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How to Install Virtuoso Open Source (VOS) on CentOS Linux

Starting Point

  1. We start from a freshly installed Linux installation having chosen the "server" package set.
  2. Linux OS configurations: when first installed, CentOS runs setup(1) on reboot. At that time or by running it again subsequently, we make a couple of changes:
    • On general principles it is wise to disable the insecure & unrequired services such as RPC, portmapper etc unless you're also going to use them.
    • It may be wise to open port 8890/tcp in the firewall configuration to allow external access to Virtuoso's web-based interfaces such as the Conductor.
  3. Run yum update in order to update the indexes of available packages.
  4. We prefer to install as a normal user and use sudo only for the final `make install' phase, so create a new user with the adduser command and run visudo to add them to sudoers.

Installing Virtuoso

Virtuoso is currently unpackaged on CentOS so has to be built from source.

Note: Useful prior reading: please see the pages VOSBuild and VOSMake in the VOS Wiki.

Dependencies

Proceed to install the required build dependencies: 

[tim@centos ~]$ sudo yum install gcc gmake autoconf automake libtool flex \
	bison gperf gawk m4 make openssl-devel readline-devel wget
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirror.as29550.net
 * extras: mirror.as29550.net
 * updates: mirror.as29550.net
Setting up Install Process
No package gmake available.
Package gawk-3.1.5-14.el5.i386 already installed and latest version
Package m4-1.4.5-3.el5.1.i386 already installed and latest version
Package 1:make-3.81-3.el5.i386 already installed and latest version
No package openssl-dev available.
Resolving Dependencies
--> Running transaction check
---> Package autoconf.noarch 0:2.59-12 set to be updated
--> Processing Dependency: imake for package: autoconf
[...]

Dependency Installed:
  cpp.i386 0:4.1.2-50.el5                        glibc-devel.i386 0:2.5-58      
  glibc-headers.i386 0:2.5-58                    imake.i386 0:1.0.2-3           
  kernel-headers.i386 0:2.6.18-238.5.1.el5      

Complete!
[tim@centos ~]$

Unpacking

Download the latest VOS archive (source tarball such as virtuoso-opensource-6.1.3.tar.gz) from SourceForge and unpack it: 

[tim@centos ~]$ tar xvpfz virtuoso-opensource-6.1.3.tar.gz 
virtuoso-opensource-6.1.3/
virtuoso-opensource-6.1.3/bin/
virtuoso-opensource-6.1.3/bin/installer/
virtuoso-opensource-6.1.3/bin/installer/virtuoso.ini
virtuoso-opensource-6.1.3/bin/installer/demo.ini
...

Configuring

  1. For the purposes of this demonstration, we use a simple configuration with no frills: 

    [tim@centos virtuoso-opensource-6.1.3]$ ./configure --prefix=/usr/local/ \
	--with-readline

  2. There are many other options that can be specified at this stage, to enable/disable the building of language-hosting plugins (Perl, Python, Ruby) or various VAD packages (sub-packages within Virtuoso); for more on these, read the relevant README files in the source distribution and run `./configure --help'.
  3. Here we settle for asking for readline support, ie the ability to cursor-up/down and use typical readline key-combinations in the commandline isql tool once built.

VOS component locations

  1. Virtuoso instances usually take the form of a designated directory somewhere in the filesystem, centred around a configuration file (nominally virtuoso.ini) which specifies operational parameters such as the filenames of database page-files to use, port-numbers to use, numbers of threads and buffers, etc.
  2. In the above command, we specify a prefix of /usr/local to Virtuoso's ./configure script. This forms a base directory under which Virtuoso will create/use the following structure:
    • /usr/local/lib/
      • various libraries for Sesame, JDBC, Jena, Hibernate, and hosting
    • /usr/local/bin/
      • where the main executables (virtuoso-t, isql) live
    • /usr/local/share/virtuoso/vad/
      • used to store VAD archives prior to installation in an instance
    • /usr/local/share/virtuoso/doc/
      • local offline documentation
    • /usr/local/var/lib/virtuoso/db/
      • the default location for a virtuoso instance
    • /usr/local/var/lib/virtuoso/vsp/
      • various VSP scripts - the default homepage before the Conductor is installed
  3. Other directory-structures are possible by specifying variously:
    • individual configure options such as --bindir, --libdir, etc.
    • --with-layout={GNU|Debian|Gentoo|RedHat|FreeBSD|opt|OpenLink}
      where each layout specifies a set of locations where the VADs, documentation (HTML and PDF), demo and default instance databases, and hosting libraries will be installed, each compatible with the packaging requirements of the named OS distribution ("opt" means a prefix of /opt and OpenLink is the default, detailed above).

