(SOA ارﮔ سﯾورﺳ یرﺎﻣﻌﻣsoea.sbu.ac.ir/resource/Practical/presentation/SOA_Protocols.pdf · (soa) ارﮔ سﯾورﺳ یرﺎﻣﻌﻣ- مرﺎﮭﭼ تﻣﺳﻗ

ا سرویس گرپروتکل های معماری (SOA)

...شرکت دوره آموزشی امیر مهجوریان

رامدیر فنی آزمایشگاه معماری سازمانی سرویس گمدیرعامل شرکت دانش بنیان کاریز سیستم

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2SOA Workshop: A. Mahjoorian , Session 4 .... System Co.

(طی هفت جلسه)سر فصل کلی مطالب

معرفی معماری سرویس گرا1.

کاربرد معماری سرویس گرا2.

شناخت تفصیلی ادبیات کسب و کار3.

پروتکل های معماری سرویس گرا4.

متد تحلیل و طراحی سرویس گرا5.

شناخت تفصیلی معماری سرویس گرا 6.

ابزارها و پیاده سازی معماری سرویس گرا7.

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SOA Server, Users and UDDI

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The Web Services Stack

Network (HTTP, FTP, …)

XML Messaging (SOAP, XML)

Service Description (WSDL)

Service Publication and Discovery (UDDI)

Service Flow (BPEL4WS)

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ASP.NET Web Service example

<%@ WebService Language="VB" Class="TempConvert" %>

Imports System

Imports System.Web.Services

Public Class TempConvert :Inherits WebService

<WebMethod()> Public Function FahrenheitToCelsius (ByVal Fahrenheit As Int16) As Int16

Dim celsius As Int16

celsius = ((((Fahrenheit) - 32) / 9) * 5)

Return celsius

End Function

<WebMethod()> Public Function CelsiusToFahrenheit

(ByVal Celsius As Int16) As Int16

Dim fahrenheit As Int16

fahrenheit = ((((Celsius) * 9) / 5) + 32)

Return fahrenheit

End Function

End Class

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ASP.NET Web Service example

This Code is a .asmx file. This is the ASP.NET file extension for XML

Web Services.

The only difference from a normal application is that this function is

defined as a "WebMethod".

Use "WebMethod" to mark the functions in your application that you

would like to make into web services.

The ASP.NET has automatically created a WSDL and SOAP

request.

C:/Documents and Settings/bpm-manager/Desktop/download/wsdl sample/tempconvert.asmx?WSDL

C:/Documents and Settings/bpm-manager/Desktop/download/wsdl sample/tempconvert.asmx?op=FahrenheitToCelsius

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XML

eXtensible Markup Language

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The XML Basics

eXtensible Markup Language (XML) is a super set of HTML. A user can define his /her own tags in XML.

Any XML documents must conform their metadata such as Document Type Definition (DTD) or Schema which specifies complex data types, elements and its attributes, and its sub-elements, etc.

A XML document is a universal format document typeused for data exchange and data storage. XML is also widely used for deployment descriptors and configuration specifications.

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A Question !?

Convert a “Data” record from Database or any other

Storage to Text Base Format , So it can easily

Understand and Import/Export between

Systems (Platforms, Storages) ..???

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A simple XML document about student GPA record.

<?xml version = “1.0”?>

<students>

<student id=1234>

<name>John Smith</name>

<gpa>3.5</gpa>

</student>

<student id=2345>

<name>Scott Tiger</name>

<gpa>4.0</gpa>

</student>

</students>

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HTML

<body>

<h1>My Favorite Book</h1>

<h1>ISBN - 1-34567-04-01</h1>

<H1>Authors:</H1>

<h3>John Smith</h1>

<h3>Peter Chen</h1>

<h1>Price: $45.00</h1>

<h1>Description: This is a grerat book</h1>

</body>

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XML

<?xml version="1.0" ?>

<Books>

<Book>

<ISBN>1-34567-04-01</ISBN>

<Authors>

<AuthorName>John Smith</AuthorName>

<AuthorName>Peter Chen</AuthorName>

<AuthorName>David Chao</AuthorName>

</Authors>

<Price> $45.00</Price>

<Description>This is a grerat book</Description>

</Book>

<Book>

<ISBN>1-34567-04-02</ISBN>

<Authors>

<AuthorName>Adam Smith</AuthorName>

</Authors>

<Price> $25.00</Price>

<Description>This is a second great book</Description>

</Book>

</Books>

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HTML vs XML

HTML is a language specifically designed for displaying information in browser. It doesn’t carry information about the structure of the content held within its page.

