JSR-356 comprises both: client and server endpoints.
This screencast demonstrates how to connect to a (Java EE 7) server from a plain Java client using the RI (tyrus):
Also checkout: hellsockets.
See also other screencasts at: http://tv.adam-bien.com or subscribe tohttp://www.youtube.com/user/bienadam.
See you at Java EE Workshops at Munich Airport, Terminal 2 or Virtual Dedicated Workshops / consulting
NEW MUC Airport Workshop: Migrating Java Client (Swing / Java FX) to Web Standards
Airport MUC workshops: Web (SPA, PWAs, Offline, Desktop, Mobile) Applications Essentials and Effective Web Applications. No migrations. #usetheplatform
Podcast: airhacks.fm and newsletter: airhacks.news
A book about rethinking Java EE Patterns