SOA_2_final_2009

SOA Part1 Lecture 2









Dr. Withalm 17-Dec-11 SOA Bratislava

Lectures at the University of Bratislava/Autumn 2009





28.09.2009 Lecture 1 Evolution Of Architectures- The long Way from OO to SOA



05.10.2009 Lecture 2 WEB-Services& Semantic WEB



12.10.2009 Lecture 3 SOA-Technological Basis



19.10.2009 Lecture 4 SOA-Basing on J2EE



23.11.2009 Lecture 5 SOA-Focus on Business Processes



30.11.2009 Lecture 6 B2B Frameworks and related Standards



07.12.2009 Lecture 7 WEB 2.0 & GRID









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Today’s Agenda









 WEB Services

 Example

 Standards

 Semantic WEB

 Example

 Ontology

 Connection to WS









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Summary of last lecture



 Progress in Architecture are primarily enabled by technology

 i.e. distributed computing by PC & Ethernet

 Distributed computing encouraged Middle ware

 i.e. RPC, CORBA, DCOM-which work efficient in EAI-projects

 Middle ware is kept enclosed within companies mainly because of “closed”

ports

 i.e. most serious obstacle when deploying CORBA applications in IAI

projects

 EJB tried to combine strenghts of ORB and TP

 Overcoming the performance issue which requested huge programming

efforts in CORBA applications

 EJB made a first “implicit” step towards services

 i.e. Session Beans-whenever their focus was mainly IT-focused and not

business oriented.









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Web-Services

Example/1







 A car rental company has a database that indicates



 What kind of cars are available at each location along with the published



rental rate



 Compact, full-size, luxury, etc.



 There is an application function that



 When provided with the location and class of car



 Returns availability and price.









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Web-Services

Example/2







 Originally, this function would have been contained wholly



 Within a booking application



 Used by the company„s agents to respond



 To telephone requests from customers and travel agents.









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Web-Services

Example/3









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Web-Services

Example/4





 The company soon learned, however, that other parts of the organization



needed access to this same function.



 Since auto rentals are highly competitive in same location



 For example: marketing requests direct access to the availability and



price function.



 So they can quickly respond to competitors moves.



 IT is asked to integrate the marketing application with the booking



application.



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Web-Services

Example/5





 For IT, integrating functions across internal applications is



commonplace.



 Several client/server technologies evolve to help achieve the



architecture.









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Web-Services

Example/6





 Then came the Web

 Now IT was asked to make the availability and price function available to users over the

Internet.

 Fortunately, Internet standards emerged to make this possible

 The browser is a standard client.

 HTTP is a standard communication protocol for the Internet.

 HTML provides data functionality that can be interpreted and displayed by browsers.

 CGI- and later application servers-provide a way for developers to interface to the

application function.









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Web-Services

Example/7





 Most of the Web development effort of the late nineties was directed toward



making an enterprise„s application functions



 Available directly to customers over the Internet.



 But this is not a Web service since it is accessed by a browser user, not a client



application.









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Web-Services

Example/8



 The next step for the rental car company is to make the availability and price

function-and even the booking function

 Available not only to browser users

 But to the booking applications of other companies

 Travel agents cannot browse the Web sites of all potential car rental companies

 Looking for the best price.

 They need an automated way to access the information and to place a

booking.

 Web-based travel services need to do this programmatically in response to

requests from browser users.









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Web-Services

Example/9





 Once the Web services have been developed

 The rental car company can announce the availability of the service

 Publish their interface specifications

 In a directory accessible to everyone in the Web.

 This allows potential partners to discover the availability of the rental

car Web services.

 And provide partners with the information required.

 To access the Web services from a client application.









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Web-Services

Example/10





 Adding the Web services to an enterprise Web application environment can



result in the following architecture



 These application functions provide data and services



 To both browser users and client applications.









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Web-Services

Example/11









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Web-Services

Example/12





 These are the needs driving the development of Web services

 Application functions that can be accessed by other applications

using Internet technology.

 The key elements of this definitions are:

 Access to the service is available to applications, not browsers

 The standard technologies that enable this access are developed

specifically for operations over the Internet.