XML (Extensible MarkUp Language) is a language used to represent data in a form that does not rely on any particular proprietary technology. It uses user-defined tags to give meaningful names to data elements. With XML, we separate the data content from the data presentation.

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Tree View of XML

Books

Book

ISBN Authors Price Description

Book

ISBN Authors Price Description

Author Author Author

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The XML Basics

This XML document shows two student records. Each record consists of student name and his/her grade point average (gpa).The tag students is a top level root element which has a number of sub-elements called student.

Each student element consists of two sub-elements called nameand gpa. The identifier id in student tag is an attribute of element student.

The tag “?” is a Processing Instruction (PI) to inform XML parser that this XML document must conform XML v. 1.0.

Every XML document must have its metadata just like a data record in a data table of any database must satisfy the definition of the table which is called schema in database.

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The XML Basics (cont.)

Since the DTD itself does not use XML syntax and is not

very flexible. Schema is getting more and more popular

now and is replacing DTD because schema itself is in

XML format.

A XML Schema Document (XSD) is a metadata of a XML

document. XSD specifies the syntax, structure, and

constraints in a corresponding XML including datatype or

complex datatype of elements, attributes of elements.

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The following Schema describes the structure of above students

XML document. A complex type can be specified by a complexType

tag as follows:

<element name = “student”>

<complexType>

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

<element name = “gpa” type = “xsd: float />

</complexType>

</element>

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Let’s examine a complete XSD Schema sample.

<?xml version=”1.0” encoding=”UTF-8”?>

<xsd:schema xmlns:xsd=http://www.w3.org/2001/XMLSchema

targetNamespace=http://www.mybooks.org”

xmlns=”http://www.mybooks.org”>

<xsd:elememt name=”student”>

<xsd:complexType>

<xsd:sequence>

<xsd:element ref=”name”/>

<xsd:element ref=“gpa”/>

</xsd:sequence>

</xsd:complexType>

</xsd:element>

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

<xsd:element name=”gpa” type=”xsd:float”/>

</xsd:schema>

http://www.w3.org/2001/XMLSchema

http://books.org/

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The sequence tag in XSD Schema specifies the order and the

occurrence of sub-elements in their parent element. In this example

name and gpa elements are the sub-elements of the student

element which in turn is an element of the students element.

Of course there may be many students in a students set. The

XMLNS plays a same role as package in Java and namespace in

C++ to prevent naming collisions.

An element name can be qualified with a namespace prefix with a

colon symbol “:”. The idea of combining a namespace URI with a

local name is to make any identifier name in XML universally

unique.

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WSDL

Web Service Description Language

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WSDL Parts

Types Used to define custom message types

Messages Abstraction of request and response messages that my client and

service need to communicate.

PortTypes Contains a set of operations.

Operations organize WSDL messages.

Bindings Binds the PortType to a specific protocol (typically SOAP over

http).

You can bind one PortType to several different protocols by using more than one port.

Services Gives you one or more URLs for the service.

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wsdl:types

Data type definitions needed to define the exchanged

messages

By default, the types are defined in terms of XML

Schema

<definitions .... ><types>

<-- type-system extensibility element --> *</types>

</definitions>

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wsdl:types - example

<types>...<xs:element name="ItemSearch">

<xs:complexType><xs:sequence><xs:element name="SubscriptionId" type="xs:string"

minOccurs="0"/><xs:element name="AWSAccessKeyId" type="xs:string"

minOccurs="0"/><xs:element name="AssociateTag" type="xs:string"

minOccurs="0"/><xs:element name="XMLEscaping" type="xs:string"

minOccurs="0"/><xs:element name="Validate" type="xs:string"

minOccurs="0"/><xs:element name="Shared" type="tns:ItemSearchRequest"

minOccurs="0"/><xs:element name="Request" type="tns:ItemSearchRequest"

minOccurs="0" maxOccurs="unbounded"/></xs:sequence>

</xs:complexType></xs:element>...

