Tuesday, December 29, 2009

Database applications in Delphi has many types


Database applications in Delphi has many types, namely:
Single System or Stand-Alone
File-Share system or Centralized
Client-Server System
Multi-Tier System
The explanation above is as follows

Single System or Stand-Alone
In this architecture database and database applications are placed on the machines (computers) the same. This architecture is the most simple architecture and is designed for single users. Database used is a local database.
Database Firewall is a security solution which protects databases from known and unknown attacks. For example: SQL injection, database rootkits, information disclosure, etc.

Database Firewall is a computer networking firewall operating at the database application layer of a protocol stack. Also known as a proxy-based firewall, it may be implemented as a piece of software running on a single computer, or a stand-alone piece of hardware. Often, it is a host using various forms of reverse proxy servers to proxy traffic before passing it to a gateway router. Because it acts on the database application layer, it may inspect the contents of the traffic, blocking specified content, such as certain websites, viruses, attempts to exploit known logical flaws in client software.

Database-layer firewalls work on the SQL application level of the TCP/IP stack (i.e., all applications (web or others) connection to the database, or SQL management interfaces), and may intercept and enforce all packets traveling to or from a database.

Database Firewall’s, most of the times include an automated SQL learning capabilities, which assists in Database Firewall policy building, The learning capabilities will list queries directed to a specific Database which will lead to a Database Firewall policy, the policy cab be configured at any time.

Network firewall lack the required sophistication to inspect the SQL application layer, so Network Firewall cannot assist in SQL application security.

File-Share System
Iini same architecture with applications stand-alone database unless the database can be accessed from several clients that are connected in a network. So the application is placed placed on each client to access the same database located at a computer in the network.
Applications stand-alone database or file-share applications included in the single-tiered application, because the application and the database of the same file system.
StorNext File System is a shared disk file system made by Quantum Corporation. It is installed on hosts that are connected to the same disk array in a storage area network (SAN) . Client systems are not required to run the same operating system to access a shared filesystem containing StorNext data. As of January 2008, the operating systems with available client software are Microsoft Windows, Mac OS X (as Xsan developed by Apple), Red Hat Linux, SuSE Linux, HP-UX, Solaris, AIX, and IRIX.

StorNext is used in environments where large files must be shared by users without network delays, or where a file must be available for access by multiple readers starting at different times. An example of the former is analysis of real time satellite image data. An example of the latter is on-demand access of a movie stored on disk.

The original name was CentraVision File System (CVFS). It was created by MountainGate Imaging Systems Corporation to provide fast data transfer between Windows and IRIX computers. Advanced Digital Information Corporation acquired MountainGate in September 1999, added additional client types, and changed the name to StorNext File System. The first new clients were Solaris and Linux. In August 2006 Quantum acquired ADIC.

The StorNext File System is the foundation for Quantum's StorNext Storage Manager, a hierarchical storage management system that is used for data archival with a back end robotic tape library.


Client-Server System
This architecture is of the main components of the client and server. Application databases are on the client machine. While there is a remote server database and database servers that will accessible. The application of this type are also often as a two-tiered application. If the application is also placed on the same machine with a remote server that contains the database server, this application is still called a two-tiered application, because the application and database servers operate in two different independent systems.

Multi-Tier System
This architecture is an extension of client-server system. This architecture consists of a remote database servers, application servers that access the remote server and client applications that access the server application. The number in the application tier can be added as needed.
In software engineering, multi-tier architecture (often referred to as n-tier architecture) is a client-server architecture in which the presentation, the application processing, and the data management are logically separate processes. For example, an application that uses middleware to service data requests between a user and a database employs multi-tier architecture. The most widespread use of "multi-tier architecture" refers to three-tier architecture.

The concepts of layer and tier are often used interchangeably. However, one fairly common point of view is that there is indeed a difference, and that a layer is a logical structuring mechanism for the elements that make up the software solution, while a tier is a physical structuring mechanism for the system infrastructure.

Embarcadero Delphi, formerly CodeGear Delphi and Borland Delphi, is a software development environment for Microsoft Windows applications originally developed by Borland and now owned and developed by Embarcadero Technologies. Delphi 2010 is the most recent version and is distributed in three different editions: Professional, Enterprise and Architect.

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