[OT] Classloader troubles
Hi all, I'm posting on Struts list because I know they're is lot's of J2EE experts here. I want to test my webapp on Tomcat, but it depends on some external system. I've got a jar that emulates it. When I package it with the webapp (WEB-INF/lib) it works fine. I would like to test the webapp packaged without this emulator jar. I tried putting it in $TOMCAT/common/lib. I get a ClassCastException. I think it comes from this : webapp requires the external API, let's say a class named ExternalSystem. It is configured to search for an implementation class named ExternalSystemMockImpl (using reflexion API). Webapp classloader doesn't find it, and delegate class searh to it's parent classloader (tomcat ones). Parent classloader finds the class from my emulator jar, run it and return some MockResult object, that implements ExternalResult from the external API Calling webapp tries to cast resulting object to ExternalResult, class that is visible to webapp classloader. Then my code is doing : ExternalResult result = (ExternalResult) obj; where obj is my MockResult instance, that implements ExternalResult from parent-Classloader, and casting it to a webapp-Classloader ExternalResult fails ! How can I solve this ClasLoader conflict ? Nico. - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: [OT] Classloader troubles
If ExternalSystemMockImpl is contained in a JAR file that's in $CATALINA_HOME/common/lib, I don't see why the app wouldn't be able to load it. For example, I've got a JAR file for the Oracle JDBC driver in common/lib and I can do the following just fine in a JSP: % ClassLoader cl = getClass().getClassLoader(); Class clazz = cl.loadClass(oracle.jdbc.OracleDriver); Object obj = clazz.newInstance(); % If there's code in the external JAR file that needs to make use of a class loader, it should probably use the result of Thread.currentThread().getContextClassLoader(). Can you provide a little more detail on how the app is using reflection to locate ExternalSystemMockImpl? Quoting Nicolas De Loof [EMAIL PROTECTED]: Hi all, I'm posting on Struts list because I know they're is lot's of J2EE experts here. I want to test my webapp on Tomcat, but it depends on some external system. I've got a jar that emulates it. When I package it with the webapp (WEB-INF/lib) it works fine. I would like to test the webapp packaged without this emulator jar. I tried putting it in $TOMCAT/common/lib. I get a ClassCastException. I think it comes from this : webapp requires the external API, let's say a class named ExternalSystem. It is configured to search for an implementation class named ExternalSystemMockImpl (using reflexion API). Webapp classloader doesn't find it, and delegate class searh to it's parent classloader (tomcat ones). Parent classloader finds the class from my emulator jar, run it and return some MockResult object, that implements ExternalResult from the external API Calling webapp tries to cast resulting object to ExternalResult, class that is visible to webapp classloader. Then my code is doing : ExternalResult result = (ExternalResult) obj; where obj is my MockResult instance, that implements ExternalResult from parent-Classloader, and casting it to a webapp-Classloader ExternalResult fails ! How can I solve this ClasLoader conflict ? Nico. -- Kris Schneider mailto:[EMAIL PROTECTED] D.O.Tech http://www.dotech.com/ - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: [OT] Classloader troubles
the webapp hasn't trouble to load ExternalSystemMockImpl. It uses reflexion to do it from some configuration data that is use to set implementation (production | mock). The problem is that the resulting object has to be casted to an interface from the API : IExternalSystem: (1)Class clazz = Class.forName(className); (2)return (IExternalSystem) clazz.newInstance(); from webapp, I think IExternalSystem is loaded by webapp ClassLoader. As ExternalSystemMockImpl is loaded from tomcat commons ClassLoader, it doesn implements the IExternalSystem loaded by this commons-ClassLoader, that cannot be casted in IExternalSystem loaded by webapp-ClassLoader. I get a ClassCastException on line 2. Nico. If ExternalSystemMockImpl is contained in a JAR file that's in $CATALINA_HOME/common/lib, I don't see why the app wouldn't be able to load it. For example, I've got a JAR file for the Oracle JDBC driver in common/lib and I can do the following just fine in a JSP: % ClassLoader cl = getClass().getClassLoader(); Class clazz = cl.loadClass(oracle.jdbc.OracleDriver); Object obj = clazz.newInstance(); % If there's code in the external JAR file that needs to make use of a class loader, it should probably use the result of Thread.currentThread().getContextClassLoader(). Can you provide a little more detail on how the app is using reflection to locate ExternalSystemMockImpl? Quoting Nicolas De Loof [EMAIL PROTECTED]: Hi all, I'm posting on Struts list because I know they're is lot's of J2EE experts here. I want to test my webapp on Tomcat, but it depends on some external system. I've got a jar that emulates it. When I package it with the webapp (WEB-INF/lib) it works fine. I would like to test the webapp packaged without this emulator jar. I tried putting it in $TOMCAT/common/lib. I get a ClassCastException. I think it comes from this : webapp requires the external API, let's say a class named ExternalSystem. It is configured to search for an implementation class named ExternalSystemMockImpl (using reflexion API). Webapp classloader doesn't find it, and delegate class searh to it's parent classloader (tomcat ones). Parent classloader finds the class from my emulator jar, run it and return some MockResult object, that implements ExternalResult from the external API Calling webapp tries to cast resulting object to ExternalResult, class that is visible to webapp classloader. Then my code is doing : ExternalResult result = (ExternalResult) obj; where obj is my MockResult instance, that implements ExternalResult from parent-Classloader, and casting it to a webapp-Classloader ExternalResult fails ! How can I solve this ClasLoader conflict ? Nico. -- Kris Schneider mailto:[EMAIL PROTECTED] D.O.Tech http://www.dotech.com/ - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: [OT] Classloader troubles
Where is the JAR file that contains IExternalSystem? Quoting Nicolas De Loof [EMAIL PROTECTED]: the webapp hasn't trouble to load ExternalSystemMockImpl. It uses reflexion to do it from some configuration data that is use to set implementation (production | mock). The problem is that the resulting object has to be casted to an interface from the API : IExternalSystem: (1)Class clazz = Class.forName(className); (2)return (IExternalSystem) clazz.newInstance(); from webapp, I think IExternalSystem is loaded by webapp ClassLoader. As ExternalSystemMockImpl is loaded from tomcat commons ClassLoader, it doesn implements the IExternalSystem loaded by this commons-ClassLoader, that cannot be casted in IExternalSystem loaded by webapp-ClassLoader. I get a ClassCastException on line 2. Nico. If ExternalSystemMockImpl is contained in a JAR file that's in $CATALINA_HOME/common/lib, I don't see why the app wouldn't be able to load it. For example, I've got a JAR file for the Oracle JDBC driver in common/lib and I can do the following just fine in a JSP: % ClassLoader cl = getClass().getClassLoader(); Class clazz = cl.loadClass(oracle.jdbc.OracleDriver); Object obj = clazz.newInstance(); % If there's code in the external JAR file that needs to make use of a class loader, it should probably use the result of Thread.currentThread().getContextClassLoader(). Can you provide a little more detail on how the app is using reflection to locate ExternalSystemMockImpl? Quoting Nicolas De Loof [EMAIL PROTECTED]: Hi all, I'm posting on Struts list because I know they're is lot's of J2EE experts here. I want to test my webapp on Tomcat, but it depends on some external system. I've got a jar that emulates it. When I package it with the webapp (WEB-INF/lib) it works fine. I would like to test the webapp packaged without this emulator jar. I tried putting it in $TOMCAT/common/lib. I get a ClassCastException. I think it comes from this : webapp requires the external API, let's say a class named ExternalSystem. It is configured to search for an implementation class named ExternalSystemMockImpl (using reflexion API). Webapp classloader doesn't find it, and delegate class