</types>

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wsdl:message

Messages exchanged to provide a service

Messages are simply containers of parts which are defined in terms of the types described in the types

section

<message name="nmtoken"> *<part name="nmtoken" element="qname"?

type="qname"?/> *</message>

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wsdl:message - example

<message name="ItemSearchRequestMsg"><part name="body" element="tns:ItemSearch"/>

</message>

<message name="ItemSearchResponseMsg"><part name="body" element="tns:ItemSearchResponse"/>

</message>

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wsdl:portType

A portType is a named set of abstract

operations and the abstract messages

involved

<wsdl:portType name="nmtoken"><wsdl:operation name="nmtoken" .... /> * </wsdl:portType>

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4 messaging types:

One-way: endpoint receives a message

Request-response: endpoint receives a message, and sends a

correlated message

Solicit-response: endpoint sends a message, and receives a

correlated message.

Notification: endpoint sends a message

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wsdl:portType - example

<portType name="AWSECommerceServicePortType">...<operation name="ItemSearch">

<input message="tns:ItemSearchRequestMsg"/><output message="tns:ItemSearchResponseMsg"/></operation>...

</portType>

In addition, a message can be used to communicate a fault:<fault message=”...”/>

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wsdl:binding

Extensibility elements allow to specify

Concrete grammar for input, output and fault messages

Concrete per-binding information

Concrete per-operation information

The WSDL specification introduces binding extensions

for:

SOAP

HTTP GET/POST

MIME

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wsdl:binding - example

<binding name="AWSECommerceServiceBinding" type="tns:AWSECommerceServicePortType">

<soap:binding style="document" transport="http://schemas.xmlsoap.org/soap/http"/>

...

<operation name="ItemSearch"><soap:operation soapAction="http://soap.amazon.com"/><input>

<soap:body use="literal"/></input><output>

<soap:body use="literal"/></output>

</operation>

...

</binding>

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wsdl:port

Defines an individual endpoint by specifying an

address for a binding

<wsdl:definitions .... >

<wsdl:service .... > *

<wsdl:port name="nmtoken" binding="qname"> *<-- extensibility element (1) -->

</wsdl:port></wsdl:service>

</wsdl:definitions>

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wsdl:port - example

<service name="AWSECommerceService">

<port name="AWSECommerceServicePort"

binding="tns:AWSECommerceServiceBinding">

<soap:address location="http://soap.amazon.com/onca/soap?Service=AWS

ECommerceService"/></port>

</service>

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The Picture So Far…

Part

Input Message

Part

Input Message

PartPart

Output Message

portType

Operation

Input

Ouput

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Binding Associations to SOAP

Binding SOAP RPC

Operation

WSDL SOAP

SOAP Action

Input

Output

SOAP Body

SOAP Body

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Port Associations to Bindings

Binding Service

OperationPort #1

Input

Output

URL #1

URL #2

Port #2

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Our Echo Messages

<wsdl:message name="echoResponse">

<wsdl:part name="echoReturn“ type="xsd:string" />

</wsdl:message>

<wsdl:message name="echoRequest">

<wsdl:part name="in0" type="xsd:string" />

</wsdl:message>

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EchoService portType

<wsdl:portType name="Echo">

<wsdl:operation name="echo" parameterOrder="in0">

<wsdl:input message="impl:echoRequest"

name="echoRequest" />

<wsdl:output message="impl:echoResponse"

name="echoResponse" />

</wsdl:operation>

</wsdl:portType>

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<wsdl:binding name="EchoSoapBinding" type="impl:Echo">

<wsdlsoap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http" />

<wsdl:operation name="echo">

<wsdlsoap:operation soapAction="" />

<wsdl:input name="echoRequest">

<wsdlsoap:body encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" namespace=“…" use="encoded" />

</wsdl:input>

<wsdl:output name="echoResponse">

<wsdlsoap:body encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" namespace=“…" use="encoded" />

</wsdl:output>

</wsdl:operation>

</wsdl:binding>

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Ports and Services

<wsdl:service name="EchoService">

<wsdl:port binding="impl:EchoSoapBinding" name="Echo">

<wsdlsoap:address location=“http://..../“ />

</wsdl:port>

</wsdl:service>

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WSDL Structure

<service><port><port><port>

<portType><operation><operation><operation>

<binding>[SOAP]

<message>[Request]

<types>[data]

<message>[Response]

<binding>[EJB]

<binding>[…]

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SOAP

Simple Object Access Protocol

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Simple Object Access Protocol (SOAP)

SOAP is an XML based message exchange protocol specified by

the W3C specification.

