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From Jayaram Ponnusamy <jayaram.ponnus...@gmail.com>
Subject Re: Connectivity Issue with Tomcat7 and WebServer (AJP Connector)
Date Tue, 09 Aug 2016 07:48:20 GMT
Thanks André,
Kindly please find my answer below:

On Tue, Aug 9, 2016 at 12:02 AM, André Warnier (tomcat) <aw@ice-sa.com>
wrote:

> On 08.08.2016 11:18, Jayaram Ponnusamy wrote:
>
>> Thanks André,
>>
>> 1. ANS-Question 1 = Both Tomcat & WebServer installed on different
>> Machines, Attached Architecture diagram of our environment. Our Tomcat are
>> configured as Application Clustering, and WebServer1 is pointing to
>> Tomcat1
>> and WebServer2 is pointing to Tomcat2
>> Tomcat's IP (Node1): 10.100.0.31
>> WebServer's IP (Node1): 10.100.15.21
>>
>> Tomcat's IP (Node2): 10.100.0.32
>> WebServer's IP (Node2): 10.100.15.22
>>
>> 2. ANS-Question 2 = Thanks, Thats fine :)
>>
>> 3. ANS-Question 3 = Attached Architecture diagram for your reference.
>>
>>
> There are a lot of separate pieces in your configuration, and the problem
> could be at any level. So we must do this step-by-step, systematically, and
> try to find out exactly where things are not working properly. The keywords
> here are "step-by-step" and "sytematically", because with so many pieces,
> if we start making changes left and right without first understanding what
> the problem is, we will never find out.
>
> First, I'll make some comments based on the configuration schema that you
> provided, and you will tell me if this is right or wrong, ok ? And I have
> some questions in between..
> Please answer the questions below directly under each question, to make it
> easier to follow.
>
>
> 1) Note : I do not know what you mean exactly by "Application Clustering",
> and I don't know exactly how an F5 load-balancer works.  But I will assume
> that in this case, we can consider only the chain from the user workstation
> to Tomcat #1, and that any results can be extrapolated to other cases.
> I also assume that Tomcat #1 and Tomcat #2 run the same applications, but
> that they are totally independent from eachother, and that Tomcat #1 and
> Tomcat #2 never talk to one another directly (true/false ?) ANS: TRUE
>
> 2) I assume that the problems that you are mentioning are happening when a
> user workstation client accesses the Tomcat application as follows :
> (You may need to reformat this as 2 text lines, to see it correctly)
>
> user wks <-- HTTP(S) --> F5 <-- HTTP --> Apache #1 + mod_jk <-- AJP -->
> Tomcat <-- webapp
>               (1)                (2)                             (3)
> where :
> - HTTP(S) is the protocol used on the connection (1) between the client
> workstation and the F5 load-balancer
> - HTTP(S) is the protocol used on the connection (2) between the F5
> load-balancer and Apache webserver #1 (IP 10.100.15.21)
> - AJP is the protocol used on the connection (3) between Apache webserver
> #1 ((IP 10.100.15.21) and Tomcat #1 (IP 10.100.0.31)  (*)
> - "Tomcat" actually means "Tomcat and its AJP <Connector>, listening on
> port 9009
>
> All correct ?
>

ANS::

         ||=> WebServer1 (http://web1abc.com/sites)====>Tomcat1 (
http://tom1abc:9090/sites)
F5 (http://f5.abc.com) =||
||=> WebServer2 (http://web1abc.com/sites)====>Tomcat1 (
http://tom21abc:9090/sites)

Application Clustering Means, While installing the Second Node (Portal
Application on Tomcat) There is an option to choose install as Application
cluster. Primarily Tomcat will not talk each other, but Portal Application
will consider both are same with clustering


> 2) To access the application, the user enters a URL in his browser.
> Can you give us an example of such a URL ? You can change the real name of
> the server for privacy, but then be consistent about this in the future,
> because it is important to follow what is going on.
> So let's say for example that the F5 is known to the outside world as "
> myF5.mycompany.com", and let's always keep using that same hostname for
> it in the future.
> So the client enters the URL : http://myF5.mycompany.com.. ?
> (Add the port if any, and a sample URL)
>
ANS:
Client Access URL: http://f5abc.com/sites/en_US/about,
http://f5abc.com/sites/en_US/offices, http://f5abc.com/sites/ar_QA/newsroom
Through Tomcat : http://tom1abc:9090/sites/en_US/about,
http://tom1abc:9090/sites/en_US/offices,
http://tom1abc:9090/sites/ar_QA/newsroom

