Definition

3-tier application

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.

Contributor(s): Cheryl Gilbert
This was last updated in April 2007
Posted by: Margaret Rouse

Email Alerts

Register now to receive SearchSoftwareQuality.com-related news, tips and more, delivered to your inbox.
By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

More News and Tutorials

  • Scaling Agile software development: Challenges and solutions

    Software consultant Nari Kannan describes how agile practices and work can be scaled appropriately for success in large organizations. Using lean thinking, reduction of waste, and appropriately organizing work and people, agile can be successfully adapted, regardless of the size of the organization.

  • Rise in hidden software glitches caused by programmer retirements

    Undiscovered software glitches in complex systems are common, and one of the primary drivers is the loss of mainframe knowledge of a retiring workforce. Software glitches are lurking in many large systems, particularly mainframe systems, and the COBOL programmers that understand the code best are retiring, according to Jeff Papows, author of the new book, "Glitch - The hidden impact of faulty software." Papows describes how faulty software caused a huge charge to debit card holder's account and why such mistakes are on the rise in this interview. Papows notes the three most pressing drivers for software glitches: loss of intellectual knowledge, market consolidation and the ubiquity of technology

  • Professional development for software testers

    Karen Johnson suggests a variety of ways that testers can gain additional skills and experience, including social networking and open source testing.

Do you have something to add to this definition? Let us know.

Send your comments to techterms@whatis.com

There are Comments. Add yours.

 
TIP: Want to include a code block in your comment? Use <pre> or <code> tags around the desired text. Ex: <code>insert code</code>

REGISTER or login:

Forgot Password?
By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy
Sort by: OldestNewest

Forgot Password?

No problem! Submit your e-mail address below. We'll send you an email containing your password.

Your password has been sent to: