Class loader in_cloud
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This document discusses classloaders, including an overview of the classloader hierarchy and dynamic class loading. It then covers classloaders in Tomcat and how servlets are loaded. Finally, it addresses classloader configuration and potential issues in a cloud environment, providing a solution to put common JAR files under the WEB-INF/lib directory to avoid classloading problems.
Class loader in_cloud
- 1. OoA | State Street Hangzhou Jun 08, 2012 1
- 2. ClassLoader In Cloud Architecture Group| Stack & Cloud Company Internal
- 3. AGENDA ClassLoader overview Class Loader Hierarchy Dynamical Class Loading ClassLoader in Tomcat Class Loader Hierarchy Servlet loading ClassLoader in Cloud Class Loader configuration Issue && solution Company Internal
- 4. CLASSLOADER OVERVIEW -- CLASS LOADER HIERARCHY Company Internal
- 5. CLASSLOADER OVERVIEW – DYNAMICAL CLASS LOADING System ClassLoader ClassLoader.getSystemClassLoader() Current class ClassLoader Class.forName(String className) Class.getResource(String name) Current thread context ClassLoader Thread.currentThread().getContextClassLoader() Company Internal
- 6. CLASSLOADER OVERVIEW – CONTEXT CLASS LOADER Q: When should I use thread.getContextClassLoader()? A: The classloading delegation model doesn’t work API (Application Programming Interface) VS SPI (Service Provider Interface) E.g. JDBC/JNDI/JAXB Company Internal
- 7. CLASSLOADER IN TOMCAT -- CLASS LOADER HIERARCHY Company Internal
- 8. CLASSLOADER IN TOMCAT – CLASSLOADER&&WEBAPPLOADER Company Internal
- 9. CLASSLOADER IN TOMCAT – LOAD SERVLET CLASS Company Internal
- 10. CLASSLOADER IN CLOUD shared.loader= ${catalina.home}/webapps/cashpro/WEB-INF/lib/*.jar, ${catalina.home}/webapps/cashpro/WEB-INF/classes/, ${catalina.home}/osa_lib, ${catalina.home}/osa_lib/*.jar Company Internal
- 11. CLASSLOADER IN CLOUD – DIFFERENT CLASSLOADER <servlet> <servlet id="XMLServlet"> <servlet-name>QuartzInitializer</servlet- <servlet-name>XMLServlet</servlet- name> name> <display-name>Quartz Initializer <display-name>XML Servlet</display- Servlet</display-name> name> <servlet-class> <description>XML Adapter servlet with com.ssc.cashpro.quartz.CashproJobStarter both request and response in </servlet-class> XML</description> <load-on-startup>3</load-on-startup> <servlet- <init-param> class>com.ssc.faw.controller.XMLServlet <param-name>shutdown-on-unload</param- </servlet-class> name> <load-on-startup>2</load-on-startup> <param-value>true</param-value> </servlet> </init-param> <init-param> <param-name>start-scheduler-on- load</param-name> <param-value>true</param-value> </init-param> </servlet> Company Internal
- 12. CLASSLOADER IN CLOUD -- ISSUE “Incorrect” value for static variable in servlet class java.lang.ClassCastException: ABC cannot be cast to ABC Company Internal
- 13. CLASSLOADER IN CLOUD -- SOLUTION put osa_framework.jar under WEB-INF/lib/ Company Internal
- 14. Company Internal