| content
| - ---+Deploying PHP applications using Virtuoso as Application Server
%TOC%
---++What
OpenLink Virtuoso has the capability to act as a host for PHP
applications. Where you're currently used to seeing a LAMP (Linux, Apache,
MySQL, PHP) stack, Virtuoso can do the job of both Apache as
web-server and MySQL as database - and lots more.
Virtuoso brings a myriad of extra features, from not just a fast
relational database store (although it does that too), to RDF
triple-store (actually a quad-store; each triple is associated with a graph),
to semantic-web engine to application-development platform and beyond.
---++Why
Existing applications such as PHPBB and WordPress are large pools of
personal and social data - a "data space" - yet the means of querying
them are mostly limited to the domain and application themselves. For
example, within a phpBB3 instance, you can type a word into the search box,
but the results are constrained to coming from only that instance, notably
the format in which it chooses to display them and the actions it permits
you to take based on the results, and (in this case) there is no URL with
which to identify the query itself (so no bookmarks, no sharing with others).
More advanced queries require digging around the underlying tables with SQL,
if you have access to the backend DB.
One could summarize the possible query-methods:
* application-provided search boxes
* site-wide statistical free-text (google)
* custom reports requiring SQL/developer abilities
None of these methods allow one to execute a search on a WordPress blog for
"red, by which I mean the square in Moscow not the colour". As we shall see,
semantic-web technologies will address this.
The good news is that the underlying data is much richer, and may be exposed
in such a way for users to deploy their own query-tools against it by opening
it up in the form of RDF.
---+++A note on RDF
RDF is a framework based on the Entity-Attribute-Value data-model; it can be
thought of as a set of statements expressed in triples subject, predicate and
object where the subject entity and predicate must be identified using URIs,
and the value object may be either a URI or a literal value.
As a separate consideration, RDF may be serialized in several formats; there
is RDF/XML which is orientated towards machine-reading, but there are also
Turtle and N-3 syntaxes more readily accessible to humans. We regard the
representation as of secondary importance compared to the fact it is
statements being represented in the form of triples.
A set of predicates combine into vocabularies known as "ontologies";
there are several well-known ontologies such as FOAF and Dublin Core which,
amongst many other things, allows you to make a statement such as
prefix dc: <http://purl.org/dc/elements/1.1/> .
<http://www.openlinksw.com/> dc:subject "database" .
Entities, described by RDF, group into "graphs" - a set of nodes linked one
to another by predicates. This is an improvement on Web-1.0 and 2.0, where
all that could be said for a link is that one page links to another,
optionally with some significance attached to the freeform keywords used for
the link.
With RDF, all links are precisely meaningful: you know what it means to be
a foaf:nickName, as well as the fact that a particular entity has a given
nickname, for example.
Further, there is a language for querying RDF data, SPARQL, where the queries
may be routed over HTTP as a transport (by the data-provider making a
/sparql endpoint visible). This gives every SPARQL query a fixed URL for later
reference.
Querying extends to browsing, made possible with generic RDF-browser
utilities such as OpenLink's [[http://ode.openlinksw.com/][ODE]] and
[[http://zitgist.com/][Zitgist]], or Tabulator, etc.
---++++When URIs and URLs collide: Linked Data
A URL is the location of a document on the Web; its purpose is to express
location only.
A URI is a unique identifier for an entity; there is implicit binding between
an entity and its metadata through a single identifier. In
programming terms it may be regarded as similar to a "variable name" or a
symbol. As such there is no obvious need to use the HTTP protocol, ie to name
everything starting http://.... but it helps if you do.
An RDF triple- or quad-store contains URIs for subjects and predicates; it
may be queried purely as though it were an abstract object-database with
no significance attached to the "names" of the subjects retrieved.
However, when HTTP URIs are used as names for entities, they become real -
they work - they can be dereferenced. You can publish RDF data on the web
simply, precisely because it takes the form of URIs using the HTTP protocol.
From an alternative perspective, the entire WWW becomes an abstract database
free to be queried. It allows data published by different organizations to
be federated, a process known as Linked Data.
As a bonus, a web-server can be configured to perform content-negotiation
based on what kind of a response a client requests; the same URL may return
text/html (better, application/xhtml+xml) for a web-browser, but a
representation in application/rdf+xml for an RDF browser requesting it.
