NetMeeting System Based On Socket

NetMeeting System, is one of the important parts in multimediacorrespondence industry at present; Its essential target is to makecomputer interaction,the correspondence distribution and theauthentic of the media to be a organic unity with the existing networkresource and the communication technology,and then provides betterservice of the communication for user. In the present, manyorganizations in the domestic and foreign are voting to this research inthe aspect.The System, which is based on an enterprise project,comes to truth and is applied in the whole office system of the oil fieldof DaQing after understanding the actual needs at last .This article, whichsynthesis the newest characteristic of thenetmeeting system, takes TCP/IP and P2P Protocol as a backing,introduces the Java network multimedia technology, describes thesystem architecture with the visible modelling method, and then applydesign pattern to outline the detail and main point of the system; Unionsoftwareengineeringknowledge,strictlycarriesonthedesign,thetestand the development according to the development regulations,proceed the UI design and the coding with the JBuilder IDE, and carrythe system out finally.The electron whiteboard is the core module of the system;it's thetypical platform of computer supported cooperative work (CSCW). Thetraditional electron whiteboard, carry the basic function (such asdrawing) out only with the text communication pattern; This Systemintroduces the more advanced technology——Object Stream as thetransmission pattern, encapsules so much parameter information ofgraphic cell and data structure to be object, after the objectserialization, transmits all these in the network as a whole, and then anti-serialization and read, simplified the parameter tansmissionprocess, and guaranteed the data can be transmited quickly, completeand safely. Meanwhile, also has realized the function in the drawingworkareaof synchronized/asynchronous,andthencausesthissystemto be more perfect.Desktop share and control is the realization key of the system.Traditional remote control software exist various kinds of problem,especially the compatibility in the actual network is so bad; All theseare improved in the system. Geting rid of the sole compression ratio inthe image compression ratio, but use the invariable compression ratio,users can configure the compression ratio by themselves; and theimage transmission speed is based on the image compression,butimage compression is take sacrificesthe quality as the price, and thenstrengthened user's initiative, so they can choose the right radiobetween the picture and the transmission speed, according to thenetwork situation and the transmission speed, enhance software'scompatibilityto the network enormously.P2P file sharing is one of characteristics of the system.FTP ismature, and is widelyused in thefield of file sharing and transmission;P2Pis growing up, and walks to mature step bystep. In the process ofdevelopment, I strickly follow the definitions and limits of P2P, designcommunication protocol and analyze the event processes, and carrythe architecture——single server,multiple client, acchive the serverand the client to be on a 50-50 basis finally. The reason why I chooseP2P as the basic pattern of file sharing, is that, try to research on theapplication in the field of P2P, and then impetus the research anddevelopment of P2P.Chatingintextisanmprovementandenhancementinthesystem.Traditional Chating only shows the content with the JTextArea control, and is so dull with single style; The System replaces it with theJTextPane which is more powerful. Though JTextArea can meet ourneeds in certain functions, JTextPane, which is the special componentdesignedforthetext andpage layout, supplysmoreprocessingin text,such as font color,font size and insering the web page and image, allthese bring termsfor the varietyof chating software.Video stream communication with JMF,increases the vitality forthe system. Java Multimedia Framework (JMF),which is an interfacefor application, locates and manages media data stream by medialocator and session manager; At the same time, RTP provides reliableprotection for the transmition of video stream. With the RTP's help, wecan get real-time transmition and control. In the system, the videostream is got byimage capture, and transmited through RTP.In the whole process of development, I act up to the theory ofsoftware engineer strickly, and link up with the actuality of the project,and set up the develop flow for the system. At the same time ofdemandanalysis,outlinedesignanddetaileddesign,setuptheplanofsystem test,integrated test and unit test. And then test theperformance according to the plan in the phase of coding, check thecorrection and strength of the code, in order to ensure the integrationof the project in function. All these vouch for the progress and plan incertain degree, and protect the achievement of the project.OOP (Object Oriented Programming) is widely used because itcan improve software productivity through reuse mechanism. In thispaper,thesystemisanalyzedanddesignedthroughOOPmethod,andUML language is used to build domain model in which use casediagram, class diagram, sequence diagram and activity diagram areused to define system functions and complete system design.In this process of system design, design patterns are also used to realize the module details and the main point of realization, especiallythe FactoryMethod and the Observer. FactoryMethod fits to the foundof basic graphic cells which implement the public interface——Shape,I succeed in postponing the instance of object; Observer isresponsible for real-time watch for the graphic cell list, and thenresponses when it turns to be changed, afterthat, inform all attendantsto update their graphicworkarea.Some software in the field of multimedia communication, whichappear in the market, exist so much problem more or less, such asthedull effect in chating, the uncorrespondence of desktop sharing andcontrol, the low protection, and so on. I centre on these aspects andmake great improvement after insearch. With extracting the dimensionfrom the image transmitted, so break the limits of the oordinates ofpixel effectly; By overriding the method of update and double-buffertechnology, succeed in solving the vague of the screen image inremote control; And then verify the user's identity adopting thepassword way, so make the control process to be safely.In a word, the article induces the charactics of the netmeetingsystem, analyze and design the system structure thoroughly with theUML technology, and implement in the process of development;Testing the code meticulously in the interim. And as regard as the keytechnology, I also describe and analyze them in detail; Meanwhile, Iimproved the problem which exit in the traditional system.Ofcourse,myknowledgeissolimitthattheremaybemanyhiddendisadvantages in the system; Welcome everyone to point it out, andthen I will do mybest to make it more perfect gradually.