BPEL - WordPress.com · 2012-04-20 · •What do we mean by Business Process Automation and workﬂow technologies? • What are the technologies and standards that constitute the

BPEL

Business Process Execu/on Language

Friday, April 20, 12

• What do we mean by Business Process Automation and workflow technologies?

• What are the technologies and standards that constitute the SOA approach for Business Process Automation?

• What are the prospects for adoption of BPEL and the future direction of standards-based Business Process Automation leveraging web services?

Key Questions


• A business process is a collection of interrelated tasks, which are designed to deliver a particular result

• Types of business processes

• Management processes - processes that govern the operation of a system

• Operational processes - processes that constitute the core activities of the business and delivers the primary value of the organization

• Loan Approval Example

• Supporting processes - which support the core processes

• A business process can be decomposed into several sub-processes, which have their own attributes, but are aligned with the goal of the overall process

• The analysis of business processes typically includes the mapping of processes and sub-processes down to an activity level

• Business processes can be automated through BPM software and workflow

Business Processes


IT becomes the enabler of business agility through the systemization of flexible processes

However…

Business processes, by nature, are a challenge to identify, document, implement, and change

What do we want to achieve?


• Who Should?

• Who is involved in the process

• Do What?

• What tasks/activities need to be performed

• To What?

• What entities (objects) and data involved

• When?

• What starts and stops the process

• In What Order?

• What is the sequence and interrelationship between tasks

• Why?

• What is the value proposition of using workflow

Business Process Automation


• Improve the speed of a business process

• Improve the consistency of a business process

• Improve the quality of a business process

• Automated solutions for adding flexibility

Benefits of workflow automation


• Basic Control Flow

• Sequence

• Parallel Split

• Synchronization

• Exclusive Choice

• Advanced Branching and Synchronization

• Multi-Choice

• Structured Synchronizing Merge

• Multi-Merge

• Structured Discriminator

• Blocking Discriminator

• Multiple Instance Patterns

• Multiple Instances without Synchronization

• Multiple Instances with a Priori Design-Time Knowledge

• Multiple Instances with a Priori Run-Time Knowledge

• State-Based Patterns

• Deferred Choice

• Interleaved Parallel Routing

• Milestone

• Cancellation and Force Completion Patterns

• Cancel Task

• Cancel Case

• Interaction Patterns

• Arbitrary Cycles

• Structured Loop

• Recursion

• Termination Patterns

• Implicit Termination

• Explicit Termination

• Trigger Patterns

• Transient Trigger

• Persistent Trigger

Workflow Patterns

workflowpatterns.com


Messaging

Quality of Service

Transport

Description

Components

Transport

Interface + Bindings

Composite

XML Non-XML

Security

Policy

Discovery, N

egotiation, Agreement

Atomic

Orchestration Protocols State

ReliableMessaging Transactions

ComponentModel

Web Service Standards for SOA


Messaging

Quality of Service

Transport

Description

Components

Transport


Composite

XML Non-XML

Security

Policy

Discovery, N


Atomic



ComponentModel



Messaging

Quality of Service

Transport

Description

Components

Transport


Composite

XML Non-XML

Security

Policy

Discovery, N


Atomic



ComponentModel

WS-RM

WSDL* WS-Policy*

HTTP, TCP/IP, SMTP, FTP, …

UD

DI, W

S-Addressing, M

etadata Exchange.,…

WS-CWS-N* WS-RFWS-BPEL

WS-Security*WS-AT WS-BA

SOAP, WS-Addr* JMS, RMI/IIOP, ...

SCA



• Business Process Execution Language (BPEL) is a language for describing business processes based on Web Services

• Processes described using BPEL execute functionality by using Web Service interfaces exclusively

• BPEL Specification is administered by OASIS

• BPEL is an orchestration language, not a choreography language

• Orchestration specifies an executable process that involves message exchanges with other systems, such that that the message exchange sequences are controlled by the orchestration designer.

