Does anyone have experience deploying GWT apps to EC2?
If I were to install tomcat or apache on a ec2 instance, could I have users connect directly to a url pointing there?
Would that be cost effective, or would java hosting services be best?
Is there any downside to hosting the edge HTTP server on a regular hosting service and have that direct requests to EC2? Performance ever an issue here?
Yes, you can host pretty much whatever you want, as you effectively have a dedicated Linux machine at your command.
As I last recall, the basic rate for an EC2 instance, on their "low end box" worked out to around $75/month, so you can use that as a benchmark against other vendors. That also assumed that the machine is up 24x7 (since you pay for it by the hour).
The major downside of an EC2 instance is simply that it can "go away" at any time, and when it does, any data written to your instance will "go away" as well.
That means you need to set it up so that you can readily restart the server, but also you need to offline any data that you generate and wish to keep (either to one of Amazons other services, like S3, or to some other external service). That will incur some extra costs depending on volume.
Finally, you will also be billed for any traffic to the service.
The thing to compare it against is another "Virtual Server" from some other vendor. There is a lot of interesting things that can be done with EC2, but it may well be easier to go with a dedicated Virtual hosting service if you're just using a single machine.
You definitely can host an http server in EC2, but you need to take into consideration the following:
To successfully host a server in EC2, you therefore need to employ some other services from Amazon. You need Elastic IP, so that you can circumvent the new IP address problem. You can also use Elastic Block Storage. This is a service that will allow you to mount in your machine a disk, that will not go away when your instance is lost.
Other answers are correct but I just wanted to share the fact that we are are developing a product that is 100% EC2/S3 based and also have a pure GWT front end.
We use maven2 for builds and the excellent gwt-maven plugin. This makes it easy to produce a WAR package of our web application as output. We use Jetty but Tomcat would work just as well.
We have pound (a http accelerator/load balancer) running on the VM listening for http & https, which then forwards to requests to lighttpd (static) or jetty (app). This also simplifies SSL certificates because pound handles SSL. I've found Java servers have always been a pain to configure with SSL certs.
Others have given good answers. I would have to add that you need to spend programmer time getting to know EC2's quirks and addressing them (e.g. with EBS). It's not completely trivial, and though it is useful knowledge to have and may be worth it for that reason alone, if you want to get up and running quickly with just a few servers, you should probably look at other hosted options.
On the other hand, if you plan to scale up massively enough (eventually hosting many servers on EC2) then I would highly recommend it. You have to architect a few things, but you need to do that anyways. The flexibility of on-demand computing, and the generally low price, makes this a killer platform once you reach a certain scale of operation.