Methods for the specification and verification of business processes MPB (6 cfu, 295AA)

Transcription

1 Methods fo the specification and veification of business pocesses MPB (6 cfu, 295AA) Robeto Buni Business pocess execution language 1

2 Object We oveview the key featues of BPEL 2

3 3

4 BPEL 4

5 Business pocess execution language Also known as: Web Sevices Business Pocess Execution Language (WS-BPEL) Business Pocess Execution Language fo Web Sevices (BPEL4WS) it is a standad executable language fo ochestating the use of Web Sevice within business pocesses it deals with impot / expot infomation, emote invocation, coelation, fault handling, compensation 5

6 Web sevices Web sevices fix a standad fo inteopeability between heteogeneous, loosely coupled, emote softwae applications (sepaately developed, unning on diffeent platfoms) ove (not only) the HTTP potocol Infomally: web sevices ae fo softwae what web sites ae fo human 6

7 WS basics Sevices must be made available on the web (need a seve) Sevices must be advetised ove the web (need some epositoies) Sevice epositoies must be queied (need sevice desciption) Sevices must be invoked (need standad communication fomat) 7

8 MLification WSFL, BPEL, Sevice composition UDDI { Sevice discovey Sevice publication WSDL SOAP Sevice desciption ML based messaging HTTP, HTTPS, SMTP Netwok 8