• Choreography specifies a protocol for peer-to-peer interactions, defining the legal sequences of messages exchanged with the objective of guaranteeing interoperability

• A choreography is not directly executable

• A choreography can be implemented through an orchestration (i.e. a BPEL process)

Business Process Execution Language


Graphical History of the Standard


• Dec 2000

• Microsoft publishes XLANG

• March 2001

• IBM publishes WSFL

• July 2002

• IBM, Microsoft, BEA converge WSFL and XLANG into BPEL4WS 1.0

• March 2003

• BPEL4WS is submitted to OASIS

• May 2003

• OASIS publishes BPEL4WS 1.1

• April 2007

• WS-BPEL 2.0 standard

History of BPEL 2.0


• Business processes defined using an XML-based language

• Web services are the model for process decomposition and assembly

• The same orchestration concepts are used for both the external (abstract) and internal (executable) views of a business process

• Both hierarchical and graph-like control regimes are used

• An identification mechanism for process instances is provided at the application message level

• The basic lifecycle mechanism is in implicit creation and termination of process instances.

• A long-running transaction model is defined to support failure recovery for parts of long-running business processes

• Language built on compatible Web services standards in a composable and modular manner

BPEL Design Goals


process

XMLschemas

WSDLdefinitions

Process Definition


process

imports

Declare dependencies on external XML Schema or WSDL definitions extensions

Declare namespaces of WS-BPEL extension attributes and

elements

XMLschemas

WSDLdefinitions

Process Definition


process

imports



elements

partnerlinks

Relationships that a WS-BPEL process will employ in its behavior

messageexchanges

Relationship between inbound and outbound message

activities

XMLschemas

WSDLdefinitions

Process Definition


process

imports



elements

variablesData holding state of a business process or exchanged with partners

partnerlinks


correlationsets

Application data fields that together identify a

conversation

messageexchanges


activities

XMLschemas

WSDLdefinitions

Process Definition


process

imports



elements


partnerlinks


correlationsets


conversation

messageexchanges


activities

eventhandlers

Concurrently process inbound messages or timer alarms

faulthandlers

Deal with exceptional situations in a process

XMLschemas

WSDLdefinitions

Process Definition


process

imports



elements


partnerlinks


correlationsets


conversation

messageexchanges


activities

eventhandlers

Concurrently process inbound messages or timer alarms

faulthandlers

Deal with exceptional situations in a process

primaryactivityPerform the process logic –

any number of activities may be recursively nested XML

schemas

WSDLdefinitions

Process Definition


Structure of a BPEL Process<process ...>

<partners> ... </partners> <!-‐-‐ Web services the process interacts with -‐-‐> <variables> ... </variables> <!– Data used by the process -‐-‐> <correlationSets> ... </correlationSets> <!– Used to support asynchronous interac/ons -‐-‐> <faultHandlers> ... </faultHandlers> <!–Alternate execu/on path to deal with faulty condi/ons -‐-‐>

<eventHandlers> ... </eventHandlers> <!–Concurrent execu/on paths -‐-‐> <compensationHandlers> ... </compensationHandlers> <!–Code to execute when “undoing” an ac/on -‐-‐> (activities)* <!– What the process actually does -‐-‐>

</process>


Loan Approval Process

PortType of the WSDL service

Financial Institution‘sWeb Service

(Loan Approver)

invoke

Interfaces exposed by the BPEL process

Interfaces used by the BPEL processes

receive

reply

Recursive Composition

• BPEL processes interact with the services through the WSDLs they expose

• BPEL processes offer services through a WSDL


Partners• Actors that are external to the process and with which the process interacts• They can offer services or use the services offered by the process• They are defined by their services through WSDL• The rela/ons between partners are specified through partner links• A partner link is an instance of a partner link type that defines the rela/onship between two generic services (even when a process does not exist yet)

PartnerLink Type

Port Type 1 Port Type 2

Process 1 Process 2


portType and partnerLink

portTypes offeredby our process

What we want to havefrom the other services


partnerLinkType

• The relationship between two services is defined by means of roles– Each role is associated with a portType

• How many roles – One role if one part only provides operations– Two roles if both parties provide operations

• This usually means– One role when the communication is synchronous– Two roles when the communication is asynchronous

