n-tier vs. n-layer - Kevin Trethewey
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Kevin Trethewey

Software Developer, Technologist, Connoisseur of things that go 'bing'.

n-tier vs. n-layer

Rockford Lhotka has some things to say on the subject (including what the point of a middle tier is if you are using business objects), i think his views are spot on - I have seen this mistake made in a number of cases (and have even made it myself :$)...

 

" You should be forced into implementing physical tiers kicking and screaming. There should be substantial justification for using tiers, and those justifications should be questioned at every step along the way.

 

At the same time, you should encourage the use of logical layers at all times. There should be substantial justification for not using layers, and any argument against layering of software should be viewed with extreme skepticism.

 

Layering is almost always good, tiers are usually bad."

 

Read the rest here: Fire bad, tree pretty

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Published Feb 21 2005, 09:23 PM by Kevin Trethewey

Comments

 

Brady Kelly said:

The man might be know his architecture, but his vocabulary needs work. Tier and layer are synonomous, logical and physical are not.

There are also often valid requirements for different physical tiers or layers, such as having multiple clients sharing the same database server. When implemented on a serparate machine, maintenance or downtime on the database need not affect the operation of clients.
February 22, 2005 10:49 AM
 

KevinT said:

I disagree on your vocab point - i think talking of a tier as being physical and a layer as logical helps to more clearly define a discussion on the topic.

You should read his business object book bro (highly recommended) - i think you will find that you are 'preaching to the choir'. :-P

February 22, 2005 11:03 AM
 

Pramodh P said:

In most cases Tier and Layers are synonymous, but there exists a subtle difference between both, Tier is the partitioning of the system like User, Business and Data. Where as layer is the partioning of the Tiers. For example an User Tier can consist of the Client Layer and a Presentation Layer (existing in the server).
April 22, 2005 8:18 AM
 

Jon said:

Regardless of what terminology is used, separating code into different objects is preferred, while using multiple machines is not desireable because of the performance hit. Rockford has defined tiers as relating to machines and layers as code objects. Sounds good to me. Let's use them.
January 26, 2006 1:55 AM
 

Tiers and Layers « rabidfox.ca said:

Pingback from  Tiers and Layers «  rabidfox.ca

September 2, 2009 5:25 AM
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