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

  1. Edit your virtuoso.ini and add the following setting:

    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: - - [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; +" - - [15/Feb/2012:21:50:45 +0100] "POST /sparql HTTP/1.0" 200 3012 "" ""
  4. The first request after midnight will open a new logfile, to make sure the logfile does not keep growing. 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.

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

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. In similar way can log other input headers, "e" modifier is for environment variable NetId in this case.

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

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.

GET /sparql?query=DESCRIBE%20%3CnodeID%3A%2F%2Fb15481%3E&output=text%2Fcxml     HTTP/1.1
Connection: Keep-alive
Accept: */*
From: googlebot(at)
User-Agent: Mozilla/5.0 (compatible; Googlebot/2.1; +
Accept-Encoding: gzip,deflate
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
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-
Accept-Encoding: gzip, deflate
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
  1. Go to the directory where the database is started from:

    mkdir sys_http_recording
    chmod 777 sys_http_recording
  2. Edit virtuoso.ini and set:

    EnableRequestTrap          = 1
  3. Next connect with isql to your database and run the following commands:

    registry_set ('__save_http_history_on_disk', '1');
    registry_set ('__save_http_history', '/');
  4. Finally restart Virtuoso.

  5. As result at this point every HTTP GET and POST request will be logged with all the parameters, headers and settings.

  1. To temporary disable the recordings, edit virtuoso.ini and set:

    EnableRequestTrap          = 0
  2. Next you should remove the two registry items:

    registry_remove ('__save_http_history_on_disk');
    registry_remove ('__save_http_history');
  3. Finally restart Virtuoso.