OGC Geospatial Summit September 15, 2008

OGC Geospatial Summit September 15, 2008

CQL and SRUCQL and SRU

Ray Denenberg, Library of Congress OASIS Search Web Services Technical Committee

Brief History

Brief History Late 90s, Pressure to make Z39.50….

Simpler, more comprehensible,more implementable



But most important: Web Compatible



But most important: Web Compatible …..while retaining the Z39.50

semantics and abstractions

Roughly speaking …. SRU/CQL is the XML/Web version of Z39.50.

Roughly speaking …. SRU/CQL is the XML/Web version of Z39.50.

Where:

SRU corresponds to the Z39.50 protocol

CQL corresponds to the Z39.50 query

Timeline

1997-2001 A few false starts … 2001 Work on SRU began 2002 Version 1.0 2004 Version 1.1 2007 Version 1.2 In progress Version 2.0, OASIS SWS TC

http://www.loc.gov/sru?version=1.1&operation=searchRetrieve&query=dinosaur&maximumRecords=1&recordSchema=dc

An SRU Protocol Request

http://www.loc.gov/sru?version=1.1&operation=searchRetrieve&

query=dinosaur

&maximumRecords=1&recordSchema=dc

Server

Parameters

CQL Query

More parameters

Break it down:

query=dinosaurCQL Query

CQL

““Contextual Contextual Query Language”Query Language”

CQL’s Goals

CQL’s Goals

Support simple queries with simplicity,

Number one goal

CQL’s Goals

Support simple queries with simplicity,

and complex expressions with exactly the complexity needed: no more, no less.

Simple CQL Queries

Simple CQL Queries cat (simplest)

Simple CQL Queries cat (simplest)

cat and dog (simple boolean)

Simple CQL Queries …… cat (simplest)

cat and dog (simple boolean)

title = cat (index search)

….. A little more complex cat

cat and dog

title = cat

dc.title = cat (index qualified)

Qualified index

title = cat dc.title = cat bib.title = cat

Qualified index

title = cat dc.title = cat bib.title = cat geo.latitude = 22.6

Qualified index

title = cat dc.title = cat bib.title = cat geo.latitude = 22.6 geo.bound encloses "45.3, 19.0"

Relations

<index> <relation> <search term>


Search Clause


Search Clause

(e.g. title = cat)

Cat

Title = cat

Both are search clauses: in the first, the index and relation are defaulted.

cat

Same as

<default Index> <default relation> cat

Some built-in relations … <, >, <=, >=, <> = the default relation, server defined

== Exact

adjAdjacency

Withinencloses

Relation Modifiers

Search Clause

<index> <relation>/<modifier> <search term>

Relation modifier

Relation Modifiers Stem relevant Fuzzy Phonetic partial

Relation Modifier Example

Geo.city =/phonetic washintin

Relation modifier

Partial

geo.area encloses/partial “washington DC"

Proximity

“Find cat and dog in the same sentence”

cat prox//sentence dog

Proximity

cat prox//sentence dogsame as:

Cat

prox/distance=0/unit=sentence/unordered

dog

Proximity

prox/distance=0/unit=sentence/unordered

geo.cityname = washington

prox/distance<=50/geo.unit=miles

geo.cityname=baltimore

Cities with name “washington” within 50 miles Of cities with name “baltimore”

Cities with name “washington” not within 50 miles Of cities with name “baltimore”

geo.cityname = washington

prox/distance<=50/geo.unit=miles/not

geo.cityname=baltimore

Proximity Exclusion(a 2.0 feature)

Window Relation (a 2.0 feature)

dc.title window/distance<5/unit=word

"fries salt vinegar"

fries, salt, and vinegar all within a span of 5 words

geo.region Window/distance<200/geo.unit=miles/cityname

“baltimore washington richmond"

Regions containing cities with names Baltimore,

Washington, and Richmond within a 200 mile area.

Context sets

Context sets Indexes

Relations

Relation modifiers

Boolean Modifiers

subject any/relevant "fish frog“

find records whose subject field includes words like shark, tuna, coelocanth, toad, amphibian, etc.

subject any/relevant "fish frog"

index relationRelationmodifier

Subject to context qualification

dc.subject any/relevant "fish frog"

Context set

dc.subject any/rel.lr "fish frog"

A specific Relevance algorithn

Context set

geo.bounds within/partial/geo.nwse "43.772 -101.411 31.7723 -77.7499") and (geo.keywords any "biologic ecologic"

geo.bounds within/partial/geo.nwse "43.772 -101.411 31.7723 -77.7499") and (geo.keywords any "biologic ecologic"

Break that down…….

geo.bounds within/partial/geo.nwse

"43.772 -101.411 31.7723 -77.7499"

and geo.keywords any "biologic ecologic"

((geo.keyword = "ozone")

and

(geo.bounds within/partial/geo.nwse "58.45 -11.95 33.72 24.61")and ((geo.begdate >= /isodate 20040101) and (geo.enddate <= /isodate 20071231)))

SRU – Search/Retrieve via URL


Features

Result sets


Features

Result sets Result set refinement Request specific records Sorting

Result sets

Retrieval

Result sets

Retrieval Ability to request records in a particular

XML schema, e.g.• MODS• DC• GML

Result sets

Retrieval

Application Specific Diagnostics

http://www.search.gov/gsdi/sru2kml.php? operation=searchRetrieve&version=1.1& maximumRecords=100&recordSchema=GML& query=(geo.bounds within/partial/nwse "43.772 -101.411 31.7723 -77.7499") and (geo.keywords any "biologic ecologic")

http://www.search.gov/gsdi/sru2kml.php?

operation=searchRetrieve&version=1.1& startRecord=30& maximumRecords=15&recordSchema=GML&

query=

geo.bounds within/partial/nwse "43.772 -101.411 31.7723 -77.7499") and (geo.keywords any "biologic ecologic"

Server

Parameters

query


operation=searchRetrieve&version=1.1& startRecord=30& maximumRecords=15&recordSchema=GML&

query=


Server

Parameters

query

Operation and version parameters (gone in 2.0)


startRecord=30& maximumRecords=15&recordSchema=GML&

query=


Server

Parameters

query

Oasis SWS TC – Phase 1 Abstract Protocol Definition

From which bindings are derived.

Bindings SRU 1.2 specification (+CQL 1.2) Opensearch

Phase 2 SRU/CQL 2.0

Description Language

Documents

OGC Geospatial Summit September 15, 2008