On Friday 17 November 2000 15:46, you wrote:
> Rachel,
>
> Thanks for that, about the static initializers... The classes that use them
> are not servlets, merely utility classes are used in the web application
> and also elsewhere.
>
> For instance, a class, or series of classes that deal with database
> connection pooling, could conceiveably have a configuration file to let
> them know what pools to set up, min and max connections, where the server
> is, what the driver class is, etc. And these classes are useful in other
> apps, not only in web applications. Now of course you can hard code into
> the class, the file to load, but this is ugly, it is nicer to say "java
> -Ddb.properties=/home/stuart/db.properties". As the classes are not
> servlets, servletContext.getResource() is not really an option.
Yes it is. Your startup servlet reads these parameters, parses that data, and
then invokes your utility classes with that initialisation data.
consider "static" harmful. :-) I only ever use it to define constants, like
database field names or whatnot, or to hold the instance of a single-instance
class.
Basically, if your database accesses are going on in the same *process* as
your servlets, ie: you have some generic headless data-access javabeans that
do the work and you want to call them from your servlets, you should still
have a servlet that's initialised on startup of the web application, and
*that* initialises your data-access beans. That way you can also catch the
web application being shut down and cleanly close down your data-access
classes too.
If your data-access is happening in another process from your servlets, and
communicating over network sockets, eg: using RMI or XML/SOAP type thing,
then you initialise that task in any way you see fit - the servlet engine
just talks to it when it wants to. If you're doing this, you may well want to
look seriously at EJB.
> I could not find anything about TOMCAT_OPTS on the web site, persumably
> this is an environment variable, what format do you put system properties
> in, is it like
> TOMCAT_OPTS="db.properties=/home/stuart/db.properties:myproperty=anotherpro
>p ertyvalue:.."?
Not quite. TOMCAT_OPTS is just given to the java command line used to invoke
Tomcat, so it's in that format, ie: "-Ddb.properties=value" etc.
--
Rachel
