Rob,
On 12/3/20 11:03, Rob Sargent wrote:
Thanks for you time. Your response goes a long way to explaining why
there is so little specific information on embedding tomcat.
Only programmers are interested in using embedded Tomcat, so having
"Tomcat Embedded For Dummies" isn't terribly useful. (I don't mean to be
insulting; I'm just trying to get my point across about "intro-level"
content regarding Tomcat as an embedded product.)
Embedding Tomcat into a product is done precisely because the standard
deployment model (which lends itself to system admins who don't really
need to know anything about Java programming) isn't sufficient for some
special-case. Indeed, every Tomcat embedded instance is by definition a
special-case so guides for "doing it" don't exist since nobody else
knows exactly what you are trying to do.
Really, just as I said. I had convinced myself from several items
encountered on the web that an embedded tomcat instance would not
read the standard conf/*.xml. If I hit any of those pages again I
will react (either on the page or perhaps post here, if that would be
appropriate).
The best references for behavior of the Tomcat class would be:
1. The Tomcat javadoc
and
2. The source code for the Tomcat class
It's fairly readable, but most everything you need to read is in the
Javadoc.
TL/DR: at heart I’m struggling with the proper initialization and
consumption of the dbpc2 datasource which I add programmatically and
might consider using the context.xml version.
Unless there is a particularly good reason not to use it, I would
recommend using META-INF/context.xml. There are some really great
reasons not to do that. For example, if you want to fetch your DBCP
configuration from Kubernetes and then use that to dynamically-configure
DBCP, then you'll probably have to forego XML-based configuration.
A litany of small issues: >
My @Resource(name, type) Datasource ds” doesn’t take (I have several more
attempts planned)
Ooh. I tend to avoid @Annotations and I'm not really sure how that one
works, anyway. I'm not a good resource, here.
Is that failure logged?
Dunno.
Is context.lookup() expensive?
No. Tomcat's implementation of JNDI contexts isn't much more complicated
than a HashMap. In some other EE containers, context.lookup() might
indeed be expensive.
Is there any configuration available only in xml?
I don't know for sure, but I suspect not. The XML configuration uses the
commons-digester to call setFoo("bar") for each foo="bar" attribute on
the <Resource>, so I don't think there is anything in there what
couldn't be done 100% in Java code. You might have to dig-around a
little to find the default implementations of various things (like
DataSource/DataSourceFactory) but that shouldn't be too tough.
DriverManager is working fine but it that the best access to the
DataSource, which I need to be able to change the current database
(in a postgres sense)
Do you need to change the user after container-initialization, like
potentially for any given request? Is there anything wrong with
registering multiple database pools and then selecting the right one
depending upon the effective user during the request?
Maybe you don't even want a connection pool. I remember you saying you'd
be wildly successful if you had 2 users per day or something like that.
-chris
On Dec 3, 2020, at 8:06 AM, Christopher Schultz <ch...@christopherschultz.net>
wrote:
Rob,
On 12/2/20 13:31, Rob Sargent wrote:
I'm old and easily confused: does an embedded tomcat server read (any)
context.xml file? I find conflicting answers /out there./
Using tomcat 9.0.40
embeddedTomcat =new Tomcat();
embeddedTomcat.setPort(tomcatPort);
embeddedTomcat.enableNaming();
embeddedTomcat.getConnector();// an init, really String contextRootPath
=System.getenv("CATALINA_HOME");
Context contextTomcat =embeddedTomcat.addContext("",new File(contextRootPath
+"/sgs").getAbsolutePath());
I know it is finding WEB-INF/web.xml (under "sgs") and finds all my servlets,
none of which are named in the web.xml.
Tomcat should be reading your web application's META-INF/context.xml file, if
one exists.
If you call Tomcat.init(), it will attempt to locate the default
conf/server.xml, conf/web.xml, and conf/context.xml based upon your
configuration source.
What are you /really/ asking?
-chris
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