Web Services and Service Oriented Architectures

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Overview. • The Garching Supercomputing Center - RZG. • Diving into the world of Web Services. • Service Oriented ... Client Server Architectures. ○. 2-Server ...
Web Services and Service Oriented Architectures Thomas Soddemann, RZG

Delaman Workshop 2004

Web Services and Service Oriented Architecture

Overview

• The Garching Supercomputing Center - RZG • Diving into the world of Web Services • Service Oriented Architectures • And beyond

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Web Services and Service Oriented Architecture

RZG – Rechen-Zentrum Garching

Supercomputing Center for the Max Planck Society (MPG) Services and involvements: • Supercomputing facility with a 5 TFlop IBM Regatta system • Linux compute farms • Data Storage • DEISA • MiGenAS • D-Grid – German Grid initiative • Data Acquisition for ASDEX Upgrade and Wendelstein 7X (Plasma Physics)

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Web Services and Service Oriented Architecture

Machine Room

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Web Services and Service Oriented Architecture

DEISA – Distributed European Infrastructure for Supercomputing Applications

• Consortium of leading national supercomputing centers • focuses in deploying an Grid empowered infrastructure • to build a distributed terascale supercomputing facility

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Web Services and Service Oriented Architecture

Web Services and more

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Web Services and Service Oriented Architecture

Client Server Architectures



2-Server Side Tier Applications

e.g. Web Server PHP app.

e.g. Web Browser Rich Client

Internet Thomas Soddemann

Legacy

Client

Server

integrated Controller/View/Business logic, legacy applications and databases

e.g. Databases Batch systems

Intranet Delaman Workshop 2004

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Web Services and Service Oriented Architecture

Client Server Architectures

e.g. Web Browser Rich Client

Internet

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e.g. Web Server and Web App.

Legacy

Enterprise

Frontend

3-Server Side Tier Applications

Client



Enterprise application

Intranet

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Web Services and Service Oriented Architecture

Client Server Architectures

Internet

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Legacy

Proxy Service Client

Enterprise

Frontend

3-Server Side Tier Applications with explicit services

Client



Enterprise application

Intranet

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Web Services and Service Oriented Architecture

Service A service ... ●

... can be discovered & dynamically bound.



... is self-contained & modular.



... exhibits a coarse grained service interface.



... is based on a loose coupling between provider & consumer.



... is interoperable.



... is addressable and locatable via a network.



... can be composed out of other services.

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Web Services and Service Oriented Architecture

Web Service Definition W3C, Web Services Architecture, http://www.w3.org/TR/ws-arch A Web Service is a software system designed to support interoperable machineto-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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Web Services and Service Oriented Architecture

Message Oriented Model View

agent

originates

processes

message header(s)

delivers

Message transport

body

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Web Services and Service Oriented Architecture

Service Oriented View

agent owns/controls realizes Service describes signals meta-data message

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Web Services and Service Oriented Architecture

Resource Oriented View

URI

has

owns

resource may have

representation

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Web Services and Service Oriented Architecture

Policy Model View

agent establishes subject to policy applies to resource

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constraints

action

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Web Services and Service Oriented Architecture

Web Services Examples Web service http://live.capescience.com/ccx/GlobalWeather ●

Provides airport and flight weather information

Amazon Web Services (AWS & ECS) http://www.amazon.com/webservices ●

Provide e-commerce services such as lookup of books

Google Web API http://www.google.com/apis/ ●

Guess ...

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Web Services and Service Oriented Architecture

Services: Roles and Interaction Implementations:

Service Broker (Registry)

find

publish

Service Consumer

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UDDI JNDI CORBA naming

bind

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Service Provider

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Web Services and Service Oriented Architecture

Services: (Dynamic) Proxy

find e.g.

WSDL

Service Broker (Registry)

Service Consumer Implementation Code

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Proxy

bind

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Service Provider

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Web Services and Service Oriented Architecture

Objects



Reference identifier to reference an object during its lifetime



State state of the object represented by its attributes



Interface “collection” of methods which are necessary to interact with the object

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Web Services and Service Oriented Architecture

Is a Service an Object in general?

