How does "distributed computing" apply to web development or programming in general?

I am about to use Apache Hadoop, the headlines read:

The Apache Hadoop project develops open-source software for reliable, scalable, distributed computing.

I can relate "scalability" to programming, but I just don't know how this "distributing" can help me in my development. According to wikipedia:

A distributed system consists of multiple autonomous computers that communicate through a computer network. The computers interact with each other in order to achieve a common goal

So does this mean I can deploy my web apps across multiple computers and do some sort of "intense computing"? The terms that come into my mind are Content Delivery Networks and Cl开发者_如何学Gooud Computing.

Web development has always been about distributed computing, since clients have been on different machines to the servers they talk to, web pages can pull in resources from many servers to build a page's content, and servers may talk to other machines to achieve their goals. CDNs make this more obvious than before, but really they're just an evolution, an introduction of a virtualization/indirection layer between what you ask for and the hardware used to provide it.

Clouds are about taking the concepts of virtualization and applying them to remote hosting, both of low-level OSes and higher-level software platforms. The really interesting thing about them is that this enables different business models on the part of customers (and with different risks too, but that's mostly not related to the fact that it's distributed computing but rather that it is not wholly under your control in your own jurisdiction).

I've found that the most effective use of distributed computing is when you think in terms of connecting together distinct services, each of which with different capabilities (which might be for technical reasons, or might not; sometimes, it's for business or legal reasons that things have to be divided up) and where each of those services may be provided by many components in multiple locations. There are, and continue to remain, issues with balancing the need for performance (which is a force that brings components together) and the need for robustness (which tends to lead to distribution and replication) within the overall context of the general capabilities map.

My goodness! That paragraph sounds like terrible piffle! What I'm trying to say is that it's all trade-offs, and you should be prepared for not getting it right first time.

(Hadoop is a mechanism for doing a distributed file store, and for efficiently applying certain classes of operation – those that fit well with MapReduce or other similar scatter-gather algorithms – across that whole dataset. If that shoe fits, use it. But it doesn't solve all problems, and thank goodness for that! Things that can do everything tend to look very much like things that can't actually do anything at all, and usefulness and comprehensibility come in the restrictions.)

Hadoop is typically used to process massive data sets by distributing the processing of that data set across multiple machines.

What this means is you probably don't want to use it to "deploy an application". You might use it to process stats on your application, however. For instance, you might have very large logs of user data. This would happen if your user data grows to become too large to fit on a single hard drive, and/or would take too long for one machine to process stats on (using standard methods like an SQL query).

Ygam. While the traditional role of "clients" and "servers" have been pretty stable from 1960 till about 2005.

I believe with every fiber of my being, that distributed computing is that we all carry processors around in our pockets.

Phones do computing work. Phones do NOT need centralized servers, but they DO benefit from them.

Phones , Smartphones, tablets are an example of where distributed computation is going.

You can make a wifi base-station out of an Android device now. So now a phone becomes a server of sorts for just that instant in the coffee shop that you turn it on for that cute person next to you without internet ....and now I digress.......