How to Install a Local RDF Store

Goal of this page

To operate the WUMM RDFData on a local site requires access to the data via a web server at localhost and a Sparql endpoint.

On this page we describe how to set up your own Sparql endpoint at http://localhost:8890/sparql based on Apache running under a recent Linux Debian Ubuntu distribution.

Preliminary Remarks

There are plenty of RDF stores based on MySQL databases. Much of them are well suited for serving WUMM RDFData, too.

Here we describe how to install an RDF infrastructure based on the more powerful RDF Engine Virtuoso.

Virtuoso is a commercial Database store of Openlink Software specially designed to serve huge RDF data that comes with a built in Sparql endpoint. We recommend to use the Virtuoso Open Source Distribution (VOS) bundled with Debian.

Install the Virtuoso engine

The virtuoso engine can easily be installed with the single command

  sudo aptitude install virtuoso-opensource

For security reasons during installation you will be asked for a password for the db users ‘dba’ and ‘dav’ (default: dba). The password should match the regex [a-zA-Z0-9]+, i.e., have only letters and ciphers.

For details see

The executables provided (in the virtuoso-opensource-6.1-bin package) are:

At server start time a Virtuoso database is started with configuration read from /etc/virtuoso-opensource-6.1/virtuoso.ini. The default settings point to

  isql-vt 1111 dba YourDBPassword

if the daemon is running.

(Optional) Create a new Virtuoso Database and start operation

Copy /etc/virtuoso-opensource-6.1/virtuoso.ini to a fresh directory /myPATH/myNewVDir, change all file names to local ones

  DatabaseFile                   = virtuoso.db
  ErrorLogFile                   = virtuoso.log
  LockFile                       = virtuoso.lck 
  TransactionFile                = virtuoso.trx
  xa_persistent_file             = virtuoso.pxa
  DatabaseFile                   = virtuoso-temp.db
  TransactionFile                = virtuoso-temp.trx

change the ports 1111 (new, e.g. 1112) and 8890 (new, e.g. 8891) to different ones and start a new daemon with

  cd /myPATH/myNewVDir; virtuoso-t +configfile virtuoso.ini 

This will generate all additional files in that directory and start the daemon. Access the database via console

  isql-vt 1112 dba dba

and first change the default password ‘dba’

  SQL> set password dba YourVerySecretPassword ;

The web front end to the new database will be available at http://localhost:8891.

Shut down the service from the console with

  isql-vt 1112 dba YourVerySecretPassword
  SQL> shutdown() ;

Data Management

To load RDF data from the files supplied in the rdf directory of the web git repo directly into the Virtuoso engine the following steps are required:

1) Check out the repo to /YourPathTo/web, add the path /YourPathTo/web to the data part of the distribution to the DirsAllowed

  DirsAllowed =., /usr/share/virtuoso-opensource-6.1/vad, /YourPathTo/web

and restart the daemon.

2) Load all or a part of the RDF graphs into the Virtuoso Engine. The perl script at web/services/ writes the required output to stdout, that contains a number of records like

   sparql create silent graph <> ; 
   DB.DBA.RDF_LOAD_RDFXML_MT (file_to_string_output('/YourPathTo/web/People.rdf'),'',''); 

Read that into Virtuoso using the command line tool isql-vt:

   perl | isql-vt 1111 dba YourVerySecretPassword

3) Check success from within the console

   isql-vt 1111 dba YourVerySecretPassword
   SQL> sparql select distinct ?s from <> where {?s ?p ?o};

and similar for the other graphs. The command will list you the URIs of all instances in the given graph. Try the same at the SPARQL endpoint http://localhost:8890/sparql with

   select distinct ?s from <> where {?s ?p ?o}

It should list the URIs of all people stored in the WUMM People knowledge base. Compare your output with that from

Additional remarks about Virtuoso

More on config.ini

Adapt at least the items ServerPort in the Parameters section (default 1111), the ServerPort in the HTTPSection (default 8890) and the DirsAllowed. Different databases have to use different ports.

DirsAllowed contains a comma separated list of all directories where the service is allowed to read files. A file location in any subdirectory of the listed directories will be accepted. It is recommended to use absolute path names without file symlinks.

Change the Password

Open the console

  isql-v <DBServerPort> dba <passwd>

and change the password (standard user = dba, passwd = dba)

  SQL>  set password <old password> <new password>;

For curious people: Direct your Browser to http://localhost:8890. It will show you the Virtuoso VSP pages with a “phpmyadmin” like administration web frontend at http://localhost:8890/conductor. Not required for beginners.

Some useful commands

Shutdown the service from the console with

   SQL> shutdown() ;

Clear Data from a given graph:

   SQL> sparql clear graph <> ; 

Graphs are not created automatically. If you have problems to display content in Ontowiki, a command as the following may help to resolve the trouble

   SQL> sparql create silent graph <> ;