public interface Taggable
Objects of classes implementing this interface can hold arbitrary tags scoped by the object's NamedCache.
A tag is a keyword associated with an object stored in StateServer. You can associate tags with objects,
remove tag associations from objects and test for the presence of a tag on an object by using the methods
defined in object's TagHolder. Once a tag or set of tags have been associated with an object, the tags
are stored as part of the object state.
To associate tags with objects stored in a NamedCache, the object's type must implement the Taggable
interface. This interface requires an implementation which has a well-known property, tagHolder, which is
used to store the tags associated with the object.
The set of strings used as tags on objects is scoped by the NamedCache in which the objects are stored.
A tagged object binds itself to the cache when it is written to that cache. All tags assigned to the object prior to
binding are saved in the global SOSS store and can be retrieved by reading that object from other clients. It is also possible
to specify tag conditions in queries by using FilterFactory.hasAllTags(java.lang.String...) and FilterFactory.hasAnyTags(java.lang.String...).
Tagged objects returned by get and retrieve methods and queries are bound to the corresponding
cache. It is possible to modify their tag sets and then do a cache update. However, to save an object into another cache,
you should first cancel binding by clearing object's tags(TagHolder.clearTags()).
An implementation of Taggable should have a non-static initialised field of type TagHolder, a
reference to which is returned by getTags(). This is necessary for saving tags in the cache.
Operations with tags are performed by calling TagHolder methods.
An example of class, implementing Taggable:
public class MyTaggable implements Taggable, Serializable {
private TagHolder th = new TagHolder();
public TagHolder getTags() {
return th;
}
public MyTaggable(String tag) {
th.addTags(tag);
}
}
If class hierarchy permits, instead of implementing Taggable it is more convenient to subclass
TaggableObject. This class provides the getTags() implementation and wrappers for
TagHolder methods.| Modifier and Type | Method and Description |
|---|---|
TagHolder |
getTags()
Method used by
NamedCache to store tags as SOSS attributes. |
TagHolder getTags()
NamedCache to store tags as SOSS attributes. It should return a reference to
a TagHolder object associated with this class.TagHolder