POCO version = 1.6.1.0

Calling the following method sometimes throw a Poco::Net::NetException "SSL Exception: error:1409F07F:SSL routines:ssl3_write_pending:bad write retry" :
Poco::Net::WebSocket::sendFrame(const void * buffer, int length, int flags)

this occurred with flags = WebSocket::FRAME_FLAG_FIN | WebSocket::FRAME_FLAG_PING
or flags = WebSocket::FRAME_TEXT

See an interesting related URL to solve such exceptions when calling SSL_write() :
http://stackoverflow.com/questions/2997218/why-am-i-getting-error1409f07fssl-routinesssl3-write-pending-bad-write-retr