Coming full-circle, to ease the production of data for existing webmasters,
RDF may be embedded in (X)HTML documents using either RDFa, GRDDL or
eRDF markup; all these and custom microformats may be translated into RDF
using an appropriate agent (such as OpenLink's
[[http://virtuoso.openlinksw.com/dataspace/dav/wiki/Main/VirtSponger][Sponger]],
which can be seen in action at
[[http://www.uriburner.com/wiki/URIBurner/][URIBurner]]).
---+++Data Example
It is possible and desirable to define a mapping between relational
and RDF-based databases.
In the most obvious form, for a given table, each field becomes a
predicate and each row an entity.
Taking as an example the case of PHPBB3's well-known phpbb_users
table,
| *user_id* | *user_type* | *group_id* | *user_permissions* | *user_perm_from* | *user_ip* | *user_regdate* | *username* | *username_clean* | *user_password* | *user_passchg* | *user_pass_convert* | *user_email* |
| 1 | 2 | 1 | null | 0 | null | 1222764432 | Anonymous | anonymous | null | 0 | 0 | root@localhost |
one can obviously make a set of statements about this user,
<http://localhost/rdf/phpBB/user_1>
<http://localhost/rdf/phpBB/has_email> "root@localhost" ;
<http://localhost/rdf/phpBB/has_name> "Anonymous" .
etc.
Obviously this doesn't gain us much. However, you could further extend this
to other well-known ontologies; for example, formulate a mapping from
PHPBB's discussion forums to sioc:Forum entities, from posts within those
forums to sioc:Post entities, etc; users can become entities of type
sioc:User, with data filled-out using the FOAF ontology to express their
properties (name, nickname, email address, homepage, etc). Then anyone using
an RDF browser will experience the well-known sense of hierarchy that SIOC
brings, that "this forum" /contains/ "this thread" which /contains/ "this
comment" - because the SIOC ontology brings that nesting structure by defining
what `/contains/' means.
This adds value to the existing data as well as transforming it. (As an
aside, consider that the same hierarchy suffices to describe Amazon's
website: a section (music/dvd/books/electronics) might correspond to a
sioc:Forum, with a product for sale being a sioc:Post and a review being a
sioc:Comment within it. This enables you to browse RDF by predicate,
impossible with current conventional search-engines.)
OpenLink Virtuoso has a system known as RDF Views, whereby this
translation from relational to RDF data is made dynamic; the triples are
not realised but rather calculated from the relational data on demand.
This way you never have out-of-date data whilst waiting for another import
or sync.
You can write the scripts to implement these RDF Views by hand, but
Virtuoso has automated the whole process, both in general with
transforming relational data from tables to RDF, and specifically for
the cases of PHPBB, Wordpress, MediaWiki and Drupal.
---++How to
---+++Using the Conductor
Virtuoso has a generalized mechanism for automatically generating a canned
RDF view from a given table, available from the Conductor administrative
interface.
First we create a simple test table:
SQL> create table timtest (id integer primary key, str varchar, dt datetime);
Done. -- 36 msec.
SQL> insert into timtest values (1, 'hello world', now());
Done. -- 2 msec.
SQL> insert into timtest values (2, 'this is a test', now());
Done. -- 2 msec.
SQL> grant all on timtest to public;
Done. -- 2 msec.
