Re: scalability and manageability

From:

=?ISO-8859-1?Q?Arne_Vajh=F8j?= <arne@vajhoej.dk>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 20 Jan 2011 20:35:48 -0500

Message-ID:

<4d38e2f4$0$23755$14726298@news.sunsite.dk>

On 20-01-2011 03:35, Patricia Shanahan wrote:

The real issue is the right set of tiers for the
application.

Agree.

If you get that right, manageability and scalability will both increase.
The essence of modularization as a strategy for building complex systems
is the fact that managing n simple subsystems plus some simple
interactions between them is often easier than managing one system that
does their combined function. Adding tiers, if they are the right tiers,
can improve manageability.

If manageability means that it is easy to manage by operations,
then they are usually not affected much (neither positive or
negative) from the structuring of the systems, because
they tend to have a black box view of the system.

On the other hand, increasing the number of tiers for the sake of doing
so, on the assumption that it will automatically increase scalability,
can have the effect of reducing scalability. Even when tiers are run on
the same hardware, communication between them tends to be more expensive
than intra-tier communication. With a bad tier design, the inter-tier
communication can be the limiting factor for scalability.

I would define:

performance = much bang for the buck

scalability = the ability to get double bang for double buck

Too many tiers decrease performance not scalability.

Arne