Re: how to do auto update/reload of a class?
Hi All, Thank you, for your response. Do you have any thoughts as to how to auto re-load the classes, which have been loaded into JVM using Custom Class loader? I tried writing custom class loader and loaded all the classes, but don't know how to re-load the same class, if it has been modified (re-compiled) without shutting down JVM, similar to JSP engine, where if we put updated JSP file, it picks up the new file. Note: I learnt that, we need to recreate new class loader and load all the classes again, but don't know exactly how to apply that technique in the system. Any help is greatly appreciated. Thank you, Babu --- Ian Darwin [EMAIL PROTECTED] wrote: On July 28, 2002 10:32 pm, you wrote: Does anyone know, how to do auto update of classes into the JVM? I tried to write my own custom class loader, and loaded all the classes through it, however if I put new updated class, it won't reload the class again. Have anyone tried this before? Help is very much appreciated. This better asked on an advanced-java list; not tomcat specific. For all the cleverness of Java's dynamic loading mechanism (ClassLoader, Class.forName, newInstance(), etc.), there is no published API for unloading or reloading. They just didn't think of it in time, perhaps. What I think Tomcat and others do is basically to manage the class loader for each Context (which has to be separate from the CL for each other Context for configuration and security reasons anyway) in such a way that you can delete it (un-reference it) and assign a new one and reload the classes for the given Context. -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED] __ Do You Yahoo!? Yahoo! Health - Feel better, live better http://health.yahoo.com -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED]
Re: how to do auto update/reload of a class?
Hi All, Does anyone have any thoughts as to how to auto re-load the classes, which have been loaded into JVM using Custom Class loader? I tried writing custom class loader and loaded all the classes, but don't know how to re-load the same class, if it has been modified (re-compiled) without shutting down JVM, similar to JSP engine, where if we put updated JSP file, it picks up the new file. Note: I learnt that, we need to recreate new class loader and load all the classes again, but don't know exactly how to apply that technique in the system. Any help is greatly appreciated. Thank you, Babu --- Ian Darwin [EMAIL PROTECTED] wrote: On July 28, 2002 10:32 pm, you wrote: Does anyone know, how to do auto update of classes into the JVM? I tried to write my own custom class loader, and loaded all the classes through it, however if I put new updated class, it won't reload the class again. Have anyone tried this before? Help is very much appreciated. This better asked on an advanced-java list; not tomcat specific. For all the cleverness of Java's dynamic loading mechanism (ClassLoader, Class.forName, newInstance(), etc.), there is no published API for unloading or reloading. They just didn't think of it in time, perhaps. What I think Tomcat and others do is basically to manage the class loader for each Context (which has to be separate from the CL for each other Context for configuration and security reasons anyway) in such a way that you can delete it (un-reference it) and assign a new one and reload the classes for the given Context. -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED] __ Do You Yahoo!? Yahoo! Health - Feel better, live better http://health.yahoo.com -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED]
Re: how to do auto update/reload of a class?
Hello Craig, Thank you, very much for your thought. You mentioned that, Jasper does this by creating a class loader for each page, can you please explain little bit more as to how the system over all works? I mean, how does the jasper creates invidual class loader for each page and make it available to other classes (servlet/another JSP) loaded by other class loader(Servlet/another Jasper), since classes loaded by one class loader is not visible to other class loader. Please, note that i would like to take similar approach in my current project, where it requires auto update of classes in the run time. Note: In the tomcat documentation, I found that these things work with Servlet Context, but no documents are available as to what technique has been used there. Thank you, very much for your time, Babu --- Craig R. McClanahan [EMAIL PROTECTED] wrote: On Wed, 31 Jul 2002, Babu Wisor wrote: Date: Wed, 31 Jul 2002 10:15:08 -0700 (PDT) From: Babu Wisor [EMAIL PROTECTED] Reply-To: Tomcat Developers List [EMAIL PROTECTED] To: Tomcat Developers List [EMAIL PROTECTED] Cc: [EMAIL PROTECTED] Subject: Re: how to do auto update/reload of a class? Hi All, Does anyone have any thoughts as to how to auto re-load the classes, which have been loaded into JVM using Custom Class loader? I tried writing custom class loader and loaded all the classes, but don't know how to re-load the same class, if it has been modified (re-compiled) without shutting down JVM, similar to JSP engine, where if we put updated JSP file, it picks up the new file. Jasper does this by creating a class loader for each page, and throwing away the class loader when the page is recompiled. The JVM doesn't let you do things any other way. Note: I learnt that, we need to recreate new class loader and load all the classes again, but don't know exactly how to apply that technique in the system. Any help is greatly appreciated. My personal advice, after living through (barely :-) getting a class loader that would reload a webapp to work, is to abandon this approach unless you are just doing it for fun and learning how class loading works. You are going to find that the fundamental architecture of Java isn't really oriented towards incremental replacement of classes (although there is a little bit better support in 1.4). Thank you, Babu Craig --- Ian Darwin [EMAIL PROTECTED] wrote: On July 28, 2002 10:32 pm, you wrote: Does anyone know, how to do auto update of classes into the JVM? I tried to write my own custom class loader, and loaded all the classes through it, however if I put new updated class, it won't reload the class again. Have anyone tried this before? Help is very much appreciated. This better asked on an advanced-java list; not tomcat specific. For all the cleverness of Java's dynamic loading mechanism (ClassLoader, Class.forName, newInstance(), etc.), there is no published API for unloading or reloading. They just didn't think of it in time, perhaps. What I think Tomcat and others do is basically to manage the class loader for each Context (which has to be separate from the CL for each other Context for configuration and security reasons anyway) in such a way that you can delete it (un-reference it) and assign a new one and reload the classes for the given Context. -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED] __ Do You Yahoo!? Yahoo! Health - Feel better, live better http://health.yahoo.com -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED] -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED] __ Do You Yahoo!? Yahoo! Health - Feel better, live better http://health.yahoo.com -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED]
how to do auto update/reload of a class?
All, Does anyone know, how to do auto update of classes into the JVM? I tried to write my own custom class loader, and loaded all the classes through it, however if I put new updated class, it won't reload the class again. Have anyone tried this before? Help is very much appreciated. Notes: I looked at Tomcat implementation of Jaxper and Loader classes, but couldn't figure out how does these things work together to accomplish auto reload of any class? Thank you, Babu __ Do You Yahoo!? Yahoo! Health - Feel better, live better http://health.yahoo.com -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED]
