What is a temporal database and how is it different from a traditional database? There are also middleware and UML. Can anyone give a brief introduction?

Different from traditional relational databases (RDBMS), temporal databases are mainly used to record the history of values ??that change over time, and these historical values ????are important to application fields. Such applications include: finance, insurance, reservation systems, decision support systems, etc.

Currently, there are no products for temporal databases like large relational databases such as Oracle and SQL Server. In the current situation where temporal database technology is not yet fully mature, DBMS providers will not easily introduce temporal processing functions into existing DBMSs. Therefore, using mature RDBMS databases to establish temporal database middleware is at this stage It is a better choice, so TimeDB and TempDB came into being.

Middleware is an independent system software or service program through which distributed application software can share resources between different technologies. Middleware sits on top of the client/server operating system and manages computer resources and network communications. It is software that connects two independent applications or independent systems. Connected systems, even if they have different interfaces, can still exchange information with each other through middleware. A key way to implement middleware is information passing. Through middleware, applications can work on multiple platforms or OS environments.

Extensible Markup Language (XML) is a markup language used to mark electronic documents to make them structural. It can be used to mark data and define data types. It is a markup language that allows users to customize their own The source language in which the markup language is defined. XML is a subset of Standard Generalized Markup Language (SGML) and is well suited for Web transport. XML provides a unified method for describing and exchanging structured data independent of applications or vendors.