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Web-Services

Example/13



 In some respects Web services are just an updated, Internet enabled



way of doing something application developers have always been able to



do.



 In other ways Web services promise to change the way business is done



 And even to enable new kinds of business



 Application integration has been around a long time



 And there exist mature technologies that can do this.









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Web-Services

Example/14







 CORBA, COM, DCOM and later J2EE provide facilities



 To create application functions with defined and accessible interfaces



 And to enable the development of clients



 That can access them-even over the Internet.









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Web-Services

Example/15





 There are two fundamental advantages by Web services over earlier application integration



approaches.



 The underlying technology is designed from the ground up to operate over the Web and



, in fact, leverages the existing standards that have made the Web successful.



 Web services, and the technologies that are used to build them, take openness to a



new level.









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Web-Services

Example/16





 While earlier approaches made it possible to provide an internal or external

partner with the interface definition of an application function

 So they could build a compatible client

 Web services include the concept of an universal directory

 To publish the availability of the service to the entire Internet

 And to make it possible for a subscriber to create a client application

 That can easily, even dynamically, access the service.

 Further, since the standards are widely implemented on most platforms

 There is a degree of platform independence (HW, OS, and middleware) not

previously available.









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Web-Services

Example/17





 In theory, a client can even be made smart enough

 To read and interpret the interface specification

 And dynamically access the Web service

 Web service promise a world in which applications can search the Web for services they

need

 And access these services in much the same way that browser users use search

engines to locate and access Web sites.









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Web-Services

Example/18





 That is the vision



 The reality is that technology is new



 The standards are still evolving



 And the Web services being developed tend to be



 Simple solutions for simple problems



 Most of them are internal integration efforts.



 What also is required is



 Semantic Web









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Core Web-Services Standards









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Other Web Service Standards/1







Business Domain Specific Extensions Various Business Domain



Distributed Management WSDM, WS-Manageability Management

Provisioning WS-Provisioning



Security WS-Security Security

Security Policy WS-SecurityPolicy

Secure Conversation WS-SecureConversation

Trusted Message WS-Trust

Federated Identity WS-Federation





Portal and Presentation WSRP Portal and

Presentation









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Other Web Service Standards /2







Asynchroneous Services ASAP Transactions

and Business

Transaction WS-Transaction, WS-Coordination

Process

Orchestration BPEL4WS, WS-CDL



Events and Notification WS-Eventing, WS-Notification Messaging

Multiple Message Sessions WS-Enumeration, WS-Transfer

Routing / Addressing WS-Addressing, WS-MessageDelivery

Reliable Messaging WS-ReliableMessaging, WS-Reliability

Message Packaging SOAP, MTOM



Publication and Discovery UDDI, WSIL Metadata

Policy WS-Policy, WS-PolicyAssertions

Service Message Description WSDL

Metada Retrieval WS-MetadataExchange







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Web Services







 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.









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Portlets/1







 In contrast with Web-Services



 which are computer-to-computer services



 Presentation Oriented Services provide a user interface



 that allows an end-user to interact directly with the service.



 Two main standards exist



 the JSR (Java Specification Request) 168 Specification



 and the WSRP (Web Service for Remote Portlets) Specification.





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Portlets/23

WSRP Specification/1



 is a production of OASIS.



 Since all of the major players in the portal market are

represented on OASIS' WSRP Technical Committee,



 the technology should continue to enjoy broad

acceptance in the industry.



 The OASIS WSRP specification defines a common, well-

defined interface



 for communicating with pluggable, presentation-

oriented Web services.



 These services process user interactions and provide

mark-up fragments for aggregation by portals.

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Web Service Standards







 OASIS and the W3C are the steering committees

responsible for the architecture and standardization of

web services. To improve interoperability between web

service implementations, the WS-I organization has been

developing a series of profiles to further define the

standards involved.









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Web Service Base Standards/1







 Simple Object Access Protocol (SOAP) - defines the runtime

message that contains the service request and response. SOAP is

independent of any particular transport and implementation

technology.



 Web Services Description Language (WSDL) - describes a Web

Service and the SOAP Message. It provides a programmatic way to

describe what a service does, paving the way for automation.



