The PIPE model in UNIX is considered to be one of UNIX's most beautiful ideas: a large number of separate gadgets are combined with pipelines, which can constitute a very complex and diverse function. For example: DIR | SORT. This is a functional orthogonal decomposition. It is impossible to have a complete symmetry between these gadgets, that is, the PIPE model itself does not limit which tools can be combined, and there is no limitation of these tools. Order. When the system is gradually complex, SYMMETRY BROKEN, the Layer model, that is, objects at different levels cannot be interchanged, and the objects at the same level can be interchangeable, such as the protocol stack. In a more complex system, a complete reusable one object is more difficult, and the component technology decomposes the object into orthogonal sub-portion through the interface, and eventually constitutes a mesh model.
