public interface OsidObject extends Identifiable, Extensible, Browsable
OsidObject is the top level interface for all OSID
Objects. An OSID Object is an object identified by an OSID Id
and may implements optional interfaces. OSID Objects also contain
a display name and a description. These fields are required but may be
used for a variety of purposes ranging from a primary name and description
of the object to a more user friendly display of various attributes.
Creation of OSID Objects and the modification of their data is managed
through the associated OsidSession which removes the
dependency of updating data elements upon object retrieval.
The OsidManager should be used to test if updates are
available and determine what PropertyTypes are supported.
The OsidManager is also used to create the appropriate
OsidSession for object creation, updates and deletes.
All OsidObjects are identified by an immutable
Id. An Id is assigned to an object upon creation of
the object and cannot be changed once assigned.
An OsidObject may support one or more supplementary
records which are expressed in the form of interfaces. Each record
interface is identified by a Type. A record interface may extend another
record interface where support of the parent record interface is implied.
In this case of interface inheritance, support of the parent record type
may be implied through hasRecordType() and not explicit in
getRecordTypes().
For example, if recordB extends recordA, typeB is a child of typeA. If a record implements typeB, than it also implements typeA. An application that only knows about typeA retrieves recordA. An application that knows about typeB, retrieves recordB which is the union of methods specified in typeA and typeB. If an application requests typeA, it may not attempt to access methods defined in typeB as they may not exist until explicitly requested. The mechanics of this polymorphism is defined by the language binder. One mechanism might be the use of casting.
In addition to the record Types, OSID Objects also have
a genus Type. A genus Type indicates a
classification or kind of the object where an "is a" relationship exists.
The purpose of of the genus Type is to avoid the creation
of unnecessary record types that may needlessly complicate an interface
hierarchy or introduce interoperability issues. For example, an OSID
object may have a record Type of Publication
that defines methods pertinent to publications, such as an ISBN number. A
provider may wish to distinguish between books and journals without having
the need of new record interfaces. In this case, the genus Type
may be one of Book or Journal. While
this distinction can aid a search, these genres should be treated in such
a way that do not introduce interoperability problems.
Like record Types, the genus Types may also exist in an implicit type
hierarchy. An OSID object always has at least one genus. Genus types
should not be confused with subject tagging, which is managed externally
to the object. Unlike record Types, an object's genus may
be modified. However, once an object's record is created with a record
Type, it cannot be changed.
Methods that return values are not permitted to return nulls. If a
value is not set, it is indicated in the Metadata of the
update form.
| Modifier and Type | Method and Description |
|---|---|
DisplayText |
getDescription()
Gets the description associated with this instance of this OSID
object.
|
DisplayText |
getDisplayName()
Gets the preferred display name associated with this instance of this
OSID object appropriate for display to the user.
|
Type |
getGenusType()
Gets the genus type of this object.
|
boolean |
isOfGenusType(Type genusType)
Tests if this object is of the given genus
Type. |
getId, isCurrentgetRecordTypes, hasRecordTypegetProperties, getPropertiesByRecordTypeDisplayText getDisplayName()
mandatory - This method must be implemented. A - display name is a string used for identifying an object in
human terms. A provider may wish to initialize the display
name based on one or more object attributes. In some cases,
the display name may not map to a specific or significant
object attribute but simply be used as a preferred display
name that can be modified. A provider may also wish to
translate the display name into a specific locale using the
Locale service. Some OSIDs define methods for more detailed
naming. DisplayText getDescription()
mandatory - This method must be implemented. A - description is a string used for describing an object in
human terms and may not have significance in the underlying
system. A provider may wish to initialize the description
based on one or more object attributes and/or treat it as an
auxiliary piece of data that can be modified. A provider may
also wish to translate the description into a specific locale
using the Locale service. Type getGenusType()
mandatory - This method must be implemented. boolean isOfGenusType(Type genusType)
Type. The
given genus type may be supported by the object through the type
hierarchy.genusType - a genus type true if this object is of the given genus
Type, false otherwiseNullArgumentException - genusType is
null mandatory - This method must be implemented.