>
> 3) the F5 decides, on the base of some criteria, to forward this HTTP
> request to Apache webserver #1 or Apache webserver #2.
> But for the sake of this example, let's assume that it chooses Apache #1
> this time.
>
> Question 3.1 : how does the F5 forward this request to Apache webserver #1
> ? does it just copy the original request transparently, and send it to the
> IP address 10.100.15.21 ?
> Or does it change the hostname to which the request is addressed ?
> (Originally, the client addressed the request to hostname "
> myF5.mycompany.com" (which resolves to the IP address of the F5); so
> normally, if the F5 does not modify the hostname and sends it "as is" to
> Apache #1, then the Apache #1 configuration should have a <VirtualHost>
> with a ServerName matching "myF5.mycompany.com" also. And if it does not,
> then Apache #1 can only have 1 VirtualHost, the "default VirtualHost",
> otherwise this would not work at all.)
>

ANS: F5 Not changing the Hostname, and keep as it is

>
> If the F5 changes the hostname of the request, then to what does it change
> it ?
>
> Question 3.2 : does Apache #1 have only 1 <VirtualHost> ?
> If yes, what are the ServerName and ServerAlias lines in the configuration
> of that <VirtualHost> ? ANS: Yes its having only one <VirtualHost> Initilly
> we kept the ServerName as hostname only, some forum recommends to keep IP
> so i modified it. Now i reverted it back to Hostname
>>
>> ServerName cmspliv1.com
>
> ServerAlias www.cmspliv1.com
>
> #ServerName 10.100.0.31
>
>
> If there are more than one <VirtualHost>, can you provide their
> ServerName/ServerAlias, in the same order in which the multiple
> <VirtualHost> are listed in the Apache #1 configuration ?
>
> 4)
> Question 4.1 : is there anything (other than a network cable or other
> passive equipment) between Apache #1 and Tomcat #1 ? (firewall for example) ANS:
> Only Firewall, but both are in different subNet
>


>
> 5) Tomcat #1 configuration :
>
> Question 5.1 : The server.xml of Tomcat #1 has only 1 <Host> tag.
> True/false ? ANS: TRUE
>
> Question 5.2 : the server.xml of Tomcat #1 contains a tag similar to this
> one :
>   <Engine name="Catalina" defaultHost="localhost">
> What is the value of the "defaultHost" attribute in your server.xml ?
> ANS: defaultHost value is "localhost"
>
> Question 5.3 : the server.xml of Tomcat #1 has only one <Host> tag.
> True/false ?
> Please paste the content of that <Host> tag here : ANS: <Host
> name="localhost"  appBase="webapps" unpackWARs="true" autoDeploy="true">
>
> 6) Apache httpd :
> Apache httpd 2.2.x has several possible configurations, in terms of how
> many processes/threads it is using. See this page :
> http://httpd.apache.org/docs/2.2/mpm.html
>
> Question 6.1 : Do you know which "model" your Apache #1 is using ? (this
> is also called the "MPM"). Is it :
> - prefork
> or
> - worker
> or
> - event
> or
> - is your Apache host a Windows machine ? (then the MPM can only be
> "mpm_winnt").  ANS: prefork.c
>
> 7) previously, you indicated that "when you access Tomcat directly", you
> do not see these problems.  With reference to your schema (and/or the
> simple schema that I showed in (2) above), can you explain how the client
> accesses Tomcat directly ? ANS: Actually Tomcat URL is not Public URL so,
> clients cannot access it from outside. But we enabled access only to our
> premisis to access all servers.
>>
>> So we will use tomcat hostname & port followed by the context. eg:
>> http://tom1abc:9090/sites or http://10.100.0.31:9090/sites
>
>
> That's it for now.. :-)
>
>
> (*) you don't have a choice about this, if you are using the mod_jk
> connector.
> For reference, the AJP protocol is not HTTP, but it carries the same
> information as HTTP.
>
> For info also, but important : the mod_jk module of Apache httpd can write
> a logfile, which can show in detail what is going on between Apache and
> Tomcat. But we do not know yet if the problem is at that level, so don't do
> that yet, and first answer the questions above.
> But for the future, possibly : the Apache configuration directives for
> setting the mod_jk logging are described here :
> http://tomcat.apache.org/connectors-doc/webserver_howto/apache.html
> --> Logging
>
>
>
>
>
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>


-- 

*Thanks & Regards,*
*Jayaram Ponnusamy*
Mobile: +974-5512-3315

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