9 WS-* 9

10 Web Sevices Standads Oveview Inteopeability Issues Basic Pofile 11 WS-I Final Specification Basic Pofile The Basic Pofile 11 povides implementation guidelines fo how elated set of nonpopietay Web Sevice specifications should be used togethe fo best inteopeability Basic Pofile 12 WS-I Woking Goup Daft Basic Pofile The Basic Pofile 12 builds on Basic Pofile 11 by incopoating Basic Pofile 11 eata, equiements fom Simple SOAP Binding Pofile 10, and adding suppot fo WS-Addessing and MTOM Basic Pofile 20 WS-I Woking Goup Daft Basic Pofile The Basic Pofile 20 is an update of WS-I BP that includes a pofile of SOAP 12 Basic Secuity Pofile 10 WS-I Boad Appoval Daft Basic Secuity Pofile defines the WS-I Basic Secuity Pofile 10, based on a set of non-popietay Web sevices specifications, along with claifications and amendments to those specifications which pomote inteopeability REL Token Pofile 10 WS-I Woking Goup Daft REL Token Pofile is based on a non-popietay Web sevices specification, along with claifications and amendments to that specification which pomote inteopeability SAML Token Pofile 10 WS-I Woking Goup Daft SAML Token Pofile is based on a non-popietay Web sevices specification, along with claifications and amendments to that specification which pomote inteopeability Confomance Claim Attachment Mechanism (CCAM) 10 WS-I Final Specification Confomance Claim Attachment Mechanism (CCAM) catalogues mechanisms that can be used to attach WS-I Pofile Confomance Claims to Web sevices atefacts (eg, WSDL desciptions, UDDI egisties) Reliable Asynchonous Messaging Pofile (RAMP) 10 WS-I Woking Daft Reliable Asynchonous Messaging Pofile (RAMP) is a pofile, in the fashion of the WS-I pofiles, that enables, among othe things, basic B2B integation scenaios using Web sevices technologies Standads Bodies Attachments Pofile 10 WS-I Final Specification Attachments Pofile The Attachment Pofile 10 complements the Basic Pofile 11 to add suppot fo inteopeable SOAP Messages with attachments-based Web Sevices Simple SOAP Binding Pofile 10 WS-I Final Specification Simple SOAP Binding Pofile The Simple SOAP Binding Pofile consists of those Basic Pofile 10 equiements elated to the seialization of the envelope and its epesentation in the message Business Pocess Specifications Business Pocess Execution Language fo Web Sevices 11 (BPEL4WS) 11 BEA Systems, IBM, Micosoft, SAP, Siebel Systems OASIS-Standad Business Pocess Execution Language fo Web Sevices 11(BPEL4WS) povides a language fo the fomal specification of business pocesses and business inteaction potocols using Web Sevices Business Pocess Execution Language fo Web Sevices 20 (BPEL4WS) 20 OASIS, BEA Systems, IBM, Micosoft, SAP, Siebel Systems Committee Daft Business Pocess Execution Language fo Web Sevices 20 (BPEL4WS) povides a language fo the fomal specification of business pocesses and business inteaction potocols using Web Sevices Metadata Specifications WS-Policy 15 W3C Woking Daft WS-Policy descibes the capabilities and constaints of the policies on intemediaies and endpoints (eg business ules, equied secuity tokens, suppoted encyption algoithms, pivacy ules) WS-PolicyAttachment 12 W3C W3C Membe Submission WS-PolicyAttachment defines two geneal-pupose mechanisms fo associating policies with the subjects to which they apply; the policies may be defined as pat of existing metadata about the subject o the policies may be defined independently and associated though an extenal binding to the subject WS-MetadataExchange 11 BEA Systems, Compute Associates, IBM, Micosoft, SAP, Sun Micosystems and webmethods Public Daft WS-MetadataExchange enables a sevice to povide metadata to othes though a Web sevices inteface Given only a efeence to a Web sevice, a use can access a set of WSDL /SOAP opeations to etieve the metadata that descibes the sevice Web Sevice Desciption Language 20 SOAP Binding 20 W3C Woking Daft Web Sevice Desciption Language SOAP Binding descibes the concete details fo using WSDL 20 in conjunction with SOAP 11 potocol Web Sevice Desciption Language W3C Note Web Sevice Desciption Language 11 is an ML-based language fo descibing Web sevices and how to access them It specifies the location of the sevice and the opeations (o methods) the sevice exposes WS-PolicyAssetions 11 BEA Systems, IBM, Micosoft, SAP Public Daft WS-PolicyAssetions povides an initial set of assetions to addess some common needs of Web Sevices applications WS-Discovey Micosoft, BEA Systems, Canon, Intel and webmethods Daft WS-Discovey defines a multicast discovey potocol fo dynamic discovey of sevices on ad-hoc and managed netwoks Univesal Desciption, Discovey and Integation (UDDI) 302 OASIS OASIS-Standad Univesal Desciption, Discovey and Integation (UDDI) defines a set of sevices suppoting the desciption and discovey of businesses, oganizations, and othe Web sevices povides, the Web sevices they make available, and the technical intefaces which may be used to access those sevices Web Sevice Desciption Language 20 Coe 20 W3C Candidate Recommendation Messaging Specifications WS-Notification 13 OASIS OASIS-Standad WS-Enumeation Systinet, Micosoft, Sonic Softwae, BEA Systems and Compute Associates Public Daft WS-Choeogaphy Model Oveview 10 W3C WS-Notification is a family of elated white papes and specifications that define a standad Web sevices appoach to notification using a topicbased publish/subscibe patten WS-Enumeation descibes a geneal SOAP-based potocol fo enumeating a sequence of ML elements that is suitable fo tavesing logs, message queues, o othe linea infomation models Woking Daft WS-Choeogaphy Model Oveview defines the fomat and stuctue of the (SOAP) messages that ae exchanged, and the sequence and conditions in which the messages ae exchanged Business Pocess Management Language (BPML) 11 BPMIog Final Daft Business Pocess Management Language (BPML) povides a meta-language fo expessing business pocesses and suppoting entities Web Sevice Desciption Language 20 Coe is an MLbased language fo descibing Web sevices and how to access them It specifies the location of the sevice and the opeations (o methods) the sevice exposes WS-BokeedNotification 13 OASIS OASIS-Standad WS-Topics 13 OASIS OASIS-Standad Web Sevice Choeogaphy Inteface (WSCI) 10 W3C Sun Micosystems, SAP, BEA Systems and Intalio Note Web Sevice Choeogaphy Inteface (WSCI) descibes how Web Sevice opeations can be choeogaphed in the context of a message exchange in which the Web Sevice paticipates ML Pocess Definition Language (PDL) 20 Final ML Pocess Definition Language (PDL) povides an ML file fomat that can be used to intechange pocess models between tools Reliability Specifications WS-BokeedNotification defines the inteface fo the NotificationBoke A NotificationBoke is an intemediay, which, among othe things, allows publication of messages fom entities that ae not themselves sevice povides WS-Topics defines thee topic expession dialects that can be used as subsciption expessions in subscibe equest messages and othe pats of the WS-Notification system Web Sevice Choeogaphy Desciption Language (CDL4WS) 10 W3C Web Sevice Choeogaphy Desciption Language (CDL4WS) is to specify a declaative, ML based language that defines fom a global viewpoint the common and complementay obsevable behaviou, whee message exchanges occu, and when the jointly ageed odeing ules ae satisfied WS-ReliableMessaging 11 OASIS Committee Daft Candidate Recommendation WS-ReliableMessaging descibes a potocol that allows Web sevices to communicate eliable in the pesence of softwae component, system, o netwok failues It defines a SOAP binding that is equied fo inteopeability WS-Reliable Messaging Policy Assetion (WS-RM Policy) 11 OASIS Committee Daft Web Sevices ReliableMessaging Policy Assetion (WS-RM Policy) descibes a domain-specific policy assetion fo WS-ReliableMessaging that that can be specified within a policy altenative as defined in WS-Policy Famewok WS-Reliability 11 OASIS OASIS-Standad WS-Reliability is a SOAP-based potocol fo exchanging SOAP messages with guaanteed delivey, no duplicates, and guaanteed message odeing WS-Reliability is defined as SOAP heade extensions and is independent of the undelying potocol This specification contains a binding to HTTP WS-BaseNotification 13 OASIS OASIS-Standad WS-BaseNotification standadizes the teminology, concepts, opeations, WSDL and ML needed to expess the basic oles involved in Web sevices publish and subscibe fo notification message exchange Management Specifications Secuity Specifications WS-Secuity 11 OASIS OASIS-Standad WS-Secuity is a communications potocol poviding a means fo applying secuity to Web Sevices WS-Secuity: SOAP Message Secuity 11 OASIS Public Review Daft WS-Secuity: SOAP Message Secuity descibes enhancements to SOAP messaging to povide message integity and confidentiality Specifically, this specification povides suppot fo multiple secuity token fomats, tust domains, signatue fomats and encyption technologies The token fomats and semantics fo using these ae defined in the associated pofile documents WS-Secuity: Kebeos Binding 10 Micosoft, IBM, OASIS Woking Daft WS-Secuity: SAML Token Pofile 11 OASIS Public Review Daft WS-Secuity: SAML Token Pofile defines the use of Secuity Assetion Makup Language (SAML) v11 assetions in the context of WSS: SOAP Message Secuity including fo the pupose of secuing SOAP messages and SOAP message exchanges WS-Secuity: 509 Cetificate Token Pofile 11 OASIS Public Review Daft Management Using Web Sevices (WSDM-MUWS) 10 OASIS OASIS-Standad Web Sevice Distibuted Management: Management Using Web Sevices (WSDM-MUWS) defines how an IT esouce connected to a netwok povides manageability intefaces such that the IT esouce can be managed locally and fom emote locations using Web sevices technologies Sevice Modeling Language IBM, BEA, BMC, Cisco, Dell, HP, Intel, Micosoft, Sun Daft Specification Sevcie Modeling Language (SML) is used to model complex IT sevices and systems, including thei stuctue, constaints, policies, and best pactices WS-Secuity: Kebeos Binding defines how to encode Kebeos tickets and attach them to SOAP messages As well, it specifies how to add signatues and encyption to the SOAP message, in accodance with WS-Secuity, which uses and efeences the Kebeos tokens WS-Secuity: 509 Cetificate Token Pofile descibes the use of the 509 authentication famewok with the WS-Secuity: SOAP Message Secuity specification WS-Eventing W3C Public Daft WS-Addessing WSDL Binding 10 W3C Candidate Recommendation WS-SecuityPolicy 11 IBM, Micosoft, RSA Secuity, VeiSign Public Daft WS-SecuityPolicy defines how to descibe policies elated to vaious featues defined in the WS-Secuity specification WS-Secuity: Usename Token Pofile 11 OASIS Public Review Daft WS-Secuity: Usename Token Pofile descibes how a Web Sevice consume can supply a Usename Token as a means of identifying the equesto by usename, and optionally using a passwod (o shaed secet, etc) to authenticate that identity to the Web Sevice poduce WS-Fedeation 10 IBM, Micosoft, BEA Systems, RSA Secuity, and VeiSign Initial Daft WS-Fedeation descibes how to manage and boke the tust elationships in a heteogeneous fedeated envionment including suppot fo fedeated identities WS-Tust BEA Systems, Compute Associates, IBM, Laye 7 Technologies, Micosoft, Netegity, Oblix, OpenNetwok, Ping Identity Copoation, Reactivity, RSA Secuity, VeiSign and Westbidge Technology Initial Daft WS-SecueConvesation BEA Systems, Compute Associates, IBM, Laye 7 Technologies, Micosoft, Netegity, Oblix, OpenNetwok, Ping Identity Copoation, Reactivity, RSA Secuity, VeiSign and Westbidge Technology Public Daft WS-SecueConvesation