I'm not sure this solves my problem...
If I pull my Servlet out of my application's code then the instance will be
constructed and loaded by Tomcat as usual, but then the Servlet can't access
my application's internal data. I need the Servlet to have a callback into
my application for it to obtain the data required for generating the response.
As a more complex example, imagine creating an HTTP front-end to, say, a
Java-based text editor. For the Servlet to see what's happening within the
editor -- which file is being edited, where's the cursor, etc --it'll need
direct access the editor's data structures. Spilling and updating this data
to a shared file/database/whatever would be wasteful; in my intended
application there's 100+ megs of constantly changing data that the Servlet
may need to examine when generating its response.
Todd
On Friday 02 November 2001 14:10, Craig R. McClanahan wrote:
> Here's the Tomcat 4 approach -- 3.x has similar things but I'm not as
> familiar with the details.
>
> You have two fundamental choices, based on whether you want to use
> server.xml to configure Tomcat or not:
>
> * To use server.xml, you just need to set up an environment
> like the "catalina.sh" script does, and call
>
> Bootstrap.main("start");
>
> in a separate thread. When you ultimately want to shut things
> down, call:
>
> Bootstrap.main("stop");
>
> * To configure all the components yourself, you will use the
> org.apache.catalina.startup.Embedded class (similar to
> EmbeddedTomcat in 3.x). This class includes a dummy main()
> program that demonstrates how you do things.
>
> For actually processing the requests yourself, you would only need a
> single webapp (the ROOT webapp) with a web.xml that configures your
> servlet to handle all requests (i.e. a <servlet-mapping> with a pattern of
> "/*"). There's no need for interceptors (3.x) or valves (4.x) to do this.
>
> I would recommend you implement the application logic as a standard
> servlet, in its own class, and separate the startup/shutdown issues out to
> their own class. There is nothing to be gained by combining them.
>
> Craig
>
> On Fri, 2 Nov 2001, Todd Wright wrote:
> > Date: Fri, 2 Nov 2001 12:25:23 -0400
> > From: Todd Wright <[EMAIL PROTECTED]>
> > Reply-To: Tomcat Users List <[EMAIL PROTECTED]>
> > To: [EMAIL PROTECTED]
> > Subject: Embedding Tomcat with intra-app Servlets
> >
> >
> > I'd like to embed Tomcat within my Java application, but where some
> > Servlet requests would *directly* call into my running application's code
> > (+data). The current "EmbededTomcat" support seems to be aimed at
> > launching a stand-alone Tomcat that only supports file contexts, with no
> > callback support for access to the launching application.
> >
> > I'm thinking of Tomcat 3.3, 'though 4.0 could be used if required.
> >
> > For example, suppose I have a calendar application that I'd like to add
> > web support. Inside my application I have all the data I need, and I'd
> > like my servlets to directly access my the data structures. Flattening
> > the data out to an external database/filesystem is not an option. All
> > Servlet requests would funnel into my application so I can call my own
> > (inner) Servlet. I still want Tomcat to do the HTTP parsing, SSL,
> > sessions, Servlet-API, etc. My application must load the internal Servlet
> > instance.
> >
> > Can I use an interceptor, or (if needed) pull apart "EmbededTomcat"? Is
> > there an example of how to do this? I hope it's clear why this would be
> > a very useful embedding scenario...
> >
> > Pseudocode:
> >
> > public class MyApp implements Runnable {
> >
> > /** launcher */
> > public static void main(String[] args) {
> > // launch!
> > (new MyApp()).run();
> > }
> >
> > public void run() {
> > // create my internal Servlet before Tomcat is launched
> > //
> > // this inner class is defined later in this method
> > Servlet myServlet = new MyServlet();
> >
> > // launch Tomcat
> > EmbeddedTomcat et = new EmbeddedTomcat();
> > et.setArgs(new String[] {"start"});
> > et.execute();
> >
> > //
> > // hand-waving here! Could be moved to before the
> > "et.execute()". //
> > insert myServlet into Tomcat to handle all "/*" requests
> >
> > //
> > // I now want "myServlet" to be called with all "/*" requests
> > //
> >
> > // run forever in this example...
> > }
> >
> > /**
> > * sample internal data method.
> > *
> > * MyServlet will call this method
> > */
> > public String getInternalString() {
> > return "foo";
> > }
> >
> > /**
> > * My inner servlet -- has access back into "MyApp"
> > * instance (non-static).
> > */
> > private class MyServlet extends HttpServlet {
> > public void doGet(
> > HttpServletRequest request,
> > HttpServletResponse response)
> > throws IOException, ServletException {
> > response.setContentType("text/html");
> > PrintWriter out = response.getWriter();
> > out.println("<html><body>Internal String is ");
> >
> > // access internal MyApp method/data!
> > out.println(getInternalString());
> >
> > out.println("</body></html>");
> > }
> > }
> >
> > Thanks!
> > Todd
> >
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