The Design And Implementation Of Application Server Based CORBA

When the traditional C/S architecture deal with the great information system, it exposures a lot of defect, for example, poor expansibility, high support and maintenance fare, limited number of databse connection,high cost, difficult upgrade, etc. The three layer architecture of application server based CORBA hugely extends the two layer architecture in the function, resolves the separation of the transaction logic and representation logic in a certain extent. To harmonize and institute the unify standard of application soft development in the distributing isomerous entironment , OMG founded in 1989 ,established a technical distributing object standard called CORBA(Common Object Requset Broker Agent Architecture) by many years'effort,which involved interface,register,database,communication and error manage,etc. CORBA is a integrate techinology absorbed Object ,distributing ,multiplayer Architecture tecnicology in the software kingdom. CORBA's ultima purpose is integration of distributing soft. CORBA delegates a software develop mode, a software develop standard, also offers the essential serve and practicable tool collection in the software development. CORBA as a whole is made up of ORB,CORBA Service,CORBA tool collection , all kinds of application and object accord with CORBA standard. CORBA, the whole name is Common Object Request Broker Architecture. It was made by OMG (Object Management Group) of USA. The aim is to let the application programs on different platform can link up each other and run. CORBA allows application program to call the others without knowing on which service the called one locates . It has the trait of span_platform. In the other side, whatever programming language is used to develop object, the object can be called after being packaged by interface defined by CORBA IDL. So we will not be forbidden by programming language through this CORBA middle component. Therefore, CORBA is a mature criterion, many productions which support it can be chosen. Among them, VisiBroker is the first ORB which supports clients and object completion (that is, both client and object adopt the same middle software), VisiBroker accords with CORBA2.0 criterion, supports span-platform and multi operation system, in-build IIOP engine. At the same time, it completed the basic services of CORBA such as transaction service, naming service and event service, it also can complete SSL protocol and IIOP encrypt transfer. Besides, it offers interface base manage implement. In our system, we adopt the C++Builder VisiBroker of Borland as the CORBA bottom support platform by using the platform to mask the differences of heterogeneous condition and turn client application systems to disparate CORBA objects, difference object communicate by VisiBroker , by adopting the form of CORBA object and request and respond to cooperate with each other to achieve responding work. In this paper we have developed and implemented a application server system based on CORBA in CORBA development entironment of BORLAND to study and discuss the application server based on CORBA. The first and second chapter analyse that the current tradition mode already can't adapt to more and more complicated application entironment in developing the great application system, and propound to develop multilayer application system in the middle piece technology. Then mainstream technology –CORBA is presented basically. We have presented the basic function mechanism of CORBA and its'the support service, etc. And we have presented detailedly ORB,IDL and UML, etc. In the third chapter we have designed a actual CORBA application server to study the CORBA technology deep. In the chapter we have presented the whole frame and each module of the application server. We have presented the main use case and static state diagram of each module in UML to make ready to implement the application server later. In the fourth chapter, the main chapter, we have utilized CBuilder's integration development environment to implement the application server based on CORBA The application server based CORBA is made up of POA transaction logic,database service ,support service,manage and maintenance of the server,CORBA Client Agent interface. The application server integrates main transaction logic, isolates client and database server,support. general CORBA service; it adopts more agility and advanced POA,multi-thread, resource release,load balance, etc. It establish a good base for later upgrade. Client develop programmers commonly don't the criterion and technology of CORBA, and studying them will spend a plenty of time and spirit and will produce much bug as unapprehensed CORBA. So we bring forward CORBA Client Agent interface as the bridge of the client and the application server. The client programmer can call it as a common subassembly, and it let CORBA client transparent to client programmers.