SOAP is also a lightweight protocol working in a distributed

heterogeneous environment. Some people simply say that SOAP

= HTTP + XML since SOAP message is an XML-document but it

conforms to a specific XML Schema.

SOAP is used to specify the format of a request and response in

the Web service computing to get and send message via HTTP

port by HTTP POST method.

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SOAP (cont.)

Every SOAP message has a required envelope and a message

body. A SOAP envelope identifies an XML document as a SOAP

message.

A SOAP envelope element must have one sub-element which is the

Body element. A Body element of a SOAP message can be data

itself, a name of method be invoked, arguments of the method be

invoked, a SOAP request message, or return results from a SOAP

response message.

A SOAP envelope may also have a header sub element but it is

optional. A header element just gives more metadata about the

message.

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SOAP Request Example

POST /StockQuote HTTP/1.1

Host: www.stockquoteserver.com

Content-Type: text/xml; charset="utf-8"

Content-Length: nnnn

SOAPAction: "http://example.org/2001/06/quotes"

<env:Envelope xmlns:env="http://www.w3.org/2001/06/soap-envelope" >

<env:Body>

<m:GetLastTradePrice

env:encodingStyle="http://www.w3.org/2001/06/soap-encoding"

xmlns:m="http://example.org/2001/06/quotes">

<symbol>DIS</symbol>

</m:GetLastTradePrice></env:Body>

</env:Envelope>

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SOAP Response Example

HTTP/1.1 200 OK

Content-Type: text/xml; charset="utf-8"

Content-Length: nnnn

<env:Envelope xmlns:env="http://www.w3.org/2001/06/soap-envelope" >

<env:Body>

<m:GetLastTradePriceResponse

env:encodingStyle="http://www.w3.org/2001/06/soap-encoding"

xmlns:m="http://example.org/2001/06/quotes">

<Price>34.5</Price>

</m:GetLastTradePriceResponse></env:Body>

</env:Envelope>

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BPEL

Business Process

Execution Language

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What is BPEL4WS

BPEL4WS: Business Process Execution Language for Web Services

Provides an XML notation and semantics for specifying business process behavior based on Web Services

In particular, expresses business processes consisting of functions defined through Web services interfaces

Where it comes from: Traditional flow models

Specified on top of WSDL and XML specifications

Merges WFSL and XLANG concepts

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BPEL Overview

History of BPEL

BPEL emerged as a convergence of language features from

IBM's Web Service Flow Language (WSFL) and Microsoft's

XLANG

BPEL 1.0 was jointly developed by IBM, BEA, SAP, Siebel, and

Microsoft in August 2002

BPEL 1.1 was submitted to OASIS in April 2003

Currently, it is the process of finalising the standard specification,

namely WS-BPEL 2.0

BPEL Engines

BEA WebLogics, IBM WebSphere, Microsoft BizTalk, SAP XI,

Oracle BPEL Process Manager, and ActiveBPEL

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BPEL Structure Overview

<process>

<partners> … </partners>

<variables> … </variables>

<correlationSets> … </correlationSets>

<faultHandler> … <faultHandler>

<compensationHandler> … </compensationHandler>

<eventHandler> … </eventHandler>

(activities)*

</process>

activities = <receive>, <reply>, <invoke>, <assign>, <throw>,<terminate>, <wait>, <empty>, <sequence>, <switch>,<while>, <pick>, <flow>, <scope>, <compensation>

