Among the responses to my endangered middle-tier post was this one by Ed Draper, architect evangelist for MSFT. While Ed makes some interesting points, on the whole his argument doesn’t hold much water.
First off, his point about Moore’s law is accurate, yet irrelevant. While Moore’s law does relate to CPU speed, I was using it as an example of the rate that overall computing power improves. Storage capacity and network speed improve along a similar trajectory. 64-bit machines are at the early stages of becoming commonplace. And while it’s true that scalability doesn’t equal performance, having better performing hardware can significantly improve scalability.
(Side note – if we’re going to be truly picky, Moore’s law actually refers to rate of improvement of the number of transistors per IC, which only roughly equates to performance. Intel’s Centrino technology is all about using those increasing numbers of transistors for other things like wireless networking and battery management.)
Ed spends quite a bit of time covering very low level computing concepts such as threads, locks, instruction cache, registers and the stack. I’m not sure why he does this. It almost feels like he only read the first part of my post, stopping right before he got to the part where I wrote: “Of course, it will be a long long time before Moore’s law can provide a single machine to run a BIG enterprise app”. In other words, I don’t expect to run my ERP, SCM, CRM or other BFD enterprise-scale app on one machine!
Ed has missed a basic point of my post that I didn’t spell out as I thought it was obvious: the independent services that make up a BIG enterprise class app can all run on different machines. I’m guessing he missed that point by the way he ended his post:
“Yes, distributed computing is a good thing.”
As Ted points out, it’s not just a good thing, “distributed computing is a necessary thing.” And a system of 100′s or 1000′s of independent services – which is what I’m describing – is significantly more distributable than the multi-tier monolithic applications we build today.
Of course, it is guaranteed that a small percentage of services will continue to need to use scale out techniques to reach their scalability requirements. For example, it will be a very very long time (if ever) before a single piece of hardware could handle the order processing load Amazon.com generates a week before Christmas or the tax return filing load at the IRS on April 15th. This problem isn’t unique to application design. To draw a parallel to the database design world, there are a small percentage of tables that benefit from using filegroups to isolate them on separate drives from the rest of the database. It happens – but it doesn’t always happen. It doesn’t even usually happen. I like Josh’s comment that “the vast majority of people who think they have workloads which require partition for scale are actually indulging in delusions of grandeur.”
The point I was making is that computers are going to continue getting faster and service-oriented systems are likely to consist of boatloads of independent services with only modest scalability requirements. The combination of these two forces drastically reduces the number of scenarios where you need to use multi-tier scale out techniques to achieve the scalability requirements. If you don’t need a multi-tier deployment, then there is a huge performance and scalability benefit to running the service logic in the database process. If you don’t need to scale-out to achieve your requirement, why would you take the performance and scalability hit to run your code outside the database?
It’s pointless to argue that computer aren’t getting faster or that running the code in process with the database doesn’t perform better. Ed (and Ted and Josh and everyone else reading this), I’d love to hear you opinions on the following:
- Will a service-oriented approach likely result in of boatloads of independent services where today we have one BIG app?
- If yes, will the vast majority of these boatloads of independent services have modest enough scalability requirements to run on a single piece of hardware in the near future?