wiki:ApertureDataFactory

An object that can create DataSources and related objects to a DataSource, like crawlers and other stuff. The Factory is one important thing in an OSGI package.

Chris> This interface assumes that a single DataSource implementation is always bundled with the same DataCrawler, DataAccessor, etc. This is typically not the case (or else there would be no use case to use OSGi at all). I would therefore advise to use a Factory interface for every API that's introduced, i.e. DataSourceFactory, DataCrawlerFactory, etc. Only then do you permit several implementations of e.g. a file system crawler to co-exist.

/**
 * An object that can create DataSources and related objects to a DataSource, like crawlers and other stuff. 
 * The Factory is one important thing in an OSGI package.
 * Each Factory represents one kind of DataSource object, and will only create objects regarding to this
 * kind of DataSource.
 */
public interface DataFactory {

 /**
  * get some Information that can be displayed to a user when the user wants to register new DataSources.
  * usually, you would return a label, an Icon ????, a description. etc
  * TODO: we could also split this in several methods, easier to do.
  * TODO: when we return an RDFMap, mutlilingual information is already there!!! (which may be very cool)
  */
 public Properties getInformation();
 

 /**
  * create a new, emtpy and unconfigured, DataSource instance of the DataSource class represented.
  */
 public DataSource createDataSource();

 /**
  * create a DataCrawler for this data source instance. The instance has to be configured already
  */
 public DataCrawler createDataCrawler(DataSource source);

 /**
  * create a DataAccessor for this data source instance. The instance has to be configured already,
  * and you should primarily use its getDataObject() function. The DataCrawler may use its own
  * methods to create a DataAccessor
  */
 public DataAccessor createDataAccessor(DataSource source);

 /**
  * create a HierachicalAccess for this data source instance. There are cases when no hierarchical 
  * access is supported. then, this method returns null.
  * @return a HierachicalAccess or null, when HierachicalAccess not supported by this kind of DataSource
  */
 public HierachicalAccess createHierachicalAccess(DataSource source);

  /**
  * create a DataOpener for this data source instance. There are cases when DataObjects
  * of this DataSource cannot be opened. then, this method returns null. Then you may
  * get an opener from somewhere else.
  * @return a HierachicalAccess or null, when data cannot be opened by the DAtaAccessor
  */
 public DataOpener createDataOpener(DataSource source);


}


Last modified 12 years ago Last modified on 10/26/05 13:34:28