How to use the Proxy Server Tool

You are reading the AEM 6.2 version of How to use the Proxy Server Tool.
This documentation is also available for the following versions:  AEM 6.1  AEM 6.0  AEM 5.6.1  AEM 5.6  CQ 5.5 

The proxy server acts as an intermediate server that relays requests between a client and a server. The proxy server keeps track of all the client-server interactions and outputs a log of the entire TCP communication. This allows you to monitor exactly what is going on, without having to access the main server.

You can find the proxy server in your AEM installation here:

crx-quickstart/opt/helpers/proxy-2.1.jar

You can use the proxy server to monitor all client-server interaction, regardless of the underlying communication protocol. For example, you can monitor the following protocols:

  • HTTP for Web pages
  • HTTPS for secure Web pages
  • SMTP for email messages
  • LDAP for user management

For example, you can position the proxy server between any two applications that communicate via a TCP/IP network; e.g. a web browser and CQ. This allows you to monitor exactly what happens when you request a CQ page.  

Starting the Proxy Server Tool

Start the server on the command line:

java -jar proxy-2.1.jar <host> <remoteport> <localport> [options]

Parameters

<host>

This is the host address of the CRX instance that you want to connect to. If the instance is on your local machine, then this will be localhost.

<remoteport>

This is the host port of the target CRX instance. For example, the default of a newly installed AEM installation is 4502 and the default for a newly installed AEM author instance is 4502.

<localport>

This is the port on your local machine that you wish to connect to to access the CRX instance through the proxy.

Options

-q (quiet mode)

Does not write the output to the console window. Use this if you do not want to slow down the connection, or if you log the output to a file (see -logfile option).

-b (binary mode)

If you are looking for specific byte combinations in the traffic, enable binary mode. The output will then contain the hexadecimal and character output.

-t (time stamp log entries)

Adds a time stamp to each log output. The time stamp is in seconds, so it may not be suitable for checking single requests. Use it to locate events that occurred at a specific time if you use the proxy server over a longer time period.

-logfile <filename> (write to log file)

Writes the client-server conversation to a log file. This parameter also works in quiet mode.

-i <numIndentions> (add indention)

Each active connection is indented for better readability. Default is 16 levels. This feature was introduced with proxy.jar version 1.16.

Log Format

The log entries produced by proxy-2.1.jar all have the following format:  

[timestamp (optional)] [Client|Server]-[ConnectionNumber]-[BytePosition] ->[Character Stream]

For example, a request for a Web page may look as follows:  

C-0-#000000 -> [GET /author/prox.html?CFC_cK=1102938422341 HTTP/1.1 ]

  • C signifies that this entry comes from the client (it is a request for a Web page)
  • 0 is the connection number (the connection counter starts at 0)
  • #00000 the offset in the byte stream. This is the first entry, so the offset is 0.
  • [GET <?>] is the content of the request, in the example one of the HTTP headers (url).

When a connection closes, the following information is logged:  

C-6-Finished: 758 bytes (1.0 kb/s)
S-6-Finished: 665 bytes (1.0 kb/s)

This shows the number of bytes that passed between client (C) and the server (S) on the 6th connection and at the average speed.

An Example of Log Output

As an example, consider a page that produces the following code when requested:

 

Example

As an example, consider a very simple html document located in the repository at

/content/test.html

alongside an image file located at

/content/test.jpg

The content of test.html is:

<html>
<head>
    <title>Test</title>
</head>  
<body>
    Test<br>
    <img src="test.jpg">
</body>
</html>
        

Code samples are intended for illustration purposes only.

 

Assuming the AEM instance is running on localhost:4502 we start the proxy like this:

java -jar proxy.jar localhost 4502 4444 -logfile test.log

The CQ/CRX instance can now be accessed though the proxy at localhost:4444 and all communication via this port is logged to test.log.

 

 

If we now watch the output of the proxy we will see the interaction between the browser and the AEM instance.

On startup the proxy outputs the following:

 

starting proxy for localhost:4502 on port 4444
using logfile: <some-dir>/crx-quickstart/opt/helpers/test.log
        

Code samples are intended for illustration purposes only.

