Number of Semantic Web Tools Passes 1000 for First Time; Many Other Changes

We have been maintaining Sweet Tools, AI3‘s listing of semantic Web and -related tools, for a bit over five years now. Though we had switched to a structWSF-based framework that allows us to update it on a more regular, incremental schedule [1], like all databases, the listing needs to be reviewed and cleaned up on a periodic basis. We have just completed the most recent cleaning and update. We are also now committing to do so on an annual basis.

Thus, this is the inaugural ‘State of Tooling for Semantic Technologies‘ report, and, boy, is it a humdinger. There have been more changes — and more important changes — in this past year than in all four previous years combined. I think it fair to say that semantic technology tooling is now reaching a mature state, the trends of which likely point to future changes as well.

In this past year more tools have been added, more tools have been dropped (or abandoned), and more tools have taken on a professional, sophisticated nature. Further, for the first time, the number of semantic technology and -related tools has passed 1000. This is remarkable, given that more tools have been abandoned or retired than ever before.

We first present our key findings and then overall statistics. We conclude with a discussion of observed trends and implications for the near term.

Key Findings

Some of the key findings from the 2011 State of Tooling for Semantic Technologies are:

• As of the date of this article, there are 1010 tools in the Sweet Tools listing, the first it has passed 1000 total tools
• A total of 158 new tools have been added to the listing in the last six months, an increase of 17%
• 75 tools have been abandoned or retired, the most removed at any period over the past five years
• A further 6%, or 55 tools, have been updated since the last listing
• Though open source has always been an important component of the listing, it now constitutes more than 80% of all listings; with dual licenses, open source availability is about 83%. Online systems contribute another 9%
• Key application areas for growth have been in SPARQL, ontology-related areas and linked data
• Java continues to dominate as the most important language.

Many of these points are elaborated below.

The Statistical Picture

The updated Sweet Tools listing now includes nearly 50 different tools categories. The most prevalent categories, each with over 6% of the total, are information extraction, general RDF tools, ontology tools, browser tools (RDF, OWL), and parsers or converters. The relative share by category is shown in this diagram (click to expand):

Since the last listing, the fastest growing categories have been SPARQL, linked data, knowledge bases and all things related to ontologies. The relative changes by tools category are shown in this figure:

Though it is true that some of this growth is the result of discovery, based on our own tool needs and investigations, we have also been monitoring this space for some time and serendipity is not a compelling explanation alone. Rather, I think that we are seeing both an increase in practical tools (such as for querying), plus the trends of linked data growth matched with greater sophistication in areas such as ontologies and the OWL language.

The languages these tools are written in have also been pretty constant over the past couple of years, with Java remaining dominant. Java has represented half of all tools in this space, which continues with the most recent tools as well (see below). More than a dozen programming or scripting languages have at least some share of the semantic tooling space (click to expand):

With only 160 new tools it is hard to draw firm trends, but it does appear that some languages (Haskell, XSLT) have fallen out of favor, while popularity has grown for Flash/Flex (from a small base), Python and Prolog (with the growth of logic tools):

PHP will likely continue to see some emphasis because of relations to many content management systems (WordPress, Drupal, etc.), though both Python and Ruby seem to be taking some market share in that area.

New Tools

The newest tools added to the listing show somewhat similar trends. Again, Java is the dominant language, but with much increased use of JavaScript and Python and Prolog:

The higher incidence of Prolog is likely due to the parallel increase in reasoners and inference engines associated with ontology (OWL) tools.

The increase in comprehensive tool suites and use of Eclipse as a development environment would appear to secure Java’s dominance for some time to come.

Trends and Observations

These dry statistics tend to mask the feel one gets when looking at most of the individual tools across the board. Older academic and government-funded project tools are finally getting cleaned out and abandoned. Those tools that remain have tended to get some version upgrades and improved Web sites to accompany them.

