The software engineering field has made unprecedented progress in 1995 and 1997, and its achievements exceed the sum of the achievements in the software engineering industry in the past 15 years. One of these most importantly, one of the more expensive results is the emergence of unified modeling languages (UML: Unified Modeling Language). In the world, in least 10 years, UML will be a standard modeling language dominated by object-oriented technical fields. UML is completely necessary: First, dozens of object-oriented modeling languages are independent of each other, and UML can eliminate some potential unnecessary differences to prevent users; secondly, Through unified semantics and symbols, it is possible to stabilize the object-oriented technology market in my country, so that the project roots in a mature standard modeling language, which can greatly broaden the applicable scope of the software system developed and developed, and greatly improve its flexibility.
