MTAT.03.229 Enterprise System Integration Lecture 1 ...… breaking apart the monolith 27 2011:...

MTAT.03.229Enterprise System Integration

Lecture 1: IntroductionLucianoGarcía-BañuelosUnivers i tyof Tartu

CourseDescriptionThe course introduces modern approaches to enterprise system integration.Its objective is to survey principles and methods of software architecture in an enterprise environment.In addition to technical aspects, the course covers organizational aspects of enterprise system integration, including architecture governance and Business-IT alignment.

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Scopeofthecourse:Thelongandwinding road…

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Analysis&Design

Middleware&Infrastructure

SoftwareFrameworks

ArchitecturalStyles

WS

Capability-driven,data-driven,process-

drivendesign

Messageorientedmiddleware

JEE .NET

SpringRoo

REST

Scopeofthecourse

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Analysis&Design

Middleware&Infrastructure

SoftwareFrameworks

ArchitecturalStyles

MOM Docker

Springboot

REST

Domain-drivendesign

Microservices

Designpatterns

Agilepractices

ServiceandAPIdesign

REST

Structure of the Course• 14 Lectures◦ 3 guest lecturers (practitioners)

• 14 Practicals• Project

◦ Presentations on 26 May◦ Report due on 26 May

• See details on the Wiki pages:◦ https://courses.cs.ut.ee/2017/esi

• Make sure you check the message board!

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Grading• 10 Assignments: 20 points◦ 4-8 hours per homework ~ 70 hours

• Project: 20 points (~ 30 hours)◦ 10 points for the product◦ Soundness of design and architectural choices◦ Scope of the solution (how much was implemented?)◦ Degree of heterogeneity of the system◦ Functional correctness/validation (does it work?)

◦ 5 points for written documentation◦ 5 points for presentation

• Exam: 60 points

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Inteamsof3-4

members

People• LucianoGarcía-Bañuelos<luciano.garciaatut.ee>◦ Lectureson◦ ArchitecturalStyles&Middleware◦ Domain-DrivenDesign◦ ServiceDesign&Enterprise IntegrationPatterns◦ Containerization

•MarlonDumas<marlon.dumas atut.ee>◦ ServiceAnalysis&Design

• Orlenys López-Pintado &Mykhailo Dorokov◦ Labassistants

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PartIPROBLEMSTATEMENTAND

INTRODUCTORYSCENARIO

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Theproblematglance• Users want to execute business

functions that span multiple applications

• Requires disparate applications to be connected to a common integration solution

• However:◦ No two applications are alike◦ Change is inevitable

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Isolated Systems

Unified Access

Copyright © 2003 Gregor Hohpe

Whychangeisimportant?

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InformationTechnology

Changeandinnovation

Yields

Yields

BusinessValue

Index Group (1982)

Enables

EnterprisesystemscenarioInformation system of a small hotelThree functional areas:◦ Guest management: reservations, check-in (including room

assignment), charges to room (e.g., room service), check-out, closing of bill

◦ Keeping track of room availability, status – how many rooms still available for a given night, forecasting how many guests will stay beyond their reservation, forecasting occupancy of hotel at a future date

◦ Scheduling room cleaning & maintenance: managing maid & maintenance staff, cleaning rooms after late check-out

• Can you see dependencies across functional areas?

INTRODUCTIONLUCIANOGARCÍA-BAÑUELOS 10Based on scenario by Richard Hull

EnterprisesystemscenarioChange # 1: A restaurant is opened for hotel guests and external customers:

• External customer pays for meal directly• Hotel guest has option to pay for meal directly or

charge to room◦ In either case, hotel likes to keep a record of the guest eating in

the restaurant, if guest is willing to reveal his room number◦ Restaurant offers breakfast for guests

èRestaurant billing system has touch-points with hotel guest system

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EnterprisesystemscenarioChange # 2: A loyalty program is introduced:• Set up new system to keep track of customers who

are in loyalty program• Loyalty program has multiple touch-points with hotel

system and restaurant system, e.g.,◦ At reservation time, inquiring if customer is a member of loyalty

program, offering promotions, giving priority for room allocation to loyalty club members

◦ At check-in, inquire if customer is in loyalty program, if not offer sign-up, if yes offer better room

