Web Database - Client / Server Architecture

Every Internet / Intranet Connection to a Web Database is Automatically a Client / Server Architecture.

Each Browser Client requests information from the Web Server, which is then returned back to the Browser Client. This creates a Single-Tier Client / Server Relationship.
Browser Client	Browser Client	Browser Client	Browser Client
Web Server
HTML Files
Web Server
Browser Client	Browser Client	Browser Client	Browser Client
This HTML Document is a Single-Tier Client / Server Relationship.

CGI Programs and Scripts are Individually Run from the Web Server, One CGI Program or Script for each of the Browser Clients. This creates a Two-Tier Client / Server Relationship. Each Copy of the CGI Program acts as both a Client and as a Server to the Web Server.
Browser Client	Browser Client	Browser Client	Browser Client
Web Server
CGI Client / Server	CGI Client / Server	CGI Client / Server	CGI Client / Server
Web Server
Browser Client	Browser Client	Browser Client	Browser Client

CGI Programs and Scripts that work with Databases that are either Flat Files or File Server Databases are still a Two-Tier Client / Server Relationship. Each Copy of the CGI Program still acts as both a Client and as a Server to the Web Server by Directly Accessing and Controlling the Databases themselves.
Browser Client	Browser Client	Browser Client	Browser Client
Web Server
CGI Client / Server	CGI Client / Server	CGI Client / Server	CGI Client / Server
Database	Database	Database	Database
CGI Client / Server	CGI Client / Server	CGI Client / Server	CGI Client / Server
Web Server
Browser Client	Browser Client	Browser Client	Browser Client
The MCSE Practice Test and the Hardware Sales are both Two-Tier Client / Server Relationships. Although each begins with an HTML Document, they each launch CGI Scripts into Flat File Databases.

CGI Programs and Scripts that work with Databases that are Client / Server Databases are now a Three-Tier Client / Server Relationship. Each Copy of the CGI Program Connects to a Single Database Server, which Directly Controls all of the Requests to the Databases, then Returns any Data (Information) to the CGI Program or Script.
Browser Client	Browser Client	Browser Client	Browser Client
Web Server
CGI Client	CGI Client	CGI Client	CGI Client
Database Server
Database Request	Database Request	Database Request	Database Request
Database
Database Request	Database Request	Database Request	Database Request
Database Server
CGI Client	CGI Client	CGI Client	CGI Client
Web Server
Browser Client	Browser Client	Browser Client	Browser Client
Our Web Database Design can act as both a Two-Tier and a Three-Tier Client / Server Relationship.

You can also run a seperate CGI Server Daemon. The advantage of doing so would be that the CGI Server Program can maintain an Open Connection with the Database Server. This would eliminate the necessity of having each CGI Client Logon to the Database for each connection. This is still a Three-Tier Client / Server Relationship.
Browser Client	Browser Client	Browser Client	Browser Client
Web Server
CGI Client	CGI Client	CGI Client	CGI Client
CGI Server
Database Server
Database Request	Database Request	Database Request	Database Request
Database
Database Request	Database Request	Database Request	Database Request
Database Server
CGI Server
CGI Client	CGI Client	CGI Client	CGI Client
Web Server
Browser Client	Browser Client	Browser Client	Browser Client
Our Web Database Design can act as both a Two-Tier and a Three-Tier Client / Server Relationship.

As Traffic Increases, you can improve your Structure into a Distributed Network with Multiple Servers running Multiple, Partially Replicated Databases. It is also possible for the Database Servers to Create Requests between Themselves allowing Different Data (Information) to be stored on each Server.
Browser Client	Browser Client	Browser Client	Browser Client	Browser Client	Browser Client	Browser Client	Browser Client
Web Server				Web Server
CGI Client	CGI Client	CGI Client	CGI Client	CGI Client	CGI Client	CGI Client	CGI Client
CGI Server				CGI Server
Database Server				Database Server
Database Request	Database Request	Database Request	Database Request	Database Request	Database Request	Database Request	Database Request
Database				Database
Database Replication Server
Database				Database
Database Request	Database Request	Database Request	Database Request	Database Request	Database Request	Database Request	Database Request
Database Server				Database Server
CGI Server				CGI Server
CGI Client	CGI Client	CGI Client	CGI Client	CGI Client	CGI Client	CGI Client	CGI Client
Web Server				Web Server
Browser Client	Browser Client	Browser Client	Browser Client	Browser Client	Browser Client	Browser Client	Browser Client
Our Web Database Design is Very Easily Extendable. Note that the Web Server and the Database Server can each reside on different computers (Servers).

The Greatest Advantage of the Web Database Client / Server Architure is that it is so Easily Extendable, while working Identically for both an Internet and an Intranet. This is true for both the Single-Tier, the Two-Tier and the Three-Tier Client / Server Relationships. This is also just as true for The Personal Web Server.

Browser Client

Web Server

CGI Client

Database / (Optional) Database Server

CGI Client

Web Server

Browser Client

Finally, even Server and Database Administration can be done through the Web Database.

Do not confuse a 3-Tier Web Database with a 3-Tier Application, even though the design schemes of the two are quite similar. A 3-tier application is an application program that is organized into three major parts, each of which is distributed to a different place or places in a network. The three parts are: The workstation or presentation interface, The business logic, The database and programming related to managing it. In a typical 3-tier application, the application user's workstation contains the programming that provides the graphical user interface (GUI) and application-specific entry forms or interactive windows. (Some data that is local or unique for the workstation user is also kept on the local hard disk.) Business logic is located on a local area network (LAN) server or other shared computer. The business logic acts as the server for client requests from workstations. In turn, it determines what data is needed (and where it is located) and acts as a client in relation to a third tier of programming that might be located on a mainframe computer. The third tier includes the database and a program to manage read and write access to it. While the organization of an application can be more complicated than this, the 3-tier view is a convenient way to think about the parts in a large-scale program. A 3-tier application uses the client/server computing model. With three tiers or parts, each part can be developed concurrently by different team of programmers coding in different languages from the other tier developers. Because the programming for a tier can be changed or relocated without affecting the other tiers, the 3-tier model makes it easier for an enterprise or software packager to continually evolve an application as new needs and opportunities arise. Existing applications or critical parts can be permanently or temporarily retained and encapsulated within the new tier of which it becomes a component. The 3-tier application architecture is consistent with the ideas of distributed object-oriented programming.

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