ICT 1 INF5120 Modellbasert systemutvikling Web Services XML Schema WSDL BPEL Forelesning 26.03.2007...

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INF5120Modellbasert systemutvikling

Web Services XML Schema WSDL BPEL

Forelesning 26.03.2007

Roy Grø[email protected]

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Outline

Web Services – Infrastructure and Architecture XML Introduction XML Schema

Web Service Description Language (WSDL) Business Process Execution Language (BPEL)

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Web Services – Infrastructure and Architecture

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What is a Web service?

The term “Web services” is confusing. There are many things that are referred to as “Web

services”. Adding to the confusion is the term “services” which is

interpreted differently by different people.

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WebWeb serviceservice

Web is short for World Wide Web.

Work performed or offered by a software system (possibly including human resources as well.)

Software services performed or offered on the Web, using open Internet standards and technologies.

What is a Web service?

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Definition (W3C): Web service

“A Web service is a software system designed to support interoperable machine-to-machine interaction over a network. It has an interface described in a machine-processable format (specifically WSDL). Other systems interact with the Web service in a manner prescribed by its description using SOAP-messages, typically conveyed using HTTP with an XML serialization in conjunction with other Web-related standards.”

- W3C Web Services Glossary, http://www.w3.org/TR/ws-gloss/

http://www.w3.org/TR/ws-gloss/

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Characteristics of a basic Web service

Fundamental requirements: It receives service requests and sends service replies over HTTP

Service requests – input data/parameters Service responses – output data/parameters

Data is normally formatted as an XML document SOAP (Simple Object Access Protocol)

Interface w/ operations and associated bindings and protocols are described using WSDL

Additionally, a Web service may: Be registered with a discovery agent through which it can be

located, typically UDDI.

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Transports

Messaging

Description

ComposableService

Assurance

ServiceComposition

HTTP HTTPS SMTP

XML SOAP WS-Addressing

XSD WSDL UDDI WS-PolicyWS-Metadata

Exchange

WS-SecurityWeb Service ReliableMessaging (WS-RM)

WS-Transactions

WS-BPEL

Web services stack

Technologystack

Conceptualstack

This part of the tutorial focuses on understanding the Web service technologies for messaging, description and composition such as XSD, WSDL and WS-BPEL.

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Web services – a conceptual view

Underlying Protocols

Messaging Encoding

Business EntitiesWeb Service Interfaces

HTTP/WEB

VANsFTP

SMTP/EMAIL MQ-Series

SOAP

EDI“Binary”

Raw XML ebXML

BPEL

____________________________________________________________

EGO-CentricWorkflow ProcessDescription

WSDL

____________________________________________________________

(Syntactic) Web Service Interface Description

Bindings and Endpoint Descriptions

WS-CHOR

____________________________________________________________

Interaction Sequencing

(Co)Constraints

XSD

____________________________________________________________

XML MessageSchemaDefinition

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Web Services Architecture

BPEL

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Relationship between Architecture model and Web Services

BPEL

WSDL

XML Schema

UML Activity

UML Interface

UML Class

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Model-driven Web Services –Two alternatives

Web Service (XML, Textual)

Model-to-modelPIM

(COMET models)

transformation

PSM (WS UML Profile)

Model-to-textModel-to-text

1

2

1

1. Transformation in two steps via UML profile

ATL

MOFScript MOFScript

2. Transformation in one step

Transformation choices:• fixed• config file• user is prompted

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XML Introduction

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XML - a Metameta Language

Metameta/How to define schema

Meta/Schema

Instances/Documents

XML SGML

MathML XSL SMIL OFX HTML

XSL Doc HTML Doc

XML Doc

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DocumentType

Definition(DTD)

