Push solutions for AJAX technology

61 Pages·2007·1.19 MB·English

Push solutions for AJAX technology
Master’s thesis
Research report
Engin Bozdag

Push solutions for AJAX technology
THESIS
submittedinpartialfulfillmentofthe
requirementsforthedegreeof
MASTEROFSCIENCE
in
SOFTWAREENGINEERING
by
EnginBozdag
borninMalatya,Turkey
SoftwareEngineeringResearchGroup
DepartmentofSoftwareTechnology
FacultyEEMCS,DelftUniversityofTechnol- BackbaseBV
ogy Stephensonstraat19
Delft,theNetherlands Amsterdam,theNetherlands
www.ewi.tudelft.nl www.backbase.com
(cid:13)c 2007EnginBozdag.
Push solutions for AJAX technology
Author: EnginBozdag
Studentid: 1119869
Email: [email protected]
Abstract
Anewbreedofwebapplication,dubbedAJAX,isemerginginresponsetoalimitedde-
greeofinteractivityinlarge-grainstatelessWebinteractions.However,AJAXstillsuffersfrom
thelimitationsoftheWeb’srequest/responsearchitecture. Thispreventsserversfrom”push-
ing”real-timealertssuchasmarketdata,newsheadlinesorauctionupdates. Itispossibleto
overcomethislimitationbyusingseveraltechniques. Thispaperfirstsummarizestwodiffer-
ent types of architectures to accomplish a push solution. It later discusses several solutions
andexamplesfromthesoftwareindustryandevaluatesthesesolutionsfromtheperspectiveof
severalsoftwarequalityattributes.
ThesisCommittee:
Chair: Prof. Dr. A.vanDeursen,FacultyEEMCS,TUDelft
Universitysupervisor: ir. AliMesbah,FacultyEEMCS,TUDelft
Companysupervisor: MarkSchiefelbein,Backbase

Contents
Contents iii
ListofFigures v
1 Introduction 1
2 ProblemStatement 3
3 AJAXArchitecture 5
3.1 Classicalwebvs. AJAX . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2 AnArchitecturalStyleforAJAX . . . . . . . . . . . . . . . . . . . . 6
4 ThePushTechnology 11
4.1 Push-basedmodel . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.2 Event-basedmodel . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5 PushandEventmodelsinpractice 19
6 WebBasedPushSolutions 21
6.1 HTTPPull . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
6.2 COMET-HTTPBasedAJAXPush . . . . . . . . . . . . . . . . . . 21
6.3 FlashXMLSockets . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
6.4 JavaRMI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
6.5 ServerSentProtocol . . . . . . . . . . . . . . . . . . . . . . . . . . 26
6.6 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
7 CurrentPushImplementations 29
7.1 JettyServer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
7.2 Grizzly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
7.3 ICEfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
7.4 Pushlets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
7.5 Lightstreamer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
7.6 Fjax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
iii
Contents Contents
7.7 iPushServer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
7.8 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
8 Discussion 39
8.1 Scalability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
8.2 Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
8.3 Visibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
8.4 User-perceivedLatency . . . . . . . . . . . . . . . . . . . . . . . . . 40
8.5 Portability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
8.6 Simplicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
8.7 NetworkPerformance . . . . . . . . . . . . . . . . . . . . . . . . . . 41
9 Conclusion 43
Bibliography 45
A Glossary 51
iv
List of Figures
3.1 The traditional model for web applications compared to the AJAX ap-
proach. Imagesaretakenfrom[31]. . . . . . . . . . . . . . . . . . . . . 6
3.2 The sequence of events in different web application models. Images are
takenfrom[31]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.3 ProcessingViewofaSPIAR-basedarchitecture. Takenfrom[48]. . . . . 8
4.1 Componentsofthepushmodel. Takenfrom[32] . . . . . . . . . . . . . 13
4.2 Twodifferentserverdesigns. Imageistakenfrom[71]. . . . . . . . . . . 16
4.3 ASEDAStage.Takenfrom[32] . . . . . . . . . . . . . . . . . . . . . . 17
4.4 Thecomparisonofserverperformances. Inthreadeddesign,thethrough-
put begins to decrease substantially after the number of threads grows
large. Inevent-drivendesign,thethroughputremainsconstant,astheload
isincreasestoaverylargenumberoftasks. Imageistakenfrom[71]. . . 18
5.1 ReactorPattern. Takenfrom[41]. . . . . . . . . . . . . . . . . . . . . . 20
6.1 Cometwebapplicationmodel. Takenfrom[67]. . . . . . . . . . . . . . . 22
7.1 Jetty’sCometeventsubscriptionandeventdeliverybasedonBayeuxpro-
tocol[56] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
7.2 PerformanceandrequirementsofaJettywebserverusingdifferentschemes.
Takenfrom[21] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
7.3 TwodifferenttypeofupdatesinGrizzly. Imagesaretakenfrom[8]. . . . 34
7.4 ICEfacesEPSDeploymentArchitecture. Takenfrom[35] . . . . . . . . . 35
7.5 SubscriptionmechanismofthePushlets,takenfrom[28] . . . . . . . . . 36
7.6 EventdispatchmechanismofthePushlets,takenfrom[28] . . . . . . . . 36
v