specifies how to manage and authenticate message exchanges between paties including secuity context exchange and establishing and deiving session keys Management Of Web Sevices (WSDM-MOWS) 10 OASIS OASIS-Standad Web Sevice Distibuted Management: Management Of Web Sevices (WSDM-MOWS) addesses management of the components that fom the netwok, the Web sevices endpoints, using Web sevices potocols WS-Tust descibes a famewok fo tust models that enables Web Sevices to secuely inteopeate It uses WS-Secuity base mechanisms and defines additional pimitives and extensions fo secuity token exchange to enable the issuance and dissemination of cedentials within diffeent tust domains WS-Eventing defines a baseline set of opeations that allow Web sevices to povide asynchonous notifications to inteested paties WS-Addessing WSDL Binding defines how the abstact popeties defined in Web Sevices Addessing Coe ae descibed using WSDL WS-Addessing Coe 10 W3C Recommendation WS-Addessing SOAP Binding 10 W3C Recommendation WS-Management AMD, Dell, Intel, Micosoft and Sun Micosystems Published Specification WS-Management descibes a geneal SOAP-based potocol fo managing systems such as PCs, seves, devices, Web sevices and othe applications, and othe manageable entities Tansaction Specifications WS-Coodination 11 OASIS Woking Daft WS-Coodination descibes an extensible famewok fo poviding potocols that coodinate the actions of distibuted applications WS-Business Activity 11 OASIS Woking Daft WS-Business Activity povides the definition of the business activity coodination type that is to be used with the extensible coodination famewok descibed in the WS-Coodination specification WS-Atomic Tansaction 11 OASIS Committee Daft WS-Atomic Tansaction defines potocols that enable existing tansaction pocessing systems to wap thei popietay potocols and inteopeate acoss diffeent hadwae and softwae vendos WS-Composite Application Famewok (WS-CAF) 10 Ajuna Technologies, Fujitsu, IONA, Oacle and Sun Micosystems Committee Specification WS-Composite Application Famewok (WS-CAF) is a collection of thee specifications aimed at solving poblems that aise when multiple Web Sevices ae used in combination It poposes standad, inteopeable mechanisms fo managing shaed context and ensuing business pocesses achieve pedictable esults and ecovey fom failue WS-Context (WS-CT) 10 Ajuna Technologies, Fujitsu, IONA, Oacle and Sun Micosystems Committee Daft WS-Context (WS-CT) is intended as a lightweight mechanism fo allowing multiple Web Sevices to shae a common context WS-Coodination Famewok (WS-CF) 10 Ajuna Technologies, Fujitsu, IONA, Oacle and Sun Micosystems Committee Daft WS-Coodination Famewok (WS-CF) allows the management and coodination in a Web Sevices inteaction of a numbe of activities elated to an oveall application WS-Tansaction Management (WS-TM) 10 Ajuna Technologies, Fujitsu, IONA, Oacle and Sun Micosystems Committee Daft WS-Tansaction Management (WS-TM) defines a coe infastuctue sevice consisting of a Tansaction Sevice fo Web Sevices WS-Addessing Coe povides tanspot-neutal mechanisms to addess Web sevices and messages This specification defines ML elements to identify Web sevice endpoints and to secue end-to-end endpoint identification in messages WS-Addessing SOAP Binding povides tanspotneutal mechanisms to addess Web sevices and messages SOAP SOAP 12 W3C Recommendation SOAP 11 W3C Note Pesentation Specifications Web Sevices fo Remote Potlets (WSRP) 20 OASIS Committee Daft Web Sevices fo Remote Potlets (WSRP) defines a set of intefaces and elated semantics which standadize inteactions with components poviding use-facing makup, including the pocessing of use inteactions with that makup Resouce Specifications SOAP Message Tansmission Optimization Mechanism (MTOM) 10 W3C Recommendation SOAP is a lightweight, ML-based potocol fo exchange of infomation in a decentalized, distibuted envionment Web Sevices Resouce Famewok (WSRF) 12 OASIS OASIS-Standad Web Sevices Resouce Famewok (WSRF) defines a family of specifications fo accessing stateful esouces using Web Sevices WS-BaseFaults (WSRF) 12 OASIS Woking Daft WS-BaseFaults (WSRF) defines a base set of infomation that may appea in fault messages WS-BaseFaults defines an ML schema type fo base faults, along with ules fo how this base fault type is used and extended by Web Sevices WS-SeviceGoup (WSRF) 12 OASIS Woking Daft WS-SeviceGoup (WSRF) defines a means by which Web Sevices and WS-Resouces can be aggegated o gouped togethe fo a domain specific pupose WS-ResoucePopeties 12 OASIS Woking Daft WS-ResoucePopeties specifies the means by which the definition of the popeties of a WS-Resouce may be declaed as pat of the Web Sevice inteface The declaation of the WS-Resouce popeties epesents a pojection of o a view on the WS-Resouce state WS-ResouceLifetime 12 OASIS Woking Daft WS-ResouceLifetime is to standadize the teminology, concepts, message exchanges, WSDL and ML needed to monito the lifetime of, and destoy WS-Resouces Additionally, it defines esouce popeties that may be used to inspect and monito the lifetime of a WS-Resouce WS-Tansfe W3C W3C Membe Submission WS-Tansfe descibes a geneal SOAP-based potocol fo accessing ML epesentations of Web sevice-based esouces Resouce Repesentation SOAP Heade Block (RRSHB) W3C Recommendation Resouce Repesentation SOAP Heade Block (RRSHB) complements MTOM by defining mechanisms fo descibing and conveying non-ml esouce epesentations in a SOAP 12 message SOAP Message Tansmission Optimization Mechanism descibes an abstact featue fo optimizing the tansmission and/o wie fomat of a SOAP message Dependencies Messaging Specifications SOAP 11 SOAP 12 SOAP Message Tansmission Optimization Mechanism WS-Notification WS-BaseNotification WS-Topics WS-BokeedNotification WS-Addessing Coe WS-Addessing WSDL Binding WS-Addessing SOAP Binding WS-Eventing WS-Enumeation Metadata Specifications WS-Policy WS-PolicyAssetions WS-PolicyAttachment WS-Discovey WS-MetadataExchange Univesal Desciption, Discovey and Integation Web Sevice Desciption Language 11 Web Sevice Desciption Language 20 Coe Web Sevice Desciption Language 20 SOAP Binding Secuity Specifications WS-Secuity WS-Secuity: SOAP Message Secuity WS-Secuity: Kebeos Binding WS-Secuity: SAML Token Pofile WS-Secuity: 509 Cetificate Token Pofile WS-Secuity: Usename Token Pofile WS-SecuityPolicy WS-Tust WS-Fedeation WS-SecueConvesation Reliability Specifications WS-ReliableMessaging WS-Reliability WS-Reliable Messaging Policy Assetion Resouce Specifications Web Sevice Resouce Famewok WS-BaseFaults WS-SeviceGoup WS-ResoucePopeties WS-ResouceLifetime WS-Tansfe Resouce Repesentation SOAP Heade Block (RRSHB) Management Specifications WS-Management Management Of Web Sevices Management Using Web Sevices Sevice Modeling Language Business Pocess Specifications Business Pocess Execution Language fo Web Sevices Web Sevice Choeogaphy Desciption Language Web Sevice Choeogaphy Inteface WS-Choeogaphy Model Oveview Business Pocess Management Language Business Pocess Execution Language fo Web Sev 20 ML Pocess Definition Language Tansaction Specifications WS-Business Activity WS-Atomic Tansaction WS-Coodination WS-Composite Application Famewok WS-Tansaction Management WS-Context WS-Coodination Famewok Pesentation Specifications Web Sevices fo Remote Potlets Tansaction Tansaction Basic Pofile Reliability Resouce Secuity Secuity Messaging Secuity Secuity Messaging Metadata Metadata Messaging Metadata Resouce Meta Secuity Messaging Reliability Metadata Secuity Reliability Messaging Messaging Secuity Tansaction Reliab Secu Mess innoq Deutschland GmbH All Rights Reseved The poste may also contain efeences to othe company, oganisation, band and poduct names These company, oganisation, band and poduct names ae used heein fo identification puposes only and may be the tademaks of thei espective ownes This poste is not to be epoduced o tansmitted in any fom o fo any pupose without the expess pemission of innoq Deutschland GmbH Copyight Vesion 30 Febuay 2007 The Oganization fo the Advancement of Stuctued Infomation Standads (OASIS) is a not-fo-pofit, intenational consotium that dives the development, convegence, and adoption of e-business standads The consotium poduces moe Web sevices standads than any othe oganization along with standads fo secuity, e-business, and standadization effots in the public secto and fo application-specific makets Founded in 1993, OASIS has moe than 4,000 paticipants epesenting ove 600 oganizations and individual membes in 100 counties The Wold Wide Web Consotium (W3C) was ceated in Octobe 1994 to lead the Wold Wide Web to its full potential by developing common potocols that pomote its evolution and ensue its inteopeability W3C has ove 350 Membe oganizations fom all ove the wold and has eaned intenational ecognition fo its contibutions to the gowth of the Web W3C is designing the infastuctue, and defining the achitectue and the coe technologies fo Web sevices In Septembe 2000, W3C stated the ML Potocol Activity to addess the need fo an ML-based potocol fo application-to-application messaging In Januay 2002, the Web Sevices Activity was launched, subsuming the ML Potocol Activity and extending its scope The Web Sevices Inteopeability Oganization (WS-I) is an open industy oganization chateed to pomote Web sevices inteopeability acoss platfoms, opeating systems and pogamming languages The oganization s divese community of Web sevices leades helps customes to develop inteopeable Web sevices by poviding guidance, ecommended pactices and suppoting esouces Specifically, WS-I ceates, pomotes and suppots geneic potocols fo the inteopeable exchange of messages between Web sevices The Intenet Engineeing Task Foce (IETF) is a lage open intenational community of netwok designes, opeatos, vendos, and eseaches concened with the evolution of the Intenet achitectue and the smooth opeation of the Intenet ML Specifications ML W3C Recommendation ML Extensible Makup Language is a paed-down vesion of SGML, designed especially fo Web documents It allows one to ceate own customized tags, enabling the definition, tansmission, validation, and intepetation of data between applications and between oganizations ML W3C Recommendation ML Extensible Makup Language is a paed-down vesion of SGML, designed especially fo Web documents It allows one to ceate own customized tags, enabling the definition, tansmission, validation, and intepetation of data between applications and between oganizations Namespaces in ML 11 W3C Recommendation Namespaces in ML povides a simple method fo qualifying element and attibute names used in ML documents by associating them with namespaces identified by IRI efeences ML Infomation Set 10 W3C Recommendation ML Infomation Set is an abstact data set to povide a consistent set of definitions fo use in othe specifications that need to efe to the infomation in a well-fomed ML document ML Schema 11 W3C Woking Daft ML Schema ML Schema Definition Language is an ML language fo descibing and constaining the content of ML documents ML binay Optimized Packaging (OP) 10 W3C Recommendation ML binay Optimized Packaging (OP) is an ML language fo descibing and constaining the content of ML documents Descibing Media Content of Binay Data in ML (DMCBD) W3C Note Descibing Media Content of Binay Data in ML (DMCBD) specifies how to indicate the content-type associated with binay element content in an ML document and to specify, in ML Schema, the expected content-type(s) associated with binay element content innoq Deutschland GmbH innoq Schweiz GmbH Halskestaße 17 Gewebestasse 11 D Ratingen CH-6330 Cham Phone Phone info@innoqcom wwwinnoqcom 10