The general feel one gets with regard to semantic technology tooling at the close of 2011 has these noticeable trends:

• A three-tiered environment – the tools seem to segregate into: 1) a bottom tier of tools (largely) developed by individuals or small groups, now most often found on Google Code or Github; 2) a middle-tier of (largely) government-funded projects, sometimes with multiple developers, often older, but with no apparent driving force for ongoing improvements or commercialization; and 3) a top-tier of more professional and (often) commercially-oriented tools. The latter category is the most noticeable with respect to growth and impact
• Professionalism – the tools in the apparent top tiers feel to have more professionalism and better (and more attractive) packaging. This professionalism is especially true for the frameworks and composite applications. But, it also applies to many of the EU-funded projects from Europe, which has always been a huge source of new tool developments
• More complete toolsets – similarly, the upper levels of tools are oriented to pragmatic problems and problem-solving, which often means they embody multiple functions and more complete tooling environments. This category actually appears to be the most visible one exhibiting growth
• Changing nature of academic releases – yet, even the academic releases seem to be increasing in professionalism and completeness. Though in the lowest tier it is still possible to see cursory or experimental tool releases, newer academic releases (often) seem to be more strategically oriented and parts of broader programmatic emphases. Programs like AKSW from the University of Leipzig or the Freie Universität Berlin or Finland’s Semantic Computing Research Group (SeCo), among many others, tend to be exemplars of this trend
• Rise of commercial interests and enterprise adoption – the growing maturity of semantic technologies is also drawing commercial interest, and the incubation of new start-ups by academic and research institutions acts to reinforce the above trends. Promising projects and tools are now much more likely to be spun off as potential ventures, with accompanying better packaging, documentation and business models
• Multiple languages and applications – with this growing complexity and sophistication has also come more complicated apps, combining multiple languages and functions. In fact, for some time the Sweet Tools listing has been justifiably criticized by some as overly “simplifying” the space by classifying tools under (largely) single applications or single languages. By the 2012 survey, it will likely be necessary to better classify the tools using multiple assignments
• Google code over SourceForge for open source (and an increase in Github, as well) – virtually all projects on SourceForge now feel abandoned or less active. The largest source of open source projects in the semantic technology space is now clearly Google Code. Though of a smaller footprint today, we are also seeing many of the newer open source projects also gravitate to Github. Open source hosting environments are clearly in flux.

I have said this before, and been wrong about it before, but it is hard to see the tooling growth curve continue at its current slope into the future. I think we will see many individual tools spring up on the open source hosting sites like Google and Github, perhaps at relatively the same steady release rate. But, old projects I think will increasingly be abandoned and older projects will not tend to remain available for as long a time. While a relatively few established open source standards, like Solr and Jena, will be the exception, I think we will see shorter shelf lives for most open source tools moving forward. This will lead to a younger tools base than was the case five or more years ago.

I also think we will continue to see the dominance of open source. Proprietary software has increasingly been challenged in the enterprise space. And, especially in semantic technologies, we tend to see many open source tools that are as capable as proprietary ones, and generally more dynamic as well. The emphasis on open data in this environment also tends to favor open source.

Yet, despite the professionalism, sophistication and complexity trends, I do not yet see massive consolidation in the semantic technology space. While we are seeing a rapid maturation of tooling, I don’t think we have yet seen a similar maturation in revenue and business models. While notable semantic technology start-ups like Powerset and Siri have been acquired and are clear successes, these wins still remain much in the minority.

Ontology Modularization and Roles within an OSF Instance

For some time now, Structured Dynamics (SD) has been touting the unique advantages of ODapps, or ontology-driven applications [1]. ODapps are modular, generic software applications designed to operate in accordance with the specifications contained in one or more ontologies. The relationships and structure of the information driving these applications are based on the standard functions and roles of ontologies (namely as domain ontologies), as supplemented by UI and instruction sets and validations and rules. When these supplements are added to standard ontology functions, we collectively term them adaptive ontologies [2].

To further the discussion around ODapps, today we are publishing two new documents, using the semantic technology foundation of the open semantic framework. OSF is a comprehensive, open source stack of SD and external tools that provides a turnkey environment for enterprises to adopt semantic technologies and approaches. OSF has been designed from the ground up to be an ontology-driven application framework.

The first new document, posted on Fred Giasson’s blog, provides a detailed discussion of the dozen or so roles ontologies can play within an OSF installation. Fred’s document is geared more to specific properties and configurations useful to deploy this framework; that is, the “drivers” in an ODapp setting. The second new document — this one — is more of a broad overview of the modularization and architecture of the constituent ontologies that make up an OSF installation. Both documents have also been posted to SD’s open content TechWiki [3], which now has about 360 technical articles on understanding and implementing an OSF installation, importantly including its ontologies.