XMLDocument

XSL(T)to rearrange/restructure

an XML document…

and to prepare a document

for rendering based on an XSL document

XPointerto positiona cursor

in an XMLdocument

XLinkto createcomplex

links

XML Schemato represent the DTD in

XML syntax and expressadditional constraints

XML Queryto query sets ofXML documents

RDFResource

DescriptionFramework -

to add metadata

OGI DISC - modified and extended by SINTEF Slide 16

Example XML Document

<?XML version="1.0"?>

<memo clearance-level = “0” status = “draft”>

<memo-header>

<from>Brian Smith</from>

<to>Mary Brown</to>

<date>March 3, 1998</date>

<subject>excessive overtime</subject></memo-header>

<memo-body><para>The Flame Project team has been working overtime for weeks and weeks. Let’s take the group to lunch on Friday. </para></memo-body>

</memo>


Example XML Document

Start- and end-tagscome in pairs



<memo-header>


<to>Mary Brown</to>



<memo-body><para>The Flame Project team has been working overtime for weeks and weeks. Let’s take the group to lunch on Friday. </para></memo-body>

</memo>


the content of simple elements:appears between start tag and end tag



<memo-header> Text content


<to>Mary Brown</to>



<memo-body><para>The Flame Project team has been working overtime for weeks and weeks. Let’s buy pizza for the group on Friday. </para></memo-body>

</memo>


the content of compound elements:appears between start tag and end tag



<memo-header>


<to>Mary Brown</to>



<memo-body><para>The Flame Project team has been working overtime for weeks and weeks. Let’s buy pizza for the group on Friday. </para></memo-body>

</memo>

a compound elementincludes all of the completesubelements: the tags andcontent of the subelements


Attributes in XML

In the document, we see:


Attributes are associated with elements….and the assignment of values to attributes always appear in the start tag for the element.

attribute name

tag name

attribute value

attribute name

attribute value


Namespaces Example

Slightly modified listings document<?xml version="1.0">

<Recent-Listings Area="Raleigh Hills" Date="March 97”

xmlns=“http://www.century21.com/listings.dtd”

xmlns:mls="urn:uuid:C2F41010-65B3-11d1-A29F-00AA00C14882" >

<For-Sale>

<Home id="h1">

<Address>8225 SW Canyon Lane</Address>

<mls:Structure>

<Num-Beds>3</Num-Beds>

<Num-Baths>2</Num-Baths>...

DefaultNamespace

“Named”Namespace

Prefix

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XML is extensively used – Examples

XML Metadata Interchange (XMI) XSLT – programming language for transformation Web Services: XML Schemas, WSDL, SOAP, BPEL Storage/Exchange formats Configuration files Advantage: Tool support for parsing, validation, editing,

visualization, ease of debugging etc. Disadvantage: Poor readability, efficiency (compared to

binary)

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XML Schema

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XML Schema Definition (XSD)

Define the legal building blocks of an XML document: Defines elements that can appear in a document. Defines attributes that can appear in a document. Defines which elements are child elements. Defines the order of child elements. Defines the number of child elements. Defines whether an element is empty or can include text. Defines data types for elements and attributes. Defines default and fixed values for elements and attributes.

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Simple types

Simple types are defined by restricting a built-in-type or another simple type

<simpleType name=“age”>

<restriction base=“integer”>

<minInclusive value=“0”/>

<maxInclusive value=“130”/>

</restriction>

</simpleType>

fourteen facets to restrict including: pattern, enumeration, length(3), period and duration

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Another Example

<simpleType name="US-Flag-Colors"> <restriction base="string"> <enumeration value="red"/> <enumeration value="white"/> <enumeration value="blue"/> </restriction></simpleType>

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Defining complex types

<xsd:complexType name="Address" >

<xsd:sequence>

<xsd:element name="name" type=”xsd:string" />

<xsd:element name="street" type=”xsd:string" />…

<xsd:element name="zip" type=”xsd:decimal" />

</xsd:sequence>

<attribute name=”country" type=”xsd:string" />

</xsd:complexType>

<xsd:complexType name="PurchaseOrderType">

<xsd:sequence>

<xsd:element name="shipTo" type="Address" />

...

