之前我一直认为Tomcat中的Catalina是一个Servlet Container(和Web Container一样，是处理Servlets+JSP的组件)。
但是我在Tomcat的启动日志中看到，Tomcat有“Catalina服务”和“Servlet引擎”。那么Tomcat的“Catalina服务”和“Servlet引擎”有什么区别呢？
дек 01, 2018 8:29:10 PM org.apache.catalina.core.StandardService startInternal
INFO: Starting service Catalina
дек 01, 2018 8:29:10 PM org.apache.catalina.core.StandardEngine startInternal
INFO: Starting Servlet Engine: Apache Tomcat/7.0.47
Tomcat JSP 引擎称为Jasper。 Tomcat 启动信息日志清楚地指出两个实体都处理 servlet，而不是 jsp -“Catalina 服务”和“Servlet 引擎”。
请您参考如下方法:
Tomcat engine表示不应与 Apache 服务器并行使用的整个 Catalina servlet 引擎:
An Engine is a Container that represents the entire Catalina servlet engine. It is useful in the following types of scenarios: You wish to use Interceptors that see every single request processed by the entire engine. You wish to run Catalina in with a standalone HTTP connector, but still want support for multiple virtual hosts. In general, you would not use an Engine when deploying Catalina connected to a web server (such as Apache),
卡特琳娜是 main service of Tomcat server
Tomcat is actually composed of a number of components, including a Tomcat JSP engine and a variety of different connectors, but its core component is called Catalina. Catalina provides Tomcat's actual implementation of the servlet specification; when you start up your Tomcat server, you're actually starting Catalina.
