WS-BPEL 2.0 Web Services Business Process Execution Language Workshop Dieter König, IBM Senior Technical Staff Member ([email protected])

WS-BPEL 2.0

www.oasis-open.org

Web ServicesBusiness Process Execution Language Workshop

Dieter König, IBM Senior Technical Staff Member([email protected])Charlton Barreto, Adobe Senior Computer Scientist/Architect([email protected])

WS-BPEL 2.0 MyProcess

invoke

receive

receive

invoke

invoke

Handlers

faulthandler

eventhandler

faulthandler

compensationhandler

terminationhandler

eventhandler

PartnerLinks

PartnerLink Type

PortType 1

PortType 2

partnerlink

partnerlink

Variables42

WSDL Message

XML SchemaType

XML SchemaElement

PropertiesCorrelation Sets

Property 1

Property 2

StructuredActivities

if-elsewhile

scope

pick

sequence

flow

repeatUntil

forEach

BasicActivities

receive

reply

invoke

throw

exit

wait

empty

compensatevalidate

assign

rethrow

extensionActivity

compensateScope

WS-BPEL 2.0

Motivation OASIS and WS-BPEL Main Concepts Examples Status and support

Integration continues to be a key problem facing businesses

Intra-enterprise integration (Enterprise Application Integration) Integrating with partners (Business-to-Business Integration) Syndication

Web services move towards service-oriented computing

Applications are viewed as “services” Loosely coupled, dynamic interactions Heterogeneous platforms No single party has complete control

Service composition How do you compose services in this domain?

Motivation

Integration

Why the Need For BPEL? WSDL defined Web services have a stateless

interaction model Messages are exchanged using

Synchronous invocation Uncorrelated asynchronous invocations

Most “real-world” business processes require a more robust interaction model

Messages exchanged in a two-way, peer-to-peer conversation lasting minutes, hours, days, etc.

BPEL provides the ability to express stateful, long-running interactions

Programming in the large Non-programmers implementing flows

Flow logic deals with combining functions in order to solve a more complex problem (such as processing an order)

Programming in the small Programmers implementing functions

Function logic deals with a discrete fine-grained task (such as retrieving an order document or updating a customer record)

Two programming models

Aiming for a single approach for both Executable processes

Contain the partner’s business logic behind an external protocol

Abstract processes Define the publicly visible behavior of some or all

of the services an executable process offers Define a process template embodying domain-

specific best practices

Process Usage Patterns

Portability and Interoperability Flexible Integration

Rich, and easily adaptable to changes in underlying services

Recursive, type-based composition, enables Third-party composition of existing services Providing different views on a composition to different parties Increased scalability and reuse

Stateful conversations and lifecycle management Supports multiple stateful long-running conversations

Recoverability Long running business processes need fault handling and

compensation mechanisms to manage and recover from errors

Process Model Requirements

Industry standard language for expressing business processes

Leverage a common skill set and language

Designed to fit naturally into the Web services stack Expressed entirely in XML Uses and extends WSDL 1.1 Uses XML Schema 1.0 for the data model

Portable across platform and vendor Will run on any BPEL-compliant engine

Interoperable between interacting processes Layering on top of Web services stack

Benefits of BPEL

BPEL is the Web Services Orchestration standard from OASIS

bee•pel’, beep’•uhl, bip’•uhl An XML-based grammar for

describing the logic to orchestrate the interaction between Web services in a business process

BPEL Historical Timeline

Dec 2000Microsoft publishes XLANG

March 2001IBM publishes WSFL

July 2002IBM, Microsoft and BEA converge WSFL & XLANG into BPEL4WS 1.0

March 2003BPEL4WS is submitted to OASIS

May 2003OASIS publishes BPEL4WS 1.1

1stH 2007WS-BPEL 2.0 released

BPEL Historical Timeline

Dec 2000Microsoft publishes XLANG

March 2001IBM publishes WSFL

July 2002IBM, Microsoft and BEA converge WSFL & XLANG into BPEL4WS 1.0

March 2003BPEL4WS is submitted to OASIS

May 2003OASIS publishes BPEL4WS 1.1

1stH 2007WS-BPEL 2.0 released

WS-BPEL 2.0

WS-BPEL

XML, Encoding

Other protocols

Other services

Transportand

Encoding

BusinessProcesses

WSDL, Policy, UDDI, Inspection Description

SecurityReliable

Messaging

Transactions

Coordination

SOAP (Logical Messaging)

QualityOf

Service

You are here

WS-BPEL in the WS-* Stack

WS-BPEL 2.0 Motivation OASIS and WS-BPEL Main Concepts Examples Status and support

Getting the Players Together

BPEL 1.1

(*)

(*) BPEL 1.1 authors, May 2003

WS-BPEL 2.0

WS-BPEL 2.0 Motivation OASIS and WS-BPEL Main Concepts Examples Status and support