Point your browser at http://localhost:8890/conductor/ and log in; navigate
your way to Database / RDF Schema Objects. You will see a list of existing
tables in the given schema/qualifier, and an action `generate single mapping'
beside:
To test the results, we first observe the line in the RDF Views script where
it declares the graph IRI (a container for triples) it's going to create:
create virtrdf:DB as graph iri ("http://^{URIQADefaultHost}^/db") option (exclusive)
Next, point your browser at http://localhost:8890/sparql/ , ie the /sparql
query endpoint in the Virtuoso instance. Set the default graph to
http://localhost:8890/db and enter the query
SELECT * WHERE {?s ?p ?o} limit 100
Execute it, and you should be presented with an HTML table showing the
RDF data mapping of your SQL table:
| *s* | *p* | *o* |
| http://gentoo:8890/DB/timtest/id/1#this | http://www.w3.org/1999/02/22-rdf-syntax-ns#type | http://localhost:8890/DB#timtest |
| http://gentoo:8890/DB/timtest/id/2#this | http://www.w3.org/1999/02/22-rdf-syntax-ns#type | http://localhost:8890/DB#timtest |
| http://gentoo:8890/DB/timtest/id/1#this | http://localhost:8890/DB#id | 1 |
| http://gentoo:8890/DB/timtest/id/2#this | http://localhost:8890/DB#id | 2 |
| http://gentoo:8890/DB/timtest/id/1#this | http://localhost:8890/DB#str | hello world |
| http://gentoo:8890/DB/timtest/id/2#this | http://localhost:8890/DB#str | this is a test |
| http://gentoo:8890/DB/timtest/id/1#this | http://localhost:8890/DB#dt | 2009-07-20T16:41:59.000000 |
| http://gentoo:8890/DB/timtest/id/2#this | http://localhost:8890/DB#dt | 2009-07-20T16:42:13.000000 |
As this table demonstrates, the RDF Views generator has decided:
* to use /db as a graph IRI to identify this transformation project
* to use /DB/timtest/id/ as a base for entity URIs
* to use /DB/#predicate as a base for predicate URIs
Naturally you can use the auto-generated RDF View script as a starting point
for your own scripts, adding value through references to existing ontologies
and using stored functions/procedures to manipulate the values into a
suitable string form for use in the URIs.
There is more information about this to be found in the
[[http://docs.openlinksw.com/virtuoso/rdfviews.html][documentation]].
---+++Existing Applications
In this case we follow the process of creating RDF data from an empty
Virtuoso instance, using PHPBB3 as an example.
Download, install and start Virtuoso:
zsh, gentoo 11:30AM virtuoso/ % ./bin/virtuoso-start.sh
Starting Virtuoso instance in [database]
By default this will give you an instance listening on port 1111 for
SQL / ODBC connections and port 8890 for HTTP.
---+++Installing ODS
Point your browser at http://hostname:8890/conductor/ and log in to
the conductor. Choose the System Admin tab and Packages there.
Select a handful of ODS packages, such as Discussion, Framework and
Wiki and definitely PHPBB3, iSPARQL and cartridges and press
'install'.
---+++Setting up ODS & PHPBB3
Background: when new ODS (WebDAV) users are created, a trigger
automatically adds them as PHPBB3 users. This is the preferred way to
register PHPBB3 users.
Point your browser at http://hostname:8890/ods/ and click
sign-up. Account-creation is simply a case of filling in the form; you
will be presented with a view of your account profile when complete.
Point your browser to http://hostname:8890/phpBB3/ - this installation
is the result of installing the VAD package earlier. Log in as the
user you created above and peruse the default post etc.
By extension, the system `dba' user has been made administrator of
this phpBB instance.
As an interface straight into the RDF data, point your browser at
http://hostname:8890/phpBB3/user/someuserid . This will present you with an
instance of the OpenLink RDF Browser, with
http://hostname:8890/phpBB3/user/someuserid as the source URI from
which to start browsing.
This is implemented using the same sort of content-negotiation as
mentioned previously. If you experiment with curl(1) on the
commandline, you'll see that the URL
http://localhost:8890/phpBB3/user/tim gives an HTTP 303 `see other'
response:
zsh, gentoo 5:14PM virtuoso/ % curl -I 'http://localhost:8890/phpBB3/user/tim'
HTTP/1.1 303 See Other
Server: Virtuoso/05.09.3035 (Linux) i686-generic-linux-glibc26-32 VDB
Connection: close
Content-Type: text/html; charset=UTF-8
Date: Fri, 15 May 2009 17:14:06 GMT
Accept-Ranges: bytes
Location: http://localhost:8890/rdfbrowser/index.html?uri=http%3A//localhost:8890/phpBB3/user/tim#this
Content-Length: 0
However, treated as a URI, by requesting RDF data, one sees:
zsh, gentoo 5:15PM virtuoso/ % curl -H 'Accept: application/rdf+xml' \
-I 'http://localhost:8890/phpBB3/user/tim'
HTTP/1.1 200 OK
Server: Virtuoso/05.09.3035 (Linux) i686-generic-linux-glibc26-32 VDB
Connection: Keep-Alive
Date: Fri, 15 May 2009 17:15:14 GMT
Accept-Ranges: bytes
Content-Type: application/rdf+xml; charset=UTF-8
Content-Length: 1457
http://localhost:8890/phpBB3/user/tim
Click around! Browse the data - check the SVG views and `raw triples'
etc. Explore the links from statements about a given phpBB3 users to
forums and articles posted by them.
