANCEL CONFIRM_TRANSACTION #1 Shipping Atom  Goods Atom  #1 #2

Choreology® The Interplays of Commerce 27 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Cohesions: #1 CONFIRMED, #2 CANCELLED Superior Composer Inferior Participant Inferiors Participants ServicesBuyer Inferior Coordinators Superior Cohesion Terminator INFERIOR_ STATUSES #1 CO’d #2 CA’d CO’d CA’d CONFIRMED CANCELLED Shipping Atom  Goods Atom  #1 #2

Choreology® The Interplays of Commerce 28 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Cohesions rely on “Open-top” Coordinator Cohesion Composer “Open-top” Atom Coordinators Cohesion Terminator CONFIRM / CONFIRMED #1 CONFIRM_TRANSACTION #1 INFERIOR_ STATUSES #1 CO’d #2 CA’d PREPARE / PREPARED CANCEL / CANCELLED PREPARE / PREPARED #2

Choreology® The Interplays of Commerce 29 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Example: Cross-company Securities Trading Hedge Fund ABN Amro NomuraCommerzDKB O S O S O S O S Stock and option – from different market makers

Choreology® The Interplays of Commerce 30 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Example: Cross-company Securities Trading Hedge Fund ABN Amro NomuraCommerzDKB O S O S O S O S Each market maker makes two guaranteed time-qualified quotes = PREPARED, from 2 participants each

Choreology® The Interplays of Commerce 31 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Example: Cross-company Securities Trading Hedge Fund ABN Amro NomuraCommerzDKB O S O S O S O S Hedge fund chooses one of each, cancels the others (or lets them timeout) 

Choreology® The Interplays of Commerce 32 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Participant time-out Inferior can limit duration of its preparedness  Inferior threatens to auto-cancel or confirm after (at least) n seconds  Inferior qualifies the PREPARED message  Prevents coordinator hogging service provider’s resources  Independent organization likely to demand this power  Risks contradiction – which will be reported Superior can negotiate the time limit  Superior qualifies the PREPARE message  Prevents service wasting coordinator’s time

Choreology® The Interplays of Commerce 33 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Failure Recovery Protocol incorporates recovery after failure  Superior system, Inferior system or network may fail  Must try to re-establish Superior-Inferior relationship  Allows outcomes to be replayed Standard “presumed abort” protocol  No durable record (log) equals absence of decision  Default decision (in absence of evidence to contrary): CANCEL Bi-directional recovery initiation  Superior can attempt to contact logged Inferiors  Inferior can attempt to contact logged Superior

Choreology® The Interplays of Commerce 34 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Active phase recovery  Allows Superior/Inferior re-synch after failures  Standard 2PC protocols allow recovery only after prepared  BTP treats failure as a potential interruption  Standard 2PC protocols treat any failure as cause to cancel  Permitted, not required  Presume-abort still applies – just it isn’t compulsory  Useful for long-running transactions  Useful with interruptible communications

Choreology® The Interplays of Commerce 35 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Messaging All BTP messages are XML documents  Can be compounded for optimization  “One-shot requests”: only 2 WAN messages instead of 6  Application response + ENROL/PREPARE  “One wire” application topologies  All traffic between two business entities over a single, authenticated link Binding of abstract set to SOAP  Defined in the specification Other bindings are possible  To any underlying communications protocol stack

Choreology® The Interplays of Commerce 36 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Qualifiers Qualifiers can be embedded in messages  Some are defined within BTP specification  Implementers/applications can define their own  Identified by URI Allows extensions to protocol messages  trading parties could use to add security data  Implementor could use to add full nested transactions Allows application data to travel with protocol  Example: confirm a two-way quote  Must include “buy” or “sell” in CONFIRM

Choreology® The Interplays of Commerce 37 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Business Transactions and Business Process BTP complements BP/Collaboration frameworks  A coordinated, mutually understood outcome requires  Special messages and acknowledgements  Consistent, durable record of decisions  Asynchronous failure recovery operations  These features are tricky, error-prone and intrusive “Build or buy”  BTP lets business people concentrate on business process  Puts housekeeping work in the background  Minimizes application exchanges  Reduces complexity of collaborative process schemas or scripts  Reduces conformance testing  Deploy new trading protocols or conventions more quickly

Choreology® The Interplays of Commerce 38 BTP Overview – OMG Web-services. Copyright © Choreology Ltd. March 2002 Do Business Together with Business Transactions Ensuring Collaboration for XML Services Internal Business Process Collaboration ProcessBTP Internal Business Process Collaboration ProcessBTP