A service ... ●

... can be referenced during its lifetime

RQ



... does not necessarily have a state

Q



... does have an interface

R

[ A service is not an Object in general.

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Web Services and Service Oriented Architecture

Service Oriented Architectures (SOA) An architecture of software which is composed of services.

Service Oriented Architecture

Web Services

CORBA

Jini

EJB

No Objects

Objects

Objects

Objects

Simple WS: No session, no state [ e.g. Shopping Cart realization? Desirable: Object like Web services

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Web Services and Service Oriented Architecture

Example: Shopping Cart in J2EE

R Request

Servlet containter

EJB containter

Controller

EJB

Response View

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Database

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Web Services and Service Oriented Architecture

Problem: Shopping Cart in a Web Service world

R Request

Servlet containter

EJB containter

Response Database

Problem: No State, no session [ no shopping cart service Note: HTTP(S) session is not enough Thomas Soddemann

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Web Services and Service Oriented Architecture

Services Architectures Web service Is not an object in general ● Rather XML documents are exchanged ● Are the interface to a part of the Business Logic ●

Enterprise Java Beans Are Objects by definition ● Encapsulate the Business Logic of J2EE applications ●

CORBA – Common Object Resource Broker Architecture CORBA Objects are Objects by definition ● Encapsulate the Business Logic of Enterprise Applications ●

Further: Jini, ... Thomas Soddemann

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Web Services and Service Oriented Architecture

From a simple Web Services to an (quasi) Object The Web Services Resource Framework WS-RF A Web Service Resource (WS-Resource) ●







... can be destroyed (explicit destroy or expiration) and its lifetime may be monitored WS-ResourceLifetime ... contains a state through attributes/properties WS-ResourceProperties ... references can be renewed WS-Addressing WS-RenewableReferences ... employs a (more) standardized fault reporting mechanism WS-BaseFault

Further: By-reference collections of Web Services can be defined. WS-ServiceGroup

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Web Services and Service Oriented Architecture

Web Services Architecture Stack

XML, XSD

Security

Processes Discovery, Aggregation, Choreography, ... Descriptions (WSDL) Messages SOAP Extensions SOAP

Communication Layer (HTTP, SMTP, ...)

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Web Services and Service Oriented Architecture

Data Services Data querying and access to mutitple data sources Component Services Atomic services potentially acting on single ERs Enterprise Resources DB

Code

Legacy

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Partners

Policies Security

Complex Services composed of component services

Interceptrors

SMTP

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HTTP

Transport

Portals

Consumers

Rich Clients

Code

Message Broker

Business Services

Core Services

Partners

k Business processes, services with external interaction

Brokers

Workflow Services

Management

Software Architecture for the Access Infrastructure

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Web Services and Service Oriented Architecture

WS-Security

Original Requester End to end security SOAP with security context

Security Intermediary SOAP with security context

Ultimate Receiver

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Web Services and Service Oriented Architecture

WS-Security Threats:



Message Alteration – modififying the message content



Confidentiality – accessing message parts such as credit card info



Man-in-the-middle – establishing complete access to messages



Spoofing – exploting trusted relationships

Denial of Service – preventing a legitimate user from accessing a service ●

Replay Attacks – interception of messages and playing to back to the service ●

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Web Services and Service Oriented Architecture

WS-Security WS-Security has to insure/provide



Authentication mechanisms (PKI)



Authorization



Data integrity and confidentiality



Integrity of transactions and communications



Non-repudiation (detection of transaction initiated/altered by a 3rd party)



End-to-end integrity and confidentiality of messages



Audit trails (trace user's behavior)

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Web Services and Service Oriented Architecture

Implementation and deployment: J2EE

Network

Web Server

EJB Container

Client Servlet Container

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Database

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Web Services and Service Oriented Architecture

Distributed Service Centers

Web Server

Network

Servlet Container

EJB Container

Database

Network

Client

Web Server

Servlet Container

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EJB Container

Database

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