Re: practical scenarios
On Tue, Apr 16, 2013 at 08:25:06PM +0200, Jakub 1983 wrote: When is it useful to define context.xml in some other place than at /META-INF/context.xml inside the application files ? When do you usually do it ? Is it frequently used ? I am not asking about theoretical possibilities, but how are they used in practical scenarios. I almost *always* write a context descriptor to place in $CATALINA_BASE/conf/Catalina/$HOSTNAME/$CONTEXTNAME.xml, after placing the app. itself somewhere far from the appBase directory so that the descriptor won't be munged by Tomcat during deployment. I am actually a bit puzzled that it's even *possible* to place the context descriptor inside the app. I gather that I am in the minority, in this. But I feel that the app., whether packed or unpacked, should be treated as an opaque object, with deployment configuration data applied from the outside. I think that muddling the concerns of developers and installers is asking for trouble. (I also feel that an app. should be able to function without any configuration at all, at least to the point of telling me what I forgot to configure.) -- Mark H. Wood, Lead System Programmer mw...@iupui.edu Machines should not be friendly. Machines should be obedient. signature.asc Description: Digital signature
practical scenarios
When is it useful to define context.xml in some other place than at /META-INF/context.xml inside the application files ? When do you usually do it ? Is it frequently used ? I am not asking about theoretical possibilities, but how are they used in practical scenarios. Most common case I encounter is in /META-INF/context.xml inside the application files. Similary, do you ofter set explicitly CATALINA_BASE outside of CATALINA_HOME ? Most common scenario I see is deploying into TomcatInstallDir(CATALINA_HOME)/webapps. When should CATALINA_BASE be defined ? Is running each webapp on separate tomcat/jboss instead of running all in the same tomcat / jboss an antipattern ? In students handbooks and lectures it was said, that jars, memory, resources are shared in one tomcat/jboss which is so good. In practice we have memory leaks and need of restarts, conflicts between versions of jars and classloaders. And what are more problems running everything in one tomcat/jboss? What do you see more ofte, all webapps in one server or each in separate ? Regards Jakub piece of doc concerning context topic http://tomcat.apache.org/tomcat-7.0-doc/config/context.html#Defining_a_context *Defining a context* *It is NOT recommended to place Context elements directly in the server.xml file.* This is because it makes modifying the *Context*configuration more invasive since the main conf/server.xml file cannot be reloaded without restarting Tomcat. Individual *Context* elements may be explicitly defined: - In an individual file at /META-INF/context.xml inside the application files. Optionally (based on the Host's copyXML attribute) this may be copied to $CATALINA_BASE/conf/[enginename]/[hostname]/ and renamed to application's base file name plus a .xml extension. - In individual files (with a .xml extension) in the $CATALINA_BASE/conf/[enginename]/[hostname]/ directory. The context path and version will be derived from the base name of the file (the file name less the .xml extension). This file will always take precedence over any context.xml file packaged in the web application's META-INF directory. - Inside a Hosthttp://tomcat.apache.org/tomcat-7.0-doc/config/host.htmlelement in the main conf/server.xml. Default *Context* elements may be defined that apply to multiple web applications. Configuration for an individual web application will override anything configured in one of these defaults. Any nested elements, e.g. Resource elements, that are defined in a default *Context* will be created once for each *Context* to which the default applies. They will *not * be shared between *Context* elements.
Re: practical scenarios
-BEGIN PGP SIGNED MESSAGE- Hash: SHA256 Jakub, On 4/16/13 2:25 PM, Jakub 1983 wrote: When is it useful to define context.xml in some other place than at /META-INF/context.xml inside the application files ? When do you usually do it ? Is it frequently used ? I am not asking about theoretical possibilities, but how are they used in practical scenarios. Two reasonably practical scenarios I can think of are: 1. When webapps are untrusted or only partially-trusted. 2. Ops team needs lots of configuration in production that the dev team doesn't need to worry about. Most common case I encounter is in /META-INF/context.xml inside the application files. Similary, do you ofter set explicitly CATALINA_BASE outside of CATALINA_HOME ? I *always* set it to something different. It makes upgrades (and rollbacks, if necessary) trivial. Most common scenario I see is deploying into TomcatInstallDir(CATALINA_HOME)/webapps. When should CATALINA_BASE be defined ? When you want a shared Tomcat install (e.g. multiple JVM setup) or you want to have the ability to upgrade and downgrade with little difficulty... just change CATALINA_BASE and re-launch. Is running each webapp on separate tomcat/jboss instead of running all in the same tomcat / jboss an antipattern ? I wouldn't say that, but it depends upon your environment. In production, we run all apps in separate JVMs because it gives us a high degree of flexibility (and offers some measure of reliability, since webapps can't interfere with each other, but we have very stable webapps so that wouldn't likely be a problem for us in general). In students handbooks and lectures it was said, that jars, memory, resources are shared in one tomcat/jboss which is so good. Disk space is dirt cheap. Memory is fairly cheap (compared to ops and dev time). You can configure ClassLoaders to load from anywhere. In practice we have memory leaks and need of restarts, conflicts between versions of jars and classloaders. Time to fix! And what are more problems running everything in one tomcat/jboss? That's mainly the problem above: memory usage and general stability. Another consideration is whether all of your webapps have been fully-tested under certain configurations. We run some webapps on Tomcat 7 and others on Tomcat 6. We even run under different JVM configurations (1.5, 1.6, and 1.7). What do you see more ofte, all webapps in one server or each in separate ? It always depends upon the environment. - -chris -BEGIN PGP SIGNATURE- Version: GnuPG/MacGPG2 v2.0.17 (Darwin) Comment: GPGTools - http://gpgtools.org Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBCAAGBQJRbZ9nAAoJEBzwKT+lPKRY5NsP/1DWvea3ueiLH623Zr0rVmB+ /7dPqg8B0dRzp5kD2hf3C8AujENfm8Bft+9TLVrTj3FjZ5TQC3v4VPJD8EB1DELl WTeIWrFu7t9+ZzjGzSjvFTV5jziwW4dUgjH2O8nVitTmbnYqv/QtK4beaN27F0CA 2tExAi+Z1VFTZR9PhYaCUt7ixmm5Tw3ahQl793YpjeBqCucFFNvt2tEpZg9rftpb GObKiDO63HCobqAn6ECQ2YDmEIJJuLz5cMYuG023E+77vPdkvgnf2MTMQwX2A8rc WT42jpIoawrJHK5QEGlgsVEm5uKJenX2WZNn0wjeGq/JfN3pzhqPN7iihGuRXLL9 ipJfJbMWVFh4j88g2bXv3/Fu3CieMi6d9PULn9/eZ2y7/fMcl4gdQKz767Bed1LH lenHmoE/gkYnI2KJOB3qG59e3bPtte83DSlqTgttQnq29zeKVScfVgIi681c0cbH q/x3WFOs2vjY27+Y+gKg2tZ9ZgtVEn0CX/WlGB5at/SV8M2LKKgVOnHFCipvSK7B xZGSfGkxZ8FiGB0pSWU2gGtsnN5z2KWM2xl4GX99/tTvkTgzGD6csESLxjCL6wfC 1sSvOx7W8s1MzYIoUSfpZ9h5g8XE3xjKtj+d8GDaFg+gZAoyyMIXz4zi02oRMnz1 qYltop1M8J8PREdJFubS =UxtZ -END PGP SIGNATURE- - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
