RE: A tangled knot: db, resources, Context, ant deploy, and Tomca t 5. 0.16-19 (further info)

[Justin Johnson <ju...@irisusainc.com>]

I've got database access working in two more ways, though the original
problem remains.

1) Adding a <ResourceLink> to /template via the admin app.
2) Adding a <DefaultContext> tag to conf/server.xml, with the
<ResourceLink>s inside.
(I tried 3) adding the <ResourceLink> to the "/" context, but it wasn't
visible in /template).

The problem with 1 is that the change is written to
conf/Catalina/localhost/template.xml, and doesn't survive 'ant remove'/'ant
deploy'.  I could leave it 'just so', but that adds a manual step to
deployment on different servers that defeats the purpose of ant automation.

The problem with 2 is that the <DefaultContext> shows up in the admin app
under Service (Catalina), but clicking on it returns an error page.  The db
access continues to work, but server.xml can no longer be maintained through
the admin app.

So, the solution to this problem looks like one of two things:  either
knowing where to put the <Context> fragment in my project so that it
survives deployment; or correctly adding a <DefaultContext> to <Engine> or
<Host> in server.xml that doesn't break the admin app.

An interesting point about the second option:  There's no way to add
<DefaultContext> to server.xml through the admin app that I can find--the
actions available under Server (Catalina) don't include it.

-----Original Message-----
From: Justin Johnson [mailto:justinj@irisusainc.com] 
Sent: Wednesday, February 25, 2004 3:18 PM
To: 'Tomcat Users List'
Subject: A tangled knot: db, resources, Context, ant deploy, and Tomcat 5.
0.16-19


It starts with this error message:  "Cannot create JDBC driver of class ''
for connect URL 'null', cause: No suitable driver".

I have Tomcat 5.0.19 installed on Windows XP Professional--a default install
from the binary, changing only one thing, the port from 8080 to 80.  I copy
my extra jars (JsqlConnect, mail.jar, JSTL jars, and JCIFS) into common/lib.
Start it, runs fine, including management and admin apps.

I build my template app following the developers guide: ant, cvs, directory
structure.  Put index.jsp and Hello.java in, 'ant deploy', both work
correctly at "/template".

Need database access.  Go to admin app, add global datasources that put the
following into conf/server.xml (stuff in [] is hidden stuff):

    <Resource name="jdbc/[server]" type="javax.sql.DataSource"/>
    <ResourceParams name="jdbc/[server]">
      <parameter>
        <name>maxWait</name>
        <value>5000</value>
      </parameter>
      <parameter>
        <name>maxActive</name>
        <value>4</value>
      </parameter>
      <parameter>
        <name>password</name>
        <value>[password]</value>
      </parameter>
      <parameter>
        <name>url</name>
        <value>jdbc:JSQLConnect://[server].[domain].com/</value>
      </parameter>
      <parameter>
        <name>driverClassName</name>
        <value>com.jnetdirect.jsql.JSQLDriver</value>
      </parameter>
      <parameter>
        <name>maxIdle</name>
        <value>2</value>
      </parameter>
      <parameter>
        <name>username</name>
        <value>[username]</value>
      </parameter>
    </ResourceParams>

In my web.xml I have, first thing under <web-app>:

	<resource-ref>
		<res-ref-name>jdbc/[server]</res-ref-name>
		<res-type>javax.sql.DataSource</res-type>
		<res-auth>Container</res-auth>
	</resource-ref>

I add the following to index.jsp:

<%
	Context ctx = new InitialContext( ) ;
	DataSource ds = (DataSource) ctx.lookup(
"java:comp/env/jdbc/[server]" ) ;
	Connection con = ds.getConnection( ) ;
	Statement st = con.createStatement( ) ;
	ResultSet rs = st.executeQuery( "SELECT 1 + 1 [Sum]" ) ;

	if( rs.next( ) )
		out.println( rs.getString( "Sum" ) + "<br />" ) ;

	rs.close( ) ;
	st.close( ) ;
	con.close( ) ;
%>

And get the error mentioned above: "Cannot create JDBC driver of class ''
for connect URL 'null', cause: No suitable driver".

I change index.jsp to:

<%
	Class.forName( "com.jnetdirect.jsql.JSQLDriver" ).newInstance(); 
	Connection con = 
		DriverManager.getConnection(
			"jdbc:JSQLConnect://[server].[domain].com/", 
			"[username]", 
                  "[password]" ) ;
	Statement st = con.createStatement( ) ;
	ResultSet rs = st.executeQuery( "SELECT 1 + 1 [Sum]" ) ;

	if( rs.next( ) )
		out.println( rs.getString( "Sum" ) + "<br />" ) ;

	rs.close( ) ;
	st.close( ) ;
	con.close( ) ;
%>

And it works fine, including retrieving a recordset by query.

So I find template.xml in conf/Catalina/localhost and paste the <Resource>
and <ResourceParams> tags into it inside the <Context> tag, and go back to
the first version of my database access code in index.jsp, 'ant reload'.
Works fine.  I'd like to use ResourceLink instead, but it's working.

The problem is that when I undeploy and redeploy /template,
/conf/Catalina/localhost/template.xml is overwritten with a fresh copy that
contains an empty <Context> tag except for path and docBase attributes (the
ant deploy task specifies a localwar, which simply adds the path to my
working copy/build to docBase).  Reading the configuration guidelines for
contexts at
http://jakarta.apache.org/tomcat/tomcat-5.0-doc/config/context.html, I think
I should put the context xml fragment into a file context.xml in META-INF.
But when I do so, I still get the empty, auto-generated <Context> in
template.xml in conf/Catalina/localhost.  When I change the deploy task in
build.xml to copy a war to [tomcat]/webapps, I get no template.xml file, and
no database access, as if my context.xml file is not being picked up.  All
this time, normal jsp stuff like <c:out value="${ 'webapp working' }" />
continues to function correctly, and I'm having no problems deploying,
undeploying, or reloading.

So, the problem as it seems to me is one or both of the following: 1) I
don't know where to put my <Context> fragment for it be picked up by ant
deploy/Tomcat, which seems to be ignoring it and using a default generated
<Context>; 2) I'm missing something in web.xml or my deploy configuration in
build.xml that will prefer my <Context> fragment.

Ideally, the datasources should be available server wide.  Where then would
I put the <ResourceLink> tags so that all applications can get at them?

Anyone who can help me out here will be greatly appreciated.

Justin

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