Building and Installing

  1. Having chosen some configure options, run make: 

    [tim@centos virtuoso-opensource-6.1.3]$ nice make

  2. Optionally, you can run `make check' to run the test-suite (beware, it takes hours and multiple gigabytes of disk-space). 

    [tim@centos virtuoso-opensource-6.1.3]$ nice make check

  3. Install it to the directory-structure chosen above: 

    [tim@centos virtuoso-opensource-6.1.3]$ sudo make install

Getting Started

  1. Take a copy of the default virtuoso.ini and store it safely in case of making erroneous changes.
  2. Change into the default database directory: 

    [tim@centos v-oss]$ cd /usr/local/var/lib/virtuoso/db/
[tim@centos db]$ ls
virtuoso.ini

    • (At this point, if you wish to run virtuoso as a non-root user you should change the ownership on this directory, e.g. sudo chown -R tim . . Virtuoso only requires root if you wish to use it as a webserver listening on port 80; by default it listens only on high ports.)
  3. Start the server: 

    [tim@centos db]$ virtuoso-t -df

                Wed Apr 13 2011
15:12:48 INFO: { Loading plugin 1: Type `plain', file `wikiv' in `/usr/local/lib/virtuoso/hosting'
...
15:13:10 INFO: Checkpoint finished, log reused
15:13:10 INFO: PL LOG: Installing Virtuoso Conductor version 1.00.7890 (DAV)
15:13:10 INFO: Checkpoint started
15:13:14 INFO: Checkpoint finished, log reused
15:13:14 INFO: HTTP/WebDAV server online at 8890
15:13:14 INFO: Server online at 1111 (pid 4125)

    • Here we see the server running in foreground mode with maximum debugging information. Because it's the first time this instance has been run, virtuoso has created a bunch of database files (virtuoso.db, virtuoso.trx (the transaction log), etc) and installed the Conductor VAD package into the database.
    • If you close your terminal while this command is running, Virtuoso will stop. To run it as a daemon instead, omit the "-df" flags. You can still see most of what's happening by running tail -f virtuoso.log.

Using Virtuoso

Web-based UI

You can access the Conductor menu by pointing your web-browser at http://localhost:8890/conductor/ (substitute hostname as appropriate).

From the Conductor you can manage users and automated backups, install VAD packages, execute SQL commands in a web-based iSQL tool, configure the RDF Sponger and loads more.

There are two system users of immediate importance: dba (the relational data administrative account) and dav (the WebDAV adminstrative account). By default both these accounts have their passwords set the same as the respective usernames; it is highly advised that you change these as soon as possible for security reasons.

Command-line

Virtuoso provides a SQL/ODBC listener on port 1111/tcp. You can connect directly to this and execute SQL statements using the isql tool:

[tim@centos db]$ isql
OpenLink Interactive SQL (Virtuoso), version 0.9849b.
Type HELP; for help and EXIT; to exit.
SQL> tables;
Connected to OpenLink Virtuoso
Driver: 06.01.3127 OpenLink Virtuoso ODBC Driver
Showing SQLTables of tables like 'NULL.NULL.NULL', tabletype/colname like 'NULL'
TABLE_QUALIFIER  TABLE_OWNER      TABLE_NAME       TABLE_TYPE       REMARKS
VARCHAR          VARCHAR          VARCHAR          VARCHAR          VARCHAR
_______________________________________________________________________________

DB               DBA              ADMIN_SESSION    SYSTEM TABLE     NULL
DB               DBA              ADM_OPT_ARRAY_TO_RS_PVIEW  SYSTEM TABLE     NULL
[...]

Resource Usage

Virtuoso is highly configurable: the same executables and packages will service anything from a small "lite-mode" installation with a database of 10Mb up to a huge multi-user enterprise installation with terabytes of data.

The defaults with Virtuoso Open-Source give a 160MB process size in memory, about 29MB database and total 237MB footprint on disk; this has 20 threads running for database and/or web-server use.

The wiki document VOSScale describes how to scale Virtuoso in some detail.

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