11 Bith of BPEL IBM was pushing fo a standad called WSFL Micosoft was pushing fo a technology called LANG Intalio was pushing fo BPML IBM and Micosoft meged thei effots and pushed togethe fo BPEL (a hybid WSFL+LANG) and BPEL was soon widely adopted 11

12 Life of BPEL BPEL4WS 10 (2002) by BEA, IBM, Micosoft SAP + Siebel joined the effot BPEL 11 (2003) submitted to OASIS Adobe + HP + NEC + Oacle + Sun + many moe joined WS-BPEL 20 (2005) 12

13 The poblem with BPEL BPEL is not a gaphical language BPEL is an ML dialect Machines like ML Humans being should not like ML 13

14 A typical BPEL tutoial Tun to page 4 of any BPEL tutoial (the fist couple of pages ae just a vebal intoduction) and you find the fist small example of about two pages of fomatted ML code (with all actual namespaces to avoid any misundestanding) 14

15 BPELexamplexml Page 1 of 2 BPELexamplexml Page 2 1!! ! 9! 10! 11! ! ! 24!! ! !! <pocess name="puchaseodepocess" tagetnamespace=" puchase" xmlns=" xmlns:lns=" <documentation xml:lang="en"> A simple example of a WS-BPEL pocess fo handling a puchase ode </documentation> <patnelinks> <patnelink name="puchasing" patnelinktype="lns:puchasinglt" myrole="puchasesevice" /> <patnelink name="invoicing" patnelinktype="lns:invoicinglt" myrole="invoicerequeste" patnerole="invoicesevice" /> <patnelink name="shipping" patnelinktype="lns:shippinglt" myrole="shippingrequeste" patnerole="shippingsevice" /> <patnelink name="scheduling" patnelinktype="lns:schedulinglt" patnerole="schedulingsevice" /> </patnelinks> <vaiables> <vaiable name="po" messagetype="lns:pomessage" /> <vaiable name="invoice" messagetype="lns:invmessage" /> <vaiable name="shippingrequest" messagetype="lns:shippingrequestmessage" /> <vaiable name="shippinginfo" messagetype="lns:shippinginfomessage" /> <vaiable name="shippingschedule" messagetype="lns:schedulemessage" /> </vaiables> <faulthandles> <catch faultname="lns:cannotcompleteode" faultvaiable="pofault" faultmessagetype="lns:odefaulttype"> <eply patnelink="puchasing" pottype="lns:puchaseodept" opeation="sendpuchaseode" vaiable="pofault" faultname="cannotcompleteode" /> </catch> </faulthandles> <sequence> <eceive patnelink="puchasing" pottype="lns:puchaseodept" opeation="sendpuchaseode" vaiable="po" ceateinstance="yes"> <documentation>receive Puchase Ode</documentation> </eceive> <flow> <documentation> A paallel flow to handle shipping, invoicing and scheduling </documentation> <links> <link name="ship-to-invoice" /> <link name="ship-to-scheduling" /> </links> <sequence> <assign> <copy> <fom>$pocustomeinfo</fom> <to>$shippingrequestcustomeinfo</to> </copy> </assign> <invoke patnelink="shipping" pottype="lns:shippingpt" 15 48!! ! ! ! ! ! ! ! opeation="equestshipping" inputvaiable="shippingrequest" outputvaiable="shippinginfo"> <documentation>decide On Shippe</documentation> <souces> <souce linkname="ship-to-invoice" /> </souces> </invoke> <eceive patnelink="shipping" pottype="lns:shippingcallbackpt" opeation="sendschedule" vaiable="shippingschedule"> <documentation>aange Logistics</documentation> <souces> <souce linkname="ship-to-scheduling" /> </souces> </eceive> </sequence> <sequence> <invoke patnelink="invoicing" pottype="lns:computepicept" opeation="initiatepicecalculation" inputvaiable="po"> <documentation> Initial Pice Calculation </documentation> </invoke> <invoke patnelink="invoicing" pottype="lns:computepicept" opeation="sendshippingpice" inputvaiable="shippinginfo"> <documentation> Complete Pice Calculation </documentation> <tagets> <taget linkname="ship-to-invoice" /> </tagets> </invoke> <eceive patnelink="invoicing" pottype="lns:invoicecallbackpt" opeation="sendinvoice" vaiable="invoice" /> </sequence> <sequence> <invoke patnelink="scheduling" pottype="lns:schedulingpt" opeation="equestpoductionscheduling" inputvaiable="po"> <documentation> Initiate Poduction Scheduling </documentation> </invoke> <invoke patnelink="scheduling" pottype="lns:schedulingpt" opeation="sendshippingschedule" inputvaiable="shippingschedule"> <documentation> Complete Poduction Scheduling </documentation> <tagets> <taget linkname="ship-to-scheduling" /> </tagets> </invoke> </sequence> </flow> <eply patnelink="puchasing" pottype="lns:puchaseodept" opeation="sendpuchaseode" vaiable="invoice"> <documentation>invoice Pocessing</documentation> </eply> </sequence> </pocess>