 Universal Discovery, Description, Integration (UDDI) - UDDI is a

cross industry initiative to create a standard for service discovery

together with a registry facility that facilitates the publishing and

discovery processes.









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Web Service Base Standards/2









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Web Service Base Standards/3









Service

Registrar









Define (WSDL)



Service Service

Use (SOAP)

Consumer Provider

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Universal Discovery, Description, Integration

(UDDI)







 UDDI is a platform-independent, XML-based registry for

businesses worldwide to list themselves on the Internet. UDDI is

an open industry initiative (sponsored by OASIS) enabling

businesses to discover each other and define how they interact

over the Internet.



 A UDDI business registration consists of three components:

 White Pages - address, contact, and known identifiers;

 Yellow Pages - industrial categorizations based on standard

taxonomies; and

 Green Pages - technical information about services exposed

by the business









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Simple Object Access Protocol

(SOAP)





 SOAP originally was an acronym for Simple Object

Access Protocol, but the acronym was dropped in Version

1.2 of the SOAP specification. Originally designed by

Dave Winer, Don Box, Bob Atkinson, and Mohsen Al-

Ghosein in 1998 with backing from Microsoft (where

Atkinson and Al-Ghosein worked at the time), the SOAP

specification is currently maintained by the XML Protocol

Working Group of the World Wide Web Consortium.









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SOAP (W3C)







 SOAP is fundamentally a stateless, one-way

message exchange paradigm, but applications

can create more complex interaction patterns

(e.g., request/response, request/multiple

responses, etc.) by combining such one-way exchanges with

features provided by an underlying protocol and/or application-

specific information.

 SOAP provides the framework by which application-specific

information may be conveyed in an extensible manner. Also, SOAP

provides a full description of the required actions taken by a SOAP

node on receiving a SOAP message.









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Web Services Description Language (WSDL)





 WSDL is an XML format published for describing Web services.

 WSDL describes the public interface to the web service. This is

an XML-based service description on how to communicate using

the web service; namely the protocol bindings and message

formats required to interact with the web services listed in its

directory. The supported operations and messages are

described abstractly, and then bound to a concrete network

protocol and message format.

 WSDL is often used in combination with SOAP and XML

Schema to provide web services over the internet. A client

(program) connecting to a web service can read the WSDL to

determine what functions are available on the server. Any

special datatypes used are embedded in the WSDL file in the

form of XML Schema.

 Basic Idea is coming from IDL/CORBA





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WSDL Elements/1









Element Name Description



types a container for abstract type definitions defined using XML Schema



A definition of an abstract message that may consist of multiple parts, each part may

message be of a different type



An abstract set of operations supported by one or more endpoints (commonly known

portType as an interface); operations are defined by an exchange of messages



binding A concrete protocol and data format specification for a particular portType



A collection of related endpoints, where an endpoint is defined as a combination of a

service binding and an address (URI)



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WSDL - Binding







 A service can support multiple

Messages

bindings for a given interface,

but each binding should be

Tcp Smtp Http accessible at a unique address

identified by a URI, also

referred to as a Web service

URI URI URI endpoint .



 Usually this information from the

WSDL is used to implement late

Interface Interface

binding.

operation operation

operation operation

operation operation

Service



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Semantic Web





 Semantics: Meaning of a word, a sentence or a text

 The existing web consists of data,

 which is readable for machines

 which should – in the future – be made understandable and

interpretable for machines









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Motivation for Semantic WEB/1





 Task: Find and buy specific audio CD on the web

 At present:

 "clicking" from one web-shop to the next

 performing the same search on each site

 comparing the prices

 A SW-agent is currently unable to find CD-retailers on the web

 If it has a list of retailers, there is another problem:

 How shall it search the site for relevant offers?









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Motivation for Semantic WEB/2







 Problems of the search request:

 Over HTTP and URL, but how exactly?

 Is there a search-function implemented in the site?

 If yes, with which URI should the request be placed?

 What are the parameter names?

 HTTP-transmission over GET- or POST-method?









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Motivation for Semantic WEB/3







 Problems with the received answer:

 Humans see the web-page as more or less beautifully designed

 It contains the price of the CD, but where?

 The SW-agent is unable to find it out

 If it would be programmed to find it in line 3, column 5?

