HTTP Logging and Recording in Virtuoso

HTTP Logging

Virtuoso can keep HTTP logs with all the requests that are made to the HTTP endpoint. Here are the steps:

  1. Edit your INI file (default, virtuoso.ini) and add the HTTPLogFile setting: 

    [HTTPServer]
HTTPLogFile                = logs/http15022012.log

  2. Restart Virtuoso.
  3. Virtuoso will now maintain a http log in the logs subdirectory, with one line per request as in: 

    180.76.5.87 - - [15/Feb/2012:21:50:44 +0100] "GET /data/Wilton_power_stations.json HTTP/1.0" 200 8014 "" 
"Mozilla/5.0 (compatible; Baiduspider/2.0; +http://www.baidu.com/search/spider.html)"
180.76.5.87 - - [15/Feb/2012:21:50:45 +0100] "POST /sparql HTTP/1.0" 200 3012 "" ""

  4. The first request after midnight will start a new logfile, to make sure one logfile does not grow to infinite size. Old logfiles can be gzipped or removed by hand to conserve disk space.

The HTTP log files that Virtuoso produces can be processed by programs like Webalizer or AWstats to accurately measure site usage.

HTTP Logging Format

Virtuoso supports HTTP Logging format string like Apache Module mod_log_config. That string can be set in the "HTTPLogFormat" INI file parameter which works in conjunction with the "HTTPLogFile" INI file parameter. For example: 


[HTTPServer]
HTTPLogFormat = %h %u %t "%r" %s %b "%{Referer}i" "%{User-agent}i" "%{NetId}e"

In this example we have %{User-Agent}i which means to log the HTTP header for user-agent. We can log other HTTP request headers in similar fashion. "e" modifier is for environment variables; NetId, in this case.

Note that not all escapes from Apache Module mod_log_config are supported.

HTTP Recording

Virtuoso can also record the complete HTTP request for both GET and POST requests, including all incoming headers, POST parameters, etc. This is a very useful tool for debugging, but it will cost performance and disk space, so it should not be left on for long periods of time. Each request will be written to a separate file.

Note: Some filesystem types like ext2 and earlier versions of ext3 on Linux cannot handle huge amounts of files in a single directory without slowing down the whole system.

Sample Log of a GET request


GET /sparql?query=DESCRIBE%20%3CnodeID%3A%2F%2Fb15481%3E&output=text%2Fcxml     HTTP/1.1
Host: localhost:8890
Connection: Keep-alive
Accept: */*
From: googlebot(at)googlebot.com
User-Agent: Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)
Accept-Encoding: gzip,deflate

Sample Log of a POST request


POST /ods_services/Http/usersGetInfo HTTP/1.1
User-Agent: Opera/9.80 (Macintosh; Intel Mac OS X 10.5.8; U; en) Presto/2.9.168 Version/11.51
Host: localhost:8890
Accept: text/html, application/xml;q=0.9, application/xhtml+xml, image/png, image/webp, image/jpeg, image/gif, 
 image/x-xbitmap, */*;q=0.1
Accept-Language: en,en-US;q=0.9,ja;q=0.8,fr;q=0.7,de;q=0.6,es;q=0.5,it;q=0.4,pt;q=0.3,pt-  
 PT;q=0.2,nl;q=0.1,sv;q=0.1,nb;q=0.1,da;q=0.1,fi;q=0.1,ru;q=0.1,pl;q=0.1,zh-CN;q=0.1,zh-TW;q=0.1,ko;q=0.1
Accept-Encoding: gzip, deflate
Referer: https://localhost:8890/ods/
Cookie: interface=js; oatSecurityCookie=0123456878794576; sid=b3fae40reb78bc4babab3cb2a70fb111
Connection: Keep-Alive
Content-Length: 77
Content-Type: application/x-www-form-urlencoded
Authorization: Basic bnQacPPuhhxs
Content-Transfer-Encoding: binary

Enabling Recording of HTTP Activity

  1. Navigate to the directory holding the INI file, and execute the following shell commands: 

    mkdir sys_http_recording
chmod 777 sys_http_recording

  2. Edit your INI file (default, virtuoso.ini) and set: 

    [HTTPServer]
EnableRequestTrap          = 1

  3. Next connect to your database with isql, and execute the following SQL commands: 

    registry_set ('__save_http_history_on_disk', '1');
registry_set ('__save_http_history', '/');

  4. Finally, restart Virtuoso.
  5. At this point, every HTTP GET and POST request will be logged with all the parameters, headers, and settings.

Disabling Recording of HTTP Activity

  1. To temporary disable recording, edit your INI file (default, virtuoso.ini) and set: 

    [HTTPServer]
EnableRequestTrap          = 0

  2. Next, remove the two Virtuoso registry items: 

    registry_remove ('__save_http_history_on_disk');
registry_remove ('__save_http_history');

  3. Finally, restart Virtuoso.

Restricting Recording of HTTP Activity

HTTP recording can be made to ignore certain types of HTTP activity (for example, the loading of images) by listing exceptions in the "WS.WS.HTTP_SES_TRAP_DISABLE" table:


insert into WS.WS.HTTP_SES_TRAP_DISABLE values ('css');
insert into WS.WS.HTTP_SES_TRAP_DISABLE values ('js');
insert into WS.WS.HTTP_SES_TRAP_DISABLE values ('png');
insert into WS.WS.HTTP_SES_TRAP_DISABLE values ('jpg');
insert into WS.WS.HTTP_SES_TRAP_DISABLE values ('gif');

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