</xsd:complexType>

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Document instance of purchase order

<PurchaseOrder orderDate="1999-05-20">

<shipTo country="US">

<name>Alice Smith</name>

<street>123 Maple Street</street>

<city>Mill Valley</city>

<state>CA</state>

<zip>90952</zip>

</shipTo>

...

</PurchaseOrder>

type="Address"

name=“shipTo"

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<complexType> or <simpleType>?

When do you use the complexType element and when do you use the simpleType element? Use the complexType element when you want to define child

elements and/or attributes of an element Use the simpleType element when you want to create a new type

that is a refinement of a built-in type (string, integer, etc)

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Defining attributes

<attribute name="Category" use="required"> <simpleType> <restriction base="string"> <enumeration value="autobiography"/> <enumeration value="non-fiction"/> <enumeration value="fiction"/> </restriction> </simpleType></attribute>

• Note: attributes can only have simpleTypes (i.e., attributes cannot have child elements).

Anonomous type

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Notes about Attributes

The attribute declarations always come last, after the element declarations.

The attributes are always with respect to the element that they are defined (nested) within.

<element name="foo"> <complexType> <sequence> … </sequence> <attribute name="bar" …/> <attribute name="boo" …/> </complexType></element>

"bar and boo areattributes of foo"

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Inheritance: Extending complex types

<complexType name="USAddress">

<extension base="Address"> <sequence> <element name="zip"

type="xsd:string"/> </sequence>

</extension></complexType>

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Elements

<element name="zip” type="xsd:string"/>

tag name ininstance document

type is either built-in types,simpleTypes or complexTypes

<zip>90210</zip>

XML instance:

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XSD: XML text editor

Can also be built using simple text editors XML editors gives contextual support, e.g. like auto-completion, suggestions

for elements, etc., as well as validation of the XML document.

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

</xs:schema> Inside here goes:• elements• complexTypes• simpleTypes

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XSD: UML profile for XSD

UML representation of XML schema.

Useful in a UML-centric development method if the modelling environment supports generation/import of XSD documents.

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PIM4SOA main mappings to XSD

PIM4SOA

element

XSD equivalent Notes

Document Schema

Entity ComplexType

Association Element An association between entities is transformed into an

element in the containing type with a reference to the

complex type generated for the target Entity

Attribute Attribute Attributes having simple types are mapped to Attributes

in complex types. Attributes with complex types in the

PIM4SOA model are mapped in the same way as

Associations.

Element SimpleType If the ItemType from the PIM4SOA model is not an

entity (meaning it is a simple type) a SimpleType

definition is created in the schema.

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Web Service Description Language (WSDL)

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Making a SOAP function call over HTTP

Body

XMLData

Header

HTTP Request

Body

XMLData

Header

HTTP Response

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The SOAP Envelope

<SOAP:Envelope> <SOAP:Header></SOAP:Header>

<SOAP:Body> <m:FunctionName>

<paramName1>paramValue1</paramName1>

<paramName2>paramValue2</paramName2> </m:FunctionName> </SOAP:Body>

</SOAP:Envelope>

Optional

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Web Services Description Language (WSDL)

Purpose Web services need to be defined in a consistent manner so that

they can be discovered by and interfaced with other services and applications.

The Web Services Description Language is a W3C specification providing the foremost language for the description of Web service definitions.

W3C, "Web Services Description Language (WSDL) Version 2.0 Part 1: Core Language", World Wide Web Consortium (W3C), W3C Working Draft, 3 August 2004. http://www.w3.org/TR/2004/WD-wsdl20-20040803/

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WSDL: Conceptual view

Underlying Protocols

Messaging Encoding

Business EntitiesWeb Service Interfaces

HTTP/WEB

VANsFTP

SMTP/EMAIL MQ-Series

SOAP

EDI“Binary”

