OODT Profile Service - Representation of Profiles

Representation of Profiles

Within the OODT Framework, profiles are represented as RDF documents, XML documents, or Java objects. The Java Profile class can yield itself as an RDF or XML document, and you can construct a Java Profile from an XML document that describes a profile.

Introduction

No matter what their origin or whether they're to be short lived, profiles have a physical representation at one time within the OODT framework. Typically, you'll use the Java class Profile when working with Java, or the RDF or XML document version when working in other environments. The RDF representation uses the RDF XML structure and RDF schema to describe profiles. The XML document version uses an OODT-specific XML vocabulary and DTD.

For C/C++ Users: There is not yet a C/C++ representation of a profile. Use the RDF or XML representation.

Note: The RDF representation is currently a work-in-progress.

If you're developing a new kind of profile server, you should become familiar with the Java Profile class. If you're searching for profiles, you can just use the RDF or XML representations.

XML Profiles

Profiles can be represented as XML documents that conform to the OODT Profile Document Type Definition (DTD). The Formal Public Identifier of the OODT Profile DTD is -//JPL//DTD Profile 1.0//EN . The normative System Identifier is http://oodt.jpl.nasa.gov/grid-profile/dtd/prof.dtd .

Although you should refer to the normative System Identifier for the latest reference version, see the following:

<!ELEMENT profiles
  (profile*)>

<!ELEMENT profile
  (profAttributes,
   resAttributes,
   profElement*)>

    <!ELEMENT profAttributes
      (profId, profVersion?, profType,
       profStatusId, profSecurityType?, profParentId?, profChildId*,
       profRegAuthority?, profRevisionNote*)>

    <!ELEMENT resAttributes
      (Identifier, Title?, Format*, Description?, Creator*, Subject*,
       Publisher*, Contributor*, Date*, Type*, Source*,
       Language*, Relation*, Coverage*, Rights*,
       resContext+, resAggregation?, resClass, resLocation*)>

    <!ELEMENT profElement
      (elemId?, elemName, elemDesc?, elemType?, elemUnit?, 
       elemEnumFlag, (elemValue* | (elemMinValue, elemMaxValue)),
       elemSynonym*,
       elemObligation?, elemMaxOccurrence?, elemComment?)>

    <!ELEMENT profId (#PCDATA)>
    <!ELEMENT profVersion (#PCDATA)>
    <!ELEMENT profType (#PCDATA)>
    <!ELEMENT profParentId (#PCDATA)>
    <!ELEMENT profChildId (#PCDATA)>
    <!ELEMENT profStatusId (#PCDATA)>
    <!ELEMENT profSecurityType (#PCDATA)>
    <!ELEMENT profRegAuthority (#PCDATA)>
    <!ELEMENT profRevisionNote (#PCDATA)>

    <!ELEMENT Identifier (#PCDATA)>
    <!ELEMENT Title (#PCDATA)>
    <!ELEMENT Format (#PCDATA)>
    <!ELEMENT Description (#PCDATA)>
    <!ELEMENT Creator (#PCDATA)>
    <!ELEMENT Subject (#PCDATA)>
    <!ELEMENT Publisher (#PCDATA)>
    <!ELEMENT Contributor (#PCDATA)>
    <!ELEMENT Date (#PCDATA)>
    <!ELEMENT Type (#PCDATA)>
    <!ELEMENT Source (#PCDATA)>
    <!ELEMENT Language (#PCDATA)>
    <!ELEMENT Relation (#PCDATA)>
    <!ELEMENT Coverage (#PCDATA)>
    <!ELEMENT Rights (#PCDATA)>
    <!ELEMENT resContext (#PCDATA)>
    <!ELEMENT resAggregation (#PCDATA)>
    <!ELEMENT resClass (#PCDATA)>
    <!ELEMENT resLocation (#PCDATA)>

    <!ELEMENT elemId (#PCDATA)>
    <!ELEMENT elemName (#PCDATA)>
    <!ELEMENT elemType (#PCDATA)>
    <!ELEMENT elemEnumFlag (#PCDATA)>
    <!ELEMENT elemDesc (#PCDATA)>
    <!ELEMENT elemSynonym (#PCDATA)>
    <!ELEMENT elemUnit (#PCDATA)>
    <!ELEMENT elemValue (#PCDATA)>	
    <!ELEMENT elemMinValue (#PCDATA)>	
    <!ELEMENT elemMaxValue (#PCDATA)>	
    <!ELEMENT elemObligation (#PCDATA)>
    <!ELEMENT elemMaxOccurrence (#PCDATA)>
    <!ELEMENT elemComment (#PCDATA)>

Collections of Profiles

As you can see from the above,an XML element, profiles is a container element to hold zero or more profiles. Use this element where it's necessary to manipulate a collection of profiles without regard to order.

