Amazon Web Services is adding new features to its hosted service platform Elastic Compute Cloud (EC2) to improve availability.

Elastic Compute Cloud is a web service that provides resizable compute capacity in the cloud. It is designed to make web-scale computing easier for developers, according to Amazon.

Two new features will be added to the platform: Availability Zones and Elastic IP Addresses.

With the Availability Zones function, applications can be placed in multiple locations so that if one location fails, a second one can take over. While EC2 users have been able to build such functionality themselves, they can now achieve the same effect with an API call, Amazon said.

Developers can also use what Amazon calls Elastic IP addresses to simplify address management. These are static, but can also be dynamically remapped on the fly to point to any instance in an Amazon EC2 account.

The feature makes it possible for developers to work around problems by moving an address to a replacement instance, instead of waiting for DNS to propagate changes or a data technician to reconfigure or replace a host.

British charity organization Comic Relief, which use Amazon's services to host some of its web sites, has tested both features and plans to start using them in its production environment, according to Ben Steel, new media developer at Comic Relief.

"Elastic IP addresses give us a certain amount of persistency. We can for example power up and down a server without having to change DNS settings," said Steel.

He also sees benefits with the Availability Zones feature. "It gives us a certain amount of redundancy," he said.

Amazon EC2 works in conjunction with other web services from Amazon, for example Simple Storage Service (S3) and SimpleDB.