How do you build and deploy a scalable web services infrastructure?

Question

I have a client asking this for a requirement and haven't done this before, what does he mean by web service infrastructure?

Answer 1

First thing that comes to mind was the Enterprise service bus.

He probably means some sort of "infrastructure" to run a lot of complex interacting web services.

Answer 2

Either an enterprise application that you call via a web service that can run on many instances of a web application server, or run a single instance that are very nicely multithreaded and scale to many CPUs, or deploying loads of different webservices that all talk to each other, often via message queues, until you have something that breaks all the time and requires a huge team of people to maintain. Might as well throw in a load of virtual machines to have a virtualised, scalable, re-deployable web service infrastructure (i.e., loads of tomcats or jbosses in linux VMs ready to deply as needed, one app per VM).

Then there is physical scalability. Is there enough CPU power for your needs? Is there enough bandwidth between physical nodes to send all these messages and SOAP transactions between machines? Is there enough storage? Is the storage available on a fast, low latency interconnect? Is the database nicely fed with CPU power, bandwidth, a disc system that doesn't lag. Is there a database backup. How about when a single machine can't handle the load of a particular function - then you need load balancers, although these are good for redundancy and software updates whilst remaining live as well.

Is there a site backup? Or are you scaling globally - will there be multiple data centres around the globe? Do you have redundant links to the internet from each data centre? What happens when a site goes down? How is data replicated between sites, to reduce inter-site communications, and how do these data caches and pushes work?

And so on and so forth. But your client probably just wants a web service that can be load balanced without thrashing (i.e., two or more instances can share data/sessions/etc, depends on the application really), with easy database configuration and backup. Ease of deployment is desirable, so make the install simple. Or even provide a Linux VM for them to add to their VM infrastructure. Talk to their sysadmin to see what they currently do.

Answer 3

That phrase encompasses a wide variety of technical aspects. Your infrastructure is all of the components that make up the systems that run a web business or application, including hardware. So it refers to your server and network setup, your bandwidth and connections in and out, your database setup, backup solutions, web server software, code deployment methods, and anything else used to successfully run a web business with high reliability and uptime and low error and bug incidents.

In order to make such a thing scalable, you have to architect all these components together into something that will work smoothly with growth over time. A scalable architecture should be flexible enough to handle sudden traffic spikes.

Methods used to facilitate scalability include replicated databases, clustered web servers, load balancers, RAID disk striping, and network switching. Your code has to take much of this into account.

It's a tough service to provide.

Answer 4

This phrase is often used as a marketing term from companies who sell some part of what they'll call a "scalable web services infrastructure".

Try to find out from the client exactly what they need. Do they have existing web services? Do they have existing business logic they've decided to expose as web services? Do they have customers who are asking to be able to access your client's systems through web services?

Does your client even know what a web service is?