Kingsley Uyi Idehen
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Virtuoso Chronicles from the Field: Nepomuk, KDE, and the quest for a sophisticated RDF DBMS.

For this particular user experience chronicle, I've simply inserted the content of Sebastian Trueg's post titled: What We Did Last Summer (And the Rest of 2009) – A Look Back Onto the Nepomuk Development Year ..., directly into this post, without any additional commentary or modification.

2009 is over. Yeah, sure, trueg, we know that, it has been over for a while now! Ok, ok, I am a bit late, but still I would like to get this one out - if only for my archive. So here goes.


Let’s start with the major topic of 2009 (and also the beginning of 2010): The new Nepomuk database backend: Virtuoso. Everybody who used Nepomuk had the same problems: you either used the sesame2 backend which depends on Java and steals all of your memory or you were stuck with Redland which had the worst performance and missed some SPARQL features making important parts of Nepomuk  like queries unusable. So more than a year ago I had the idea to use the one GPL’ed database server out there that supported RDF in a professional manner: OpenLink’s Virtuoso. It has all the features we need, has a very good performance, and scales up to dimensions we will probably never reach on the desktop (yeah, right, and 64k main memory will be enough forever!). So very early I started coding the necessary Soprano plugin which would talk to a locally running Virtuoso server through ODBC. But since I ran into tons of small problems (as always) and got sidetracked by other tasks I did not finish it right away. OpenLink, however, was very interested in the idea of their server being part of every KDE installation (why wouldn’t they ;)). So they not only introduced a lite-mode which makes Virtuoso suitable for the desktop but also helped in debugging all the problems that I had left. Many test runs, patches, and a Virtuoso 5.0.12 release later I could finally announce the Virtuoso integration as usable.

Then end of last year I dropped the support for sesame2 and redland. Virtuoso is now the only supported database backend. The reason is simple: Virtuoso is way more powerful than the rest - not only in terms of performance - and it is fully implemented in C(++) without any traces of Java. Maybe even more important is the integration of the full text index which makes the previously used CLucene index unnecessary. Thus, we can finally combine full text and graph queries in one SPARQL query. This results in a cleaner API and way faster return of  search results since there is no need to combine the results from several queries anymore. A direct result of that is the new Nepomuk Query API which I will discuss later.

So now the only thing I am waiting for is the first bugfix release of Virtuoso 6, i.e. 6.0.1 which will fix the bugs that make 6.0.0 fail with Nepomuk. Should be out any day now. :)

The Nepomuk Query API

Querying data in Nepomuk pre-KDE-4.4 could be done in one of two ways: 1. Use the very limited capabilities of the ResourceManager to list resources with certain properties or of a certain type; or 2. Write your own SPARQL query using ugly QString::arg replacements.

With the introduction of Virtuoso and its awesome power we can now do pretty much everything in one query. This allowed me to finally create a query API for KDE: Nepomuk::Query::Query and friends. I won’t go into much detail here since I did that before.

All in all you should remember one thing: whenever you think about writing your own SPARQL query in a KDE application - have a look at libnepomukquery. It is very likely that you can avoid the hassle of debugging a query by using the query API.

The first nice effect of the new API (apart from me using it all over the place obviously) is the new query interface in Dolphin. Internally it simply combines a bunch of Nepomuk::Query::Term objects into a Nepomuk::Query::AndTerm. All very readable and no ugly query strings.

Dolphin Search Panel in KDE SC 4.4

Shared Desktop Ontologies

An important part of the Nepomuk research project was the creation of a set of ontologies for describing desktop resources and their metadata. After the Xesam project under the umbrella of had been convinced to use RDF for describing file metadata they developed their own ontology. Thanks to Evgeny (phreedom) Egorochkin and Antonie Mylka both the Xesam ontology and the Nepomuk Information Elements Ontology were already very close in design. Thus, it was relatively easy to merge the two and be left with only one ontology to support. Since then not only KDE but also Strigi and Tracker are using the Nepomuk ontologies.

At the Gran Canaria Desktop Summit I met some of the guys from Tracker and we tried to come up with a plan to create a joint project to maintain the ontologies. This got off to a rough start as nobody really felt responsible. So I simply took the initiative and released the shared-desktop-ontologies version 0.1 in November 2009. The result was a s***-load of hate-mails and bug reports due to me breaking KDE build. But in the end it was worth it. Now the package is established and other projects can start to pick it up to create data compatible to the Nepomuk system and Tracker.