For background reading: see this [[http://www.vimeo.com/2030393][video of
PHP hosting on Windows Vista]].
---+++Other PHP Applications
The above process can be repeated for MediaWiki, Drupal and WordPress;
OpenLink has a VAD package for each of these applications and existing
documentation pages with the same workflow as the above phpBB3 example:
| *Application* | *DataSpace* | *Documentation* | *Characteristic data URI* |
| phpBB3 | Bulletin-board, forums | [[http://ods.openlinksw.com/dataspace/dav/wiki/ODS/OdsIntegrationphpBB][phpBB]] | http://localhost:8890/phpBB3/user/me |
| Drupal | Content-management system | [[http://ods.openlinksw.com/dataspace/dav/wiki/ODS/OdsIntegrationDrupal][Drupal]] | http://localhost:8890/drupal/user/me |
| WordPress | Blog and CMS | [[http://ods.openlinksw.com/dataspace/dav/wiki/ODS/OdsIntegrationWordPress][WordPress]] | http://localhost:8890/wordpress/user/me |
| MediaWiki | Wiki documentation server | [[http://ods.openlinksw.com/dataspace/dav/wiki/ODS/OdsIntegrationMediaWiki][MediaWiki]] | http://localhost:8890/MediaWiki/user/me |
---+++Browsing
Each of these examples shows how to get "my URI" out of these things and
play with an RDF mapping straight away. Additionally you can use a
standalone RDF browser, such as the OpenLink Data Explorer, Tabulator or Disco
to browse the data.
---++Developers: building Virtuoso Open-Source with PHP support
Here we walk through the process of hosting PHP in Virtuoso, building from
compiling sources to extensions, writing a simple web-application and viewing
data.
At this point it would be wise to double-check the top-level README.php5
file in the open-source distribution, as it may contain more up-to-date
instructions.
There are three stages involved in using a custom build of PHP with Virtuoso;
* build PHP
* add any required PHP modules
* configure and build Virtuoso to reference the PHP you built.
---+++Building PHP
In the event that you have to recompile the PHP hosting module yourself for
use with an existing application, the following options are a /minimum/
starting point:
./configure \
--prefix=/usr/local/php5 \
--enable-maintainer-zts \
--with-tsrm-pthreads \
--enable-embed=shared \
--disable-static \
--with-config-file-path=. \
--disable-cgi \
--disable-cli \
--disable-ipv6 \
--with-zlib \
--with-iodbc=/usr
.....
The ZTS and TSRM pthread options are particularly important; without them,
Virtuoso will have serious threading incompatibilities. Note that many or
most Linux distributions do not use these options, as they tend to package
PHP for use as mod_php with the Apache web-server.
For reference, OpenLink uses the following configure options:
zsh/scr, gentoo 2:17PM php-5.2.10/ % ./configure \
--prefix=/usr/local/php5 \
--enable-maintainer-zts \
--enable-embed=shared \
--with-config-file-path=. \
--with-tsrm-pthreads \
--disable-static \
--disable-cgi \
--disable-ipv6 \
--without-mysql \
--without-pear \
--enable-bcmath=shared \
--enable-calendar \
--enable-dbase=shared \
--enable-dba=shared \
--enable-dom=shared \
--enable-exif=shared \
--enable-ftp=shared \
--enable-gd-native-ttf \
--enable-mbstring=shared \
--enable-pdo \
--enable-shmop=shared \
--enable-soap=shared \
--enable-sockets=shared \
--enable-sysvmsg=shared \
--enable-sysvsem=shared \
--enable-sysvshm=shared \
--enable-wddx=shared \
--enable-xmlreader=shared \
--enable-xmlwriter=shared \
--with-bz2=shared \
--with-curl=shared \
--with-gd=shared \
--with-iodbc=/usr/local/iODBC \
--with-ldap=shared \
--with-mime-magic=shared \
--with-openssl=shared \
--with-pdo-odbc="generic,/usr/local/iODBC,iodbc,\
-L/usr/local/iODBC/lib,-I/usr/local/iODBC/include" \
--with-sqlite=shared \
--with-xmlrpc=shared \
--with-xsl=shared \
--with-xsl=shared \
--with-zlib \
&& nice make
...