searh to it's parent classloader (tomcat ones). Parent classloader finds the class from my emulator jar, run it and return some MockResult object, that implements ExternalResult from the external API Calling webapp tries to cast resulting object to ExternalResult, class that is visible to webapp classloader. Then my code is doing : ExternalResult result = (ExternalResult) obj; where obj is my MockResult instance, that implements ExternalResult from parent-Classloader, and casting it to a webapp-Classloader ExternalResult fails ! How can I solve this ClasLoader conflict ? Nico. -- Kris Schneider mailto:[EMAIL PROTECTED] D.O.Tech http://www.dotech.com/ -- Kris Schneider mailto:[EMAIL PROTECTED] D.O.Tech http://www.dotech.com/ - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: [OT] Classloader troubles
Api is in a separate jar (api.jar) that is both in webapp commons : when I don't put it in commons, I get a NoClassDefFoundError from line (1) : Class clazz = Class.forName(className); I can't exclude it from webapp (WEB-INF/lib) as it is part of webapp with the production implementation jar. I need some way to force ClassLoading to search webapp first, even when it delegates a class search to commons ClassLoader. Perhaps they're is no solution... Nico. Where is the JAR file that contains IExternalSystem? Quoting Nicolas De Loof [EMAIL PROTECTED]: the webapp hasn't trouble to load ExternalSystemMockImpl. It uses reflexion to do it from some configuration data that is use to set implementation (production | mock). The problem is that the resulting object has to be casted to an interface from the API : IExternalSystem: (1)Class clazz = Class.forName(className); (2)return (IExternalSystem) clazz.newInstance(); from webapp, I think IExternalSystem is loaded by webapp ClassLoader. As ExternalSystemMockImpl is loaded from tomcat commons ClassLoader, it doesn implements the IExternalSystem loaded by this commons-ClassLoader, that cannot be casted in IExternalSystem loaded by webapp-ClassLoader. I get a ClassCastException on line 2. Nico. If ExternalSystemMockImpl is contained in a JAR file that's in $CATALINA_HOME/common/lib, I don't see why the app wouldn't be able to load it. For example, I've got a JAR file for the Oracle JDBC driver in common/lib and I can do the following just fine in a JSP: % ClassLoader cl = getClass().getClassLoader(); Class clazz = cl.loadClass(oracle.jdbc.OracleDriver); Object obj = clazz.newInstance(); % If there's code in the external JAR file that needs to make use of a class loader, it should probably use the result of Thread.currentThread().getContextClassLoader(). Can you provide a little more detail on how the app is using reflection to locate ExternalSystemMockImpl? Quoting Nicolas De Loof [EMAIL PROTECTED]: Hi all, I'm posting on Struts list because I know they're is lot's of J2EE experts here. I want to test my webapp on Tomcat, but it depends on some external system. I've got a jar that emulates it. When I package it with the webapp (WEB-INF/lib) it works fine. I would like to test the webapp packaged without this emulator jar. I tried putting it in $TOMCAT/common/lib. I get a ClassCastException. I think it comes from this : webapp requires the external API, let's say a class named ExternalSystem. It is configured to search for an implementation class named ExternalSystemMockImpl (using reflexion API). Webapp classloader doesn't find it, and delegate class searh to it's parent classloader (tomcat ones). Parent classloader finds the class from my emulator jar, run it and return some MockResult object, that implements ExternalResult from the external API Calling webapp tries to cast resulting object to ExternalResult, class that is visible to webapp classloader. Then my code is doing : ExternalResult result = (ExternalResult) obj; where obj is my MockResult instance, that implements ExternalResult from parent-Classloader, and casting it to a webapp-Classloader ExternalResult fails ! How can I solve this ClasLoader conflict ? Nico. -- Kris Schneider mailto:[EMAIL PROTECTED] D.O.Tech http://www.dotech.com/ -- Kris Schneider mailto:[EMAIL PROTECTED] D.O.Tech http://www.dotech.com/ - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
