Abstract: A server according to an embodiment includes a processor configured to receive a friend add request for a target account from a user terminal accessed with a user account; based on one of the user account and the target account being a protected account, transmit an approval request for the friend add request to a protector account connected to the protected account; and based on receiving a reply to the approval request from the protector terminal, add the target account to a friend list of the user account.

Abstract: A cab of a heavy construction vehicle comprising an arc-shaped front wall, an arc-shaped movable front window and arc-shaped guide rails, all of which have substantially the same radius of curvature. During the movement of the front window between its full opening position and full closing position, the movement trace of the front window is present substantially near and along the front wall of the cab so that inner space of the cab may not reduced upon opening and closing of the front window. As a result, there is no danger that the operator may injured by the moving front window. It is also possible to lock the front window at an optionally desired position between its full opening position and full closing position. The cab also comprises a locking device including a plurality of engaging members each provided with a cam surface and an engaging surface and a lock bolt adapted to be slidably contactable with a required engaging member and engagable with the engaging surface of the engaging member.