You should pick and choose the options starting from the minimal requirements
and whatever modules your application requires and/or are likely to be useful
from the above. Note that many of these options require external libraries to
build (eg openldap, bzip2, curl, libxml2, etc).
Some time later, the build completes and we install PHP:
...
Build complete.
Don't forget to run 'make test'.
zsh/scr, gentoo 12:56PM php-5.2.10/ % sudo make install
Password:
Installing PHP SAPI module: embed
Installing build environment: /usr/local/php5/lib/php/build/
Installing header files: /usr/local/php5/include/php/
Installing helper programs: /usr/local/php5/bin/
program: phpize
program: php-config
Installing man pages: /usr/local/php5/man/man1/
page: phpize.1
page: php-config.1
---+++Building Virtuoso with PHP
Now proceed to build Virtuoso, being sure to use the --enable-php5 option to
configure:
zsh/scr, gentoo 4:34PM virtuoso-opensource-5.0.11/ % ./configure \
--prefix=/usr/local/virtuoso \
--enable-php5=/usr/local/php5 --enable-imagemagick --with-readline \
--with-iodbc=/usr/local/iODBC
When it's done configuring, check the BUILD_OPTS line in the summary
output contains the word `php5':
Options
BUILD_OPTS xml ssl imsg pldebug php5 pthreads readline odbc
Then proceed to use make and make install as usual.
Once you have installed Virtuoso, you should copy the php5 hosting library,
libphp5.so and extensions (*.so) into
place in the /usr/local/virtuoso/lib/virtuoso/hosting/ directory;
the php.ini file goes in the database directory, by default
/usr/local/virtuoso/var/lib/virtuoso/db/ .
---+++Enabling the PHP Hosting plugin
Now we must enable the hosting module; Virtuoso has a standard module
system for the optional inclusion of various areas of functionality,
enabled through the `Plugins' section of virtuoso.ini:
[Plugins]
LoadPath = ../hosting
Load1 = plain, wikiv
Load2 = plain, mediawiki
Load3 = plain, creolewiki
Load4 = plain, im
Load5 = attach, libphp5.so
Load6 = Hosting, hosting_php.so
Here we see the wiki markup parsers, an imagemagick plugin (for use in the
ODS-Gallery application), and a link to the PHP library.
To host a PHP application within Virtuoso, it should suffice to enable the
relevant lines (5 and 6) above.
---+++Using PHP5 and Virtuoso (Commercial Edition)
OpenLink's commercial Virtuoso packages already come with PHP hosting
support; to use your own library, simply copy the libphp5.so and/or any
extensions required into place:
cp /usr/local/php5/lib/libphp5.so hosting/php/
Aside: failure to copy libphp5.so into the same place as is referenced by
the [Plugins] section in virtuoso.ini will give rise to the following
error:
16:28:50 INFO: { Loading plugin 7: Type `attach', file `libphp5.so' in `/usr/local/virtuoso/lib/virtuoso/hosting'
16:28:50 ERROR: FAILED plugin 7: Unable to locate file }
---+++Compiling your own PHP extensions
If you build your PHP as above, extra extensions can be added as required
afterwards.
Our commercial builds of Virtuoso include the following PHP modules as
standard:
|apc| dbase| ldap| soap| sysvshm|
|bcmath| dom| mbstring| sockets| wddx|
|bz2| exif| mime_magic| sqlite| xmlreader|
|curl| ftp| openssl| sysvmsg| xmlrpc|
|dba| gd| shmop| sysvsem| xmlwriter|
| xsl |
In this case, all you need do to enable a module is uncomment it in the
php.ini file (search for `Extensions'):
;;;;;;;;;;;;;;;;;;;;;;
; Dynamic Extensions ;
;;;;;;;;;;;;;;;;;;;;;;
;;extension=apc.so
;;extension=bcmath.so
;;extension=bz2.so
;;extension=curl.so
;;extension=dbase.so
...
As a worked example, we continue by compiling the
[[http://pecl.php.net/package/APC][Alternative PHP Cache]] (APC) PHP
extension for ourselves.
