Comments on: How to do some service discovery on Amazon EC2 http://blog.elastic-grid.com/2008/06/30/how-to-do-some-service-discovery-on-amazon-ec2/ Where Dynamicity Meets the Cloud Fri, 05 Feb 2010 13:15:21 -0800 http://wordpress.org/?v=abc hourly 1 By: jeje http://blog.elastic-grid.com/2008/06/30/how-to-do-some-service-discovery-on-amazon-ec2/comment-page-1/#comment-572 jeje Wed, 10 Jun 2009 20:53:11 +0000 http://blog.elastic-grid.com/2008/06/30/how-to-do-some-service-discovery-on-amazon-ec2/#comment-572 Probably a hack, but probably one of the most used solutions I would say. Actually our implementation evolved quite a bit since that post (gosh about a year ago ;-)) and the cluster topology can easily change over time without any problem now. Your solution is another "hack" ;-) we though of too but we preferred to avoid extra charges to SDB and more importantly to NOT require our customers to sign up on SDB in order to use Elastic Grid. Our approach actually is based on leases (we use Jini & Rio underneath) and if an agent/cybernode can't renew the leases, then the monitor consider them as being dead. The same thing happen the other around. So it's quite like the idea of updating nodes statuses in SDB except we don't need to persist that stuff much. But if actually the AWS team was able to allow multicast on their network most of those problems would not be anymore ;-) Probably a hack, but probably one of the most used solutions I would say.
Actually our implementation evolved quite a bit since that post (gosh about a year ago ;-) ) and the cluster topology can easily change over time without any problem now.

Your solution is another “hack” ;-) we though of too but we preferred to avoid extra charges to SDB and more importantly to NOT require our customers to sign up on SDB in order to use Elastic Grid.
Our approach actually is based on leases (we use Jini & Rio underneath) and if an agent/cybernode can’t renew the leases, then the monitor consider them as being dead. The same thing happen the other around. So it’s quite like the idea of updating nodes statuses in SDB except we don’t need to persist that stuff much.

But if actually the AWS team was able to allow multicast on their network most of those problems would not be anymore ;-)

]]> By: Alfredo Ramos http://blog.elastic-grid.com/2008/06/30/how-to-do-some-service-discovery-on-amazon-ec2/comment-page-1/#comment-570 Alfredo Ramos Wed, 10 Jun 2009 16:04:55 +0000 http://blog.elastic-grid.com/2008/06/30/how-to-do-some-service-discovery-on-amazon-ec2/#comment-570 LOL That is really funny, using the security groups as metadata, what a hack! The things that EC2 force developers to do by their lack of features. You could probably used SDB (Simple DB) and make each instance to register an entry with a time stamp. The time stamp should be renewed by your instance, say... each 5 minutes. Any other instance interested in finding others could simply query the DB entries whose timestamp is less or o equal to 5 minutes. It would be better if AWS were more responsive to their client requests. Alfredo LOL

That is really funny, using the security groups as metadata, what a hack!

The things that EC2 force developers to do by their lack of features.

You could probably used SDB (Simple DB) and make each instance to register an entry with a time stamp. The time stamp should be renewed by your instance, say… each 5 minutes. Any other instance interested in finding others could simply query the DB entries whose timestamp is less or o equal to 5 minutes.

It would be better if AWS were more responsive to their client requests.

Alfredo

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