Today the ontologies (and the shared-desktop-ontologies package) are maintained in the Oscaf project at Sourceforge. The situation is far from perfect but it is a good start. If you need specific properties in the ontologies or are thinking about creating one for your own application - come and join us in the bug tracker

Timeline KIO Slave

It was at the Akonadi meeting that Will Stephenson and myself got into talking about mimicking some Zeitgeist functionality through Nepomuk. Basically it meant gathering some data when opening and when saving files. We quickly came up with a hacky patch for KIO and KFileDialog which covered most cases and allowed us to track when a file was modified and by which application. This little experiment did not leave that state though (it will, however, this year) but another one did: Zeitgeist also provides a fuse filesystem which allows to browse the files by modification dates. Well, whatever fuse can do, KIO can do as well. Introducing the timeline:/ KIO slave which gives a calendar view onto your files.

Tips And Tricks

Well, I thought I would mention the Tips And Tricks section I wrote for the techbase. It might not be a big deal but I think it contains some valuable information in case you are using Nepomuk as a developer.

Google Summer Of Code 2009

This time around I had the privilege to mentor two students in the Google Summer of Code. Alessandro Sivieri and Adam Kidder did outstanding work on Improved Virtual Folders and the Smart File Dialog.

Adam’s work lead me to some heavy improvements in the Nepomuk KIO slaves myself which I only finished this week (more details on that coming up). Alessandro continued his work on faceted file browsing in KDE and created:


Alessandro is following up on his work to make faceted file browsing a reality in 2010 (and KDE SC 4.5). Since it was too late to get faceted browsing into KDE SC 4.4 he is working on Sembrowser, a stand-alone faceted file browser which will be the grounds for experiments until the code is merged into Dolphin.

Faceted Browsing in KDE with Sembrowser

Nepomuk Workshops

In 2009 I organized the first Nepomuk workshop in Freiburg, Germany. And also the second one. While I reported properly on the first one I still owe a summary for the second one. I will get around to that - sooner or later. ;)

CMake Magic

Soprano gives us a nice command line tool to create a C++ namespace from an ontology file: onto2vocabularyclass. It produces nice convenience namespaces like Soprano::Vocabulary::NAO. Nepomuk adds another tool named nepomuk-rcgen. Both were a bit clumsy to use before. Now we have nice cmake macros which make it very simple to use both.

See the techbase article on how to use the new macros.


Without my knowledge (imagine that!) Andrew Lake created an amazing new media player named Bangarang - a Jamaican word for noise, chaos or disorder. This player is Nepomuk-enabled in the sense that it has a media library which lets you browse your media files based on the Nepomuk data. It remembers the number of times a song or a video has been played and when it was played last. It allows to add detail such as the TV series name, season, episode number, or actors that are in the video - all through Nepomuk (I hope we will soon get tvdb integration).

Edit metadata directly in Bangarang

Dolphin showing TV episode metadata created by Bangarang

And of course searching for it works, too...

And it is pretty, too...

I am especially excited about this since finally applications not written or mentored by me start contributing Nepomuk data.

Gran Canaria Desktop Summit

2009 was also the year of the first Gnome-KDE joint-conference. Let me make a bulletin for completeness and refer to my previous blog post reporting on my experiences on the island.

Well, that was by far not all I did in 2009 but I think I covered most of the important topics. And after all it is ‘just a blog entry’ - there is no need for completeness. Thanks for reading.

# PermaLink Comments [0]
01/28/2010 11:14 GMT-0500 Modified: 02/01/2010 09:02 GMT-0500
New ADO.NET 3.x Provider for Virtuoso Released (Update 2)

I am pleased to announce the immediate availability of the Virtuoso ADO.NET 3.5 data provider for Microsoft's .NET platform.

What is it?

A data access driver/provider that provides conceptual entity oriented access to RDBMS data managed by Virtuoso. Naturally, it also uses Virtuoso's in-built virtual / federated database layer to provide access to ODBC and JDBC accessible RDBMS engines such as: Oracle (7.x to latest), SQL Server (4.2 to latest), Sybase, IBM Informix (5.x to latest), IBM DB2, Ingres (6.x to latest), Progress (7.x to OpenEdge), MySQL, PostgreSQL, Firebird, and others using our ODBC or JDBC bridge drivers.



It delivers an Entity-Attribute-Value + Classes & Relationships model over disparate data sources that are materialized as .NET Entity Framework Objects, which are then consumable via ADO.NET Data Object Services, LINQ for Entities, and other ADO.NET data consumers.

The provider is fully integrated into Visual Studio 2008 and delivers the same "ease of use" offered by Microsoft's own SQL Server provider, but across Virtuoso, Oracle, Sybase, DB2, Informix, Ingres, Progress (OpenEdge), MySQL, PostgreSQL, Firebird, and others. The same benefits also apply uniformly to Entity Frameworks compatibility.

Bearing in mind that Virtuoso is a multi-model (hybrid) data manager, this also implies that you can use .NET Entity Frameworks against all data managed by Virtuoso. Remember, Virtuoso's SQL channel is a conduit to Virtuoso's core; thus, RDF (courtesy of SPASQL as already implemented re. Jena/Sesame/Redland providers), XML, and other data forms stored in Virtuoso also become accessible via .NET's Entity Frameworks.


