Re: httpd/Tomcat load balancing question

Thu, 23 Dec 2010 05:15:50 -0800

I'll top post and reply to an earlier message at the same time, although I'm sure that this is frowned upon in both cases. 

Considering the sum of the answers so far :
1) According to Pid*, yes, the "<c:url .." encapsulation is the reason for the added ";jession-id" suffix, which interferes when Apache httpd is asked to deliver the target of these links to static elements.
2) it would seem to me that the best (most efficient) way, in your context, would be to remove that encapsulation for all links directed to static elements. That would not only fix the problem you are having, but also avoid some unnecessary processing on the Tomcat side (and on the httpd side, see #4 below).
3) one point made by Konstantin is that of course in this case, these static elements themselves will not be subject to the Tomcat authentication and access-control rules. 
But that is already implicit, since they are delivered by Apache httpd anyway.
4) in the worst case - aka your Dev team cannot easily remove the encapsulation - there are ways to remove the ";jessionid" suffix at the Apache httpd level, using mod_rewrite for instance. But that definitely sounds like doing the work twice : once for Tomcat to add the suffixes, then again for httpd to remove them.
5) There is also a way to remove the jessionid suffix, using mod_jk as the connector between httpd and tomcat instead of mod_proxy, as per Rainer's suggestion (JkStripSession configuration directive). mod_jk is (at least) as good as mod_proxy in terms of connecting and load-balancing, but it is a different configuration.
6) and if these java guys don't get it cooked, there are other ways to do this, but this would become off-topic for this list, so maybe we should then do that offline.
7) your proposed course of action below is self-defeating, since if you manage to convince them it will mean that they are not what you think they are. 

Jeffrey Janner wrote:

Definitely the culprit.  Now, I just have to convince the Dev team that they 
are, once again, a bunch of idiots.

I'm sure it's some framework/tool they are using.  The question now is, if I 
can't get them to not use it in this case, is there some way to modify httpd to 
strip the ;jsessionid stuff, or pass it on to the Tomcat server if it's there?  
That is, ignore the local feed if there is a sticky session id embedded in the 
URL?

Jeff


-----Original Message-----
From: Jeffrey Janner [mailto:jeffrey.jan...@polydyne.com]
Sent: Wednesday, December 22, 2010 4:50 PM
To: 'Tomcat Users List'
Subject: RE: httpd/Tomcat load balancing question

In the specific case I mention below, this is the source from the jsp:
        <link rel="icon" type="image/x-icon" href="<c:url
value="/static/images/icons/favicon.ico"/>" />

I'm not a jsp programmer, but I'm betting it has something to do with
the <c:url /> encapsulation.
Jeff


-----Original Message-----
From: Jeffrey Janner [mailto:jeffrey.jan...@polydyne.com]
Sent: Wednesday, December 22, 2010 4:40 PM
To: 'Tomcat Users List'; 'Tomcat Users List'
Subject: RE: httpd/Tomcat load balancing question

Thanks, that was what I was thinking.
Since the only JSP I have access to is the welcome-file, I'm not sure

I

can verify.

Q: I would think the getContextPath would be desirable, in case we
change the war-file name, etc., but I wouldn't think that would cause
the jsessionID string to get appended to the end of the path.  That

is,

they are coming out as


"/Portal/static/images/icons/favicon.ico;jsessionid=B4E3E4AA3D79B8877A0

9CFCC32827D09.tomcat1".

Jeff


-----Original Message-----
From: André Warnier [mailto:a...@ice-sa.com]
Sent: Wednesday, December 22, 2010 2:43 PM
To: Tomcat Users List
Subject: Re: httpd/Tomcat load balancing question

Hi.

Not knowing anything about JSP per se, I would nevertheless guess

that

the links are
written using something like
<img src="<%getContextPath%>/static/mylogo.jpg"/> or similarly,

instead

of just plain html
<img src="/Portal/static/mylogo.jpg"/>.
That probably leads the JSP compiler to think it has to

"relativise"

the links to the app
context and so on, while in this case it should not, because they

will

be served by the
front-end, not by Tomcat.



Jeffrey Janner wrote:

Httpd 2.2.17
Tomcat 6.0.29
Sun JDK 1.6.0_22
Spring Framework (3.0.2 I think)
All on Windows

The Dev team is creating a new app that we are planning to deploy

using httpd as a load-balancer to two Tomcats on separate servers.
Httpd is configured to serve static files - graphics, css, etc. -

with

everything else being sent to the Tomcat servers over AJP.  The

Tomcat

app has one jsp file setup as the welcome-file, which just does a
redirect to host/app/login, which is an internal action that

generates

the real login screen.  All other parts of the app are buried in

the

WEB-INF/classes structure (as far as I can tell).