 What happens if the layout is changed?









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Solutions/1





 Parts of the HTML-code could be made interpretable for the agent with

the help of XML

 If tags like ... were added to the HTML elements, the

agent could recognize the requested data

 W3C recommends the XML-schemata for establishing the required

vocabulary









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Solutions/2







 Another problem arises if the simple example is translated into

another language, resulting in tags like .... (German)

or .... (French)

 in this case, another element-type name is used to express the

same term









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Solutions/3





 But do they really have the same meaning?

 Do 20 and 20 have exactly the

same significance?

 Obviously the currency is not defined!

 Does the price include taxes? (USA!)

 Fluctuations of exchange rates:

 Are 20 US$ at the time when the product is ordered the same

as when the invoice is issued?









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Solutions/4







 price and preis are closely related

 In the W3C scenario, the nature of this relationship is explained by:

 RDF (Resource Description Framework) is the basis for expressing

information about all things that can be addressed by a URI Basis

 OWL (Ontology Web Language) provides a notation for ontology

 An ontology is the description of terms and their interrelations

within a domain (a context-sensitive vocabulary)









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Semantic Web Example/1







Listing 1: Wine Ontolgy























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Semantic Web Example/2







 This is a section of an ontology that classifies wines

 If it is predefined, the SW-agent‟s job becomes easier...

 ...e.g. if it is given the task of finding offers from wine

merchants for:

 red wine

 vintage 1995









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Semantic Web Example/3







Listing 2: Merchant Data





040 / 1234

Mo – Fr 10am -4pm/Office Hours>









......

2007

20

25 Boxes







...................



...................











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Semantic Web Example/4







 This document contains neither the term "red wine" or "vintage"

 but with its ontology knowledge, the agent conceives that Chianti is a

red wine

 if the ontology defines that in the wine-domain "year" and "vintage"

have the same meaning, the problem is solved

 Furthermore, the data type is defined:

 Type integer according to the XML-scheme









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Semantic Web Example/5







Listing 3: Same Meaning



















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Semantic WEB







 The Semantic Web is a vision for the future of the Web

 in which information is given explicit meaning

 making it easier for machines to automatically process and integrate

information available on the Web.

 The Semantic Web will build on XML's ability

 to define customised tagging schemes

 and RDF's flexible approach to representing data.

 The next element required for the Semantic Web is a web ontology language

 which can formally describe the semantics of classes and properties used in

web documents.

 In order to machines perform useful reasoning tasks on these documents

 the language must go beyond the basic semantics of RDF Schema.

 OWL has been designed to meet this need for a Web Ontology Language.







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Semantic WEB: Summary/2







 A further step is to:

 develop useful tools such as the wine agent

 so that content providers will provide the required meta-data

as a supplement to HTML









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Semantic Web Layers

[Tim Berners-Lee]









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Ontology/1







 hierarchical structure of terms

 which are brought into relationship through pre-defined

associations

 the definition of sub-classes is the most common way of

establishing a hierarchy

 specialisation of the terms

 every term can be structured further by attributes









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Ontology/2







 ontology focus on connecting terms in order to allow statements

 for example:

 the residential address of Person Smith is identical with the working

address of person Smith

 the household at the residential address consists of only one

address

 therefore we conclude that Person Smith runs a small company









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Ontology/3







 further partial ontology can be derived:

 residential address is a sub-class of address

 working address is a sub-class of address

 household is the entirety of persons with identical residential

address

 small company is a sub-class of company









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Ontology/4







 Ontology is the attempt to formulate an exhaustive and rigorous

conceptual schema

 within a given domain, typically a hierarchical data structure

 containing all the relevant entities and their relationships and

rules (theorems, regulations) within that domain.

 For example: in the automotive industry Bill of Material

 To be useful, ontology must be expressed in a concrete notation.

 An ontology language is a formal language by which an ontology is

built.

 There have been a number of data languages for ontology

 both proprietary and standards-based:

 CycL (ontology language based on first-order logic)

 KIF (syntax for first order logic)

 OWL, a language compatible with the architecture of the World

Wide Web in general, and the Semantic Web in particular.