Java Representation of Profiles

The OODT source code includes a class jpl.eda.profile.Profile for object represenation of a profile. You can construct a Profile object from an RDF or XML document or create a blank one to populate with metadata later.

To construct a new, blank profile, use the no-arguments constructor. To construct a profile from an RDF or XML document, use the constructor accepting a Resource or a DOM Node , respectively. The DOM node should be a Element representing the profile element. Alternatively, if your XML document exists as a string, call the constructor taking a single string.

Accessing Profile Metadata

To access the metadata of a profile, call the methods to retrieve the profile attributes, the resource attributes, or the profile elements.

Accessing the Profile Attributes

You retrieve the profile attributes by calling getProfileAttributes on a Profile . This returns an ProfileAttributes object which provides methods to get and set the various attributes. Setting a value sets it for the Profile to which the Profil eAttributes belongs.

A value of null for an optional attribute means the value isn't set.

Accessing the Resource Attributes

You retrieve the resource attributes similarly as for profile attributes, calling getResourceAttributes to yield a ResourceAttributes object.

The ResourceAttributes has methods to get and set various attributes. Note that many of the attributes are multi-valued. For example, the resource profiled will likely cover several subjects. In this case, the "get" method, getSubjects , returns a java.util.List of String s. There is no set method. Instead, you just manipulate the list to add and remove subjects.

Note: All of the "get" functions that return List s return lists of String s, except for getDates , which returns a list of java.util.Date s.

For other attributes which are singly valued, there is both a set and get method. For optional values, a value of null means the attribute isn't set.

Accessing the Profile Elements

The profile stores its profile elements in a java.util.Map , mapping the name of the profile element (as a String ) to an object of class ProfileElement . To access this map, call the method getProfileElements on a Profile . Because this method returns a reference to the Profile 's map, any updates to the map affect the profile immediately.

Caution: Never store anything but String s as keys and ProfileElement s (or objects of its subcla sses) as values in a profile element map. The software will not operate correctly if any other kind of object is stored.

Common Attributes of Profile Elements

The class jpl.eda.profile.ProfileElement contains the common parts of every profile element, such as its required name, its optional description, and so forth. Use the value null for any optional attribute that's unset.

The ProfileElement stores its synonyms as a java.util.List of String s. Manipulate the list directly to add or remove synonyms.

The ProfileElement class is abstract. To create new profile elements for a profile, you need to create objects of one of the concrete ProfileElement subclasses:

EnumeratedProfileElement
RangedProfileElement
UnspecifiedProfileElement

The following sections detail each kind of profile element.

Elements with Enumerated Values

For profile elements that maintain a specified list of valid values, use the EnumeratedProfileElement class. Objects of this class maintian a java.util.List of values. You can pass in a list of values when constrcuting the object, or can call the getValues method and manipulate the list directly.

Queries that arrive for an enumerated profile element must match one of the listed elements exactly unless it's a negative (not-equal-to) query. For example, suppose we had an enumerated profile element filter with values infrared , visible , and ultraviolet . A query asking for a filter equal to infrared should match, as well as a query asking for a filter greater than or equal to infrared. A query asking for a filter not equal to infrared shouldn't match, while a query asking for a filter not equal to x-ray should match.

Elements with a Range of Values

You can represent profile elements that have a range of valid values with the RangedProfileElement class. Construct this class with the minimum and maximum values, which must be numeric.

Use the getMinValue to get the minimum value and getMaxValue to get the maximum value.

Querying a profile that uses a range of values considers the range as inclusive. For example, suppose the ranged profile element temperature has a minimum value of 32 and a maximum value of 212. A query that requests temperatures less than 32 shouldn't match, but less than or equal to 32 should match.

Elements with no Specified Values

For profile elements that you always want to match a query without explicitly listing each valid value or a range of legal numeric values you can use the class UnspecifiedProfileElement . This class identifies an element with no range or list of valid values.

Queries that arrive at such an element will always match, even if they're negative (not-equal-to) queries.