• The definition of partnerLinkTypes is part of the process’ WSDL


partnerLink

• Instance of a partnerLinkType

• Defined within the BPEL process

• Specifies the actual actors that play the roles

– myRole identifies the role played by the process - uses EPR

– partnerRole identifies the role played by the other service - uses EPR

• It defines one or two roles depending on the associated partnerLinkType

<partnerLinks> <partnerLink name="NCName" partnerLinkType="QName" myRole="NCName"? partnerRole="NCName"? initializePartnerRole="yes|no"? />+</partnerLinks>


Variables

• Necessary to maintain the process state

• Their types can be:

– A message

– A simple XML type

– A complex XML type

• They allow us to save the contents of messages

<variables> <variable name="BPELVariableName" messageType="QName"? type="QName"? element="QName"?>+ from-spec? </variable></variables>


Using Variables

22

process


Using Variables

22

process

WSDLmessage

WSDLmessage

WSDLmessages

Variables defined using WSDL messages


Using Variables

22

process

WSDLmessage

WSDLmessage

WSDLmessages


42XMLschemas

XML Schemaelements / types

Variables defined using XML schema elements or types


Using Variables

22

process

assign

xsl:transform

receive

request

response

invoke

request

reply

response

42

WSDLmessage

WSDLmessage

WSDLmessages


42XMLschemas

XML Schemaelements / types

Variables defined using XML schema elements or types


Properties

• General way of naming and representing distinguished data elements

– usually have a process-wide relevance

• Separates its use in the business logic from its structure

– the variable’s structure is free to evolve while the process references the property

23

<wsdl:definitions name="NCName"> <vprop:property name="NCName" type="QName"? element="QName"? /> ...</wsdl:definitions>


Property Aliases

• A property alias maps a property to a field in a specific message part or variable value

• object bpel:getVariableProperty(string, string)

– This function extracts property values from variables.

• The first argument names the source variable for the data and

• the second is the QName of the property to select from that variable

24

<vprop:propertyAlias propertyName="QName" messageType="QName"? part="NCName"? type="QName"? element="QName"?> <vprop:query queryLanguage="anyURI"?>? queryContent </vprop:query> </vprop:propertyAlias>


Data Handling• BPEL provides an extensible mechanism for the language used in queries and expressions.

• The languages are specified by the queryLanguage and expressionLanguage attributes of the process element.

– Default is XPath 1.0

• The <assign> activity can be used to copy data from one variable to another, or to construct and insert new data using expressions.

25

<assign validate="yes|no"? standard-attributes> standard-elements ( <copy keepSrcElementName="yes|no"? ignoreMissingFromData="yes|no"?> from-spec to-spec </copy> | <extensionAssignOperation> assign-element-of-other-namespace </extensionAssignOperation> )+</assign>


Data Handling• Expressions operate on variables, properties, and literal constants to produce a new value.

• The <assign> activity can also be used to copy EPRs to and from partnerLinks

26

<from variable="BPELVariableName" part="NCName"?> <query queryLanguage="anyURI"?>? queryContent </query></from><from partnerLink="NCName" endpointReference="myRole | partnerRole" /><from variable="BPELVariableName" property="QName" /><from expressionLanguage="anyURI"?>expression</from><from><literal>literal value</literal></from><from/>

<to variable="BPELVariableName" part="NCName"?> <query queryLanguage="anyURI"?>? queryContent </query></to><to partnerLink="NCName" /><to variable="BPELVariableName" property="QName" /><to/>


Advanced Data Handling• Supports XSL Transformations

27

<variables> <variable name="A" element="foo:AElement" /> <variable name="B" element="bar:BElement" /></variables>...<sequence> <invoke ... inputVariable="..." outputVariable="A" /> <assign> <copy> <from> bpel:doXslTransform("urn:stylesheets:A2B.xsl", $A) </from> <to variable="B" /> </copy> </assign> <invoke ... inputVariable="B" ... /></sequence>


• How to identify stateful instances via stateless WS interfaces?

