-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Mathieu,
On 10/24/19 14:26, Mathieu Dubois wrote: > Dear Christopher, > > Le 24/10/2019 à 00:36, Christopher Schultz a écrit : >> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 >> >> Mathieu, >> >> On 10/23/19 17:23, Mathieu Dubois wrote: >>> I noticed that the application also need to access to a >>> directory to store the result of some computation usually >>> outside the location of tomcat (the results can be rather >>> large). As for the DB this depends on each instance of the >>> application. Is there a similar mechanism for such a case ? >> It's not exactly clear what you are asking, but it sounds like >> you are looking for a configuration similar to the JNDI binding >> that can be split between conf/server.xml and >> META-INF/context.xml for connecting to a database. >> >> You have some choices, here, and the "right one" probably will >> require you to make a decision based upon your requirements. >> >> In WEB-INF/web.xml, there are some optional configuration data >> called "context parameters". They look something like this: >> >> <?xml version="1.0"?> <web-app >> xmlns="http://java.sun.com/xml/ns/javaee"; >> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"; >> xsi:schemaLocation="http://java.sun.com/xml/ns/javaee >> http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"; version="3.0" >> metadata-complete="true"> <context-param> <description> You can >> put whatever you want in here. It's just documentation for human >> readers. </description> >> <param-name>my-configuration-property-name</param-name> >> <param-value>my value</param-value> </context-param> ... >> </web-app> >> >> If you want to put, for example, a directory path in here for >> storing temporary files, you could do it like this: >> >> <web-app> <context-param> <description>Path to the temporary file >> directory where we write filed.</description> >> <param-name>fr.cns.genoscope.appname.tmpfiledir</param-name> >> <param-value>/tmp/app/temp-files</param-value> </context-param> >> ... </web-app> >> >> In order to use these configuration values, your code needs to >> read them explicitly, so you'll need to make some code changes in >> order to put your configuration into WEB-INF/web.xml. Something >> like this in your servlet: >> >> String tmpDir = >> getServletContext().getInitParam("fr.cns.genoscope.appname.tmpfiledir "); >> >> // ... use the tmpDir for all your file-writing needs >> >> Now, WEB-INF/web.xml is bundled inside your WAR file and, as >> you've mentioned, it's not very flexible with your builds. So, >> here's what you can do: >> >> The file META-INF/context.xml (also bundled within your >> application's WAR file -- hold that thought for a minute) can be >> used to override the values of your context-param values, like >> this: >> >> <?xml version="1.0"?> <Context> <Parameter >> name="fr.cns.genoscope.appname.tmpfiledir" >> value="/usr/local/other/location/for/client/X" override="true"/> >> ... </Context> >> >> More info can be found at: >> http://tomcat.apache.org/tomcat-9.0-doc/config/context.html#Context_P ara >> >> meters >> >> So, you could put the right value into WEB-INF/web.xml (which is >> inconvenient) or into META-INF/context.xml (which is also >> inconvenient) or -- and here's where things get a little >> interesting - -- you can copy the file META-INF/context.xml from >> the WAR file and put it into Tomcat's configuration directory >> structure like this: >> >> conf/[enginename]/[hostname]/[appname].xml >> >> ...and it will *override* the file supplied by the WAR file in >> META-INF/context.xml. So you get to use the same WAR file >> everywhere and customize those XML files on a per-client basis. >> >> Above, the [enginename] is almost always "Catalina" and matches >> the "name" attribute of the <Engine> in your conf/server.xml >> file. By default, it's name="Catalina" and pretty much nobody >> ever changes it. Your [hostname] comes from the "name" attribute >> of the <Host> in which your context/webapp is defined, and is >> often just "localhost" although it would be anything depending >> upon your environment. The [appname] is whatever you want it to >> be: the [appname] sets the context-path of the application. But >> the [appname].xml must match your [appname].war file name. >> >> So if you don't mind modifying your code a little, this can get >> your a lot of flexibility. >> >> This feature goes back to Tomcat 5.5, so you should be able to >> use it. I'd of course encourage you to look at upgrading to at >> least Tomcat 8.5 in the near-term. You may find that you can just >> drop-in the latest Tomcat 8.5.x in place of your Tomcat 5.5 and >> everything still works. (You will have to re-write your >> conf/server.xml file from scratch, as those files are not >> compatible between major releases.) > > Thanks for your in-depth explanation, it really helps. If I > summarize, I can use conf/[enginename]/[hostname]/[appname].xml to > configure both the DB connection (with a Resource) and the > directory where to write files (with a param). That sounds exactly > like what we need. You can do exactly that. In order to use context-params, though, you will probably need to modify your code to pick-up that configuration. Hopefully, it's not too much trouble to do that. If you define your data source(s) in conf/[engine]/[host]/[app].xml then you don't even need to "map" them into your application because they should already be mapped. - -chris -----BEGIN PGP SIGNATURE----- Comment: Using GnuPG with Thunderbird - https://www.enigmail.net/ iQIzBAEBCAAdFiEEMmKgYcQvxMe7tcJcHPApP6U8pFgFAl2yIrAACgkQHPApP6U8 pFjQcg//d+cw86NIByikbnYsCccD7e5Ca4NjBkf9IoDLbqHaxIKZf6Ci3dHhWApB JcgzWBlL/+c51rz5xwCyz9qUxfOwPrQbxdhjrgkW5huGESAINl8tg01P5mlXtPs1 NsiecH/whevzUZhUiKEXq5bJBffoBQYsUMdgaRN3yATF8aXyyKjmfJT1kZ6aZhHA uUTPrK7lftpufddGjkTWFGbHAVcaY5728cp+BIAc1eZ51TZrfi3WxtHWRZvn8OoK a2B81Y7he+QN+OG25w3E5JwX8XWEVNWH10iPqSmvO+h5efZlBol46AtP9saJ0lno BCqjIoc4uMBgFXPkKJJluvgWRQdthHK03iKK/cAVYxrBeOSqnIliRfl1iJUmj+jZ gDzY9mNgp1Y/ICe+PGHy5zIguHGyaCTWDHn1qar6EaU7Zi67qiSORKCRFBeSTWFy gZH0uqWo4X/Neq4z96E+iuDVhPJlM+WRYl/uH4BfkubK/DmMXIZ1LcCX7frnDXoA Q8hDzrAKcQV3txe5JgsoCe7QrKaQsPM784lFAQta2joZ3RIwG0O0T7t6UXINgTKP kNJ1V0dnMa+li5w3c+g7cQNDHH33aJ5I0RcwBaP1gT9qpszuJ5znaHoOKs10U25V K73FfcDngC/Z9eh0O0P7ug/g0McJZZL2BM9DRPTJKajPT8Bk0GA= =DeCG -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