Having downloaded and unpacked the sources, run the phpize command
installed as part of your new build of PHP:
zsh/scr, gentoo 5:06PM APC-3.1.2/ % /usr/local/php5/bin/phpize
Configuring for:
PHP Api Version: 20090626
Zend Module Api No: 20090626
...
zsh/scr, gentoo 5:05PM APC-3.1.2/ % ./configure --cache-file=config.cache \
--prefix=/usr/local/php5 \
--enable-apc-mmap \
--with-php-config=/usr/local/php5/bin/php-config \
--disable-static
...
appending configuration tag "CXX" to libtool
configure: updating cache config.cache
configure: creating ./config.status
config.status: creating config.h
zsh/scr, gentoo 5:07PM APC-3.1.2/ % make
/bin/sh /home/tim/C/APC-3.1.2/libtool --mode=compile cc -I. \
-I/home/tim/C/APC-3.1.2 -DPHP_ATOM_INC -I/home/tim/C/APC-3.1.2/include \
-I/home/tim/C/APC-3.1.2/main -I/home/tim/C/APC-3.1.2 \
-I/usr/local/php5/include/php -I/usr/local/php5/include/php/main \
-I/usr/local/php5/include/php/TSRM -I/usr/local/php5/include/php/Zend \
-I/usr/local/php5/include/php/ext -I/usr/local/php5/include/php/ext/date/lib \
-DHAVE_CONFIG_H -g -O2 -c /home/tim/C/APC-3.1.2/apc.c -o apc.lo
...
zsh/scr, gentoo 5:08PM APC-3.1.2/ % sudo make install
Password:
Installing shared extensions: /usr/local/php5/lib/php/extensions/no-debug-zts-20090626/
zsh/scr, gentoo 5:08PM APC-3.1.2/ %
To use the extension,
* copy it into the ../hosting/php/ directory
* edit the php.ini file and search for `Extensions'. Add and remove
lines there as required.
Aside: note that if you fail to copy the libphp5.so and/or extensions
(*.so) into the right directory, you'll have a mismatch with the prebuilt
versions, leading to this error:
16:05:04 { Loading plugin 7: Type `Hosting', file `hosting_php.so' in `../hosting'
16:05:04 Hosting version 3034 from OpenLink Software
16:05:04 PHP engine version 5.2.7-dev
16:05:04 PHP Warning: PHP Startup: apc: Unable to initialize module
Module compiled with module API=20060613
PHP compiled with module API=20090626
These options need to match
in Unknown on line 0
***
*** Please fix the above issue(s) before trying again.
---+++Testing
As with any other PHP environment, it makes sense to test the setup:
Create a file (say info.php) in the ../vsp/ directory
containing the text:
This file can be downloaded:
info.php
Copy this file into the ../vsp/ directory of your Virtuoso installation and
point your browser at the relevant URL - eg http://localhost:8890/info.php
and see what the output of phpinfo() is. You should see a section with title
corresponding to the module you compiled - here `APC':
---+++Bringing it together: PHP, web-apps and data
Given that Virtuoso provides not just a webserver with PHP hosting ability,
but the whole backend ODBC-compatible database environment as well all in one
package, it makes sense to be able to connect back to the hosting RDBMS
instance from within your PHP application/script.
To ease this process, Virtuoso's PHP-hosting module adds support for a
parameter to identify the "local DSN". Normally there is a DSN configured
called "VOS" but in case that has been changed to "Local Virtuoso" for ex., or some other
instance should be used. There are parameters in php.ini that can be specified respectively:
[Virtuoso]
virtuoso.logging = On
virtuoso.local_dsn = VOS
virtuoso.allow_dba = 0
The `virtuoso.allow_dba' property controls whether the administrative dba
user can be used as the username to connect to the ODBC data-source; by
default, it cannot, as a security measure.
Using this in your application is simple. First, wherever you would
previously have had to compose an ODBC connection-string, you can now just
drop this function into place:
The results of the __virt_internal_dsn() function
may be configured through the Virtuoso Conductor:
* point your web-browser at http://localhost:8890/conductor/ (or hostname
as appropriate)
* log in as dba, and navigate to "web application server" and "Virtual
Domains and Directories"
* expand the relevant hostname (or default) and click `edit' on the
directory corresponding to the URL in which your PHP application resides
* Click "Edit"
* scroll down to set the VSP user
* choose an appropriate user as which your PHP application should run
The function verifies that the Virtual Directory has been properly configured
with a user valid for SQL logins and not disabled, else it logs a message and
returns FALSE.
