Slurp.. technical blogs!: dispatcher

Set up Dispatcher in AEM on Windows

In this tutorial, i am going to take you through how to set up a dispatcher in AEM on windows.

What is Dispatcher?

Dispatcher is Adobe Experience Manager's caching and/or load balancing tool. Dispatcher also helps to protect your AEM server from attack.

The Dispatcher helps realize an environment i.e. both fast and dynamic. It works as a part of a static HTML server, with the aim of:

Storing as much of the site content as is possible, in the form of a static website.
Accessing the layout as little as possible.

You need an Apache server to run Dispatcher. So first we need to set up the Apache server then we will add configuration of the dispatcher.

Install Apache Webserver on Windows:

Download Apache server from the trusted Apache site. Follow below link:

http://archive.apache.org/dist/httpd/binaries/win32/

A lot of new versions are available for Apache. I am using apache server 2.2. Follow the below steps to set up on windows:

Step 1: Download httpd-2.2.25-win32-x86-no_ssl.msi

Step 2: Double click the downloaded msi file and click next and finish

By default, it will install at C:\Program Files (x86)\Apache Software Foundation\Apache2.2

Apache location

Step 3: Go to your httpd.conf file C:\Program Files (x86)\Apache Software Foundation\Apache2.2\conf

· Change default Define SRVROOT or ServerRoot path to absolute path of your apache2.2 folder “ C:\Program Files (x86)\Apache Software Foundation\Apache2.2\conf” (Line – 38).

· Update listen port Listen 8080 (Line – 47), it is optional if you don’t want to change you can keep default port as 80.

· Update ServerName localhost:8080 (Line – 173), it is optional if you don’t want to change you can keep default port as 80.

· Now Go to the bin folder (C:\Program Files (x86)\Apache Software Foundation\Apache2.2\bin) and open command prompt.

· run httpd -k start to start the server.

#Common Issue while starting the server

If it says the port is already bound to 80 port on 0.0.0.1:80 then change port in httpd.conf file.

Then change the port. Let’s say I am changing to port 81. Change port at line #47 and save it.

Step 4: Run httpd -k start command to start the apache server.

Check error.log in the logs folder of C:\Program Files (x86)\Apache Software

Foundation\Apache2.2\logs.

If no error then opens a browser and type localhost. It shows it works!

You can change this content. For this:

Go to C:\Program Files(x86)\ApacheSoftwareFoundation\Apache2.2\htdocs
Open Index.html file.

Save this file and refresh the browser. You can see Updated content.

Step 5: Now set up dispatcher on apache server.

You just need to follow below steps:-

· Download dispatcher build

· Modify Apache web server httpd.conf file

· Modify dispatcher.any file

· Restart Apache web server and you are done.

Download dispatcher build:

Go to below link:

https://www.adobeaemcloud.com/content/companies/public/adobe/dispatcher/dispatcher.html

Download the selected file. I am selecting no ssl.

Unzip dispatcher-apache2.2-windows-x86-4.2.3.zip file

Note# Its better to use the same version for both dispatcher and apache. I am using 2.2 for both. if you are working with 2.4 apache and 2.2 dispatcher then you might face some issue.

It contains below files:

§ disp_apache2.2.dll – This is my dispatcher module file, which we will plugin with web server.

§ dispatcher.any – It is our dispatcher configuration file.

§ author_dispatcher.any – Sample file for configuring our dispatcher.

§ httpd.conf.disp2.conf – sample file to configure apache webserver.

Now follow the below steps to configure dispatcher:

Go to C:\Program Files (x86)\Apache Software Foundation\Apache2.2\conf location where you have installed your apache server.

Open httpd.conf file.

Go to path where you have unzipped dispatcher.

Open httpd.conf.disp2 file.

Go to line #234

Copy LoadModule dispatcher_module modules/mod_dispatcher.so and paste anywhere in httpd.conf file

I am pasting line #130 where my load modules are ending.

Change module "mod_dispacther.so" to modules/disp_apache2.2.dll as dispatcher has .dll file.

Note:-This setting is used by apache webserver to load my dispatcher when next time Apache web server is started

Copy line #236-248 from httpd.conf.disp2.conf file and paste it to httpd.conf file after ending of </IfModule>.

Below are the lines, you can use it directly.

# location of the configuration file. eg: 'conf/dispatcher.any'

DispatcherConfig conf/dispatcher.any

# location of the dispatcher log file. eg: 'logs/dispatcher.log'

DispatcherLog logs/dispatcher.log

# log level for the dispatcher log, can be either specified

# as a string or an integer (in parentheses)

# error(0): Errors

# warn(1): Warnings

# info(2): Infos

# debug(3): Debug

# trace(4): Trace

DispatcherLogLevel warn

# if turned on, the dispatcher looks like a normal module

DispatcherNoServerHeader Off

# if turned on, request to / are not handled by the dispatcher

# use the mod_alias then for the correct mapping

DispatcherDeclineRoot Off

# if turned on, the dispatcher uses the URL already processed

# by handlers preceeding the dispatcher (i.e. mod_rewrite)

# instead of the original one passed to the web server.

DispatcherUseProcessedURL Off

# if turned to 1, the dispatcher does not spool an error

# response to the client (where the status code is greater

# or equal than 400), but passes the status code to

# Apache, which e.g. allows an ErrorDocument directive

# to process such a status code.

# Additionally, one can specify the status code ranges that should

# be left to web server to handle, e.g.

# DispatcherPassError 400-404,501

DispatcherPassError 0

# DispatcherKeepAliveTimeout specifies the number of seconds a

# connection to a backend should be kept alive. If not set or

# set to zero, connections are not kept alive.

#DispatcherKeepAliveTimeout 60

</IfModule>

It contains below entries:

· DispatcherConfig – location of the configuration file

· DispatcherLog– location of the dispatcher log file

· DispatcherPassError – to use your dispatcher for handling errors, if set to 1 then webserver will handle errors.

· DispatcherKeepAliveTimeout – Time interval for which your request should be kept alive.

Now copy the dispatcher handler from httpd.conf.disp2.conf (line #370) to httpd.conf file(line #238). this will override the default handle of web server and allow the dispatcher to entertain all incoming requests.

Add below code:

ModMimeUsePathInfo On

# enable dispatcher for ALL request. if this is too restrictive,

# move it to another location

SetHandler dispatcher-handler

</IfModule>

Options FollowSymLinks

AllowOverride None

</Directory>

It might present in your httpd.conf. If it is there, then ignore the above step.

Copy this disp_apache2.2.dll file from downloaded dispatcher and paste it under C:\Program Files (x86)\Apache Software Foundation\Apache2.2\modules.

Copy dispatcher.any file from downloaded dispatcher and paste it under C:\Program Files (x86)\Apache Software Foundation\Apache2.2\conf directory.

Now open dispatcher.any file.

Change the port number in line 38. If you are setting up dispatcher for publish instance then use 4503 (default port of publish) or add your publish port here if not 4503.

If you want to set up for author then set it 4502.

Then go to line #77

Allow all paths for the author. Instead of denying, I am allowing this for testing purposes.

§ For Publish the instance you should deny all request and allow specific, For an author instance you should allow all and deny specific.

Then go to /cache section.

§ Update cache Doc Root. It should exactly match my httpd.conf Documentroot path. Copy Document root path from httpd.conf file and paste it in dispatcher.any file at line 132.