Layers and Tiers

[runtime]

Hello!

First time posting...

Question about the difference between layers and tiers:

How many tiers are in the WAMP environment?

This is not an exam question, but the answer will help me dispute one. I have a professor who believes the following:

"one may infer Apache as tier 1(for static content), PHP as tier 2 (for dynamic content) and MySql as tier 3 (database management)."

I believe he is wrong, and this comment almost seems like he is grasping for definition himself. I thought it was pretty simple:

Tier 1 = Browser
Tier 2 = Server
Tier 3 = Database

You can quibble about the layer configurations for each tier, or the semantics (i.e. Browser is really Presentation, etc.), but isn't that what it comes down to? This question is specific to everything running on one PC (WAMP) but it shouldn't change the theory.

Thank you for any confirmation..

JR

[ronverdonk]

The classical 3-tier structure for web is

In the Web development field, three-tier is often used to refer to Websites, commonly Electronic commerce websites, which are built using three tiers:

1. A front end Web server serving static content.

2. A middle dynamic content processing and generation level Application server, for example Java EE platform.

3. A back end Database, comprising both data sets and the Database management system or RDBMS software that manages and provides access to the data.

See also Multitier architecture

also shown in the following article

Tier 1: the client contains the presentation logic, including simple control and user input validation. This application is also known as a thin client.

Tier 2: the middle tier is also known as the application server, which provides the business processes logic and the data access.

Tier 3: the data server provides the business data.

See Three-Tier Architecture

When you have read this you'll understand why your opinions differ.

Ronald

[ronverdonk]

After I posted the previous reply I realized that this thread was started in the MySQL forum. I much as I like the subject, I don't think it belongs there and that you can expect more responses in the Community Discussions area, so I will move it there.

moderator

[runtime]

Thank you for the reply Ronald.

I think the problem is that this professor sees Apache and PHP as separate tiers in a WAMP development environment (that is not an application server). Correct me if I am wrong, but, it would break down like this even when everything is running on the same PC:

(The 3 Tiers)

1) The client browser
2) Apache with PHP
3) MySQL

Here is concise definition I ran across:

"A Layer becomes a Tier if it can be physically separated from the layers consuming it."

So, if you can move it to a computer all by itself, you have a tier:

1) Client computer with browser
2) Apache server with PHP
3) MySQL server

So it breaks down the same except for the application server part, which does not really apply to Apache/PHP (excluding recent PHP application developments), correct?


JR

[ronverdonk]

In my opinion you should consider Apache/PHP as a tier.

Ronald

[runtime]

In my opinion you should consider Apache/PHP as a tier.

Ronald

I agree, but not as two separate Tiers...which is what the Prof. is suggesting.

Thank you for your replies,
John