title: “Application Boot-up Process” lang: en ref: application-boot-process permalink: /docs/users/application-boot-process/ excerpt: “Application Boot-up Process” last_modified_at: 2017-08-15T15:01:43-04:00 redirect_from:
The starup process of a service provider includes initializing Log4j, loading bean(including its parameters), and registering service.
Initialize Log4j:
By default, Log4jUtils obtains the configuration of log4j from the classpath\*:config/base/log4j.properties and classpath\*:config/log4j.properties files. combines them, and transfer them to PropertyConfigurator of log4j to initialize log4j. If the configuration file having the highest priority is stored on the disk and its directory has write permission, save the combined configuration to this directory to view which parameters take effect during maintenance.
Load the bean.
By default BeanUtils loads the configuration file from the classpath\*:META-INF/spring/\*.bean.xml path and transfer the configuration to ClassPathXmlApplicationContext of the Spring framework to load the context. In this process, BeanUtils loads the bean of foundation-config module.
Register the microservice.
After Spring context has been loaded, org.apache.servicecomb.core.CseApplicationListener will configure the handler, load the information about the provider schema, and the register microservice to service center.
NOTE: The three level of configuration items for ServiceComb are the configuration center, environment variables, and local files, listed in a descending order by priority. If configuration items with the same name exist, the one in the highest level overwrites others. Configuration items stored in the configuration center can be modified during running.