You can choose which entity oriented data access model works best for you: RDF Linked Data & SPARQL or .NET Entity Frameworks & Entity SQL. Either way, Virtuoso delivers a commercial grade, high-performance, secure, and scalable solution.

How do I use it?

Simply follow one of guides below:

Note: When working with external or 3rd party databases, simply use the Virtuoso Conductor to link the external data source into Virtuoso. Once linked, the remote tables will simply be treated as though they are native Virtuoso tables leaving the virtual database engine to handle the rest. This is similar to the role the Microsoft JET engine played in the early days of ODBC, so if you've ever linked an ODBC data source into Microsoft Access, you are ready to do the same using Virtuoso.


# PermaLink Comments [0]
01/08/2009 04:36 GMT-0500 Modified: 01/08/2009 09:12 GMT-0500
Virtuoso Universal Server 5.0.4 Release Details

We've just released version 5.0.4 of the Virtuoso Universal Server platform for SQL, XML, and RDF. The new release includes the following enhancements:

Web Server:

    - HTTP 1.1 compliant Transparent content-negotiation in URL-rewrite rules for Linked Data Deployment.

RDF Data Management:

    - New providers for the Jena, Sesame and Redland frameworks
    - support for SPARQL INSERT and UPDATE via HTTP POST
    - New SPARQL-BI extenstions that make Business Intelligence feasible via SPARQL
    - new "rdf_sink" folder for handling HTTP PUTs into WebDAV that automatically sync with Quad Store.
    - There are new Sponger (RDFizer) cartridges that map Amazon book-search results to the Biliographic Ontology, supports production of Linked Data from OAI, XBRL, and Yahoo finance data sources.
    - HTTPS protocol support added to Sponger
    - performance optimizations for SPARQL `DESCRIBE' and `CONSTRUCT', alongside general performance enhancements for RDF data set loading.

Core DBMS Engine:

    - PHP hosting a module re-implemented as a Virtuoso plugin inline with otherlanguage hosting modules
    - improved deadlock condtion management
    - enhanced POP and FTP server side protocol implementations that allow larger data transfers.

Additional Information

# PermaLink Comments [1]
02/04/2008 14:25 GMT-0500 Modified: 02/04/2008 20:30 GMT-0500
W3C's SPARQLing Data Access Ingenuity

The W3C officially unveiled the SPARQL Query Language today via a press release titled: W3C Opens Data on the Web with SPARQL.

What is SPARQL?

A query language for the burgeoning Structured & Linked Data Web (aka Semantic Web / Giant Global Graph). Like SQL, for the Relational Data Model, it provides a query language for the Graph based RDF Data Model.

It's also a REST or SOAP based Web Service that exposes SPARQL access to RDF Data via an endpoint.

In addition, it's also a Query Results Serialization format that includes XML and JSON support.

Why is it Important?

It brings important clarity to the notion of the "Web as a Database" by transforming existing Web Sites, Portals, and Web Services into bona fide corpus of Mesh-able (rather than Mash-able) Data Sources. For instance, you can perform queries that join one or more of the aforementioned data sources in exactly the same manner (albeit different syntax) as you would one or more SQL Tables.


-- SPARQL equivalent of SQL SELECT * against my personal data space hosted FOAF file

FROM <> 
WHERE {?s ?p ?o}

-- SPARQL against my social network -- Note: My SPARQL will be beamed across all of contacts in the social networks of my contacts as long as they are all HTTP URI based within each data space

PREFIX foaf: <>
WHERE {?s a foaf:Person; foaf:knows ?Person}

Note: you can use the basic SPARQL Endpoint, SPARQL Query By Example, or SPARQL Query Builder Demo tool to experiment with the demonstration queries above.

How Do I use It?

SPARQL is implemented by RDF Data Management Systems (Triple or Quad Stores) just as SQL is implemented by Relational Database Management Systems. The aforementioned data management systems will typically expose SPARQL access via a SPARQL endpoint.

Where are it's implementations?

A SPARQL implementors Testimonial page accompanies the SPARQL press release. In addition the is a growing collection of implementations on the ESW Wiki Page for SPARQL compliant RDF Triple & Quad Stores.

Is this really a big deal?

Yes! SPARQL facilitates an unobtrusive manifestation of a Linked Data Web by way of natural extension of the existing Document Web i.e these Web enclaves co-exist in symbiotic fashion.

As DBpedia very clearly demonstrates, Linked Data makes the Semantic Web demonstrable and much easier to comprehend. Without SPARQL there would be no mechanism for Linked Data deployment, and without Linked Data there is no mechanism for Beaming Queries (directly or indirectly) across the Giant Global Graph of data hosted by Social Networks, Shard Bookmarks Services, Weblogs, Wikis, RSS/Atom/OPML feeds, Photo Galleries and other Web accessible Data Sources (Data Spaces).