• A process instance is assigned one or more keys

• Business data is used as key, e.g., customerID

• A key can be compound, e.g., (customerID, orderNumber)

• BPEL calls a key a correlation set – it is used to correlate an incoming message with a process instance

Process 4(0123,15)

Process 3(0815,42)

Process 2(4711,37)

Process 1(0815,12)

0815 42

Message 2

customerID

orderNumber

4711 37

Message 1

Correlation Sets

<correlationSets>? <correlationSet name="NCName" properties="QName-list" />+</correlationSets>


Basic ac/vi/es

process

receive reply

invokeInvoke a one-way or request-response operation

Do a blocking wait for a matching message to arrive / send a message in reply

validate

assignUpdate the values of variables or partner links with new data

Validate XML data stored in variables

exit

Immediately terminate execution of a business process

instance

waitWait for a given time period or until a certain time has passed

emptyNo-op instruction for

a business process

extensionActivityWrapper for language

extensions


<receive>• The execution of a receive can activate the execution of a new process instance

– This is specified through attribute createInstance

– The default value is no

– We need at least one receive to activate the process

<receive partnerLink="NCName" portType="QName"? operation="NCName" variable="BPELVariableName"? createInstance="yes|no"? standard-attributes> standard-elements <correlations>? <correlation set="NCName" initiate="yes|join|no"? />+ </correlations> <fromParts>? <fromPart part="NCName" toVariable="BPELVariableName" />+ </fromParts></receive>


<reply>

31

<reply partnerLink="NCName" portType="QName"? operation="NCName" variable="BPELVariableName"? faultName="QName"? standard-attributes> standard-elements <correlations>? <correlation set="NCName" initiate="yes|join|no"? />+ </correlations> <toParts>? <toPart part="NCName" fromVariable="BPELVariableName" />+ </toParts></reply>


<invoke>

<invoke partnerLink="NCName" portType="QName"? operation="NCName" inputVariable="BPELVariableName"? outputVariable="BPELVariableName"? standard-attributes> standard-elements</invoke>

• One way invocation• only inputVariable

• Request-response• both inputVariable and outputVariable


Structured Activities

33

process

flowContained activities are executed in parallel, partially ordered through control links

sequenceContained activities are performed sequentially in lexical order

whileContained activity is repeated while a predicate holds

repeatUntilContained activity is repeated until a predicate holds

pick Block and wait for a suitable message to arrive (or time out)

forEach Contained activity is performed sequentially or in parallel, controlled by a specified

counter variable

if-elseif-else Select exactly one branch of activity from a set of choices

scope Associate contained activity with its own local variables, partner

links, etc., and handlers

2. N.1. …

B C

A

c

c

c1 c2…

2. N.1. …

… AM2M1


Structured activities

<sequence> <receive .../> <flow> <sequence> <invoke .../> <while ... > <assign>...</assign> </while> </sequence> <sequence> <receive .../> <invoke ... > </sequence> </flow> <reply></sequence>

receive

invoke

invoke

assign

sequence

sequencesequence

while

receive

reply

flow


Sequence

35

<sequence standard-attributes> activity+</sequence>

<sequence> <flow>...</flow> <scope>...</scope> <pick>...</pick></sequence>


If-Then-Else

36

<if> <condition expressionLanguage="anyURI"?>bool-expr</condition> activity <elseif>* <condition expressionLanguage="anyURI"?>bool-expr</condition> activity </elseif> <else>? activity </else></if>


If-Then-Else

36

<if xmlns:inventory="http://supply-chain.org/inventory" xmlns:FLT="http://example.com/faults"> <condition> bpel:getVariableProperty('stockResult','inventory:level') > 100 </condition> <flow>  </flow> <elseif> <condition> bpel:getVariableProperty('stockResult','inventory:level') >= 0 </condition> <throw faultName="FLT:OutOfStock" variable="RestockEstimate" /> </elseif> <else> <throw faultName="FLT:ItemDiscontinued" /> </else></if>


While

37

<while standard-attributes> <condition expressionLanguage="anyURI"?>bool-expr</condition> activity</while>

<while> <condition>$orderDetails > 100</condition> <sequence>...</sequence></while>


Pick

38

<pick createInstance="yes|no"? standard-attributes> <onMessage partnerLink="NCName" portType="QName"? operation="NCName" variable="BPELVariableName"? <correlations>? <correlation set="NCName" initiate="yes|join|no"? />+ </correlations> <fromParts>? <fromPart part="NCName" toVariable="BPELVariableName" />+ </fromParts> activity </onMessage> <onAlarm>* ( <for expressionLanguage="anyURI"?>duration-expr</for> | <until expressionLanguage="anyURI"?>deadline-expr</until> ) activity </onAlarm></pick>


