There's an important difference between physical tiers and logical tiers
(often called layers).
Physical tiers are a tradeoff between things like performance, scalability,
fault-tolerance, security and so forth.
Logical layers are all about improving maintainability of code, decreasing
cost of development, promoting reuse and so forth.
In general terms, software should be built using an organized set of logical
layers - often Presentation/Business/Data.
Sometimes, typically due to scalability or security requirements those
layers may be deployed to separate physical tiers - thus resulting in an
n-tier system. This invariably increases the cost and complexity of a
system, and so should only be done if the scalability or security benefits
outweigh the costs.
Rocky
--
Rockford Lhotka
Magenic Technologies
rocky at lhotka dot net
http://www.lhotka.net
"Michael C#" <(E-Mail Removed)> wrote in message
news:UuFAe.11084$(E-Mail Removed)...
> Three tier is more scalable than two tier. In three-tier, or n-tier, your
> middle tiers can take on the responsibility of "traffic cops", cache data
> if you require, and cut down on the number of database connections
> required for hundreds or thousands of users.
>
> "John" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
>> How does number of user relate to the tiers of the app?
>>
>> Thanks
>>
>> Regards
>>
>> "Michael C#" <(E-Mail Removed)> wrote in message
>> news:fSEAe.165791$(E-Mail Removed)...
>>>A well-developed three-tier is better, but it might be overkill. It
>>>depends on a lot of factors like how many people are going to be using
>>>the system simultaneously? Number and complexity of business rules?
>>>Network bandwidth (thin client/fat client)? How much data is being
>>>stored? Etc.
>>>
>>> For a simple, basic app that only one or two people at a time will use,
>>> two-tier would probably be sufficient; especially if you're on a tight
>>> deadline. For a scalable app that has more complex busines logic and
>>> needs to handle many simultaneous users, three-tier/n-tier is the way to
>>> go.
>>>
>>> "John" <(E-Mail Removed)> wrote in message
>>> news:(E-Mail Removed)...
>>>> Hi
>>>>
>>>> I am making a simple contacts app involving clients, suppliers etc.
>>>> Mostly it involves data entered by the user being saved in the db and
>>>> then user able to search/browse the data. My question is; is it still
>>>> advantageous to bind ui elements to clients, suppliers "business"
>>>> objects which in turn deal with the db or can I bind ui elements
>>>> directly to db? In other words is it useful to have a three-tier app
>>>> instead of a two-tier one even in this simple case? Reasons?
>>>>
>>>> Thanks
>>>>
>>>> Regards
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>
>
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