Related items

    Detailed SPARQL Query Examples using SIOC Data Spaces
# PermaLink Comments [0]
01/15/2008 22:58 GMT-0500 Modified: 01/17/2008 15:41 GMT-0500
OpenLink Ajax Toolkit (OAT) 2.6 Released!

OpenLink Software are pleased to announce release 2.6 of the OpenLink AJAX Toolkit (OAT).

New Semantic Data Web related features and enhancements include:

    * A Javascript-based Fresnel processor enabling declarative RDF-based display templates for RDF Data Sources
    * An XSLT template for generating HTML pages from the Fresnel processor's XML output
    * Enhanced Javascript-based N3/Turtle parser
Related Items:
# PermaLink Comments [0]
08/01/2007 18:34 GMT-0500 Modified: 08/01/2007 14:49 GMT-0500
Enterprise 0.0, Linked Data, and Semantic Data Web

Last week we officially released Virtuoso 5.0.1 (in Commercial and Open Source Editions). The press release provided us with an official mechanism and timestamp for the current Virtuoso feature set.

A vital component of the new Virtuoso release is the finalization of our SQL to RDF mapping functionality -- enabling the declarative mapping of SQL Data to RDF. Additional technical insight covering other new features (delivered and pending) is provided by Orri Erling, as part of a series of post-Banff posts.

Why is SQL to RDF Mapping a Big Deal?

A majority of the world's data (especially in the enterprise realm) resides in SQL Databases. In addition, Open Access to the data residing in said databases remains the biggest challenge to enterprises for the following reasons:

  1. SQL Data Sources are inherently heterogeneous because they are acquired with business applications that are in many cases inextricably bound to a particular DBMS engine
  2. Data is predictably dirty
  3. DBMS vendors ultimately hold the data captive and have traditionally resisted data access standards such as ODBC (*trust me they have, just look at the unprecedented bad press associated with ODBC the only truly platform independent data access API. Then look at how this bad press arose..*)

Enterprises have known from the beginning of modern corporate times that data access, discovery, and manipulation capabilities are inextricably linked to the "Real-time Enterprise" nirvana (hence my use of 0.0 before this becomes 3.0).

In my experience, as someone whose operated in the data access and data integration realms since the late '80s, I've painfully observed enterprises pursue, but unsuccessfully attain, full control over enterprise data (the prized asset of any organization) such that data-, information-, knowledge-workers are just a click away from commencing coherent platform and database independent data drill-downs and/or discovery that transcend intranet, internet, and extranet boundaries -- serendipitous interaction with relevant data, without compromise!

Okay, situation analysis done, we move on..

At our most recent (12th June) monthly Semantic Web Gathering, I unveiled to TimBL and a host of other attendees a simple, but powerful, demonstration of how Linked Data, as an aspect of the Semantic Data Web, can be applied to enterprise data integration challenges.

Actual SQL to RDF Mapping Demo / Experiment


A SQL Schema can be effectively mapped declaratively to RDF such that SQL Rows morph into RDF Instance Data (Entity Sets) based on the Concepts & Properties defined in a Concrete Conceptual Data Model oriented Data Dictionary (RDF Schema and/or OWL Ontology). In addition, the solution must demonstrate how "Linked Data in the Web" is completely different from "Data on the Web" or "Linked Data on the Web" (btw - Tom Heath eloquently unleashed this point in his recent podcast interview with Talis).


An Ontology - in this case we simply derived the Northwind Ontology from the XML Schema based CSDL (Conceptual Schema Definition Language) used by Microsoft's public Astoria demo (specifically the Northwind Data Services demo). SQL Database Schema - Northwind (comes bundled with ACCESS, SQL Server, and Virtuoso) comprised of tables such as: Customer, Employee, Product, Category, Supplier, Shipper etc. OpenLink Virtuoso - SQL DBMS Engine (although this could have been any ODBC or JDBC accessible Database), SQL-RDF Metaschema Language, HTTP URL-rewriter, WebDAV Engine, and DBMS hosted XSLT processor Client Tools - iSPARQL Query Builder, RDF Browser (which could also have been Tabulator or DISCO or a standard Web Browser)

Experiment / Demo

  1. Declaratively map the Northwind SQL Schema to RDF using the Virtuoso Meta Schema Language (see: Virtuoso PL based Northwind_SQL_RDF script)
  2. Start browsing the data by clicking on the URIs that represent the RDF Data Model Entities resulting from the SQL to RDF Mapping


  1. Via a single Data Link click I was able to obtain specific information about the Customer represented by the URI "ALFKI" (act of URI Dereferencing as you would an Object ID in an Object or Object-Relational Database)
  2. Via a Dynamic Data Page I was able to explore all the entity relationships or specific entity data (i.e Exploratory or Entity specific dereferencing) in the Northwind Data Space
  3. I was able to perform similar exploration (as per item 2) using our OpenLink Browser.