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Activities

Basic activities (or primitive activities) correspond to

atomic actions and stand for work being performed

within a process

Structured activities impose behavioural and execution

constraints on a set of activities contained within them

Can be nested and combined in arbitrary ways

Enable the presentation of complex structures

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Basic Activities

Invoke: invoking an operation on some Web service

Receive: waiting for a message from an external partner

Reply: replying to an external partner

Wait: pausing for a certain period of time

Assign: copying data from one place to another

Throw : indicating errors in the execution

Compensate: undoing the effects of already completed activities

Exit: terminating the entire service instance

Empty: doing nothing

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Structured Activities

sequence: executes one or more activities sequentially

flow: executes one or more activities in parallel

switch: executes one of several paths based on the value of a

condition

pick: block and wait for a suitable message to arrive

while: executes a specified activity as long as a condition is true

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BPEL at Work

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Elements of a BPEL Process

! ! !

JavaSnippet

Wait

JavaSnippet

Receive

Assign

Assign

Receive

Invoke

Receive

Invoke

Throw

PartnerLinksplaceholders for process callers

and service providers

Variableshold data used in

the business process

FaultHandlersenclose activities

that are performed in cases of error

CorrelationSets

support process instance identification

Activitiessubtasks of the process

Control Linksdefine the process'

control flow

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BPELA Simplified Example (1)

<process>

...

<partnerLink name=“customer” ... />

...

<variables>

<variable name = incomingRequest … />

<variable name = customerInfo … />

</variables>

<sequence>

<receive partnerLink="customer"

variable=“incomingRequest“ />

Identifies a

communication partner

Declares variables

Receives a

message

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BPELA Simplified Example (2)

<assign>

<copy>

<from variable=“incomingRequest"

property="props:customerNumber"/>

<to variable=“customerInfo"

property="props:customerID"/>

</copy>

</assign>

...

</sequence>

</process>

Performs an assignment

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BPEL Structure

BPEL draws upon concepts and constructs from imperative

programming languages

lexically scoped variables, variable assignment, sequential execution,

conditional branching, structured loops, and exception handling (try-

catch blocks)

BPEL extends this basic set of constructs with constructs related to

Web services and business process management

Messaging: send, receive, send/receive

Concurrency: block-structured parallel execution, race conditions,

event-action rules

XML typing: XML Schema, WSDL, XPath, XSLT

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Basic Activities for Interactions

Invoke, receive, and reply are three types of interaction actions Invoke/reply “send” action

Receive “receive” action

Invoke: synchronous (“request-response”) vs. asynchronous (“one-way”) operation

Receive: instantiation of a new process instance

Restrictions “conflictingReceive” and “conflictingRequest”

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Defining a Graphical Process Notation

The Business Process Modeling Notation (BPMN) aims

at defining a standard graphical notation for defining

process logic

It’s owned by the Object Management Group (OMG)

Receive

Invoice

PO

Found?

Process

POSend

PaymentYes

OK?

Yes

NoNo

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Example

<sequence>

<receive name=“startBusProcess” partnerLink=“Buyer”

operation=“request” variable=“request” createInstance=“yes”/>

<flow name=“supplier_flow”>

<invoke name=“quote1” partnerLink=“Supplier1”

operation=“request_quote” inputVariable=“part_request”

outputVariable=“part_quote”/>

<invoke name=“quote2” partnerLink=“Supplier2”………/>

</flow>

<reply name=“respond” partnerLink=“Buyer”

operation=“send_proposal” variable=“proposal”/>

</sequence>

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Example

A correlation set contains a set of properties shared by all messages in a correlated group

<invoke partnerLink="Buyer" portType="SP:BuyerPT"

operation="AsyncPurchaseResponse"

inputVariable="POResponse">

<correlations>

<correlation set="PurchaseOrder" initiate="no"

pattern="out">

<correlation set="Invoice" initiate="yes" pattern="out">

</correlations>

</invoke>

<correlationSet name="PurchaseOrder"

properties="cor:customerID cor:orderNumber"/>

<correlationSet name="Invoice"

properties="cor:vendorID cor:invoiceNumber"/>

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Sequence contains activities that are performed sequentially

Switch supports conditional routing between activities case – normal conditional branches

otherwise – default branch

Pick captures race conditions based on timing or external triggers onMessage – message events

onAlarm – alarm events

While supports repeated performance of an activity in a structured loop

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Flow provides parallel execution and synchronization of activities Support the usage of control links for imposing further control

dependencies between activities

Scope is used for grouping activities into blocks, each being treated as a unit to which the same event and exception handling can be applied A primary activity defines its normal behaviour