◦ Offer discounts at restaurant◦ Offer discounts on other services at check-out and record

length of stay and points earned

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EnterprisesystemscenarioChange # 3: Hotel is bought out by a franchise:• Reservations can be made either through the

franchise system or by calling the hotel◦ Room availability have to deal with this dual sourcing◦ Forecasting & pricing outsourced to franchise’s system

• Loyalty program merged into franchise’s program ◦ Hotel no longer operates the loyalty program, but must

interoperate with loyalty program system of franchise◦ Benefits of existing loyal customer must be honored◦ The franchise loyalty program gives points for all expenses

paid, whereas the original loyalty program looked only at nights stayed in hotel

• Room cleaning/maintenance still managed locally

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PartIIEVOLUTIONOFENTERPRISESOFTWARE

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TheAnatomyofanEnterpriseSystem

15

Enterprisesoftw

are Presentation

Applicationlogic

Dataaccess

Applicationlayers

• Usersinteractwiththesystemthroughapresentationlayer(akauserinterface orUI)

• Theapplicationlogic (akabusiness logic)determineswhatthesystemactuallydoes:◦ Enforcesbusinessrules◦ Coordinatesbusinessprocesses

• Thedataaccesslayer facilitatestheaccesstopersistentdatamanipulatedbytheapplicationlogic.◦ Includesaccesstodatabases,searchengines,documentmanagersand/orafilesystem.

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TiersorLayers?• N-tierarchitecturesaimatsplittingtheapplicationincomponents intodifferenttiers/layers

• Tiersrefertophysicaldistribution ofcomponents◦ Componentscanbeexecutedoveracollectionofcomputers

• Layersrefertologicalseparationofcomponents◦ Layeredarchitecture:Communicationshouldonlyhappenwiththecontiguouslayers

◦ Promotesreuseandlogicindependence (componentsshouldbeseamlesslyreplaceable)

☛ Thenumberoftiersinthesystemsomehowreflectstheevolutionofsoftwarearchitecturesw.r.t. distribution

16INTRODUCTIONLUCIANOGARCÍA-BAÑUELOS

Evolutionofcomputation60’s 70’s 80’s 90’s 00’s 10’

IBMmainframes

IBM, DECMini-comp.Unix,VAX

PC, DOSMac,MacOSWANs&LANs

WindowsInternetWeb &HTTP

Web2.0Mac OSXWindows XP

iOS, AndroidHTML5SaaS, PaaS,IaaS

Monolithicapplications

Batchprocessing

Dumbterminals

Time-sharing

Client-Server

RelationalDBMSs

CORBA&Browsers

CGI

Applicationservers

SOA&ROA

Cloudcomputing

MicroservicesNoSQL

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1-tierarchitecture• Alllayersarebundledinamonolithicentity

• Typical“mainframe”architecture◦ Usersaccessthesystemthroughdumbterminals

◦ Allcomputationhappens inasinglecomputer

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Enterprisesoftw

are Presentation

Applicationlogic

Dataaccess Pros ConsNocontextswitching inthecontrolflow

Limitedscalabilityduetorestrictionsinthenumberofprocessors

Centralization easesresourcemanagement/sharing

Oftentimesthecodeisplatformspecific,limitingportability

Code highlyoptimisable Intertwined codehinderingmaintenance

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2-tierarchitecture (1/2)• Withtheintroductionofcomputernetworks,computationstartedtobephysicallydistributed

• Applicationlayersaredistributeddependingonthecomputingpowerofclients:◦ Thinclientsexecuteonlypresentationlayer◦ Fatclientsexecutebothpresentationandapplicationlogiclayers

• TheconceptofAPImakesitsappearance

• Notableexample:Databasemanagementsystems◦ Theseparationofdataaccesslayerpromoteslogicalindependence, reducingtheimpactofreplacingadatabasetechnology onthepresentationapplicationlogiclayers

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Presentation

Applicationlogic

DataaccessEnterprisesoftw

are

Client

Server

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2-tierarchitecture (2/2)• WiththearrivalofPCs,thepresentationlayermovedtotheclient◦ Smartphones?