The vision of data, information, or knowledge at your fingertips is nigh! Thanks to the infrastructure provided by the Semantic Data Web (URIs, RDF Data Model, variety of RDF Serialization Formats[1][2][3], and Shared Data Dictionaries / Schemas / Ontologies [1][2][3][4][5]) it's now possible to Virtualize enterprise data from the Physical Storage Level, through the Logical Data Management Levels (Relational), up to a Concrete Conceptual Model (Graph) without operating system, development environment or framework, or database engine lock-in.

Next Steps

We produce a shared ontology for the CRM and Business Reporting Domains. I hope this experiment clarifies how this is quite achievable by converting XML Schemas to RDF Data Dictionaries (RDF Schemas or Ontologies). Stay tuned :-)

Also watch TimBL amplify and articulate Linked Data value in a recent interview.

Other Related Matters

To deliver a mechanism that facilitates the crystallization of this reality is a contribution of boundless magnitude (as we shall all see in due course). Thus, it is easy to understand why even "her majesty", the queen of England, simply had to get in on the act and appoint TimBL to the "British Order of Merit" :-)

Note: All of the demos above now work with IE & Safari (a "remember what Virtuoso is epiphany") by simply putting Virtuoso's DBMS hosted XSLT engine to use :-) This also applies to my earlier collection of demos from the Hello Data Web and other Data Web & Linked Data related demo style posts.

# PermaLink Comments [1]
06/14/2007 15:28 GMT-0500 Modified: 02/04/2008 23:19 GMT-0500
"Free" Databases: Express vs. Open-Source RDBMSs

Very detailed and insightful peek into the state of affairs re. database engines (Open & Closed Source).

I added the missing piece regarding the "Virtuoso Conductor" (the Web based Admin UI for Virtuoso) to the original post below. I also added a link to our live SPARQL Demo so that anyone interested can start playing around with SPARQL and SPARQL integrated into SQL right away.

Another good thing about this post is the vast amount of valuable links that it contains. To really appreciate this point simply visit my Linkblog (excuse the current layout :-) - a Tab if you come in via the front door of this Data Space (what I used to call My Weblog Home Page).

"Free" Databases: Express vs. Open-Source RDBMSs: "Open-source relational database management systems (RDBMSs) are gaining IT mindshare at a rapid pace. As an example, BusinessWeek's February 6, 2006 ' Taking On the Database Giants ' article asks 'Can open-source upstarts compete with Oracle, IBM, and Microsoft?' and then provides the answer: 'It's an uphill battle, but customers are starting to look at the alternatives.'

There's no shortage of open-source alternatives to look at. The BusinessWeek article concentrates on MySQL, which BW says 'is trying to be the Ikea of the database world: cheap, needs some assembly, but has a sleek, modern design and does the job.' The article also discusses Postgre[SQL] and Ingres, as well as EnterpriseDB, an Oracle clone created from PostgreSQL code*. Sun includes PostgreSQL with Solaris 10 and, as of April 6, 2006, with Solaris Express.**

*Frank Batten, Jr., the investor who originally funded Red Hat, invested a reported $16 million into Great Bridge with the hope of making a business out of providing paid support to PostgreSQL users. Great Bridge stayed in business only 18 months , having missed an opportunity to sell the business to Red Hat and finding that selling $50,000-per-year support packages for an open-source database wasn't easy. As Batten concluded, 'We could not get customers to pay us big dollars for support contracts.' Perhaps EnterpriseDB will be more successful with a choice of $5,000, $3,000, or $1,000 annual support subscriptions .

**Interestingly, Oracle announced in November 2005 that Solaris 10 is 'its preferred development and deployment platform for most x64 architectures, including x64 (x86, 64-bit) AMD Opteron and Intel Xeon processor-based systems and Sun's UltraSPARC(R)-based systems.'

There is a surfeit of reviews of current MySQL, PostgreSQL and—to a lesser extent—Ingres implementations. These three open-source RDBMSs come with their own or third-party management tools. These systems compete against free versions of commercial (proprietary) databases: SQL Server 2005 Express Edition (and its MSDE 2000 and 1.0 predecessors), Oracle Database 10g Express Edition, IBM DB2 Express-C, and Sybase ASE Express Edition for Linux where database size and processor count limitations aren't important. Click here for a summary of recent InfoWorld reviews of the full versions of these four databases plus MySQL, which should be valid for Express editions also. The FTPOnline Special Report article, 'Microsoft SQL Server Turns 17,' that contains the preceding table is here (requires registration.)