Pick

38

<pick> <onMessage partnerLink="buyer" portType="orderEntry" operation="inputLineItem" variable="lineItem">  </onMessage> <onMessage partnerLink="buyer" portType="orderEntry" operation="orderComplete" variable="completionDetail">  </onMessage>  <onAlarm> <for>'P3DT10H'</for>  </onAlarm></pick>


Flow

39

<flow standard-attributes> <links>? <link name="NCName">+ </links> activity+</flow>

<sequence> <flow> <invoke partnerLink="Seller" ... /> <invoke partnerLink="Shipper" ... /> </flow> <invoke partnerLink="Bank" name="transferMoney" ... /></sequence>


Synch links

40

<targets>? <joinCondition expressionLanguage="anyURI"?>? bool-expr </joinCondition> <target linkName="NCName" />+</targets> <sources>? <source linkName="NCName">+ <transitionCondition expressionLanguage="anyURI"?>? bool-expr </transitionCondition> </source></sources>


Example of synch links

41


Example of synch links

41

<flow suppressJoinFailure="yes"> <links> <link name="buyToSettle" /> <link name="sellToSettle" /> <link name="toBuyConfirm" /> <link name="toSellConfirm" /> </links> <receive name="receiveBuyerInformation" ...> <sources> <source linkName="buyToSettle" /> </sources> </receive> <receive name="receiveSellerInformation" ...> <sources> <source linkName="sellToSettle" /> </sources> </receive>

<invoke name="settleTrade" ...> <targets> <joinCondition>$buyToSettle and $sellToSettle </joinCondition> <target linkName="buyToSettle" /> <target linkName="sellToSettle" /> </targets> <sources> <source linkName="toBuyConfirm" /> <source linkName="toSellConfirm" /> </sources> </invoke> <reply name="confirmBuyer" ...> <targets> <target linkName="toBuyConfirm" /> </targets> </reply> <reply name="confirmSeller" ...> <targets> <target linkName="toSellConfirm" /> </targets> </reply></flow>


ForEach

42

<forEach counterName="BPELVariableName" parallel="yes|no"> <startCounterValue expressionLanguage="anyURI"?> unsigned-integer-expression </startCounterValue> <finalCounterValue expressionLanguage="anyURI"?> unsigned-integer-expression </finalCounterValue> <completionCondition>? <branches expressionLanguage="anyURI"? successfulBranchesOnly="yes|no"?>? unsigned-integer-expression </branches> </completionCondition> <scope ...>...</scope></forEach>


Scopes

process

scope

scope

scope

scope

Scopes provide a context which influences the execution behavior of its enclosed activities

Isolated scopes provide control of concurrent access to shared resources

scope

Local declarations – partner links, variables, correlation sets

Local handlers – event handlers, fault handlers, a termination handler, and a compensation handler

primary activity


Scopes

44

<scope isolated="yes|no"? exitOnStandardFault="yes|no"? standard-attributes> standard-elements <variables>? ... </variables> <partnerLinks>? ... </partnerLinks> <correlationSets>? ... </correlationSets>

<eventHandlers>? ... </eventHandlers> <faultHandlers>? ... </faultHandlers> <compensationHandler>? ... </compensationHandler> activity</scope>


Compensation Handler

• Allows the definition of compensation logic, together with forward logic

– underpinning of BPEL’s error handling framework

• Always attached to a completed scope.

– Can be attached inline to an invoke for simplicity

45

<scope> <compensationHandler> <invoke partnerLink="Seller" portType="SP:Purchasing" operation="CancelPurchase" inputVariable="getResponse" outputVariable="getConfirmation"> </invoke> </compensationHandler> <invoke partnerLink="Seller" portType="SP:Purchasing" operation="Purchase" inputVariable="sendPO" outputVariable="getResponse"> </invoke></scope>


Process State Usage in CHs• A compensation handler always uses the current state of the process at the time the

compensation handler is executed.