• Withthisapproach,itispossibletohavemultiplepresentationlayers◦ Text(console)application◦ Graphicaluserinterfaces(e.g.,Javaswing)◦ Webapplications(e.g.,HTML5,Javascript,etc.)

• Webastheuniversalplatformforcomputing?◦ Google’sChromiumOS

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UI1

Applicationlogic

DataaccessEnterprisesoftw

are

Clients

Server

UI2 UIn

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3-tierarchitecture:Themiddlewarearrives• Middlewareisalevelofindirectionbetweenclientsandotherlayers◦ Simplifiesthedesignofclientapplicationsbyreducingthenumberofinterfaces

◦ Encapsulatesintegrationlogicandglobalapplicationlogic

◦ Locatesresources,accessesthem,andintegratesresults(mediatesbetweenapplicationlogic/dataaccesslayers)

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Presentation

Localapplicationlogic

Localdataaccess

ServerA

Localapplicationlogic

Localdataaccess

ServerB

MiddlewareorglobalapplicationlogicIntegrationlogic

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N-tierarchitecture• N-tierarchitecturesresultfromconnectingseveral3- tiersystemsand/oraddingalayertoallowclientstoaccessthesystemthroughaWebserver (“Weblayer”)

• TheWeblayerishostedinaWebapplicationserver:amiddlewareaccessiblethroughtheWeb.

• Webapplicationservers aretakingalsopartsofthefunctionalityoftraditionalmiddleware– theboundarybetween theWeblayerandthemiddlewareisblurred.

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client

Dataaccesslayer

Applicationlogiclayer middleware

Presentationlayer

Webserver

Webbrowser

HTMLfilter

© Gustavo Alonso, ETH Zurich INTRODUCTIONLUCIANOGARCÍA-BAÑUELOS

FlexibilityversusPerformance• Themoreboxes,themoremodularthesystem:moreopportunities fordistributionandparallelism;moreextensibilitypoints.

• Themoreboxes,themorearrows:moreconnectionsneedtobemaintained,morecoordinationisneeded.Complexityincreases.

• Themoreboxes,thegreaterthenumberofcontextswitchesandintermediatestepstogettothedata.Performancedegrades.

• Systemdesignerstrytobalancetheflexibilityofmodulardesignwithperformancedemands.

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Thereisnoprobleminsystemdesignthatcannotbesolved

byaddingalevelofindirection.Thereisnoperformance

problemthatcannotbesolvedbyremovingalevelof

indirection.

© Gustavo Alonso, ETH Zurich INTRODUCTIONLUCIANOGARCÍA-BAÑUELOS

Backtothe…future?

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Productcatalog

Usermanager

Shoppingcart

Shipping

Payment

Applicationserver

TheGILTexperience

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we sell every day at noon

Adrian Trenaman, VP Engineering, GiltMicroservices DublinMeetup,Feb2015

Onceuponatime…

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2007 - ruby-on-rails monolith

INTRODUCTIONLUCIANOGARCÍA-BAÑUELOSAdrian Trenaman, VP Engineering, GiltMicroservices DublinMeetup,Feb2015

…breakingapartthemonolith

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2011: java, scala, loosely-typed services

Hidden linkages; buried business logic

Monolithic Java App; huge bottleneck for innovation.

lots of duplicated code :(

teams focused on business lines

Large loosely-typed JSON/HTTP services

INTRODUCTIONLUCIANOGARCÍA-BAÑUELOSAdrian Trenaman, VP Engineering, GiltMicroservices DublinMeetup,Feb2015

…andthestorycontinues

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2015: micro-services

INTRODUCTIONLUCIANOGARCÍA-BAÑUELOSAdrian Trenaman, VP Engineering, GiltMicroservices DublinMeetup,Feb2015

Microservices:Amatterofscale…

29JamesLewis&MartinFowler:Microserviceshttp://martinfowler.com/articles/microservices.html INTRODUCTIONLUCIANOGARCÍA-BAÑUELOS

Organizational implications

30

Anyorganizationthatdesignsasystem(definedbroadly)willproduceadesignwhosestructureisacopyoftheorganization'scommunicationstructure.

-- MelvynConway,1967

JamesLewis&MartinFowler:Microserviceshttp://martinfowler.com/articles/microservices.html INTRODUCTIONLUCIANOGARCÍA-BAÑUELOS