OSF Constituent Ontologies

As presently configured, an OSF installation may typically utilize most or all of the following internal ontologies:

• The SCO Ontology (Semantic Component Ontology)
• The WSF Ontology (Web Service Framework Ontology)
• The AGGR Ontology (Aggregation Ontology)
• The irON Ontology (Instance Record and Object Notation Ontology)
• One or more domain ontologies, to capture the concepts and relationships for the purposes of a given OSF installation, and
• Possibly UMBEL (optional) or other upper-level concept ontologies, used for linkages to external systems.

(Note: the internal wiki links to each of these ontologies also provides links to the actual ontology specifications on Github.)

Depending on the specific OSF installation, of course, multiple external ontologies may also be employed. Some of the common external ones used in an OSF installation are described by the external ontologies document on the TechWiki. These external ontologies are important — indeed essential in order to ensure linkage to the external world — but have little to do with internal OSF control structures. That is why the rest of this discussion is focused on internal ontologies only.

The OSF Ontologies Architecture

The actual relationships between these ontologies are shown in the following diagram. Note that the ontologies tend to cluster into two main areas:

1. Content (or domain) ontologies, which tend to embody more of the traditional ontology functions such as information interoperability. inferencing, reasoning and conceptual and knowledge capture of the applicable domain; and
2. Administrative ontologies, which govern internal application use and user interface interactions.

This ontology architecture supports the broader open semantic framework:

(click for full size)

The WSF ontology plays a special role in that it sets the overall permission and access rights to the other components and ontologies. The UMBEL ontology (or other upper-level ontologies that might be chosen) is also optional. Such vocabularies are included when interoperability with external applications or knowledge bases is desired.

Summary of OSF Roles

We can further disaggregate these ontology splits with respect to the specific dozen or so ontology roles discussed in Fred’s complementary piece on ontology roles in OSF. These dozen roles are shown by the rows with interactions marked for the various ontologies:

One of the unique aspects of adaptive ontologies is their added role in informing user interfaces and supporting specific semantic tools. Note, for example, the role of the content ontologies in informing interface displays, as well as their use in tagging concepts (via information extraction). These additional roles are the reason that these ontologies are shown as straddling both content and administrative functions in the first figure.

See Fred’s piece to learn more about these dozen roles.

Interactions Are More Complex than Arrows

Naturally, a simple drawn arrow between ontologies (first figure) or a checkmark on a matrix (table above) can hide important details of how these interactions between ontologies and components actually work. In an earlier article, we discussed how the whole workflow takes place between users and user interface selections affecting the types of data returned by those selections, and then the semantic components (widgets) used to display them. This example interaction is shown by the following animation:

(click for full size)

The blue nodes show the ontology interactions. These, in turn, instruct how the various components (yellow) and code (green) need to operate. These interactions are the essence of an ontology-driven app. The software is expressively designed to respond to specifications in the ontology(ies) used, and the ontologies themselves embrace some additional properties specific to driving those apps.

Possible Future Directions

ODapps are a relatively new paradigm, from which we continue to learn more about uses and potentials. We have wanted to write the first versions of these two new documents for some time, but have held off as we learned and exploited further the latent potentials in this design. As it stands, we see further potentials in this approach, and will therefore be likely adding new ontologies and capabilities to the general system for some time.

Some of the areas that look promising to us include:

• A generalized statistical ontology, especially as it can inform data displays in the semantic components
• Even more capable widgets in business intelligence (BI) uses, with a concomitant expansion of the vocabulary (predicates and classes) in some of the underlying ontologies
• More aggregation and summation functions supported by the AGGR ontology, and
• Still further improved permissions and access layers in the WSF ontology.

These potentials arise from the native power of the design basis for ontology-driven apps. Conceptually, the design is simplicity itself. Operationally, the system is extremely flexibile and robust. Strategically, it means that development and specification efforts can now move from coding and programmers to ontologies and the subject matter users who define and depend on them. With these advantages, who can argue with that?