CS8630 Database SystemsIntroduction2-tier Client-Server Model3-tier Client-Server ModelJava in the IndustryJava AppletsJSPs & Java BeansFinal CommentsReferencesKennesaw State UniversityDept. of Computer Science& Information SystemsCS8630 Database SystemsResearch Paper:Java Applications, Java Applets, and JSPsDue:07/06/2004Prepared by: Christopher Grey1IntroductionThis paper is a basic overview of various Java technologies used in 2-tier and 3-tier networks. Java and all the peripheral technologies directly and not so directly related to it have really made a name for themselves in the industry due to the benefits each offer. Java’s flexibility and multi-platform interoperability are discussed with regard to why thisis so important in the industry. Java can be implemented in a number of forms including: 1. Native Java code executing as a stand alone application2. Java code embedded in HTML to form JSPs3. Java Applets 4. Java Servlets/JavaBeansWith each of these Java technologies, a company can deploy very secure web-based applications. A user from anywhere on the Internet can look up movie times and locations, buy the tickets to see the movie, check their bank account, and even check the DOT for traffic conditions getting to the theatre. If traffic is bad, a user can even view rented moves over the Internet streamed directly to their computer. Each of these tasks has their own set of challenges to make happen on the Internet, but they all have one thing in common. They all must serve information to a user and do it with the use of a database of some sort and they could all be Java based in part or in whole.22-tier Client-Server ModelFor the longest time, networks have been configured to based on the typical 2-tier client/server model. This is where the Client runs software to display information to a user. Over the network, the client communicates with a server to get the information to bedisplayed where the data being served is held locally to the server, possibly even in a proprietary format. This has worked, but is not very scalable nor interoperable with other products. Before affordable tools were available for maintaining a database, programmers of software often came up with either their own protocols for storing data or maintained a lightweight database local to their application. For every application that utilized a local database of information, system administrators had to learn the backup/restore/maintenance procedures for each proprietary application used. This type of architecture does not lend itself to scalability well either. This application topology also poses a data security threat as well. If an attacker were to gain access to the application server, they have access to both the server application and all the data it uses. 33-tier Client-Server ModelThe 3-tier Client-Server Model is the more preferred method of scaling for most medium-to-large enterprise level applications today since this method lends itself to future scalability and much better security options. In the 3-tier Client-Server, the Client still runs software used to display information to the user. This client software still communicates back to an application server, which serves and maintains the data being sent to and from the client machine. However, the server is only an application server at this point because the application server must communicate to a database server to accessthe information being requested by the client. In this model, the server application and the data are separated in order to allow for scalability, multiple layers of security, and easier maintenance of the data being served. With a separate database server, a database administrator can maintain, secure, and backup all of the databases being maintained. In addition, the database server can make the same data available to multiple application servers simultaneously, each with custom permissions based on the type of data access they require. In addition, multiple dissimilar applications can access a common database server for their data with security permissionsto deny all other applications access. Finally, a database administrator can perform all theadministration and maintenance functions from one place in a controlled and standardized fashion. As the database server’s load increases, the database administrator has multiple options for upgrading the server to meet the demand; all of which are transparent to the application servers communicating to their databases. 4Java in the IndustryMost enterprise environments such as large corporations or universities have a central location where most of their servers are held. Rarely are all the machines in this area running the same Operating System or even the same hardware platform. With the multitude of Unix based server platforms, it is common to run across at least two different hardware platforms in large enterprise environments. With the cheapness and gained reliability of the Intel based platform, many of the computers in this area will undoubtedly be Linux or Windows based. For handling the heavy loads, HP or Sun based Unix machines may be deployed as well. Since many applications in the industry are still very proprietary, an effective system administrator will need to be adept at a number of different server platforms and operating systems. This is where Java comes into play. Java is an inter-platform programming standard. C and C++ attempted this, and came close but missed the mark in two major ways. 1. C & C++ executables are very platform dependent even if the source code, for themost part, is not. Since most software developers do not give their source code up to be freely compiled for the target hardware/OS platform, the inter-platform efforts of C and C++ are not as useful to end users of the applications programmed. 2. Since C and C++ are programmed and execute at a very low level on the target machine, often calls to various I/O devices will be different on different machines running different hardware/OSs. Because of this, simply having the source code does not guarantee the software will work once ported to the alternate platform. 5Regardless of the platform used to program a Java application, if done right, a Java application can execute from any hardware and operating system that a Java Virtual Machine has been developed for. Thus, final compiled code can be delivered to a number of different hardware/OS specific platforms and still have a