can anybody tell me some of the best ror web applications hosting providers?
heroku
i know that heroku provides free hosting for rails application with size less than 50MB, and also the domain name format is xxxxx.heroku.com
but heroku provides the official hosting?
50MB is trailer you want host just purchase from http://heroku.com/
The major providers I know of off the top of my head are Heroku (www.heroku.com), EngineYard (www.engineyard.com), and Rails Machine (www.railsmachine.com). I believe both Heroku and EngineYard provide "front-ends" to Amazon EC2 (in other words, what they provide is an access layer to EC2 specifically geared toward Rails apps, to make them easier to deploy and administer). Lots of rails applications that I know of are hosted directly on Amazon EC2 or Rackspace Cloud Servers, which are just straight-up virtual servers running your choice of operating system. This approach gains you a lot of flexibility, but it can be a pain to administer several different apps on several different servers - keeping up with patches, making sure that the system continues to work correctly post-patch, etc. can be a full time job in and of itself! That's why providers like Heroku are really useful.
If you're looking at virtual hosting, you can look at Amazon EC2, Rackspace Cloud, Linode (www.linode.com), or Slicehost (www.slicehost.com). There are lots of companies in the VPS marketspace, but those are some options I can give you off the top of my head.
Hi, I've only got experience with VPS so far. I've got mixed feelings about ocssolutions.com, they were quite good at first (4 years ago), but I didn't like their support in the long run, I've not used them for a while so they may have improved. On my latest project, we had an horrible experience with HostingRails, some of it were caused by specific connection problems between their server and our region, but overall it was a nightmare.
Finally we recently moved to SpeedyRails (speedyrails.com) managed hosting and it has been amazing so far. Their server are incredibly fast and the support is very professional. The only downside is that they are quite new and their administration interface isn't all done yet, but it isn't much of a problem with managed hosting. It remains to be seen if they'll stand the test of time.