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    • VOS.VirtTipsAndTricksRecording(1.1) -- DAVWikiAdmin? , 2017-06-13 05:48:20 Edit
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    WebDAV System Administrator 2017-06-13 05:48:20

    HTTP Logging and Recording in Virtuoso

    HTTP Logging

    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: 

      [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 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.

    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 param which works in conjunction with the "HTTPLogFile" INI file param. 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. 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.

    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.

    Example 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

    Example 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

    Example Enabling recording

    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: 

      [HTTPServer]
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.

    Example Disabling recording

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

      [HTTPServer]
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.

    Restricting recording of HTTP activities

    The HTTP recordings can be made to skip the recording of certain HTTP types of activities, like the loading of images for example, by inserting exceptions into 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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