We then open a browser and access the test page:

http://localhost:4444/content/test.html 

and we see the browser make a GET request for the page:

C-0-#000000 -> [GET /content/test.html HTTP/1.1 ]
C-0-#000033 -> [Host: localhost:4444 ]
C-0-#000055 -> [Connection: keep-alive ]
C-0-#000079 -> [User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_4) AppleWebKit/536.11 (KHTML, like Gecko) Chrome/20.0.1132.57 Safari/536.11 ]
C-0-#000212 -> [Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 ]
C-0-#000285 -> [Accept-Encoding: gzip,deflate,sdch ]
C-0-#000321 -> [Accept-Language: en-US,en;q=0.8 ]
C-0-#000354 -> [Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3 ]
C-0-#000402 -> [Cookie: login-token=179ba6bd-e0a7-4909-a965-e11c7f2bc2fc%3a618bd8a8-fbaf-43c5-827d-c84c62248c5e_22ee860cc9036fee%3acrx.default%3b21148fb0-eb6c]
C-0-#000543 -> [-43c9-a2b9-c8d40618d8ae%3ad87a3d1a-5e9a-4d5a-bab1-0ee60ad6d8df_d0e4ddce0fcd84b6%3acrx.default%3b5cb95227-ea51-47bf-850b-68ad1dfd7297%3af3bbb6]
C-0-#000684 -> [59-7913-4285-8857-832c087bafd5_c484727d3b3665ad%3acrx.default; ys-cq-siteadmin-tree=o%3Awidth%3Dn%253A240%5EselectedPath%3Ds%253A/content ]
C-0-#000824 -> [ ]
        

Code samples are intended for illustration purposes only.

The AEM instance responds with the contents of the file test.html:

S-0-#000000 -> [HTTP/1.1 200 OK ]
S-0-#000017 -> [Connection: Keep-Alive ]
S-0-#000041 -> [Server: Day-Servlet-Engine/4.1.24  ]
S-0-#000077 -> [Content-Type: text/html;charset=utf-8 ]
S-0-#000116 -> [Content-Length: 104 ]
S-0-#000137 -> [Date: Mon, 16 Jul 2012 11:23:38 GMT ]
S-0-#000174 -> [Last-Modified: Mon, 16 Jul 2012 11:19:27 GMT ]
S-0-#000220 -> [ ]
S-0-#000222 -> [<html>]
S-0-#000229 -> [<head>]
S-0-#000236 -> [    <title>Test</title>]
S-0-#000260 -> [</head> ]
S-0-#000269 -> [<body>]
S-0-#000276 -> [ Test<br>]
S-0-#000286 -> [    <img src="test.jpg">]
S-0-#000311 -> [</body>]
S-0-#000319 -> [</html>]
        

Code samples are intended for illustration purposes only.

Uses of the Proxy Server

The following scenarios illustrate a few of the purposes for which the Proxy Server can be used:

Check for Cookies and their Values

The following log entry example shows all cookies and their values sent by the client on the sixth connection opened since the proxy started:

C-6-#000635 -> [Cookie: cq3session=7e39bc51-ac72-3f48-88a9-ed80dbac0693; Show=ShowMode; JSESSIONID=68d78874-cabf-9444-84a4-538d43f5064d ]

Checking for Headers and their Values

The following log entry example shows that the server is able to make a keep-alive connection and the content length header was properly set:

S-7-#000017 -> [Connection: Keep-Alive ]
...
S-7-#000107 -> [Content-Length: 124 ]

Checking if Keep-Alive works

Keep-alive is a feature of HTTP that allows a client to re-use the TCP connection to the server to make multiple requests (for the page code, pictures, style sheets and so on). Without keep-alive, the client has to establish a new connection for each request.

To check if keep-alive works:

  • Start the proxy server.
  • Request a page.
  • If keep-alive is working, the connection counter should never go above 5 to 10 connections.
  • If keep-alive is not working, the connection counter increases rapidly.

Finding Lost Requests

If you lose requests in a complex server setting, for example with a firewall and a dispatcher, you can use the proxy server to find out where the request was lost. In case of a firewall:

  • Start a proxy before a firewall
  • Start another proxy after a firewall
  • Use these to see how far the requests are getting.

Requests Hanging

If you experience hanging requests from time to time:

  • Start the proxy.
  • Wait or write the access log into a file with each entry having a timestamp.
  • When the request start hanging you can see how many connections were open and which request is causing trouble.

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