SPARQL 1.1 Status

1.1
What’s coming and what might be coming?
October, 2009
Latest at http://www.slideshare.net/LeeFeigenbaum/sparql2-status
Lee Feigenbaum, Co-chair, SPARQL Working Group
lee@thefigtrees.net

Disclaimer
The SPARQL Working Group has not yet decided many of the technical questions surveyed in these slides. All examples are subject to change; please do not construe them as indicators or endorsements of specific technical designs/decisions.
All opinions are Lee Feigenbaum’s alone.

Naming
SPARQL 1.1 is the collective name of the work produced by the current SPARQL Working Group. The actual components being worked on are known as:SPARQL 1.1 QuerySPARQL 1.1 Update
SPARQL 1.1 Service Description
…

Where are we now?
Today
August 2010
March 2009
???
Last Call and beyond of core SPARQL specifications
July 2009
FPWD of SPARQL New Features and Rationales document
October 2009
FPWD of core SPARQL specifications

Overview

Projected Expressions
Select expressions other than variables (literals, functions on literals and variables, etc.)
Issues around:
Do expressions require an aliased name?
Syntax (main issue here)
SELECT ?price * ?qty AS ?total_price
WHERE {
…
}

Aggregates
À la SQL aggregates (MIN, MAX, COUNT, AVG, etc.)
Issues around:
Which aggregates to include
Aggregates over mixed datatypes
Syntax, keywords, custom aggregates
SELECT MIN(?price) AS ?min_price …
WHERE { … }
GROUP BY ?item

Subqueries
Nested queries allow multiple queries to be combined into one.
Issues around:
Variable scope & evaluation model
Precise syntax
SELECT ?article ?authorWHERE { ?article ex:author ?author . { SELECT ?article WHERE { … ?article … } ORDER BY … LIMIT … }}

Negation
Supplant the mystifying OPTIONAL/!bound method of negation with a dedicated construct
Issues around:
Filter semantics vs. set-difference semantics
Choice of keyword(s)
SELECT … WHERE { ?person a foaf:Person .
NOT {
?person foaf:mbox ?email
}
}

Service Description
A standard discovery mechanism and vocabulary for describing the capabilities, extensions, data sets, and more for a SPARQL endpoint
Discovery. How can a client find the RDF that describes a SPARQL endpoint at a particular URI?
Description. What predicates, classes, values, etc. should a client expect to find (and be able to query) once it locates a service description?
Issues around:
Choice of discovery mechanism
Which predicates and enumerations to define URIs for

Update Language
Based on the SPARQL Update member submission
Batch insert & delete
Insert & delete based on triple patterns
Graph management (creation, removal)
Issues around:
Graph stores vs. triple stores
Which language statements to include?
Transactions/atomicity/concurrency?

Update Protocol
The ability to issue SPARQL/Update language statements via a standard protocol (e.g. via HTTP POST)
Issues around:
Relation to existing SPARQL (Query) Protocol
Security
Need for WSDL description? SOAP bindings?

RESTful Update
Where appropriate, map RESTful HTTP requests to SPARQL/Update operations
DELETE /foo/g1 …-> DELETE DATA FROM ex:g1 …
Issues around:
Which mappings to include?
Updating graphs with URIs that are not under the control of the SPARQL endpoint

Property Paths
Support arbitrary-length predicate paths in triple patterns – “regular expressions” on predicates?
Query hierarchical structures such as RDF collections
Issues around:
Can variables be used in path expressions?
Can the length of a path be found?
Are paths first-class datatypes?
SELECT … WHERE { ?person foaf:knows+ ?network .
}

Basic Federated Query
Initial scaffolding for authoring federated SPARQL queries
Likely will involve a keyword to explicitly target portions of a query to specific endpoints
Initial plan: Start with ARQ’s SERVICE keyword
SELECT … WHERE { … SERVICE ex:books {
…
}
}

Entailment Regime Semantics
SPARQL/Query 1.0 defines a mechanism to extend SPARQL semantics for additional entailment regimes
Use this mechanism to define the semantics of SPARQL queries for:
RDF Schema
OWL flavors
RIF rule sets
…
Issues around:
Requiring consistency checks
How to limit infinite results (e.g. from axiomatic inferences)

Common Functions
Extend the set of functions that SPARQL engines must support to include some of…
Common string functions (e.g. substr)
Common date/time/datetime functions
Logical functions (COALESCE, IF, …?)
Limited discussion to date about which functions to include

Get Involved
Join.
Email team-sparql-chairs@w3.org
Follow.
WG materials at http://www.w3.org/2009/sparql/wiki/
Comment.
Public feedback at public-rdf-dawg-comments@w3.org
Use.
Discuss SPARQL at public-sparql-dev@w3.org