SQL Server 2005 Express Edition SP-1 Advanced Features

SQL Server 2005 Express Edition with Advanced Features enhances SQL Server 2005 Express Edition (SQL Express or SSX) dramatically, so it deserves special treatment here. SQL Express gains full text indexing and now supports SQL Server Reporting Services (SSRS) on the local SSX instance. The SP-1 with Advanced Features setup package, which Microsoft released on April 18, 2006, installs the release version of SQL Server Management Studio Express (SSMSE) and the full version of Business Intelligence Development Studio (BIDS) for designing and editing SSRS reports. My 'Install SP-1 for SQL Server 2005 and Express' article for FTPOnline's SQL Server Special Report provides detailed, illustrated installation instructions for and related information about the release version of SP-1. SP-1 makes SSX the most capable of all currently available Express editions of commercial RDBMSs for Windows.

OpenLink Software's Virtuoso Open-Source Edition

OpenLink Software announced an open-source version of it's Virtuoso Universal Server commercial DBMS on April 11, 2006. On the initial date of this post, May 2, 2006, Virtuoso Open-Source Edition (VOS) was virtually under the radar as an open-source product. According to this press release, the new edition includes:

  • SPARQL compliant RDF Triple Store
  • SQL-200n Object-Relational Database Engine (SQL, XML, and Free Text)
  • Integrated BPEL Server and Enterprise Service Bus
  • WebDAV and Native File Server
  • Web Application Server that supports PHP, Perl, Python, ASP.NET, JSP, etc.
  • Runtime Hosting for Microsoft .NET, Mono, and Java
VOS only lacks the virtual server and replication features that are offered by the commercial edition. VOS includes a Web-based administration tool called the "Virtuoso Conductor" According to Kingsley Idehen's Weblog, 'The Virtuoso build scripts have been successfully tested on Mac OS X (Universal Binary Target), Linux, FreeBSD, and Solaris (AIX, HP-UX, and True64 UNIX will follow soon). A Windows Visual Studio project file is also in the works (ETA some time this week).'

InfoWorld's Jon Udell has tracked Virtuoso's progress since 2002, with an additional article in 2003 and a one-hour podcast with Kingsley Idehen on April 26, 2006. A major talking point for Virtuoso is its support for Atom 0.3 syndication and publication, Atom 1.0 syndication and (forthcoming) publication, and future support for Google's GData protocol, as mentioned in this Idehen post. Yahoo!'s Jeremy Zawodny points out that the 'fingerprints' of Adam Bosworth, Google's VP of Engineering and the primary force behind the development of Microsoft Access, 'are all over GData.' Click here to display a list of all OakLeaf posts that mention Adam Bosworth.

One application for the GData protocol is querying and updating the Google Base database independently of the Google Web client, as mentioned by Jeremy: 'It's not about building an easier onramp to Google Base. ... Well, it is. But, again, that's the small stuff.' Click here for a list of posts about my experiences with Google Base. Watch for a future OakLeaf post on the subject as the GData APIs gain ground.

Open-Source and Free Embedded Database Contenders

Open-source and free embedded SQL databases are gaining importance as the number and types of mobile devices and OSs proliferate. Embedded databases usually consist of Java classes or Windows DLLs that are designed to minimize file size and memory consumption. Embedded databases avoid the installation hassles, heavy resource usage and maintenance cost associated with client/server RDBMSs that run as an operating system service.

Andrew Hudson's December 2005 'Open Source databases rounded up and rodeoed' review for The Enquirer provides brief descriptions of one commercial and eight open source database purveyors/products: Sleepycat, MySQL, PostgreSQL, Ingres, InnoBase, Firebird, IBM Cloudscape (a.k.a, Derby), Genezzo, and Oracle. Oracle Sleepycat* isn't an SQL Database, Oracle InnoDB* is an OEM database engine that's used by MySQL, and Genezzo is a multi-user, multi-server distributed database engine written in Perl. These special-purpose databases are beyond the scope of this post.

* Oracle purchased Sleepycat Software, Inc. in February 2006 and purchased Innobase OY in October 2005 . The press release states: 'Oracle intends to continue developing the InnoDB technology and expand our commitment to open source software.'

Derby is an open-source release by the Apache Software Foundation of the Cloudscape Java-based database that IBM acquired when it bought Informix in 2001. IBM offers a commercial release of Derby as IBM Cloudscape 10.1. Derby is a Java class library that has a relatively light footprint (2 MB), which make it suitable for client/server synchronization with the IBM DB2 Everyplace Sync Server in mobile applications. The IBM DB2 Everyplace Express Edition isn't open source or free*, so it doesn't qualify for this post. The same is true for the corresponding Sybase SQL Anywhere components.**

* IBM DB2 Everyplace Express Edition with synchronization costs $379 per server (up to two processors) and $79 per user. DB2 Everyplace Database Edition (without DB2 synchronization) is $49 per user. (Prices are based on those when IBM announced version 8 in November 2003.)

