org.lappsgrid.odrl

LAPPS Open Digital Rights Language

ODRL is an open international specification for Policy Language expressions. ODRL is typically expressed in some form of RDF (XML, Turtle, N-Quads, JSON-LD, etc.)

The LAPPS ODRL Language (LOL) is a Groovy DSL that can use used to generate ODRL RDF in any format from a simple and expressive DSL. Under the hood LOL uses the ODRLAPI for the data model (i.e. the Java objects) and Apache Jena for serialization.

Policy Types

The following policy types are currently supported.

1. Agreement formal contracts stipulating all the terms of usage and all the parties involved.
2. Offer proposed terms of usage from a Asset owner.
3. Request proposed terms of usage made to an Asset owner.
4. Set a set of entities from the complete model. Set policies are typically refined by other systems or profiles that process the information at a later time. No priviledges are granted to any party.
5. Ticket policy expression that stipulates the terms of usage and is redeemable by any Party who currently

Structure

The general format of a LOL policy file is:

    <policy-type>("<id>") {
        permission {
            target <URL>
            assigner <URL>
            assignee <URL>
            actions <URL>, ...
            constraint { ... }
            duty { ... }
        }
        prohibition {
            // Same as permission, but no duties.
        }
    }

Example: Offer Policy

Sony is offering permission to download a song for 0.50USD. Distribution is not allowed.

    offer("http://example.com/policy/1") {
        permission {
            assigner "http://www.sony.com"
            target "http://example.com/media/songs/blue_suede_shoes"
            actions "http://www.w3.org/ns/odrl/2/download", "http://www.w3.org/ns/odrl/2/play"
            duty {
                actions "http://www.w3.org/ns/odrl/2/pay"
                target "http://example.com/currency/usd/0.50"
            }
        }
        prohibition {
            target "http://example.com/media/songs/blue_suede_shoes"
            actions "http://www.w3.org/ns/odrl/2/distribute"
        }
    }

Example: Request and Agreement

Rasheed request permission to play the game Titanfall from Microsoft

request("http://example.com/policy/2") {
    permission {
        target "http://games/micrsoft.com/titanfall"
        actions "http://www.w3.org/ns/odrl/2/play"
    }
}

Microsoft agrees, but grants permission until the end of 2015 only,

agreement("http://example.com/policy/3") {
    permission [
        target "http://games/micrsoft.com/titanfall"
        actions "http://www.w3.org/ns/odrl/2/play"
        assigner "http://microsoft.com"
        assignee "http://facebook.com/rasheed"
        constraint {
            operator "lt"
            rightOperand "http://www.w3.org/ns/odrl/2/dateTime"
            value "2015-12-31"
        }
        duty {
            action "http://www.w3.org/ns/odrl/2/pay"
            target "http://example.com/currency/usd/19.99"
        }
    }
}

Programming Language Features

LOL is not simply an alternative RDF syntax, LOL files are full blown Groovy scripts capable of using the suite of Groovy language constructs.

Variables

Groovy is a dynamically typed language so variables may be introduced simply by using them.

// A local scoped variable.  Only visible in the odrl file that defined it.
def i = o

// If this is the first use of j then this declares a global variable.  Global
// variables are visible in files that include the file that declares j.
j = 0

// Types aren't required, but are useful for documenting the code.
String odrl = "http://www.w3.org/ns/odrl/2"
String play = "${odrl}/play"
String copy = "${odrl}/copy"

set("http://example.com/policy/4") {
   actions play, copy
}

Collections

The full suite of Java collections can be used as well as the Groovy extensions to the Java collections. The most commonly used collection types (List and Map) have simplified syntax in Groovy.

// Creates an empty ArrayList
def list = []
// Create an empty HashMap
def map = [:]

Groovy also provides a simplified for Map access using the dot notation where the identifier after the dot is used as the map key.

def Actions = [:]
Actions.play = "http://www.w3.org/ns/odrl/2/play"
Actions.copy = "http://www.w3.org/ns/odrl/2/copy"

// Is the same as
Map<String,String> Actions = new HashMap<String,String>()
Actions.put("play", "http://www.w3.org/ns/odrl/2/play")
Actions.put("copy", "http://www.w3.org/ns/odrl/2/copy")

Command Line Usage

The project uses Maven to build a runnable JAR file that includes all external dependencies; Groovy, Jena, etc.

> java -jar odrl-x.y.z.jar -l [rdf|jsonld|ttl|n3] <input_file>

The output types are RDF/XML, JSON-LD, Turtle and N3.