Please use the following links to download the specification.

OSGi Service Platform Release 4 Version 4.1 Core Specification 
OSGi Service Platform Release 4 Version 4.1 Compendium Specification 
OSGi Service Platform Release 4 Version 4.1 Core Companion Code 
OSGi Service Platform Release 4 Version 4.1 Compendium Companion Code 
OSGi Service Platform Release 4 Version 4.1 Minimum Execution Environment 
OSGi Service Platform Release 4 Version 4.1 Foundation Execution Environment