Distributed ArchitectureTopics:What’s Distributed SystemDistributed System ExampleAdvantage of distributed System.Distributed Computing TechnologyDistributed Message PassingBasic Message-Passing PrimitivesRemote Procedure CallsPowerPoint PresentationObject-Oriented MechanismsCommunication Protocol ModelsSocketsSockets AdvantagesCommon Gateway Interface (CGI)Build HTML Page on flyLimitation of CGICommon object Request Broker (CORBA)CORBA continue…The structure of CORBA interfaceCORBA Interface architectureSlide 22Slide 23Slide 24CORBA SummeryRemote Method Invocation (RMI)RMI up sides?Distributed component Object Model (DCOM)What is SOAPMechanism of SOAPSOAP architectural diagramSOAP SpecificationSOAP SummerySummeryResourceThank you01/14/19 CSE 8343 1Distributed ArchitectureGroup A3- presentation ‘1’Advanced OS CSE8343Kathryn beanWafa’ Jaffal01/14/19 CSE 8343 2Topics:What’s Distributed System?Distributed system advantages.Distributed Computing Technology.Technology alternativesCORBARMISocketsDCOMCGI\ASP\ServletSOAPEvaluationsSummery01/14/19 CSE 8343 3What’s Distributed SystemDefinition: A distributed system is a collection of loosely coupled processors interconnected by a communication network.The Processor in a distributed system may vary on:Size (small microprocessor, work station, minicomputer)Function01/14/19 CSE 8343 4Distributed System Example01/14/19 CSE 8343 5Advantage of distributed System.Resource sharing.sharing and printing files at remote sitesprocessing information in a distributed databaseusing remote specialized hardware devicesComputation speedup – load sharingReliability – detect and recover from site failure, function transfer, reintegrate failed siteCommunication – message passing.01/14/19 CSE 8343 6Distributed Computing TechnologyThe GoalA seamless, web-enabled integration of services for applications on various platforms.Key point: interoperability - the capacity of disparate systems to communicate and to share data seamlessly.01/14/19 CSE 8343 7Distributed Message PassingMessage passed used to communicate among processesSend and receive messages as used in a single system ORRemote procedure calls01/14/19 CSE 8343 8Basic Message-Passing Primitives01/14/19 CSE 8343 9Remote Procedure CallsAllow programs on different machines to interact using simple procedure call/return semanticsWidely acceptedStandardizedClient and server modules can be moved among computers and operating systems easily01/14/19 CSE 8343 1001/14/19 CSE 8343 11Object-Oriented Mechanisms01/14/19 CSE 8343 12Communication Protocol Models Sockets.Common Gateway interface CGI, ASP, Servlet.Common Object Request Broker Architecture(CORBA).Remote Method Invocation(RMI).Distributed Component Object Model(DCOM)Simple Object Access Protocol (SOAP).01/14/19 CSE 8343 13SocketsSockets are not easy to use, user handle all the details.Parameters are primitive ( no objects).To create a simple client-side Locate the remote server and open socket connection to it.Marshal parameters to be transmitted.Transmit the parameters.Listen for, and receive, the response from the server.Decode the response from the server, unmarshaling its components if necessary.01/14/19 CSE 8343 14Sockets AdvantagesTo communicate with non-Java objects and programs: Not all software on networks is written in java, so we need to interface java program with a non java program.To communicate as efficiently as possible: the convenience of RPC, RMI increase the processing overhead.01/14/19 CSE 8343 15Common Gateway Interface (CGI) CGI is a way to program the web server so that it can offer more than the static form of HTML file.When a client requests a CGI page, the server runs a program that builds an HTML page on fly.CGI program can perform a simple computation, access a database, access another hosts. CGI is supported by every web browsers and most web servers.01/14/19 CSE 8343 16Build HTML Page on fly 111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111 11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111101/14/19 CSE 8343 17Limitation of CGICGI is slow.CGI can compromise server security.CGI cannot store information.Limitations of the CGI led SUN to introduce its own alternative Java ServletMicrosoft has also an alternative which ASP.01/14/19 CSE 8343 18Common object Request Broker (CORBA)CORBA attempts to build standards for distributed objects.There are 3 standard elements:The Internet inter-ORB Protocol (IIOP)IIOP enable objects to interact a cross a network, using an ORB, IIOP forms an object bus can link objects and ORB into systems.IIOP is analogous to HTTP.The Interface Definition Language (IDL).Describes the interface of an object regardless of its implementation language.Database stored procedure can be described using IDL.IDL encapsulate a non-object-oriented legacy system.01/14/19 CSE 8343 19CORBA continue…System Services and facilities.Provide general-purpose functionality to objects traveling on CORBA’s IIOP bus.One example is the interface repository, implemented as distributed DB that contains IDL descriptions of all objects on the bus, so objects can discover and use servers without being aware of the servers location at runtime.CORBA provides many other services including security services that supports authentication and access control.01/14/19 CSE 8343 20The structure of CORBA interface01/14/19 CSE 8343 21CORBA Interface architecture Client-side interfaceIDL stubs- presents interfaces comprised of IDL-defined operations and linked into the client program.Dynamic Invocation Interface (DII)- provides dynamic construction of object invocation to specify and build a request at run time.ORB interface- is the interface direct to ORB.- is shared by both the client side and the implementation side architecture.01/14/19 CSE 8343 22CORBA Interface architectureServer\implementation-side interfaceIDL Skeleton is server-side counterpart of the IDL interface.Dynamic Skeleton Interface (DSI) is an interface for servers to deliver request from an ORB to an object implementation that does not have compile-time knowledge of the type of the object.Object Adapter provides the run-time environment for an implementation access services provided by the