Downloading Atmosphere Jars - Atmosphere/atmosphere Wiki

To install Atmosphere, the recommended way is to use Maven and just do:

     <dependency>
         <groupId>org.atmosphere</groupId>
         <artifactId>atmosphere-{atmosphere-module}</artifactId>
         <version>1.0.x</version>
      </dependency>

All the dependencies can also be downloaded from Maven Central

If you aren't using Maven, just download the library from here and unzip it.