distribution and integration technologies › ~apm › tdin › docs › 01dist.pdf · distributed...

Distributed Architecture

Distribution and Integration

Technologies

Distributed Architectures

Patterns and Styles

APM@FEUP 1


Distributed applications infrastructure

intranet

ISP

desktop computer:

backbone

satellite link

wireless

server:

network link: • inside an organization (intranet)

• with external clients

• between organizations

Mobile

wireless link:

laptops:

tablets:

smartphones:

APM@FEUP 2


Ubiquitous computing / spontaneous network

Internet

gateway

Mobile

service

Music service

serviceDiscovery

Alarm

Camera

Guestsdevices

LaptopTV/PC

Internet

gateway service

Music service

serviceDiscovery

Alarm

Camera

Guestsdevices

LaptopTV/PC

Hotel / Shopping

wireless network

APM@FEUP 3


Characteristics / challenges

❖ Heterogeneity▪ Use: many OSs, hardware, programming languages, frameworks, …

❖ Extensibility▪ Easy integration of new services, components, nodes, …

❖ Security▪ Protection: confidentiality, integrity, authentication, availability, …

❖ Scalability▪ Architecture: allow more users with more resources without degrading

❖ Fault tolerance and treatment▪ Response to communication, node, service faults and failures …,

❖ Concurrency▪ Several simultaneous clients and users

❖ Transparency▪ To the user and to the programmer

APM@FEUP 4


Enterprise applications

Sales Marketing Client

Services

ITHuman

ResourcesProduction

Account

Management

Product

Distribution

Stock

Management

CRM

ERP

Departments

Front-office

Back-office

APM@FEUP 5


Application logic architecture

Interface

Data

Business

Logic

Client tier Middle tier Data tier

APM@FEUP 6


Tiered architecture

Pre

sen

tati

on

User

Inte

rface

Bu

sin

ess

Lo

gic

Data

Acce

ss

Data

Man

ag

em

en

t

an

d S

tora

ge

Presentation – Interface design and data visualization/input

LogicInterface Data

UI – Interaction and data transport to the business logic layer

Business – Data validation, manipulation, processing and security

Access – Data encapsulation and transformation to storage models/formats.

Extraction and storage actions.

Storage – DBMS’s and access drivers

APM@FEUP 7


An enterprise application (detail)P

rese

nta

tio

n

La

ye

r

Se

rvic

es

La

ye

rB

us

ines

s

La

ye

r

Da

ta

La

ye

r

Service Interfaces Message Formats

UI Components

Presentation

Logic Components

Application Façade

Business

Workflows

Business

Entities

Business

Components

Data Access

Components

Data

Utilities

Cro

ss

Cu

ttin

g

Secu

rity

Co

mm

un

ica

tio

n

External

Applications

External

Services

Service

Agents

Data

Presentation

Entities

APM@FEUP 8


Workflows / BPM

Services and Activities orchestration to form a business process

Business Workflow

Service Agent

Service Interface

Service Interface

Component

APM@FEUP 9


Distributed architecture styles (1)

❖ Client / Server

▪ One half of the application (Client) emits requests to the other

half (Server)

▪ Client and Server execute in different processes in the same or

different machines

▪ Server can be client of other Servers

▪ Clients can obtain answers concurrently

▪ This style exists practically in every distributed application

APM@FEUP

Workstation Server

10


❖ Component based architecture

▪ The application is decomposed in functional and reusable

portions exposing a known and defined interface

▪ The components can generally be installed in different

processes and can be remotely invoked using RPC


Comp A

Comp B

Comp C

Comp D

Client

Process 1

Process 2

Process 3

APM@FEUP 11


Components

Interface 1:

method 1

method 2

Interface 2:

method 3

method 4

Remote class 1

Interface 3:

method 5

method 6

Interface 4:

method 7

method 8

Remote class 2

Installation unit:

component (executable code file)

A middleware provides a functionality set

allowing the easy creation of new instances

of the remote classes and the invocation

of their methods (implementing transparent

RPC and other common services)

properties (general OO):

encapsulation

inheritance

polymorphism

component composition:

contention

aggregation

other properties:

binary specification

language independence

localization independence

APM@FEUP 12


❖ Domain Driven

▪ Models the application following the business process and the

intervenient entities. The main application objects represent the

entities, with their state and behavior in the business process

(business entities or business objects)


Business objects

APM@FEUP 13


Business objects

State

Behavior

Interface Entities from the application logical model

Entity class

code

Entity class

code

Serialization

P1 P2 Creation

Initialization

Use of a

remote entity Transport channel

Remote entity

APM@FEUP 14


❖ Layered Multi-Tiered Architecture

▪ The layered architecture divides the application functionality in

stacked groups that can communicate between them. A layer

becomes a tier if it can be installed in a separate machine.


Browser

Web Server Application Server Database Server

DatabasePresentation

Business

Logic

Web Server

Presentation

Application Server

Business

Logic

Database Server

Database

Replication

Web Server

Presentation

Application Server

Business

Logic

APM@FEUP 15


❖Message bus

▪ Applications are built in a way that can consume and expose

functionalities through message sending and receiving. They

must know only the message format and meaning and not the

specific details of the senders and receivers.


Application A Application B

Application C

APM@FEUP 16


❖ Service Oriented Architecture (SOA)

▪ The applications are built in a way to expose and consume

functionalities presented as services, using well defined

contracts (interfaces) and messages


Service A

Service B Service D

Service EService C

Application

APM@FEUP 17


Integration ways

Presentation

Interface

Presentation

Interface

Presentation

Interface

Logic

Logic

Logic

Logic

Data

Access

Logic

ApplicationsDBs

Messages

or

Services

Messages

or

Services

Data

Access

Data

Access

APM@FEUP 18


Distribution models and ways

❖ Shared memory

▪ SMP systems, global variables, multithreading --- OpenMP

❖ Distributed shared memory

▪ Difficult to implement

▪ But simple programming

❖Mobile code

▪ Mobile agents, where code and data can move from node to node

❖Message passing

▪ Needs a communication channel

▪ Explicit sending and receiving

❖ Remote invocation – RPC

▪ Function invocation, similar to local calls

▪ Data is moved as parameters and results

▪ OO paradigm easy to achieve

APM@FEUP 19


Remote invocation mechanism

Client Remote function

var = func_a( ... )

“proxy” of

func_a( ... )

“dispatcher” of

func_a( ... )

func_a( )

.

.

.

.

.

.

.

.

.

.

communication channel

marshalling

APM@FEUP 20


Distributed platform architecture

Hardware

Operating System

communications

Middleware

Applications

External data representation

Protocols for calls and responses

Names and location

High level abstractions: RMI, events, ...

Middleware: - Implements a distributed programming model above processes,

communication channels and message passing;

- Isolates the hardware and the operating system, allowing

interoperability between different platforms;

- Supplies a high level of programming transparency, ‘emulating’

a local programming model;

APM@FEUP 21

APM@FEUP Distributed Architecture

Middleware function

Communication Network

Operating

System

Operating

System

Operating

System

Middleware Middleware Middleware

Application Application Application

specific API

standard API

22

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