– from its associated scope and all enclosing scopes

– includes the state of variables, partner links and correlation sets.

• Compensation handlers are able to both read and write the values of all such data

46


Fault Handler• It is a mode switch from the normal processing in a scope.

• Designed to be treated as "reverse work," in that its aim is to undo the partial and unsuccessful work of a scope in which a fault has occurred.

– can launch compensation handlers for completed scopes (not for the same scope!)

• The completion of the activity of a fault handler, even when it does not rethrow the handled fault, is not considered successful completion of the scope.

• Defined through catch and catchall constructs

47

<faultHandlers> <catch faultName="QName"? faultVariable="BPELVariableName"? ( faultMessageType="QName" | faultElement="QName" )? >* activity </catch> <catchAll>? activity </catchAll></faultHandlers>


Catching a Fault

When faults are thrown without associated data the fault MUST be caught as follows:

1. If there is a <catch> construct with a matching faultName value that does not specify a faultVariable attribute then the fault is passed to the identified catch activity.

2. Otherwise if there is a <catchAll> fault handler then the fault is passed to the <catchAll> fault handler.

3. Otherwise, the fault will be handled by the default fault handler

48


Catching a Fault

In the case of faults thrown with associated data the fault MUST be caught as follows:

1. matching faultName value, faultVariable whose type matches the type of the fault data

2. fault data is a WSDL message type, matching faultName value, faultVariable’s associated faultElement’s QName matches the QName of the runtime element data

3. matching faultName value, no faultVariable attribute

4. no faultName attribute, faultVariable whose type matches the type of the runtime fault data

5. fault data is a WSDL message type, no faultName attribute, faultVariable whose associated faultElement’s QName matches the QName of the runtime element data

6. <catchAll>

7. default fault handler

49


Termination

• The behavior of a fault handler for a scope C begins by

– disabling the scope's event handlers and

– implicitly terminating all activities enclosed within C that are currently active

• The <assign> activities are sufficiently short-lived that they MAY be allowed to complete

• <wait>, <receive>, <reply> and <invoke> activity MUST be interrupted and terminated prematurely. When a request-response <invoke> is interrupted and terminated prematurely, the response (if received) for such a terminated activity MUST be ignored.

• The <empty>, <throw> and <rethrow> activities MAY be allowed to complete.

• The <exit> activity, once started, MUST NOT be terminated

50


Termination

51

• The iteration of <while>, <repeatUntil>, and serial <forEach> MUST be interrupted and termination MUST be applied to the loop body activity.

• For a parallel <forEach>, termination MUST be applied to all parallel executing branches.

• If an <if> or <pick> activity has already selected a branch, then the termination MUST be applied to the activity of the selected branch. If either of these activities has not yet selected a branch, then the <if> or <pick> activity itself MUST be terminated immediately.

• The <sequence> and <flow> constructs MUST be terminated by terminating their behavior and applying termination to all nested activities currently active within them.

• The <compensateScope> and <compensate> activity MUST be terminated by propagating the termination to the invoked compensation handler instances and applying termination to the activities of the compensation handlers.


Event Handler• Event Handlers run concurrently and are invoked when the corresponding event occurs

• There are two types of events.

– inbound messages that correspond to a WSDL operation

– alarms, that go off after user-set times

52

<onEvent partnerLink="NCName" portType="QName"? operation="NCName" ( messageType="QName" | element="QName" )? variable="BPELVariableName"?>* <scope ...>...</scope> </onEvent>

<onAlarm>* ( <for expressionLanguage="anyURI"?>duration-expr</for> | <until expressionLanguage="anyURI"?>deadline-expr</until>)? <repeatEvery expressionLanguage="anyURI"?>? duration-expr </repeatEvery> <scope ...>...</scope> </onAlarm>


Isolated Scopes

• The isolated attribute of a scope, when set to "yes", provides control of concurrent access to shared resources: variables, partner links, and control dependency links

• Two concurrent isolated scopes, S1 and S2, access a common set of variables and partner links.

– Isolation ensures that the results would be no different if all activities on all shared data were reordered so that either all such activities within S1 are completed before any in S2 or vice versa.