** Sybase's iAnywhere subsidiary calls SQL Anywhere 'the industry's leading mobile database.' A Sybase SQL Anywhere Personal DB seat license with synchronization to SQL Anywhere Server is $119; the cost without synchronization wasn't available from the Sybase Web site. Sybase SQL Anywhere and IBM DB2 Everyplace perform similar replication functions.

Sun's Java DB, another commercial version of Derby, comes with the Solaris Enterprise Edition, which bundles Solaris 10, the Java Enterprise System, developer tools, desktop infrastructure and N1 management software. A recent Between the Lines blog entry by ZDNet's David Berlind waxes enthusiastic over the use of Java DB embedded in a browser to provide offline persistence. RedMonk analyst James Governor and eWeek's Lisa Vaas wrote about the use of Java DB as a local data store when Tim Bray announced Sun's Derby derivative and Francois Orsini demonstrated Java DB embedded in the Firefox browser at the ApacheCon 2005 conference.

Firebird is derived from Borland's InterBase 6.0 code, the first commercial relational database management system (RDBMS) to be released as open source. Firebird has excellent support for SQL-92 and comes in three versions: Classic, SuperServer and Embedded for Windows, Linux, Solaris, HP-UX, FreeBSD and MacOS X. The embedded version has a 1.4-MB footprint. Release Candidate 1 for Firebird 2.0 became available on March 30, 2006 and is a major improvement over earlier versions. Borland continues to promote InterBase, now at version 7.5, as a small-footprint, embedded database with commercial Server and Client licenses.

SQLite is a featherweight C library for an embedded database that implements most SQL-92 entry- and transitional-level requirements (some through the JDBC driver) and supports transactions within a tiny 250-KB code footprint. Wrappers support a multitude of languages and operating systems, including Windows CE, SmartPhone, Windows Mobile, and Win32. SQLite's primary SQL-92 limitations are lack of nested transactions, inability to alter a table design once committed (other than with RENAME TABLE and ADD COLUMN operations), and foreign-key constraints. SQLite provides read-only views, triggers, and 256-bit encryption of database files. A downside is the the entire database file is locked when while a transaction is in progress. SQLite uses file access permissions in lieu of GRANT and REVOKE commands. Using SQLite involves no license; its code is entirely in the public domain.

The Mozilla Foundation's Unified Storage wiki says this about SQLite: 'SQLite will be the back end for the unified store [for Firefox]. Because it implements a SQL engine, we get querying 'for free', without having to invent our own query language or query execution system. Its code-size footprint is moderate (250k), but it will hopefully simplify much existing code so that the net code-size change should be smaller. It has exceptional performance, and supports concurrent access to the database. Finally, it is released into the public domain, meaning that we will have no licensing issues.'

Vieka Technology, Inc.'s eSQL 2.11 is a port of SQLite to Windows Mobile (Pocket PC and Smartphone) and Win32, and includes development tools for Windows devices and PCs, as well as a .NET native data provider. A conventional ODBC driver also is available. eSQL for Windows (Win32) is free for personal and commercial use; eSQL for Windows Mobile requires a license for commercial (for-profit or business) use.

HSQLDB isn't on most reviewers' radar, which is surprising because it's the default database for (OOo) 2.0's Base suite member. HSQLDB is an open-source (BSD license) Java dembedded database engine based on Thomas Mueller's original Hypersonic SQL Project. Using OOo's Base feature requires installing the Java 2.0 Runtime Engine (which is not open-source) or the presence of an alternative open-source engine, such as Kaffe. My prior posts about OOo Base and HSQLDB are here, here and here.

The HSQLDB 1.8.0 documentation on SourceForge states the following regarding SQL-92 and later conformance:

HSQLDB 1.8.0 supports the dialect of SQL defined by SQL standards 92, 99 and 2003. This means where a feature of the standard is supported, e.g. left outer join, the syntax is that specified by the standard text. Many features of SQL92 and 99 up to Advanced Level are supported and here is support for most of SQL 2003 Foundation and several optional features of this standard. However, certain features of the Standards are not supported so no claim is made for full support of any level of the standards.

Other less well-known embedded databases designed for or suited to mobile deployment are Mimer SQL Mobile and VistaDB 2.1 . Neither product is open-source and require paid licensing; VistaDB requires a small up-front payment by developers but offers royalty-free distribution.

Java DB, Firebird embedded, SQLite and eSQL 2.11 are contenders for lightweight PC and mobile device database projects that aren't Windows-only.

SQL Server 2005 Everywhere

If you're a Windows developer, SQL Server Mobile is the logical embedded database choice for mobile applications for Pocket PCs and Smartphones. Microsoft's April 19, 2006 press release delivered the news that SQL Server 2005 Mobile Editon (SQL Mobile or SSM) would gain a big brother—SQL Server 2005 Everywhere Edition.