16 A syntax called semantics Leaning BPEL by looking at ML documents is like leaning Peti nets by looking at PNML documents o simila to leaning Java by looking at the bytecode 16

17 1 <?xml vesion="10" encoding="utf-8"?><pnml> 78 <tansition id="t3"> 2 <net type=" id="noid"> 79 <name> 3 <place id="p6"> 80 <text>t3</text> 4 <name> 81 <gaphics> 5 <text>p6</text> 82 <offset x="240" y="320"/> 6 <gaphics> 83 </gaphics> 7 <offset x="430" y="270"/> 84 </name> 8 </gaphics> 85 <gaphics> 9 </name> 86 <position x="240" y="280"/> 10 <gaphics> 87 <dimension x="40" y="40"/> 11 <position x="430" y="230"/> 88 </gaphics> 12 <dimension x="40" y="40"/> 89 <toolspecific tool="woped" vesion="10"> 13 </gaphics> 90 <time>0</time> 14 </place> 91 <timeunit>1</timeunit> 15 <place id="p5"> 92 <oientation>1</oientation> 16 <name> 93 </toolspecific> 17 <text>p5</text> 94 </tansition> 18 <gaphics> 95 <tansition id="t2"> 19 <offset x="300" y="320"/> 96 <name> 20 </gaphics> 97 <text>t2</text> 21 </name> 98 <gaphics> 22 <gaphics> 99 <offset x="240" y="220"/> 23 <position x="300" y="280"/> 100 </gaphics> 24 <dimension x="40" y="40"/> 101 </name> 25 </gaphics> 102 <gaphics> 26 </place> 103 <position x="240" y="180"/> 27 <place id="p4"> 104 <dimension x="40" y="40"/> 28 <name> 105 </gaphics> 29 <text>p4</text> 106 <toolspecific tool="woped" vesion="10"> 30 <gaphics> 107 <time>0</time> 31 <offset x="180" y="320"/> 108 <timeunit>1</timeunit> 32 </gaphics> 109 <oientation>1</oientation> 33 </name> 110 </toolspecific> 34 <gaphics> 111 </tansition> 35 <position x="180" y="280"/> 112 <tansition id="t1"> 36 <dimension x="40" y="40"/> 113 <name> 37 </gaphics> 114 <text>t1</text> 38 </place> 115 <gaphics> 39 <place id="p3"> 116 <offset x="120" y="270"/> 40 <name> 117 </gaphics> 41 <text>p3</text> 118 </name> 42 <gaphics> 119 <gaphics> 43 <offset x="300" y="220"/> 120 <position x="120" y="230"/> 44 </gaphics> 121 <dimension x="40" y="40"/> 45 </name> 122 </gaphics> 46 <gaphics> 123 <toolspecific tool="woped" vesion="10"> 47 <position x="300" y="180"/> 124 <time>0</time> 48 <dimension x="40" y="40"/> 125 <timeunit>1</timeunit> 49 </gaphics> 126 <oientation>1</oientation> 50 </place> 127 </toolspecific> 51 <place id="p2"> 128 </tansition> 52 <name> 129 <tansition id="t4"> 53 <text>p2</text> 130 <name> 54 <gaphics> 131 <text>t4</text> 55 <offset x="180" y="220"/> 132 <gaphics> 56 </gaphics> 133 <offset x="360" y="270"/> 57 </name> 134 </gaphics> 58 <gaphics> 135 </name> 59 <position x="180" y="180"/> 136 <gaphics> 60 <dimension x="40" y="40"/> 137 <position x="360" y="230"/> 61 </gaphics> 138 <dimension x="40" y="40"/> 62 </place> 139 </gaphics> 63 <place id="p1"> 140 <toolspecific tool="woped" vesion="10"> 64 <name> 141 <time>0</time> 65 <text>p1</text> 142 <timeunit>1</timeunit> 66 <gaphics> 143 <oientation>1</oientation> 67 <offset x="40" y="270"/> 144 </toolspecific> 68 </gaphics> 145 </tansition> 69 </name> 146 <tansition id="t5"> 70 <gaphics> 147 <name> 71 <position x="40" y="230"/> 148 <text>t5</text> 72 <dimension x="40" y="40"/> 149 <gaphics> 73 </gaphics> 150 <offset x="240" y="150"/> 74 <initialmaking> 151 </gaphics> 75 <text>1</text> 152 </name> 76 </initialmaking> 153 <gaphics> 77 </place> 154 <position x="240" y="110"/> PNMLnetxml Page 3 of 4 PNMLnetxml 155 <dimension x="40" y="40"/> 232 </insciption> 156 </gaphics> 233 <gaphics/> 157 <toolspecific tool="woped" vesion="10"> 234 <toolspecific tool="woped" vesion="10"> 158 <time>0</time> 235 <pobability>10</pobability> 159 <timeunit>1</timeunit> 236 <displaypobabilityon>false</displaypobabilityon> 160 <oientation>1</oientation> 237 <displaypobabilityposition x="5000" y="00"/> 161 </toolspecific> 238 </toolspecific> 162 </tansition> 239 </ac> 163 <ac id="a9" souce="t1" taget="p4"> 240 <ac id="a1" souce="p1" taget="t1"> 164 <insciption> 241 <insciption> 165 <text>1</text> 242 <text>1</text> 166 </insciption> 243 </insciption> 167 <gaphics/> 244 <gaphics/> 168 <toolspecific tool="woped" vesion="10"> 245 <toolspecific tool="woped" vesion="10"> 169 <pobability>10</pobability> 246 <pobability>10</pobability> 170 <displaypobabilityon>false</displaypobabilityon> 247 <displaypobabilityon>false</displaypobabilityon> 171 <displaypobabilityposition x="5000" y="00"/> 248 <displaypobabilityposition x="5000" y="00"/> 172 </toolspecific> 249 </toolspecific> 173 </ac> 250 </ac> 174 <ac id="a17" souce="p3" taget="t4"> 251 <ac id="a2" souce="t1" taget="p2"> 175 <insciption> 252 <insciption> 176 <text>1</text> 253 <text>1</text> 177 </insciption> 254 </insciption> 178 <gaphics/> 255 <gaphics/> 179 <toolspecific tool="woped" vesion="10"> 256 <toolspecific tool="woped" vesion="10"> 180 <pobability>10</pobability> 257 <pobability>10</pobability> 181 <displaypobabilityon>false</displaypobabilityon> 258 <displaypobabilityon>false</displaypobabilityon> 182 <displaypobabilityposition x="5000" y="00"/> 259 <displaypobabilityposition x="5000" y="00"/> 183 </toolspecific> 260 </toolspecific> 184 </ac> 261 </ac> 185 <ac id="a14" souce="p5" taget="t4"> 262 <ac id="a5" souce="p2" taget="t2"> 186 <insciption> 263 <insciption> 187 <text>1</text> 264 <text>1</text> 188 </insciption> 265 </insciption> 189 <gaphics/> 266 <gaphics/> 190 <toolspecific tool="woped" vesion="10"> 267 <toolspecific tool="woped" vesion="10"> 191 <pobability>10</pobability> 268 <pobability>10</pobability> 192 <displaypobabilityon>false</displaypobabilityon> 269 <displaypobabilityon>false</displaypobabilityon> 193 <displaypobabilityposition x="5000" y="00"/> 270 <displaypobabilityposition x="5000" y="00"/> 194 </toolspecific> 271 </toolspecific> 195 </ac> 272 </ac> 196 <ac id="a21" souce="p3" taget="t5"> 273 <ac id="a6" souce="t2" taget="p3"> 197 <insciption> 274 <insciption> 198 <text>1</text> 275 <text>1</text> 199 </insciption> 276 </insciption> 200 <gaphics/> 277 <gaphics/> 201 <toolspecific tool="woped" vesion="10"> 278 <toolspecific tool="woped" vesion="10"> 202 <pobability>10</pobability> 279 <pobability>10</pobability> 203 <displaypobabilityon>false</displaypobabilityon> 280 <displaypobabilityon>false</displaypobabilityon> 204 <displaypobabilityposition x="5000" y="00"/> 281 <displaypobabilityposition x="5000" y="00"/> 205 </toolspecific> 282 </toolspecific> 206 </ac> 283 </ac> 207 <ac id="a13" souce="t3" taget="p5"> 284 <ac id="a18" souce="t4" taget="p6"> 208 <insciption> 285 <insciption> 209 <text>1</text> 286 <text>1</text> 210 </insciption> 287 </insciption> 211 <gaphics/> 288 <gaphics/> 212 <toolspecific tool="woped" vesion="10"> 289 <toolspecific tool="woped" vesion="10"> 213 <pobability>10</pobability> 290 <pobability>10</pobability> 214 <displaypobabilityon>false</displaypobabilityon> 291 <displaypobabilityon>false</displaypobabilityon> 215 <displaypobabilityposition x="5000" y="00"/> 292 <displaypobabilityposition x="5000" y="00"/> 216 </toolspecific> 293 </toolspecific> 217 </ac> 294 </ac> 218 <ac id="a10" souce="p4" taget="t3"> 295 <toolspecific tool="woped" vesion="10"> 219 <insciption> 296 <bounds> 220 <text>1</text> 297 <position x="11" y="33"/> 221 </insciption> 298 <dimension x="755" y="490"/> 222 <gaphics/> 299 </bounds> 223 <toolspecific tool="woped" vesion="10"> 300 <teewidth>2</teewidth> 224 <pobability>10</pobability> 301 <veticallayout>false</veticallayout> 225 <displaypobabilityon>false</displaypobabilityon> 302 <esouces/> <displaypobabilityposition x="5000" y="00"/> </toolspecific> </ac> <ac id="a24" souce="t5" taget="p2"> <insciption> <simulations/> <patnelinks/> <vaiables/> </toolspecific> </net> 231 <text>1</text> </pnml>

