As noted above, dynamic web applications provide up-to-date information. In this case, an interaction occurs between the browser and the database. But studying the nature of this interaction can reveal a certain complexity that requires a preliminary analysis of the nature of the application (transactional or interactive). Transactional application case. When it comes to real-time access to the database, we are faced with the concept of a transaction, the web becomes truly dynamic, and applications work as client-server applications. Such an architecture requires the interaction of the web server with the transaction monitor, which is responsible for the dialogue with the database server.
For this type of application, a variant of the system reboot client, development comes from an environment using the fourth generation language (L4G). This is a case that generates transactional applications whose client interfaces are directly accessible via a web browser. Case of an interactive application. These are applications for which response time is not a critical factor. For this, there are Web / DBMS interface controllers. These tools allow the designer to have previously defined components in the visual environment. Microsoft also offers IDC, which we will explain in detail.
Cyber reboot. Other products consist of at least two modules: one for developing web pages and forms, the other is a CGI program that is called at the server level and involves connecting to the database server using native drivers or ODBC. This access is the oldest; it consists in using the CGI call to run programs containing SQL queries to the database. This method consumes a lot of system resources because every request from a web client calls an HTTP server to call an external program.
API (Application Programming Interface) More modern than CGI, it consists in using the existing API between the HTTP server and the database. This access is very fashionable, but it interferes with the transfer of applications, both in respect of HTTP servers and database management systems. The latest technology is aimed at providing the client with software that allows him to independently establish communication with the database. This is one of the problems of JAVA which, with the JDBC extension, provides an “applet” for connecting to the server through an ODBC connection.
JAVA is a development language that is well suited for the Internet for two reasons: firstly, applet execution is performed on the Java virtual machine, regardless of the platform; then applets are compact, so they are easily transmitted over the network. Its advantage is that it does not require drivers on the client computer. Dynamic applet loading simplifies queries to heterogeneous databases regardless of their location. However, the client workstation must take over part of the processing, while the clean network should concentrate the processing on the server.
The satisfactory results already obtained using IDC / HTX technology pushed us to implement our first developments. IDC / HTX Access to IDC is part of Microsoft’s information server on the Internet. It corresponds to a file, which, as its name implies, is based on the standard. The advantage of this approach is that this gateway works with any driver, which makes it a universal solution that can be adapted to different application contexts. The various components of this solution are interconnected as follows: two types of files are used by httpodbc.dll to send a query to the database and display the results.
Database Connector (.idc) Internet files provide access to the database and query execution, and HTML extension template files (.htx) provide a presentation of the results as HTML pages. The IDC file indicates the source to which you need to access, information necessary to identify the user, a request to send to a file containing an HTML representation, which must be observed to view the result of the request.