53


Example

compensa=onhandler

chargecredit card

refundcustomer ship

goods

faulthandler

no=fymanager

compensatefault

handler

rethrow

Process

flow

scopescope


Abstract Processes

• Different use cases

– standard provides a common base and profiles (identified by URIs) for refinement

• Common base

– abstractProcessProfile attribute must exist and point to a profile definition

– all constructs for executable processes are permitted

– certain syntactic constructs may be hidden

• opaque placeholder for activities, expressions, from specs (Assign)

• can be used for defining extension points

– must be syntactically valid

– may omit the createInstance property

55


Process Completion

• Executable Completion is a process derived by

– changing the namespace to executable and removing the profile URI

– syntactic transformations

• opaque token replacement

• addition of BPEL constructs

– validating the resulting process

• Basic Executable Completion is an executable completion in which transformations are

– opaque token replacement

– addition of a start activity

– addition of imports, partnerLinks, and variables at the process level

56


Profile for Observable Behaviour• for the definition of business process contracts

– hide private aspects of execution

– rich data manipulation is not needed (opaque Assigns)

• Executable Completions

– can add additional interactions with other partners (existing vs new)

– should not change order of existing interactions

– data writings may change control flow! Beware!

– existing EPRs should not be changed

– lexical parent of an existing activity must never be changed

• cannot add nesting (while, scope, etc.)

– must not add new branches to if structures (unless it is an else)

– must not add new branches to pick structures

– must not add new handlers to a scope (ok on process level)

– must not add new exit structures

– must not hide variable declarations by adding new ones in scopes

57


Template Profile• For describing a process within an organiza/on at design-‐/me

– hides arbitrary implementa/on details

– allows organiza/ons to “fill in the blanks” later

• template:createInstance extension attribute to mark an opaque activity as a start activity

• Explicit opaque tokens must be used to mark where new activities will be added

• No omission shortcuts are allowed

• All new start activities must substitute opaque activities with a template:createInstance property

• Only things that can be added:

– correlations (if none are already there)

– data declarations

– handlers

– import at the process level

58


The Shipping Service

• Offers 2 options

– shipping of all goods

– shipping of partial goods

59

<plnk:partnerLinkType name="shippingLT"> <plnk:role name="shippingService" portType="sif:shippingServicePT" /> <plnk:role name="shippingServiceCustomer" portType="sif:shippingServiceCustomerPT" /> </plnk:partnerLinkType>


Messages and Port Types

60

<wsdl:definitions targetNamespace="" xmlns:ship="" xmlns:tns= "" xmlns:wsdl=""xmlns:xsd=""> <wsdl:types> <xsd:schema>  </xsd:schema> </wsdl:types> <wsdl:message name="shippingRequestMsg"> <wsdl:part name="shipOrder"

type="ship:shipOrder" /> </wsdl:message> <wsdl:message name="shippingNoticeMsg"> <wsdl:part name="shipNotice"

type="ship:shipNotice" /> </wsdl:message>

<wsdl:portType name="shippingServicePT"> <wsdl:operation name="shippingRequest"> <wsdl:input

message="tns:shippingRequestMsg" /> </wsdl:operation> </wsdl:portType> <wsdl:portType

name="shippingServiceCustomerPT"> <wsdl:operation name="shippingNotice"> <wsdl:input

message="tns:shippingNoticeMsg" /> </wsdl:operation> </wsdl:portType></wsdl:definitions>


Proper/es

61

<wsdl:types> <xsd:schema targetNamespace="http://example.com/shipping/ship.xsd"> <xsd:simpleType name="itemCountType"> <xsd:restriction base="xsd:int"> <xsd:minInclusive value="1" /> <xsd:maxInclusive value="50" /> </xsd:restriction> </xsd:simpleType> </xsd:schema> </wsdl:types>

<vprop:property name="shipOrderID" type="xsd:int" /><vprop:property name="shipComplete" type="xsd:boolean" /><vprop:property name="itemsTotal" type="ship:itemCountType" /><vprop:property name="itemsCount" type="ship:itemCountType" />


