lass="keyword">val</span> session_id : <span><a href="../Types/Session/index.html#type-t">Types.Session.t</a> Ctypes_static.ptr</span> <span>&#45;&gt;</span> <span>unit Ctypes_static.ptr</span> <span>&#45;&gt;</span> Unsigned.size_t <span>&#45;&gt;</span> Unsigned.size_t</code></dt><dd><p><code>session_id sess id id_len</code></p><p>An identifier for this session. Will be the same for both ends of the conversation. If the id buffer is too small then olm_session_last_error() will be &quot;OUTPUT_BUFFER_TOO_S