Currently, the SSM client is licensed (at no charge) to run in production on devices with Windows CE 5.0, Windows Mobile 2003 for Pocket PC or Windows Mobile 5.0, or on PCs with Windows XP Tablet Edition only. SSM also is licensed for development purposes on PCs running Visual Studio 2005. Smart Device replication with SQL Server 2000 SP3 and later databases has been the most common application so far for SSM.

By the end of 2006, Microsoft will license SSE for use on all PCs running any Win32 version or the preceding device OSs. A version of SQL Server Management Studio Express (SSMSE)—updated to support SSE—is expected to release by the end of the year. These features will qualify SSE as the universal embedded database for Windows client and smart-device applications.

For more details on SSE, read John Galloway's April 11, 2006 blog post and my 'SQL Server 2005 Mobile Goes Everywhere' article for the FTPOnline Special Report on SQL Server."

(Via OakLeaf Systems.)

# PermaLink Comments [1]
05/05/2006 16:02 GMT-0500 Modified: 07/21/2006 07:21 GMT-0500
Solutions to allow XMLHttpRequest to talk to external services

Solutions to allow XMLHttpRequest to talk to external services: "

Over on they published Fixing AJAX: XmlHttpRequest Considered Harmful.

This article discusses a few ways to get around the security constraints that we have to live with in the browsers theses days, in particular, only being able to talk to your domain via XHR.

The article walks you through three potential solutions:

  1. Application proxies. Write an application in your favorite programming language that sits on your server, responds to XMLHttpRequests from users, makes the web service call, and sends the data back to users.
  2. Apache proxy. Adjust your Apache web server configuration so that XMLHttpRequests can be invisibly re-routed from your server to the target web service domain.
  3. Script tag hack with application proxy (doesn't use XMLHttpRequest at all). Use the HTML script tag to make a request to an application proxy (see #1 above) that returns your data wrapped in JavaScript. This approach is also known as On-Demand JavaScript.

I can't wait for Trusted Relationships within the browser - server infrastructure.

With respect to Apache proxies, these things are priceless. I recently talked about them in relation to Migrating data centers with zero downtime.

What do you guys think about this general issue? Have you come up with any interesting solutions? Any ideas on how we can keep security, yet give us the freedom that we want?

(Via Ajaxian Blog.)

Well here is what I think (actually know):

Our Virtuoso Universal Server has been sitting waiting to deliver this for years (for the record see the Virtuoso 2000 Press Release). Virtuoso can proxy for disparate data sources and expose disparate data as Well-Formed XML using an array of vocabularies (you experience this SQL-XML integration on the fly every time you interact with various elements of my public blog).

Virtuoso has always been able to expose Application Logic as SOAP and/or RESTful/RESTian style XML Web Services. This blog's search page is a simple demo of this capability.

Virtuoso is basically a Junction Box / Aggregator / Proxy for disparate Data, Applications, Services, and BPEL compliant business processes. AJAX clients talk to this single multi-purpose server which basically acts as a conduit to content/data, services, and processes (which are composite services).

BTW - there is a lot more, but for now, thou shall have to seek in order to find :-)

# PermaLink Comments [1]
11/11/2005 21:01 GMT-0500 Modified: 07/21/2006 07:23 GMT-0500
Gates touts the merits of blogs in speech to CEOs
Gates touts the merits of blogs in speech to CEOs Bill Gates didn't announce plans for his own Web log yesterday, but in a speech to top corporate executives, he extolled the virtues of the online journals and related technologies.
# PermaLink Comments [0]
05/21/2004 16:16 GMT-0500 Modified: 06/22/2006 08:56 GMT-0500
Search Beyond Google

Search Beyond Google

Google has a large lead over its rivals in U.S. audience share, accounting for 77 percent of all searches in August 2003 (including searches conducted at AOL and Yahoo!, which used the Google search engine). But in the search industry, innovation is a wild card. In 1999, you could have said that AltaVista had pretty much finished off the search market,notes Whit Andrews, a research director at technology advisory firm Gartner. In 1997, it was Inktomi. In 1995, it was Yahoo!. You never know in the search business when there?s somebody down the street who is going to make you look like yesterday's news.

Good article on the future of search engines. One that caught my eye was Mooter; I'll be watching that one closely. [via Lockergnome's Technology News]

Great piece! I took a quick look at Mooter, and I was very impressed. I certainly remember the internal emails that brought AltaVista, AllTheWeb, and eventually Google to my attention. Of course there will be search beyond Google, that's what makes us human (our

# PermaLink Comments [0]
02/17/2004 12:59 GMT-0500 Modified: 06/22/2006 08:56 GMT-0500
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