18 A matte of abstaction ML SOAP WSDL UDDI A technology should not become THE model (though it can seve as a souce of inspiation) this way of thinking can have a bad impact sevice in the nea futue (in taining technical pesonnel) inteact equeste publish discove <opeation name = "CheckAvailability"> < input message = "CheckInDate"/> < input message = "CheckOutDate"/> < input message = "NRooms"/> <output message = "Result"/> </opeation> UDDI egisty 18

19 The souce of the poblem BPEL is designed to wok with WSDL documents of the sevices equied by the pocess A pocess can itself be exposed as a sevice which needs its own WSDL document Fo us: we can foget that WSDL documents ae witten in ML we egad them as abstact inteface desciptions 19

20 BPEL guidelines 20

21 Stuctued contol vs fee flow BPEL4WS should povide both hieachical and gaph-like contol egimes, and allow thei usage to be blended as seamlessly as possible 21

22 About data handling BPEL4WS povides limited data manipulation functions that ae sufficient fo the simple manipulation of data that is needed to define pocess elevant data and contol flow 22

23 Coelation BPEL4WS should suppot an identification mechanism fo pocess instances that allows the definition of instance identifies at the application message level Instance identifies should be patne defined and may change ove time 23

24 Abstact vs executable BPEL4WS should define a set of Web sevice ochestation concepts that ae meant to be used in common by both the extenal (abstact) and intenal (executable) views of a business pocess Such a business pocess defines the behavio of a single autonomous entity, typically opeating in inteaction with othe simila pee entities It is ecognized that each usage view will equie a few specialized extensions, but these extensions ae to be kept to a minimum and tested against equiements 24

25 Tansactions BPEL4WS should define a long-unning tansaction model that is based on pactically poven techniques like compensation actions and scoping to suppot failue ecovey fo pats of long-unning business pocesses 25

26 WSDL peliminaies 26

27 Sevice A sevice can be thought of as a containe fo a set of (logically elated) opeations that ae made available via web-based potocols Roughly: a emote object 27

28 PotType / Inteface The <pottype> element, enamed to <inteface> in WSDL 20, defines a web sevice, the opeations that can be pefomed, and the messages that ae used to pefom the opeation Roughly: the type of a emote object ie, a emote (abstact) class 28

