How to use inferencing with the sw_Sparql stored procedure and how to get the InferenceIndex for a specific ontology in the database

johndeu — Mon, 08 Dec 2008 23:22:48 GMT

It’s often very useful when creating custom SPARQL queries against the IMM Metadata Store using the sw_Sparql stored procedure to pull in some “inferred” metadata from the ontologies that you have imported. For example, you may have ingested a bunch of metadata into the IMM data table that stores the “facts” but you want to query back for information that is generated dynamically based on you ontology definitions.

One simple example of this is you may have saved a VideoItem in the database with it’s rdf:type set to imm:VideoItem, but you never provided the metadata to explain that this item is also derived from imm:MediaItem. That information is provided in the IMM core ontology. To write a query for that directly against the sw_sparql stored procedure in the database, you need to know two well known graph URI’s.

The first one is the URI to the IMM data graph which stores all of the known “facts". Note that the “IMM” in this URI is case sensitive!

http://schemas.microsoft.com/IMM/data

The next URI you will need is the one for the inferred metadata generated from your imported ontology.

If I execute the following query in SQL Server Management Studio against the IMMMetadata database, it will select all the VideoItems from the “facts” table as you can see in the FROM clause. If you have the Litware sample data installed, you should get some results back. If you look at the Litware rdf data, you will notice that we have set the type of these objects to VideoItem already, so the “facts” table contains their types.

     exec sw_Sparql '

    PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>

    PREFIX dii: <urn:mpeg:mpeg21:2002:01-DII-NS#>

    PREFIX did: <urn:mpeg:mpeg21:2002:02-DIDMODEL-NS#>

    PREFIX imm: <http://schemas.microsoft.com/imm/2.0/core/>

    SELECT ?s 

    FROM <http://schemas.microsoft.com/IMM/data>

    WHERE {  

        ?s rdf:type imm:VideoItem.

    }',

    1

If I execute this query, which is the same as above except now this time I am asking for a type that is in the IMM core Ontology, but not declared in the facts that I imported – it will return no results. Notice that the only change I made is the name of the type.

    exec sw_Sparql '

    PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>

    PREFIX dii: <urn:mpeg:mpeg21:2002:01-DII-NS#>

    PREFIX did: <urn:mpeg:mpeg21:2002:02-DIDMODEL-NS#>

    PREFIX imm: <http://schemas.microsoft.com/imm/2.0/core/>

    SELECT ?s 

    FROM <http://schemas.microsoft.com/IMM/data>

    WHERE {  

        ?s rdf:type imm:MediaItem.

    }',

    1

So, how do I get back these “inferred” types in a query. First we need to know the graph name that was generated for us when we imported our Ontology. IMM automatically creates an inference graph when you import the core and any custom ontology. We automatically add those inference graphs if you pass in the URI to to your ontology in the GetResource or Query methods on the web service.

In order to get back this information from the database you can execute the following SQL script which will return back a list of the known ontologies that are imported into IMM, as well as an ID that is used to identify their inference graph name.

    exec sw_sparql '

    SELECT ?s ?o 

    FROM <http://schemas.microsoft.com/IMM/ontology>

    WHERE { graph ?g { ?s <http://schemas.microsoft.com/imm/2.0/core/InferenceIndex> ?o. }}

    order by ?o',

    1

Now, we can rewrite the script above to add a extra FROM clause that uses this inference index to point to the correct inference graph.
Look at the results of the above query and locate the Ontology that you are interested in using. Append the InferenceIndex that is returned in column 2 of the results to the following URI “http://schemas.microsoft.com/IMM/inference_” and you will get the URI for that inference graph.

For example the results from my database contains the index number “8” for the IMM Core ontology, so my resulting graph URI would be “http://schemas.microsoft.com/IMM/inference_8”.

My new query with ontology inferencing enabled would then look like this:

    exec sw_Sparql '

    PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>

    PREFIX dii: <urn:mpeg:mpeg21:2002:01-DII-NS#>

    PREFIX did: <urn:mpeg:mpeg21:2002:02-DIDMODEL-NS#>

    PREFIX imm: <http://schemas.microsoft.com/imm/2.0/core/>

    SELECT ?s 

    FROM <http://schemas.microsoft.com/IMM/data>

    FROM <http://schemas.microsoft.com/IMM/inference_8>

    WHERE {  

        ?s rdf:type imm:MediaItem.

    }',

    1

If you execute this against the Litware sample metadata you will now get back the same (or more if you have other items that are derived from MediaItem) number of results as in the first query.

John Deutscher
Group Program Manager
Microsoft
johndeu@microsoft.com

Interactive Media Manager Blog : sw_Sparql

How to use inferencing with the sw_Sparql stored procedure and how to get the InferenceIndex for a specific ontology in the database