Craig,
Thanks for the clarifications. I am all for servlets. I have already delivered
products
using servlets. Actually, I am spoilt by all the features that servlets support. My
code
hinges on the - getServletContext().getServlet("ServletName')- feature (I ignored the
the warning note in Sun's documentation) . I am wondering how to fix my production
code,
when that feature goes away in the new servlet API specification. Do you have any
insights
?
Thanks
Santhosh.
"Craig R. McClanahan" wrote:
> Santhosh Annira wrote:
>
> > Craig,
> >
> > I feel that, running separate JVMs is an overkill, and it defeats the whole
> > idea behind using servlets instead of old fashioned CGI processes. JVMs have
> > considerable startup time
>
> When running Apache JServ with separate JVMs, you do this yourself, separate from the
> web server. Typically, an ISP would start the JVM for each of their hosting
>customers
> once, and it would stay running all the time. This is totally unlike CGI, where you
> have to pay the process startup cost on every single request.
>
> > and each JVM needs a separate port number.
>
> With 63k of them available (you don't get to use ports < 1024 unless you're root), I
> hardly think this is going to cause you any grief :-).
>
> The port numbers required are also invisible to users of the servlet-based web sites,
> since they are only for communication between Apache and the JVMs. These port
>numbers
> are not visible in the URLs that people accessing the web sites use.
>
> > Also, there
> > could be a limit on the number of JVMs that you can run. JVMs are started when
> > Apache server is started, and how do we decide how many to start initially (one
> > per every user ?).
>
> The separate-JVM-per-user approach is the most secure, but I have seen ISPs that
>offer
> two-tiered prices -- a higher price for a separate JVM, or a lower price if you're
> willing to share JVMs with other customers (each in their own zone), at the modest
> risk that the other customers you are sharing with might cause you a problem (like
> executing System.exit()). The sysadmin sets up separate JVMs or not based on
>customer
> request, just like they set up DNS entries, mailboxes, virtual hosts, database
> connections, and everything else uniquely per customer. If they are doing it a lot,
> they've got scripts to do all the grunt work.
>
> The Apache JServ zone approach also allows you to run the JVMs on separate servers,
>if
> you want. At the cost of hardware nowdays, it's not that tough to get real quick
> paybacks on the hardware investment required for this.
>
> Note also that heavily used CGI-based apps on shared servers have memory-usage
>impacts
> as well ... different ones, but still real.
>
> > Only Apache servlet engine is free. For JRUN, the amount that
> > you pay, depends on the number of JVMs that you wish to run. WebSphere lets you run
> > only one JVM per machine.
> >
>
> The only reason I bothered to respond to your initial comments at all was to point
>out
> the incorrectness of your blanket assertions about zones. If you like CGI, then by
> all means stay with it ... but my apps, even in shared environments, are going to be
> servlet+JSP based.
>
> >
> > cheers
> > Santhosh
> >
>
> Craig
>
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