*Permissions Note*: If you are deploying an application that runs as a specific user,
permission must be granted for it to access tables.
Additionally, for deploying an application package (eg as a VAD of your
own), you can export the virtual-directory specification and have it
create your endpoint, including specifying a user as which it should run,
all executable as SQL/PL from within your package.
-- Create and use the MYAPP schema
use MYAPP;
-- Create a user myapp
db.dba.user_create (
'myapp', -- Account name
uuid (), -- Random UUID as password
vector ('LOGIN_QUALIFIER', 'MYAPP',
'SQL_ENABLE', 1,
'DAV_ENABLE', 0,
'FULL_NAME', 'MYAPP Administrator'));
db.dba.vhost_remove (lpath=>'/myapp');
db.dba.vhost_define (
lpath=>'/myapp',
ppath=>'/testapp',
is_dav=>0,
is_brws=>0,
vsp_user=>'myapp',
def_page=>'myapp.php');
---+++The Pièce de Résistance
Finally, putting it all together, a simple sample PHP script: home-grown
build of PHP, dynamic RDF data (created using an RDF view above), accessed
using SPARQL over SQL, via ODBC using the
__virt_internal_dsn() function:
Please re-read the previous section "putting it all together", above, and note the requirements
for permissions to be granted on relevant tables to the user as which your PHP application will run.
grant select on rdf_quad to tim;
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>PHP ODBC test</title>
<style type="text/css">
body { padding: 1em; }
pre { padding: 0.3em; background-color: #e0e0e0; border: solid 1px silver }
</style>
</head>
<body>
<h1>Test PHP / ODBC / Virtuoso connection</h1>
<hr />
<p>The __virt_internal_dsn() function returns:</p>
<pre>
<?php
ini_set("odbc.default_cursortype", "0");
$con=odbc_connect(__virt_internal_dsn(), "", "");
if($con) {
printf("<p>Connected [%s].\n</p>\n", $con);
$query="sparql select distinct ?s ?p ?o from <http://localhost:8890/db>
where { ?s ?p ?o . } limit 100";
print "Executing query [$query]<br />\n";
$rs = odbc_exec($con, $query);
$err=odbc_errormsg($con);
print "Current error state: [$err]<br />\n";
print "Results:<br />\n";
odbc_result_all($rs, "border=2");
odbc_close($con);
} else {
print "<p>Failed to connect!</p>\n";
}
?>
?>
<hr />
</body>
</html>
This script can be downloaded here:
sparql-retrieve.php
Results:
The __virt_internal_dsn() function returns:
DSN=VOS;UID=tim;PWD=censored
Connected [Resource id #2].
Executing query [sparql select distinct ?s ?p ?o from <http://localhost:8890/db> where { ?s ?p ?o . } limit 100]
Current error state: []
Results:
| s | p | o |
|---|
| http://localhost:8890/DB/timtest/id/1#this | http://www.w3.org/1999/02/22-rdf-syntax-ns#type | http://localhost:8890/DB#timtest |
| http://localhost:8890/DB/timtest/id/2#this | http://www.w3.org/1999/02/22-rdf-syntax-ns#type | http://localhost:8890/DB#timtest |
| http://localhost:8890/DB/timtest/id/1#this | http://localhost:8890/DB#id | 1 |
| http://localhost:8890/DB/timtest/id/2#this | http://localhost:8890/DB#id | 2 |
|
![[RDF Data]](/fct/images/sw-rdf-blue.png)
![[cxml]](/fct/images/cxml_doc.png)
![[csv]](/fct/images/csv_doc.png)
![[text]](/fct/images/ntriples_doc.png)
![[turtle]](/fct/images/n3turtle_doc.png)
![[ld+json]](/fct/images/jsonld_doc.png)
![[rdf+json]](/fct/images/json_doc.png)
![[rdf+xml]](/fct/images/xml_doc.png)
![[atom+xml]](/fct/images/atom_doc.png)
![[html]](/fct/images/html_doc.png)