As noted in the sqlex1.c file, the texisd daemon must be running on the host. The sqlex1 example utilizes the Network API, so it makes network calls to the texisd server. See the Texis manual for texisd options; it is typically started as: texisd -o/logs/texisd.log -l
No, running texis starts the Texis Monitor, which performs some maintenance and housekeeping tasks. texisd must be explicitly started, since it provides network access to database(s).