Server-side function

In this chapter, we extend the one-dimensional MRTM transport and adsorption model (Zeng et al., 2002 Selim et al., 1990) to three-dimensional applications, using the altemating-direction-implicit (ADI) numerical algorithm to reduce computational complexity. We also discuss the development of a web-based system with a user-friendly interface providing client-side and server-side computing applications and web-based visualization functionality. The accuracy and efficiency issues of solution algorithms will be addressed in future publications. 

There is a smaller set of tools that are typically run on the server. Any SQL commands and any procedural language functions are run on the server. In principle, there is complete flexibility of the server side tools, since in principle any computer program can be written in any computer language. Later chapters of this book show how the RDBMS server itself can be extended using server side programming to handle chemical information. These extensions may directly solve the needs of a particular project, but more importantly they increase the flexibility of the RDBMS to handle chemical information. Client programs can use the results of chemical searches and other computations as well. 

Most new client programs will benefit from a judicious use of both new server-side SQL functions and new client functions. It is wise to carefully consider which operations are best done on the RDBMS server and which are done using a client program. There are several suggestions to consider in designing the best system for a project. 

Do not implement the same functionality in different clients. If many different clients require the same functionality, it is better to encapsulate that in one central location—namely the RDBMS. For example, if it is necessary to compute molecular weight, it is better to have a server-side function do this in a consistent way rather than to implement such a function in each of the languages used for client applications. This may be more obvious for functions like fingerprints that are more difficult to re-implement in various languages. Moreover, it is essential that fingerprints be... 

To solve some problems of the two-tier architecture and improve the reliability and performance of the system, a three-tier architecture has been adopted. In a three-tier architecture, the business logic is separated from the presentation and data layers and becomes the middle layer between them. The presentation logic resides in the first tier (the client side), and the data logic in the third tier (the server side), and the business logic in the second tier (the middle) between both tiers. This solves the problems occurring with the two-tier architecture. Figure 6 shows a three-tier architecture where the business logic and some connection functions are placed in the second tier. 

The client block diagram in the Figure 2 illustrates the dient-side functionalities. The client block controls the microphone and web/video camera connected to the client machine, captures the multimedia data and sends data packages over a stream to the server-side component. In the same maimer, the video sequences captured from the multimedia peripherals such as multimedia equipanents, using the TV timer, can be broadcasted within the shared sp>ace component. 

The scalability is an important aspect when designing multimedia distributed systems and the proposed framework is developed according to the rules that define the scalability. The differences between the client components for the web access and the compwnents that allow the access from the desktop/Pocket PC are insignificant. They are developed as extensions of the client-side generic components that implement basic functionalities such as interface between the apvplication and the peripherals (access control to sound and video blasters, or TV tuner), audio/video data manipulation (data transmission/retrieval to/ from the media server), audio rendering, video playback, and handwriting/drawing features. 

The Species File Group (SFG) has developed a template that contains the basic database table structure as well as the stored procedures, user-defined functions and views used by Species Files. The template is used as the starting point for new Species File databases (SpeciesFile-Databases ). Species File is a MS Visual Studio application. Progranmiing for Species File is done with Visual Studio.NET. The Active Server Pages (ASP) use Visual Basic Script and client side programming is done using JavaScript. 

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