How to preview an alfresco document in another application using api?(Alfresco Community v5.1.0)

[prasobhraj]

I would like to preview documents stored in alfresco in my custom applications. please advice how to achieve it. my alfresco version is 

Alfresco Community v5.1.0

[angelborroy]

Probably the better way is using the REST API or the CMIS protocol.