Chapter 4: Core Web TechnologiesContents - Chapter 1Before and after the webProxyGatewayFirewallTunnelSecure Socket Layer (SSL)Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19SummaryChapter 4:Core Web TechnologiesContents - Chapter 1 Exchanging information over the InternetHTTP, HTMLURI, URIWeb server, web browserWeb services for supporting remote clientsAppletsCommon Gateway Interface (CGI)ServletsApplication serversMiddleware for Web applicationsJ2EEWeb technologies for application integrationMiddleware extensionsFirewalls and tunnelingBefore and after the web Early protocols, applicationsTelnet: to log in to a remote machineSMTP: Simple Mail Transfer ProtocolFTP: File Transfer ProtocolArchie: FTP to create a distributed file systemGopher: GUI for publishing and accessing text files over the InternetWeb technologiesWeb serverWeb browserHTTP: HyperText Transfer ProtocolHTML: HyperText Markup LanguageURI: Uniform Resource IdentifierURL: Uniform Resource LocatorProxyActs as a server and clientCachingBlock undesired sitesLog usageBypass blocksScan outgoing trafficHTTPclientwide area network (Internet)HTTPproxy HTTPserverHTTPgateway frewallfrewallHTTP tunnelGatewayActs as an intermediary for a serverKeeps machines anonymousControls access to the networkPerforms load-balancing, authentication, decryptionHTTPclientwide area network (Internet)HTTPproxy HTTPserverHTTPgateway frewallfrewallHTTP tunnelFirewallBlocks unauthorized access, permits authorized communicationspermit / deny / encrypt / decrypt / proxy all computer traffic between different security domainsHTTPclientwide area network (Internet)HTTPproxy HTTPserverHTTPgateway frewallfrewallHTTP tunnelTunnelActs as a blind relay between two connectionsEncapsulate protocols within HTTP or SSH (Secure Shell) to get through what the firewall would preventHTTPclientwide area network (Internet)HTTPproxy HTTPserverHTTPgateway frewallfrewallHTTP tunnelSecure Socket Layer (SSL)Normally HTTP traffic is not encrypted, it can be “sniffed”SSL uses public key encryptionHTTPS: HyperText Transfer Protocol over Secure sockets layerHTTP “cookies” are used to store data on the client machineHTTPSclientSecure Sockets Layer (SSL)HTTPSserverTCP/IPnetwork layerapplication layerclientclientserver (resource manager)middlewarewide area network (Internet)HTTPclientHTTPserverCopyright Springer Verlag Berlin Heidelberg 2004 A 3-tier architecture on the web“Let’s put an ATM” in every home”Business-to-consumer (B2C) interactionThe web browser is a universal clientmiddlewareWeb server clientbrowserjava virtual machineappletwide area network (Internet)frewallserver (resource manager)Copyright Springer Verlag Berlin Heidelberg 2004 AppletsHTTP is a document exchange protocol, it’s staticApplets are downloadable programsThe server sends the appropriate program each timeThe web browser becomes a universal clientCode must be small for rapid transfermiddlewareWeb server browserwide area network (Internet)frewallHTTP GET requestclientCGI programserver (resource manager)Copyright Springer Verlag Berlin Heidelberg 2004 Common Gateway InterfaceThe CGI program is on the server and it has a URLWhen the URL is accessed, the CGI program is executed and its output is saved as an HTML documentThis saved document is returned to the web browser which then displays itIt is possible to pass parameters to CGI programsmiddlewarebrowserwide area network (Internet)frewallHTTP GET requestclientWeb serverJava server processJava threadserver (resource manager)Copyright Springer Verlag Berlin Heidelberg 2004 ServletsSimilar to CGI, but “lightweight”Run as Java threadsSaves the cost of context switchingMemory efficientCan be statelessconnection to resource mgmt layerpresentation layerresource management layerapplication logic layerclientapplication serverWeb serverwide area network (Internet)frewallHTTPbrowserother protocolsother servers (email, SOAP,..)Copyright Springer Verlag Berlin Heidelberg 2004 Application serversIt’s a middleware platform that provides support for Web accessCovers both the application logic and the presentation layerPrepares, dynamically generates, manages documentsupport for communication and presentationServletsJavaServer Pages (JSP)Enterprise Java Beans (EJB)Java DataBase Connectivity (JDBC)Java Naming and Directory Interface (JNDI)support for the application integrationJava 2 Connector Architecture (J2CA)Java Message Service (JMS)Java transaction API (JTA)Java API for XML Processing (JAXP)JavaMailJava Authentication and Authorization Service (JAAS)support for access to resource managersCopyright Springer Verlag Berlin Heidelberg 2004 J2EE – main componentsapplication logic layerpresentation layerservices(load balancing, pooling, caching, transaction, persistence,…)administration(management and security)application serverEJB EJBJDBCEJBJNDIJ2CA resource adapterJ2CA resource adapterother adaptersDBMS applicationsenterprise system 1enterprise system 2enterprise system nEJB containerJMSCopyright Springer Verlag Berlin Heidelberg 2004Web serverE-mail serverservers for other connections (e.g., WAP)presentation layerServlets JSPsmultidevice content deliverypersonalization logicconnection to resource mgmt layerresource management layerapplication logic layerservices(load balancing, pooling, caching,…)XML supportWeb services supportadministration(management and security)application serverclientCopyright Springer Verlag Berlin Heidelberg 2004clientserver (resource manager)middlewareclientserver (resource manager)middlewarewide area network (Internet)Copyright Springer Verlag Berlin Heidelberg 2004 Possible ways to connectclientserver (resource manager)middlewareclientserver (resource manager) middlewarewide area network (Internet)remote-middlewareprotocolWAN communicationprotocolremote-middlewareprotocolWAN communicationprotocolCopyright Springer Verlag Berlin Heidelberg 2004 Direct integration of middleware platformsclientwide area network (Internet)Web server clientWeb serverfrewallfrewallHTTP tunnelserver (resource manager)server (resource manager)middlewareremote-middlewareprotocolWAN communicationprotocolmiddlewareremote-middlewareprotocolWAN communicationprotocolCopyright Springer Verlag Berlin Heidelberg