29 Opeation Each opeation can be thought of as a method o function call in some pogamming language Fou kinds of opeations (one-way, equest-esponse, notification, solicit-esponse) Thee kinds of paametes/aguments (input, output, fault) (not all combinations allowed) Roughly: a emote (abstact) method 29

30 Pot / Endpoint The <pot> element, enamed to <endpoint> in WSDL 20, declaes the addess of a web sevice It typicaily involves a name, a binding and a URL 30

31 Binding The binding specifies the inteface as well as the SOAP binding style (message fomat) and SOAP tanspot potocol 31

32 WSDL (fom wikipedia) 32

33 PuchaseExamplewsdl Page 1 of 2 PuchaseExamplewsdl Page 2 of 1 2 3! 4! 5! ! 11! ! 15! ! <?xml vesion="10" encoding="utf-8"?> <wsdl:definitions name="puchaseexample" tagetnamespace=" sams/puchaseexamplewsdl" xmlns:tns=" PuchaseExamplewsdl" xmlns:soap=" soap/" xmlns:wsdl=" <wsdl:types> <xsd:schema tagetnamespace=" wwwfluidimaginationcom/sams/poducttypewsdl" xmlns:xsd=" MLSchema"> <xsd:complextype name="scannetype"> <xsd:all> <xsd:element name="upc" type="upctype"/> <xsd:element name="isbn" type="isbntype"/> </xsd:all> </xsd:complextype> <xsd:simpletype name="upctype"> <xsd:estiction base="xsd:sting"> <xsd:patten value="[0-9]{12}"/> </xsd:estiction> </xsd:simpletype> <xsd:simpletype name="isbntype"> <xsd:estiction base="xsd:sting"> <xsd:patten value="([0-9]- ){10}"/> </xsd:estiction> </xsd:simpletype> </xsd:schema> </wsdl:types> <!-- Adding a message that has two addesses --> <wsdl:message name="puchasemessage"> <wsdl:pat name="poductcode" element="tns:scannetype"/> </wsdl:message> <!--ceate a pot type with one opeation --> ! 42 43! ! 52 53! <wsdl:pottype name="puchasetype"> <wsdl:opeation name="puchaseopeation"> <wsdl:input name="tns:puchasemessage"/> </wsdl:opeation> </wsdl:pottype> <!--Bind the message to SOAP using HTTP --> <wsdl:binding name="puchasebinding" type="tns:puchasetype"> <soap:binding style="document" tanspot=" http"/> <wsdl:opeation name="tns:puchaseopeation"> <wsdl:input> <soap:body use="liteal"/> </wsdl:input> </wsdl:opeation> </wsdl:binding> <!--Bind the message to SOAP ove SMTP --> <wsdl:binding name="puchasebindingsmtp" type="tns:puchasetype"> <soap:binding style="document" tanspot=" smtp"/> <wsdl:opeation name="tns:puchaseopeation"> <wsdl:input> <soap:body use="liteal"/> </wsdl:input> </wsdl:opeation> </wsdl:binding> </wsdl:definitions> 33

34 BPEL ingedients (mateial patly stolen fom Antonio Bogi s slides on Softwae Sevices, thanks!) 34

35 BPEL ingedients Data flow (scoped vaiables) Patne links and Message coelation Message flow (one-way, equest-esponse, notify, solicit-esponse) Contol flow (stuctued activities and synchonization links) Handling events, faults, compensations 35

36 Vaiable Vaiables can be defined (within a local scope) The activity <assign> can be used to copy data (messages, pat of messages, sevice efeences) between vaiables <assign> <copy> <fom vaiable="po" pat="customeinfo"/> <to vaiable="shippingrequest" pat="customeinfo"/> </copy> </assign> 36

37 Patne Link A patne is a sevice that the pocess invokes, o a client that invokes the pocess A BPEL pocess inteacts with a patne using a <patnelink> a (typed) connecto that the pocess offes to/equies fom its patne (to be declaed in the BPEL document) <patnelinks> <patnelink name="shipping" patnelinktype="lns:shippinglt" myrole="shippingrequeste" patnerole="shippingsevice"/> </patnelinks> 37

38 Stateless sevices, stateful pocesses When a message fo (WS-BPEL) sevice aives, it must be deliveed eithe to a new o to an existing instance of the pocess Stateful business pocesses ae instantiated to act accoding to inteaction histoy Messages should not only be deliveed to the coect pot, but also to the coect instance of the business pocess that povides that pot 38

39 Message coelation Message coelation is the way to tie togethe messages coming fom diffeent communications A coelation set is a set of popeties such that all messages having the same values of all popeties ae pat of the same inteaction The patne that fist fixes the values of the popeties in the coelation set is the initiato of the exchange, the othe patnes ae called the followes 39

40 Message flow Basic activities ae available to send and eceive messages to patnes Activity <invoke>: asynchonous (one-way) o synchonous (equest-esponse) Activity <eceive>: a equest fom a patne to execute one of the (WSDL) opeations implemented by the pocess Activity <eply>: to etun the esult of a <eceive>d synchonous equest-esponse opeation 40

41 Invoke Needed infomation: the <patnelink>, the WSDL <pottype> of the sevice to be invoked, and the name and paametes of the <opeation> <invoke patnelink="shipping" pottype="lns:shippingpt" opeation="equestshipping" inputvaiable="shippingrequest" outputvaiable="shippinginfo"> <souce linkname="ship-to-invoice"/> </invoke> 41

42 Receive Needed infomation: the <patnelink>, the WSDL <pottype> of the exposed sevice, and a <vaiable> whee to copy the paametes of the <opeation> <eceive patnelink="puchasing" pottype="lns:puchaseodept" opeation="sendpuchaseode" vaiable="po"> </eceive> 42

43 Reply A pocess can <eply> to a message it <eceive>d <eply patnelink="puchasing" pottype="lns:puchaseodept" opeation="sendpuchaseode" vaiable="invoice" /> Asynchonous opeations do not use <eply> If a eply must sent, <invoke> is used to call back a client opeation 43

44 44

45 Stuctued activities <sequence> fo specifying sequential compositions only one banch is selected <switch> fo (local) intenal choices (odeed list of conditional <case> banches, possibly ended by an <othewise> banch) <pick> fo (global) extenal choices (set of event handles of the fom event activity, <onmessage> aival of a message o <onalam> time) <flow> fo paallel composition <while> fo iteations (guads ae Path expessions) 45

46 Link A <link> expesses synchonisation dependencies among activities in a pocess Each <link> has a name, one souce activity, one taget activity, and it may be associated with a tansition condition (a pedicate to be evaluated when the souce activity ends) 46

47 Join condition Any activity that is the taget of one o moe links may have an explicit <joincondition>, (a pedicate on the status values of the incoming links, to be evaluated once all such values have been detemined) othewise the implicit join condition is the OR If the <joincondition> evaluates to: TRUE the activity can be executed, FALSE a <joinfailue> fault may be thown (depending on the <suppessjoinfailue> flag 47