It can provide event handlers, fault handlers, and compensation handlers

The entire process is seen as the top level scope

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BPEL Models

<sequence>

<flow>

<pick>

Serialized <send>,

<receive>,

<invoke>, <…>

parallel <send>,

<receive>, <invoke>,

<…>

Wait for one or more

<receive> or an

alarm condition

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BPEL Models

<switch>

<case />

</switch>

While

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Control Links

Control links are a non-structural construct defined in BPEL

A control link denotes a conditional transition between two activities

Notions related to control links A transition condition (associated with a control link) is a boolean

expression over the process variables

A join condition (associated with an activity) is a boolean expression in terms of tokens carried by incoming control links to the activity

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Compensation

Compensation refers to application-specific activities that

attempt to undo the already completed actions

A compensation handler is defined for a scope, and

specifies the actions need to be taken for the

compensation of the scope

A compensate activity is used to invoke the

compensation of an inner scope, i.e., its occurrence

triggers the compensation handler associated with that

scope

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BPEL at Work

salesBP: example of a BPEL process for sales service It interacts with a

customer process (customerBP) via asynchronous messages

salesBP is the service provider

Customer is the service requester

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Conclusion

BPEL is being used primarily as a language for implementing Web services using a process-oriented paradigm It is competing with existing enhancements to mainstream

programming environments

BPEL abstract processes can be viewed as adding “behaviour semantics” on top of the basic structural definitions of service interactions provided by WSDL interfaces Tool vendors give little attention to exploring the possibilities

opened by BPEL abstract processes

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UDDI

Universal Description,

Discovery and Integration

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UDDI

• Universal Description, Discovery and Integration

• Platform-independent, open framework for describing services,

discovering businesses, and integrating business services.

• A layer above SOAP, it is the glue that connects all the SOAP

objects into a Business Web

• DNS like model implementation of the directory

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UDDI

UDDI Business Registry

3. UBR assigns a programmatically unique

identifier to each service and business

registration

Service Type

Registrations

Business

Registrations

SW companies, standards

bodies, and programmers

populate the registry with

descriptions of different types

of services

1.

Businesses

populate

the registry with

descriptions of

the services they

support

2.

Business uses this

data to facilitate easier

integration with each

other over the Web

5.

Marketplaces, search

engines, and business apps

query the registry to

discover services at other

companies

4.

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UDDI

The Web service provider can register their Web services at these UDDI registries and Web service requester can lookup a specificWeb service by its provider name (business name), category info, Web service name, or even by the keys of them if requester knows.

A Web service provider actually registers a WSDL (web Service Description Language) interface at UDDI registry which is a contract interface of the Web service to be used by its client.

Both UDDI query requests and UDDI query results are in the SOAPformats.

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Registry Data

Businesses register public

information

about themselves

Standards bodies,

Programmers, Businesses

register information about

their Service Types

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Business name

Text description

List of multi-language text strings

Contact info

Names, phone numbers,

fax numbers, web sites…

Known identifiers

List of identifiers that a business may be known by -

DUNS, Thomas, other

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Business categories

3 standard taxonomies in V1

Industry: NAICS (Industry codes - US Govt.)

Product/Services: UN/SPSC (ECMA)

Location: Geographical taxonomy

Implemented as name-value pairs to allow any valid

taxonomy identifier to be attached to the business

white page

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New set of information businesses use to

describe how to “do e-commerce” with them

Nested model

Business processes

Service descriptions

Binding information

Programming/platform/

implementation agnostic

Services can also be categorized

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UDDI

A Web service provider must publish/register its services with a Universal Description, Discovery, and Integration (UDDI) registry so that it can be accessed by any Web services requester globally.

It just looks like a phonebook where all businesses register their phones there for customers to lookup services. A customer must lookup the phonebook either on-line or by phonebook unless a customer knows the phone number before.

A Web service can also be reached without any assistance from UDDI if the Web service client knows the contact information such as Web service’s URL, name of method, argument signature of the method including types of return value.

79

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