WS-BPEL Language Structure Process Partner links Data handling Properties and correlation Basic and structured activities Scopes

WS-BPEL Process Definition

process

imports

Declare dependencies on external XML Schema or WSDL definitions extensions

Declare namespaces of WS-BPEL extension

attributes and elements

variablesData holding state of a business process or exchanged with partners

partnerlinks

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

correlationsets

Application data fields that together identify a

conversation

messageexchanges

Relationship between inbound and outbound

message activities

eventhandlers

Concurrently process inbound messages or timer alarms

faulthandlers

Deal with exceptional situations in a process

primaryactivity

Perform the process logic – any number of activities may be recursively nested

XMLschemas

WSDLdefinitions

BPEL is layered on top of and extends the WSDL service model

WSDL defines the specific operations allowed BPEL defines how WSDL operations are

orchestrated to satisfy a business process BPEL also specifies extensions to WSDL in

support of long-running asynchronous business processes

WSDL 1.1

BPEL 2.0

BPEL-defined WSDL extensions

Relationship with WSDL

Recursive Composition BPEL processes interact with WSDL services

exposed by business partners

WebService

Loan Approval Process

WebService

WSDLLoan Approval

PortType

Financial Institution‘sWeb Service

(Loan Approver)invoke

Interfaces exposed

by the BPEL process

Interfaces consumed

by the BPEL process

receive

reply

Composition of Web Services

Partner Link Type Partner Link Type

Service PService A Service B

A’s WSDL P’s WSDL B’s WSDL

invoke

receive

receive

invoke

invoke

Partner Links

process

partnerlink

partner link type

Peer-to-peer conversational partner relationship

WSDLport type

myRole

Provided port type

WSDLport type

partnerRole

Required port type

receive

Inbound request – service provided by the process

invoke

Outbound request – service required by the process

Variables

process

assign

xsl:transform

receive

request

response

invoke

request

reply

response

42

WSDLmessage

WSDLmessage

WSDLmessages

Variables defined using WSDL messages

42XML

schemas

XML Schemaelements / types

Variables defined using XML schema elements or types

process

Variable Properties

XML schema element

WSDL message

part part part... propertyproperty

alias

Typed properties are mapped (aliased) to

parts of WSDL messages or XML schema elements

propertyproperty

alias

A property creates a name

that has semantic significance

beyond an XML schema type

getVariableProperty( variable, property )

Properties isolate the process logic

from the details of a variable definition

process instance 3

process

Properties and Correlation Sets

correlation set

customerId

orderNumber

process instance 1

process instance 2

process instance 4

receive

Submit purchase orderHow to identify stateful instances

via stateless Web service interfaces?

Messages inlong-running conversations

are correlated tothe correct process instance

locate

purchaseOrder

cId = 0815

orderNo = 42

receive

Query order status

queryOrderStatus

custId = 0815

oNo = 42

customerId

orderNumber

4(0815, 49)

3(0815, 42)

2(0707, 11)

1(0311, 33)

initiate

process instance 3

process

Basic Activities

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

throw

rethrow

Generate a fault from inside the business process

Forward a fault from inside a fault handler

exit

Immediately terminate execution of a business

process instance

compensate

compensateScope

Invoke compensation on all completed child scopes

in default order

Invoke compensation on one completed child scope

waitWait for a given time

period or until a certain time has passed

empty No-op instruction fora business process

extensionActivityWrapper for language

extensions

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

Structured Activities

2. N.1. …

B C

A

c

c

c1 c2…

2. N.1. …

… AM2M1

Nesting Structured Activities

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

receive

reply

receive

invoke

invoke

assign

sequence

sequencesequence

flow

while

process

Scopes

scope

scope

scope

scopescope

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, message exchanges, variables, correlation sets

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

Compensation handler to undo persisted effects of

already completed activities

Termination handler to deal with forced scope termination

(external faults)

primary activity

scope

Process

Process Instance Lifecycle Business processes defined in

BPEL represent stateful Web services When a process is started, a new

instance is created according to the process definition

The creation and destruction of BPEL process instances is by design implicit

receive replyinvokeinvoke invoke

WS-BPEL 2.0

Motivation OASIS and WS-BPEL Main Concepts Examples Status and support

Graph-Oriented Authoring Style

1. A customer asks for a loan, providing name and amount info2. Two services are involved: a) A risk assessor which can approve the loan if the risk is low b) A loan approver which checks the name and approves/disapproves

the loan3. The reply is returned to the customer

invoke

receive

invoke

reply

assign

loanApprovalPT

loanapprover

riskAssessmentPT

loanassessor

amount < 10000 amount >= 10000

risk = "high"

risk = "low" approved = "true"

approved = "false"

flow

scope

eventhandler

parallelforEach

scope

flow

. . .