Property Aliases

62

<vprop:propertyAlias propertyName="tns:shipOrderID" messageType="sif:shippingRequestMsg" part="shipOrder"> <vprop:query> ship:ShipOrderRequestHeader/ship:shipOrderID </vprop:query> </vprop:propertyAlias> <vprop:propertyAlias propertyName="tns:shipOrderID" messageType="sif:shippingNoticeMsg" part="shipNotice"> <vprop:query>ship:ShipNoticeHeader/ship:shipOrderID</vprop:query> </vprop:propertyAlias> <vprop:propertyAlias propertyName="tns:shipComplete" messageType="sif:shippingRequestMsg" part="shipOrder"> <vprop:query> ship:ShipOrderRequestHeader/ship:shipComplete </vprop:query> </vprop:propertyAlias>


Property Aliases

63

<vprop:propertyAlias propertyName="tns:itemsTotal" messageType="sif:shippingRequestMsg" part="shipOrder"> <vprop:query> ship:ShipOrderRequestHeader/ship:itemsTotal </vprop:query> </vprop:propertyAlias> <vprop:propertyAlias propertyName="tns:itemsCount" messageType="sif:shippingRequestMsg" part="shipOrder"> <vprop:query> ship:ShipOrderRequestHeader/ship:itemsCount </vprop:query> </vprop:propertyAlias> <vprop:propertyAlias propertyName="tns:itemsCount" messageType="sif:shippingNoticeMsg" part="shipNotice"> <vprop:query>ship:ShipNoticeHeader/ship:itemsCount</vprop:query> </vprop:propertyAlias>


The process

64

receive shipOrder if condition shipComplete send shipNotice else itemsShipped := 0 while itemsShipped < itemsTotal itemsCount := opaque // non-deterministic assignment // corresponding e.g. to // internal interaction with // back-end system send shipNotice itemsShipped = itemsShipped + itemsCount


The process

65

<partnerLinks> <partnerLink name="customer" partnerLinkType="plt:shippingLT" partnerRole="shippingServiceCustomer" myRole="shippingService" /> </partnerLinks> <variables> <variable name="shipRequest" messageType="sif:shippingRequestMsg" /> <variable name="shipNotice" messageType="sif:shippingNoticeMsg" /> <variable name="itemsShipped" type="ship:itemCountType" /> </variables>


The process

66

<sequence> <receive partnerLink="customer" operation="shippingRequest" variable="shipRequest"> </receive> <if> <condition> bpel:getVariableProperty('shipRequest','props:shipComplete') </condition> <sequence> <assign> <copy> <from variable="shipRequest" property="props:shipOrderID" /> <to variable="shipNotice"property="props:shipOrderID" /> </copy> <copy> <from variable="shipRequest" property="props:itemsCount" /> <to variable="shipNotice" property="props:itemsCount" /> </copy> </assign> <invoke partnerLink="customer"operation="shippingNotice"

inputVariable="shipNotice"> </invoke> </sequence>


The Process

67

<else> <sequence> <assign><copy><from>0</from> <to>$itemsShipped</to></copy></assign> <while> <condition> $itemsShipped < bpel:getVariableProperty('shipRequest',props:itemsTotal') </condition> <sequence> <assign><copy><opaqueFrom/><to variable="shipNotice" property="props:shipOrderID" /> </copy> <copy><opaqueFrom/><to variable="shipNotice" property="props:itemsCount" /> </copy></assign> <invoke partnerLink="customer" operation="shippingNotice" inputVariable="shipNotice"> </invoke> <assign><copy><from>$itemsShipped+bpel:getVariableProperty('shipNotice','props:itemsCount') </from> <to>$itemsShipped</to> </copy></assign> </sequence> </while> </sequence></else></if></sequence>


BPEL’s Limits

• Closed solution – In treating dynamic BPEL processes only dynamic binding is supported • dynamic modification of partnerLinks

• The execution is a possible bottleneck– Many research projects tend towards distributed processes

• Limited expressiveness– Pushes engine producers to introduce non-standard activities to invoke components

that are not web services


Addi/onal Material

69


Loan Approval BPMN

70

calculateRisk

thoroughAssessment

loanRequest

amount >= 10000

amount < 10000

loan[approved]

risk == low

risk != low

loan[decision]

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