48 Scope A scope povides fault and compensation handling capabilities to the activities nested within it A <scope> activity consists of: a pimay activity, a set of (optional) fault handles, a single (optional) compensation handles, a set of (optional) event handles (executed concuently with the pocess, they enable a scope to eact to messages and alam events) 48

49 Fomal Semantics and Analysis of Contol Flow in WS-BPEL (Revised Vesion) Chun Ouyang 1, Eic Vebeek 2, Wil MP van de Aalst 2,1, Stephen Beutel 1, Malon Dumas 1, and Athu HM te Hofstede 1 1 Faculty of Infomation Technology, Queensland Univesity of Technology, GPO Box 2434, Bisbane QLD 4001, Austalia {couyang,swbeutel,mdumas,atehofstede}@quteduau 2 Depatment of Technology Management, Eindhoven Univesity of Technology, GPO Box 513, NL-5600 MB, The Nethelands {hmwvebeek,wmpvdaalst}@tmtuenl Fomal semantics of Abstact Web sevice composition efes to the ceation of new (Web) sevices by combination of functionality povided by existing ones This paadigm has gained significant attention in the Web sevices community and is seen as a pilla fo building sevice-oiented applications A numbe of domain-specific languages fo sevice composition have been poposed with consensus being fomed aound a pocess-oiented language known as WS-BPEL (o BPEL) The kenel of BPEL consists of simple communication pimitives that may be combined using contol-flow constucts expessing contol flow in BPEL sequence, banching, paallelism, synchonisation, etc As a esult, BPEL pocess definitions lend themselves to static flow-based analysis techniques This epot aims at validating the feasibility of using Peti nets fo static analysis of BPEL pocesses We pesent a compehensive and igoously defined mapping of BPEL constucts into Peti net stuctues This leads to the implementation of a tool which opeates by tanslating BPEL pocesses into Peti nets and exploiting existing Peti net analysis techniques The tool pefoms two useful types of static checks and extacts meta-data to optimise dynamic esouce management Keywods: Business pocess modelling, Web sevices, BPEL, tool-based veification, Peti nets 1 Intoduction Thee is an inceasing acceptance of Sevice-Oiented Achitectues (SOA) as a paadigm fo integating softwae applications within and acoss oganisational boundaies In this paadigm, independently 49 developed and opeated applications ae exposed as (Web) sevices that communicate with each othe matedì 10 dicembe using 13 ML-based standads, most notably SOAP and associated specifications [3] While the technology

50 Motivation BPEL specification: igouous ML syntax English pose semantics (of appaent claity) Consequences: inconsistencies, ambiguities, incompleteness ty to google fo WS BPEL issues list, eg Issue 32 Link Semantics in Event Handles (esolved) Issue 39 Inconsistent syntax fo quey attibute values in spec examples (esolved) Issue 42 Need fo Fomalism (esolved) ES 50

51 Appoaches Pomela (SPIN) Pocess algebas Abstact State Machines Automata Weakest peconditions / stongest postconditions Axiomatic semantics Peti nets 51

52 Goal Unveil ambiguities in BPEL specification (epoted to BPEL standadization committee) Complete fomalization of all contol-flow constucts Checking fo uneachable activities Checking fo potential conflicting message eceipt actions Detemining which messages can be eventually consumed 52

53 ting<flow ambiguities name="fl" suppessjoinfailue="yes"> and contadictions in the woding of the BPEL specification [5] Fo ation effot, some of these issues wee epoted and discussed in the BPEL standad and changes to the specification s woding have been poposed, albeit not yet adopt execution of this pocess, eithe A1 o A2 will be skipped because these two activities ae <links> Flow iffeent <link banches name="x1"/> Example: of a switch and in any execution BPEL of a switch only with one banch is taken Thus, two <link contol name="x2"/> </links> links x1 o x2 will cay a negative token On the othe hand, we assume that Switch ndition <switch attached name="sw"> to activity A3 (denoted by keywod AND ) evaluates to tue if and only if <case> x1 and <invoke x2 cay name="a1"> positive values Hence, this join condition will always evaluate Contol to Link false and 3 is always <souces> skipped (ie it is uneachable) uneachable activity <souce linkname="x1"/> </souces> ilst the contol flow constucts of BPEL have been designed in a way to ensue t ss execution can deadlock 5, some combinations of stuctued activities (in paticula ith contol links can lead to situations whee some activities ae uneachable Consi </invoke> </case> FL ss definition in Fig 1 whee both the ML code and alegend: gaphical epesentation ae p Basic SWActivity <pocess <othewise> name="uneachabletask" tagetnamespace=" suppessjoinfailue="yes" <invoke name="a2"> xmlns:tns=" <souces> <souce linkname="x2"/> </souces> xmlns:sevices=" </invoke> xmlns=" pocess/"> </othewise> </switch> <flow name="fl" suppessjoinfailue="yes"> <invoke <links> name = "A3"> <link name="x1"/> <tagets> <link name="x2"/> </links> <joincondition> <switch bpws:getlinkstatus( x1 ) name="sw"> and bpws:getlinkstatus( x2 ) <case> </joincondition> <taget <invoke linkname="x1"/> name="a1"> <souces> <souce linkname="x1"/> </souces> <taget </invoke> linkname="x2"/> </tagets> </case> </invoke> <othewise> </flow> <invoke name="a2"> tagetnamespace=" <souces> <souce linkname="x2"/> </souces> suppessjoinfailue="yes" </invoke> xmlns:tns=" </othewise> </switch> xmlns:sevices=" <invoke name = "A3"> <tagets> <flow <joincondition> name="fl" suppessjoinfailue="yes"> <links> bpws:getlinkstatus( x1 ) and bpws:getlinkstatus( x2 ) <link </joincondition> name="x1"/> <link <taget name="x2"/> linkname="x1"/> </links> <taget linkname="x2"/> <switch </tagets> name="sw"> </invoke> <case> </flow> </pocess> <invoke name="a1"> 53 execution of this pocess, eithe A1 o A2 will be skipped because these two activi ffeent banches of a switch and in any execution of a switch c1 onlyc2one banch is taken Flow wo contol links x1 o x2 will cay a negative token On the othe hand, we assum dition attached to activity A3 (denoted by keywod AND ) A1 Switch evaluates A2 to tue if and x1 1 and x2 cay positive values Hence, this join condition will always evaluate to fa Contol Link is always skipped (ie it is uneachable) AND A3 <pocess name="uneachabletask" </pocess> c1 xmlns=" pocess/"> A1 SW c2 A2 FL Legend: Basic Activity Fig 1 Example of a BPEL pocess with an uneachable activity Flow x1 le scopes ae not coveed in this pape since they ae not a contol-flow constuct a AND A3 e scope of this wok Instead, seializable scopes ae fundamentally x2switch elated to data ma it has not been fomally poved that BPEL pocesses ae deadlock-fee, to the best of ou Contol Link le of<souces> a deadlocking <souce linkname="x1"/> BPEL pocess </souces> has been put fowad Also, Kiepuszewski et al </invoke> x2