Use ows4R with OGC CSW (Catalogue Service for the Web)

Create CSW Client

In order to operate on a Catalogue Service, you need to create an interface in R to this CSW. This is done with the class CSWClient, as follows:

CSW <- CSWClient$new("http://localhost:8080/csw", "2.0.2", logger = "INFO")

You can define the level of logger: “INFO” to get ows4R logs, “DEBUG” for all internal logs (such as as Curl details). It is also possible to define a username and credentials in case operations would require an authentication to use the Catalogue Service.

For operations that require authentication (e.g. CSW Transaction operations on GeoNetwork), you may need to specify the user and pwd parameters.

Get Capabilities (GetCapabilities)

When create the CSWClient, ows4R will run a GetCapabilities request. To access the CSW Capabilities and its sections, you can use the following code:

caps <- CSW$getCapabilities()

Describe a record (DescribeRecord)

NOT YET SUPPORTED

Get a record (GetRecordById)

Query with OGC filters

Instead of using a CQL text filter, ows4R allows to specify an OGC Filter as basis to build the CSWConstraint. OGC Filters can be created with the class/function OGCFilter specifying an expression, among the following:

• Simple OGC expressions
  • PropertyIsEqualTo / PropertyIsNotEqualTo
  • PropertyIsLessThan / PropertyIsGreaterThan
  • PropertyIsLessThanOrEqualTo / PropertyIsGreaterThanOrEqualTo
  • PropertyIsLike
  • PropertyIsNull
  • PropertyIsBetween
  • BBOX
• Combinations of OGC expressions
  • And
  • Or
  • Not

Query with OGC filter - PropertyIsLike

The below example constructs a constraint with an OGCFilter made of a PropertyIsLike predicate on CSW AnyText. The result will be a list of records for which _any text is like ‘%Physio%’ (all records for which the string ‘Physio’ is included):

filter <- OGCFilter$new( PropertyIsLike$new("csw:AnyText", "%Physio%"))
cons <- CSWConstraint$new(filter = filter)
query <- CSWQuery$new(constraint = cons)
records <- csw2$getRecords(query = query)

Query with OGC filter - PropertyIsEqualTo

filter <- OGCFilter$new( PropertyIsEqualTo$new("csw:AnyText", "species"))
cons <- CSWConstraint$new(filter = filter)
query <- CSWQuery$new(constraint = cons)
records <- CSW$getRecords(query = query)

Transaction - Insert,Update,Delete (Transaction)

If the CSW server used supports Transaction operations (Insert, Update, Delete), ows4R allows you to perform these operations. The following examples highlight the different operations available:

Insert

mdfile <- system.file("extdata/data", "metadata.xml", package = "ows4R")
md <- geometa::ISOMetadata$new(xml = XML::xmlParse(mdfile))
insert <- CSW$insertRecord(record = md)
insert$getResult() #TRUE if inserted, FALSE otherwise

Update (Full)

md$identificationInfo[[1]]$citation$setTitle("a new title")
update <- CSW$updateRecord(record = md)
update$getResult() #TRUE if updated, FALSE otherwise

Update (Partial)

recordProperty <- CSWRecordProperty$new("apiso:Title", "NEW_TITLE")
filter = OGCFilter$new(PropertyIsEqualTo$new("apiso:Identifier", md$fileIdentifier))
constraint <- CSWConstraint$new(filter = filter)
update <- CSW$updateRecord(recordProperty = recordProperty, constraint = constraint)
update$getResult() #TRUE if updated, FALSE otherwise

Delete

delete <- CSW$deleteRecordById(md$fileIdentifier)
delete$getResult() #TRUE if deleted, FALSE otherwise