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Ontology Interoperability







 Ontology, as the means for conceptualising and structuring domain

knowledge

 has become the backbone to enable the fulfilment of the

Semantic Web vision.

 It aims to make data more sharable.

 However, ontology themselves can be heterogeneous.

 Mapping between different ontology thus becomes essential to

ontology interoperability.

 Ontology mapping is the task of finding semantic relationships

between entities of two ontology.

 i.e. concept, attribute, and relation.









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Heterogeneity of Ontology/1







 In order to reach interoperability over heterogeneous ontology,

two problems must be dealt with,

 i.e.: metadata heterogeneity and instance heterogeneity .

 Metadata heterogeneity concerns the intended meaning of

described information. There are two kinds of conflicts in

metadata heterogeneity:

 structure conflict, which means that ontology for same domain

knowledge may have different semantic structures; and

 name conflict, which means that the same concept may use

different names or different concepts may use the same

name.









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Heterogeneity of Ontology/2







 Instance heterogeneity concerns the different representations of

instances.

 Information described by the same ontology can be represented

in different ways, also called representation conflict.

 For example,

 date can be represented as “2004/2/27” or “Feb, 27,

2004”;

 person name can be represented as “Jackson Michael”

and “Michael, Jackson”, etc.

 Representation conflict requires normalisation before ontology

interoperation.









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Different solutions for Ontology Interoperability/4







 Following a summary of the main approaches to ontology

Interoperability

 Ontology mapping/matching.

 Ontology alignment.

 Ontology translation.

 Ontology transformation.

 Ontology merging/integrating.

 Ontology checking.

 Ontology evolution/ versioning.









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WS Language Descriptions/1







 The Semantic Web should enable greater access not only

to content but also to services on the Web.

 Users and software agents should be able

 to discover, invoke, compose, and monitor Web

resources

 offering particular services and having particular

properties,

 and should be able to do so with a high degree of

automation when desired.

 To make use of a Web service,

 a software agent needs a computer-interpretable

description of the service

 and the means by which it is accessed.





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WS Language Descriptions/2







 An important goal for Semantic Web markup languages

 is to establish a framework within which these descriptions are

made and shared.

 Web sites should be able to employ a standard ontology

 consisting of a set of basic classes and properties

 for declaring and describing services

 and the ontology structuring mechanisms of OWL

 provide an appropriate and Web-compatible

representation language framework within which to do

this.









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OWL-S/2

Top Level of the Service Ontology









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OWL-S/3







 OWL-S has three main parts:

 What does the service provide for prospective clients?

The answer to this question is given in the “profile”

(ServiceProfile class), which is used to advertise the

service.

 How is it used? The answer to this question is given in

the “process model”. This perspective is captured by

the ServiceModel class.

 How does one interact with it? The answer to this

question is given in the “grounding”. A grounding

(ServiceGrounding class) provides the needed details

about transport protocols.









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Thank you

for your attention!









SOA Bratislava

Farbpalette mit Farbcodes







Primäre Flächenfarbe: Akzentfarben:

R 255 R 255 R 245 R 229 R 000 R 000 R 000

G 255 G 210 G 128 G 025 G 133 G 084 G 000

B 255 B 078 B 039 B 055 B 062 B 159 B 000





R 255 R 248 R 236 R 064 R 064 R 064

G 221 G 160 G 083 G 164 G 127 G 064

Sekundäre Flächenfarben: B 122 B 093 B 105 B 110 B 183 B 064





R 215 R 170 R 130 R 255 R 250 R 242 R 127 R 127 R 127

G 225 G 190 G 160 G 232 G 191 G 140 G 194 G 169 G 127

B 225 B 195 B 165 B 166 B 147 B 155 B 158 B 207 B 127





R 220 R 185 R 145 R 255 R 252 R 248 R 191 R 191 R 191

G 225 G 195 G 155 G 244 G 223 G 197 G 224 G 212 G 191

B 230 B 205 B 165 B 211 B 201 B 205 B 207 B 231 B 191





R 255 R 254 R 252 R 229 R 229 R 229

G 250 G 242 G 232 G 243 G 238 G 229

B 237 B 233 B 235 B 235 B 245 B 229









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