Raw XML ebXML

WSDL

____________________________________________________________

(Syntactic) Web Service Interface Description

Bindings and Endpoint Descriptions

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WSDL: Conceptual model

WS Provider

WSClient

WS Interface

Ports

Operations

Name,Abstract Message Parts SchemaMessage Exchange Pattern

Porttype

Operation

Concrete Message EncodingConcrete Messaging Protocol

(Reusable) Binding

Concrete Endpoint Address

Operations Invoked through Ports

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WSDL: Message exchange patterns

WS Provider

WSClient

Time

Request-Response

Solicit-Response

One-Way

Notification

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WSDL 1.1 metamodel

WSDL DocumentWSDL Component

0..10..1

Port

+ Name

Operation

+ Name

Part

+ Name

+ Type

+ Element

Service

+ Name

1..*1..*

Binding

+ Name

1

1

1

1

Port Type

+ Name

11 11

Message

+ Name

1..*

0..1

1..*

+input

0..10..1

+output

0..10..1+fault 0..1

0..*0..*

Import

+ NameSpace

+ Location

Include

+ Location

Element

+ Name

+ BaseType

+ MinOccurs

+ MaxOccurs

Definition

+ Name

+ TargetNameSpace0..*0..*

0..*0..*0..*0..*

0..*0..*

0..*0..*

Schema

+ TargetNameSpaceTypes

0..10..1

A collection of related endpoints

A single endpoint defined as a combination of a binding and a network address

A concrete protocol and data format specification for a particular port type

An abstract set of operations supported by one or more endpoints

An abstract, typed definition of the data being communicated

An abstract, description of an action supported by the service

A container for data type definitions

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UML profile for WSDL

UML representation Text representation

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MyWebService<<BusinessService>>

BasicWFS

getCapabilities()describeFeatureType()getFeature()

<<Interface>>

TransactionWFS

lockFeature()transaction()

<<Interface>>

Payment

validate(card : CreditCard) : boolean

<<Interface>>

CreditCard

number : stringexpires : date

<types> <schema> <complexType name="CreditCard">...

<element name="number" type="string"/><element name="expires" type="date"/>...

</types> <message name="validateRequest"> <part name="card" type="CreditCard"/></message>... <portType name="Payment"> <operation name="validate">

<input message="validateRequest"/><output message="validateResponse"/>

</operation></portType> <portType name="TransactionWFS"> <operation name="getCapabilities">... <operation name="describeFeatureType">... <operation name="getFeature">... <operation name="lockFeature">... <operation name="transaction">... <binding name="PaymentSOAPBinding" type="Payment"> <soap:binding transport="http://schemas.xmlsoap.org/soap/http" ...>

<operation name="validate">...</binding> <binding name="TransactionWFSSOAPBinding" type="Payment"> <operation name="getCapabilities">... <operation name="describeFeatureType">... <operation name="getFeature">... <operation name="lockFeature">... <operation name="transaction">...</binding> <service name="myWebService"> <port name="Payment_Port”

binding="PaymentSOAPBinding"><soap:address location=”..www.myWebService.com"/>...

<port name="TransactionWFS_Port” binding="TransactionWFSSOAPBinding">…

Class

Copy-down Inheritance

Inte

rfac

e

BusinessService

Interface

Realize

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Business Process Execution Language (BPEL)

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BPEL

BPEL is a Web service composition language. It defineshow to compose other Web services so to accomplish amore complex task. A BPEL engine is capable of executing the composite service described by BPEL.

The outcome will be a composite BPEL-defined Web service which itself can be regarded as a Web service.

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BPEL language

XML notation Interaction with other Web services:

<receive>. Wait for an incoming message. Typically at the process start <invoke>. Call another Web service <reply>. Send a response message from the entire BPEL service

Control flow <sequence>. Sequential control flow <flow>. Parallel control flow <switch>. Conditional branching <while>. Loop

Data flow <variable>. Defines the data objects involved <assign>. Copy a data object from one variable to another possibly w/

data transformation

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BPEL: Simplified view

Web Service

portType

portType

portType

<receive>

<receive>

<reply>

<reply>

BPEL4WSProcess

A BPEL process is a composite Web service with a WSDL description.

