Abstract: An application programming interface facilitates development of portable, multithreaded application programs. An application is a collection of instances of agent classes. Agent classes are organized in class hierarchies because new subclass agents may be derived from existing base class agents. Each agent class has its own message dispatching function; this allows the application programmer to alter the message passing framework provided by the application programming interface. Each agent instance within the program is independent because it is a sub-process aware only of its own data and context. Multithreading is provided by the application programming interface which contains a master dispatcher process non-preemptively allocating time to individual agents. Therefore, an application's multithreading capability is independent of the platform's operating system. In addition, a thread of execution may be split when the currently activated agent activates the master dispatcher.

Abstract: A hand-held pipette with a liquid dispensing knob at one end operably connected therewithin to a piston and piston cylinder assembly at the opposite end that is detachable from the pipette body for cleaning or replacement. An internal pawl and rack mechanism causes the piston to advance a small amount each time the knob is pressed, thereby repetitively dispensing small volumes of liquid therefrom. A second knob cooperatively engages an internal mechanism for both urging the piston to an overshoot position within the piston chamber and to disengage the piston from the internal mechanism in the pipette housing.

Abstract: A hand-held liquid dispenser of the type using a piston and piston cylinder for precise dispensing of desired volumes of liquid, including an improvement that automatically eliminates any air from the piston cylinder when an operator normally fills the piston cylinder with the desired liquid. A second piston of larger diameter than the first is disposed to draw fluid through the piston chamber at a much faster rate during a first short segment of an intake stroke than would the first piston, thereby to exhaust all dead air from the cylinder and fill it entirely with liquid.