1. A model-oriented programming (MOP) method for computer-based software system development, the method comprising the steps of: obtaining the problem specifications of said computer-based software system; building a model of said computer-based software system; recognizing threads of execution at design stage and appearance of said threads of execution in said model; segmenting said model into model segments, wherein each of said model segments is assigned to a programmer; manually writing program code for each of said model segments, wherein said program code created by each respective said assigned programmers implements said iteratively updated respective model segment; debugging said program code segments by each of said assigned programmers, wherein the expected intermediate values within said program code segment execution are obtained from said model segments, and upon detection of a model error fixing said detected model error and proceeding with segmenting said model into model segments, wherein each of said model segments is assigned to a programmer; integrating said code corresponding to each of said model segments into a computer-based software system, wherein said integrated computer-based software substantially implements said iteratively updated model, and upon detection of a model error fixing said detected model error and proceeding with segmenting said model into model segments, wherein each of said model segments is assigned to a programmer; delivering said integrated computer-based software to the client; maintaining said delivered computer-based software system, wherein said maintenance prolongs said software system development and requires keeping said model up-to-date for all versions of said software system after delivering said software system to the client.