. . .

. . .

. . .

. . .. . .

scopescope

scopescope

scopescope

scope

eventhandlerevent

handlereventhandlerevent

handlereventhandlerevent

handlereventhandlerevent

handlereventhandlerevent

handler

Parallel Processing

compensationhandler

chargecredit card

refundcustomer

shipgoods

faulthandler

notifymanager

compensate

faulthandler

rethrow

Process

sequence

scopescope

Fault Handling & Compensation

Abstract & Executable Processes

Executable Processes Contain the partner’s business logic

behind an external protocol Model actual behavior of a participant

in a business interaction Encompass enough detail to fully

specify execution

Abstract & Executable Processes

Abstract Processes Partially specified processes that are

not intended to be executed May hide some of the required

concrete operational details Serve a descriptive role Used to guide executable processes More than one possible use case

Travel Reservation - ExampleAbstract Process ViewExecutable Processes View

getitinerary

getorder

ordertickets

receiveconfirmation

confirmflight

sendtickets

sendconfirmation

submitto agent

receivetickets

receiveconfirmation

selectairline

reserveseats

chargecredit card

plantrip

Agent Process Airline ProcessTraveler Process

Abstract Profiles

Profiles address varying requirements among Abstract Processes

Two profiles provided in WS-BPEL Observable Behavior Process Template

Abstract Profiles & Use Cases

Use cases Constraints on message exchange

Specify order in which messages are consumed or produced View on internal processes

Only projection of internal (executable) process is visible Bridge model to executable

Provide hooks to executable for model definition to enable abstraction

Template as “best practice” Specification of common activities, major data structures, and

main control flow

WS-BPEL 2.0

Motivation OASIS and WS-BPEL Main Concepts Examples Status and support

Conditional behavior – if {elseif} [else] Replacing the BPEL4WS 1.1 switch activity

Repetitive execution – repeatUntil Like BPEL4WS 1.1 while activity with at least one iteration

Processing multiple branches – forEach Sequential or parallel iteration controlled by a counter variable and a completion

condition Reversing work – compensate and compensateScope

Compensate all child scopes or one specific child scope Propagating faults – rethrow

Rethrow the fault caught in a fault handler Validating data – validate

Explicit XML schema validation of WS-BPEL variable content Validation also possible within assignment

Immediately ending a process – exit Replacing the BPEL4WS 1.1 terminate activity

Adding new activity types – extensionActivity Designated WS-BPEL extension point for new activity types

What’s new since BPEL 1.1?

Variable initialization Inline within variable declaration

Partner links Intent for partner role initialization

Locally declared messageExchange Internal correlation of receive/pick/onEvent and reply activities

Correlation sets Join behavior for multiple start activities

XML schema variables in Web service activities Usability enhancement for WS-I compliant doc/lit-style WS interactions

Assignment Clarification of copy behavior Keep source element name Ignore missing from data Extension assign operation

XSLT for variable transformations New XPath extension function bpel:doXslTransform(...)

XPath access to variable data XPath variable syntax $variable[.part]/location

Flow activity Scope isolation and link semantics

What’s new since BPEL 1.1?

Fault handlers XML schema typed fault variables Exit on standard fault behavior

Compensation handlers New scope snapshot semantics Fault handling during compensation

Event handlers Recurring events Resolution of variable, partnerLink, messageExchange, correlationSet

Termination handler Customize scope termination behavior

Import Predefined import types WSDL and XSD

Extensibility Global documentation element

Extension namespace declarations Mandatory and optional extensions

Abstract processes Common base (syntax) and profiles (semantics) Opacity and omission of activities, expressions, attributes

What’s new since BPEL 1.1?

WS-BPEL Schedule

Status (March 2007) First and second public reviews completed Approved Committee Specification submitted

for standardization Five organizations have certified use of WS-

BPEL in product ActiveEndpoints, IBM, Intalio, SEEBURGER, Sun

WS-BPEL Schedule

Next steps OASIS standard - April 2007

Voting opens March 19 and closes March 30 OASIS Symposium - April 15-20, 2007

San Diego, California, USA WS-BPEL Lightning Round - April 16 Business Process Sessions - April 16 WS-BPEL Workshop - April 18

WS-BPEL Follow-on Work BPEL4People

Human user interactionshttp://www-128.ibm.com/developerworks/webservices/library/specification/ws-bpel4people/

BPEL Subprocesses Based on a coordination protocol

http://www-128.ibm.com/developerworks/webservices/library/specification/ws-bpelsubproc/

BPELJ Inline Java code in activities and expressions

http://www-128.ibm.com/developerworks/library/specification/ws-bpelj/

Currency with related standards WSDL 2.0, XPath 2.0, XQuery, etc.