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BPEL Foundations

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BPEL: Details• Two Uses

– Executable process descriptions– Business protocol descriptions – Abstract

processes• Partner links

– Paired WSDL interfaces– Correlation sets

Bind messages to process/activity instances.– Endpoint references

• Partner– Grouping constraint on partner links to a single

business partner.• Process Activities

– Basic - assign, throw, terminate, wait, empty, compensate

– Partner interaction - receive, reply, invoke– Structured - sequence, switch, while, pick,

flow, scope

Process

Partner - Links

WSDL PortType

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BPEL example

PO : POMessage

Invoice : InvMessage

receive

reply

shippingInfo

shippingSchedule

flow

sequence sequence sequence

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BPEL Process<process name="purchaseOrderProcess"

xmlns="http://schemas.xmlsoap.org/ws/2003/03/business-process/">

<partnerLinks>

<partnerLink name="purchasing"

partnerLinkType="lns:purchasingLT"

myRole="purchaseService"/>

<partnerLink name="invoicing"

partnerLinkType="lns:invoicingLT"

myRole="invoiceRequester"

partnerRole="invoiceService"/>

<partnerLink name="shipping"

partnerLinkType="lns:shippingLT"

myRole="shippingRequester"

partnerRole="shippingService"/>

<partnerLink name="scheduling"

partnerLinkType="lns:schedulingLT"

partnerRole="schedulingService"/>

</partnerLinks>

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BPEL process

<sequence><receive partnerLink="purchasing" portType="lns:purchaseOrderPT" operation="sendPurchaseOrder" variable="PO"/><flow>

<links><link name="ship-to-invoice"/><link name="ship-to-scheduling"/>

</links><sequence>

<assign><copy>

<from variable="PO" part="customerInfo"/><to variable="shippingRequest" part="customerInfo"/>

</copy></assign>

...

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BPEL process

<invoke partnerLink="shipping"portType="lns:shippingPT" operation="requestShipping" inputVariable="shippingRequest" outputVariable="shippingInfo">

<source linkName="ship-to-invoice"/></invoke>

<receive partnerLink="shipping" portType="lns:shippingCallbackPT" operation="sendSchedule" variable="shippingSchedule">

<source linkName="ship-to-scheduling"/></receive>

...

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UML profile for BPEL

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PIM4SOA main mappings to BPEL

PIM4SOA element BPEL

equivalent

Notes

ServiceProviderProcess

Process

Task (i) (participating in collaboration) Receive, Invoke, Reply The type of communication with other service providers must be

deduced from parameters passed to or from the task in question.

Task (ii) (no collaboration use)

Empty This might be a task requiring further implementation or human

interaction beyond the scope of the PIM4SOA.

Flow Sequence, Flow, (…) The structure of flows between Steps must be analysed to deduce the

applicable BPEL structure.

Interaction, Pin Assign Interactions have a role to play both in determining collaboration type

(see Task (ii) above), and passing particular parts of messages

between tasks (data flow, a BPEL assign).

Message Variable All messages sent and received must have appropriate variables

defined within the BPEL

CollaborationUseRoleBinding

PartnerLink The CollaborationUses defined for the ServiceProvider tell us what

PartnerLinks we will need. See CollaborationUsePath.

CollaborationUsePath PartnerLink, Role(…) This defines a specific use of a PartnerLink, alongside what role we

are playing, and even the PortType being used. See links to the

WSDL transformation described below.

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RSM and UML profile for Web services

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Referanser, neste forelesning...

XML, XML Schema, WSDL: www.w3c.org BPEL: http://en.wikipedia.org/wiki/BPEL www.oasis-open.org

NB! Utskrift av foilene fra denne forelesningen blir lagt ut på neste forelesning.

Neste forelesning: 16.april, Interoperability and MDI – EIF and EIM (Brian)

ICT 1 INF5120 Modellbasert systemutvikling Web Services XML Schema WSDL BPEL Forelesning 26.03.2007...

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