We are currently testing the setup, and if you go to

http://prtltest.polydyne.com, everything seems to work just fine.

The

browser gets redirected to

http://prtltest.polydyne.com/Portal/login

and the screen looks fine.  The problem is if you go directly to

the

login page, bypassing the welcome-file redirect, then you don't get

the

static files.  If you refresh the page, everything shows up again.

Looking at the source of the login page, it appears that all the

static links have the jsessionid appended to them on the first

load,

but not on subsequent loads.  I assume this is because Tomcat

hasn't

determined cookie support yet when it generates the page the first
time, but does know about it on the refresh.  My question is, is

there

something the Dev team should be doing before generating the login
page, or generating the static links, or is there a configuration
setting I'm missing in the httpd.conf file?  Or perhaps in the

web.xml?

Jeff

The httpd.conf file is pretty stock, with the following added for

the

load-balancer configuration:

<Location /balancer-manager>
  SetHandler balancer-manager

  Order Deny,Allow
  Deny from all
  Allow from 10.1.1 127.0.0.1
</Location>

<Proxy balancer://mycluster>
                BalancerMember ajp://prtltest01:8009/Portal

route=tomcat1 loadfactor=50

                BalancerMember ajp://prtltest02:8009/Portal

route=tomcat2 loadfactor=50

</Proxy>

ProxyPass /Portal/static !
ProxyPass /Portal balancer://mycluster

stickysession=JSESSIONID|jsessionid scolonpathdelim=On

ProxyPass / balancer://mycluster/

stickysession=JSESSIONID|jsessionid

scolonpathdelim=On

The web.xml file is:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee";

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd";>

    <display-name>Polydyne Portal Application</display-name>
    <!-- Log4J Config -->
    <context-param>
        <param-name>log4jConfigLocation</param-name>
        <param-value>/WEB-INF/log4j.properties</param-value>
    </context-param>
    <listener>
        <listener-

class>org.springframework.web.util.Log4jConfigListener</listener-

class>

    </listener>
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>
            /WEB-INF/Portal-service.xml
            /WEB-INF/Portal-security.xml
        </param-value>
    </context-param>
    <listener>
        <listener-

class>org.springframework.web.context.ContextLoaderListener</listener-

class>

    </listener>

    <!-- Concurrent Session Control -->
    <listener>
        <listener-

class>org.springframework.security.web.session.HttpSessionEventPublishe

r</listener-class>

    </listener>

    <!-- Reads request input using UTF-8 encoding -->
    <filter>
        <filter-name>characterEncodingFilter</filter-name>
        <filter-

class>org.springframework.web.filter.CharacterEncodingFilter</filter-

class>

        <init-param>
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
        <init-param>
            <param-name>forceEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>characterEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <!-- Spring Security settings start -->
    <filter>
        <filter-name>springSecurityFilterChain</filter-name>
        <filter-

class>org.springframework.web.filter.DelegatingFilterProxy</filter-
class>

    </filter>
    <filter-mapping>
        <filter-name>springSecurityFilterChain</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <!-- Spring Security settings end -->
    <!-- Servlet Definition -->
    <!--
     - Map static resources to the default servlet
     - examples:
     -     http://localhost:8080/static/images/pets.png
     -     http://localhost:8080/static/styles/petclinic.css
    -->
    <servlet-mapping>
        <servlet-name>default</servlet-name>
        <url-pattern>/static/*</url-pattern>
    </servlet-mapping>

    <servlet>
        <servlet-name>Portal</servlet-name>
        <servlet-

class>org.springframework.web.servlet.DispatcherServlet</servlet-

class>

        <load-on-startup>2</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>Portal</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    <!-- Servlet Definition End -->
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>redirect.jsp</welcome-file>
    </welcome-file-list>
    <error-page>
        <exception-

type>javax.servlet.UnavailableException</exception-type>

        <location>/WEB-

INF/views/errors/Unavailable.html</location>

    </error-page>
    <error-page>
        <exception-type>503</exception-type>
        <location>/WEB-

INF/views/errors/Unavailable.html</location>

    </error-page>
</web-app>


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