thredds.crawlabledataset.CrawlableDataset Maven / Gradle / Ivy
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The NetCDF-Java Library is a Java interface to NetCDF files,
as well as to many other types of scientific data formats.
/*
* Copyright 1998-2009 University Corporation for Atmospheric Research/Unidata
*
* Portions of this software were developed by the Unidata Program at the
* University Corporation for Atmospheric Research.
*
* Access and use of this software shall impose the following obligations
* and understandings on the user. The user is granted the right, without
* any fee or cost, to use, copy, modify, alter, enhance and distribute
* this software, and any derivative works thereof, and its supporting
* documentation for any purpose whatsoever, provided that this entire
* notice appears in all copies of the software, derivative works and
* supporting documentation. Further, UCAR requests that the user credit
* UCAR/Unidata in any publications that result from the use of this
* software or in any product that includes this software. The names UCAR
* and/or Unidata, however, may not be used in any advertising or publicity
* to endorse or promote any products or commercial entity unless specific
* written permission is obtained from UCAR/Unidata. The user also
* understands that UCAR/Unidata is not obligated to provide the user with
* any support, consulting, training or assistance of any kind with regard
* to the use, operation and performance of this software nor to provide
* the user with any updates, revisions, new versions or "bug fixes."
*
* THIS SOFTWARE IS PROVIDED BY UCAR/UNIDATA "AS IS" AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL UCAR/UNIDATA BE LIABLE FOR ANY SPECIAL,
* INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
* FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE ACCESS, USE OR PERFORMANCE OF THIS SOFTWARE.
*/
package thredds.crawlabledataset;
import java.util.Date;
import java.util.List;
import java.io.IOException;
/*
* [Once support alias paths, these sentences or something like them should
* start the third paragraph below.]
*
* Two standard implementations affect what characters are allowed in a
* CrawlableDataset path.The CrawlableDatasetAlias class uses wildcard
* characters ("?", "*", and "**") to define a collection of CrawlableDatasets.
* Therefore, the wildcard characters can not be used in a CrawlableDataset
* path.
*/
/**
* CrawlableDataset represents an abstract dataset that is part of a
* hierarchical dataset collection. Parent and child datasets can be accessed
* allowing the collection to be crawled.
*
* The CrawlableDataset interface is a generalization (and simplification) of
* the java.io.File class. A CrawlableDataset path is made up of ONE or more
* path segments each seperated by a slash ("/"). The path may start or end with
* a slash ("/").
*
* Implementation Notes:
*
* - The thredds.crawlabledataset.CrawlableDatasetFactory requires each
* CrawlableDataset implementation to define a public constructor with one
* String argument and one Object argument. The String argument is the path
* for the CrawlableDataset being constructed, the Object argument is a
* configuration object.
* - The thredds.cataloggen.CollectionLevelScanner framework does not support
* building a catalog for the collection based at the CrawlableDataset path "/".
* So, do not implement your CrawlableDataset so that the path "/"
* is allowed, or at least so that it is not likely to be used as the root of
* a dataset collection (e.g., CrawlableDatasetFile is probably safe because
* the root directory ("/") should never be used as the base of a data
* collection. If the backend data source on top of which you are implementing
* CrawlabeDataset uses "/" as its root, you can simply prepend a string (e.g.,
* "myDataCollection" or "root") to the backend path for the CrawlableDataset
* view of the path.
*
*
* @author edavis
* @see thredds.cataloggen.CollectionLevelScanner CollectionLevelScanner uses CrawlableDatasets to scan a dataset collection and create a THREDDS catalog.
* @since May 3, 2005 20:18:59 -0600
*/
public interface CrawlableDataset {
/**
* Return the configuration Object (can be null).
* @return the configuration Object (can be null).
*/
public Object getConfigObject();
/**
* Set the configuration Object.
* @param config the config object.
*/
// public void setConfigObject(Object config);
/**
* Returns the dataset path.
* @return the dataset path.
*/
public String getPath();
/**
* Returns the dataset name, i.e., the last part of the dataset path.
* @return the dataset name, i.e., the last part of the dataset path.
*/
public String getName();
/**
* Returns the parent CrawlableDataset or null if this dataset has no parent.
* @return the parent CrawlableDataset or null if this dataset has no parent.
*/
public CrawlableDataset getParentDataset();
/**
* Return true if the dataset represented by this CrawlableDataset actually
* exists, null if it does not or an I/O error occurs.
*
* @return true if the dataset represented by this CrawlableDataset actually exists.
*/
public boolean exists();
/**
* Return true if the dataset is a collection dataset.
* @return true if the dataset is a collection dataset.
*/
public boolean isCollection();
/**
* A factory method for getting a descendant of this datasets.
*
* @param relativePath the path relative to this dataset of the requested dataset.
* @return the requested descendant of this dataset.
* @throws IllegalArgumentException if the relative path is not relative (e.g., starts with a slash ("/")).
*/
public CrawlableDataset getDescendant(String relativePath);
/**
* Returns the list of CrawlableDatasets contained in this collection dataset.
* The returned list will be empty if this collection dataset does not contain
* any children datasets. If this dataset is not a collection dataset, this
* method returns null.
*
* @return Returns a list of the CrawlableDatasets contained in this collection dataset.
* The llist will be empty if no datasets are contained in this collection dataset.
* @throws IOException if an I/O error occurs while accessing the children datasets.
* @throws IllegalStateException if this dataset is not a collection, the isCollection() method should be used to check.
*/
public List listDatasets() throws IOException;
/**
* Returns the list of CrawlableDatasets contained in this collection dataset
* that satisfy the given filter. The returned list will be empty if this
* collection dataset does not contain any children datasets that satisfy the
* given filter.
*
* @param filter a CrawlableDataset filter (if null, accept all datasets).
* @return Returns a list of the CrawlableDatasets contained in this collection dataset
* that satisfy the given filter. The list will be empty if no datasets are
* contained in this collection dataset.
* @throws IOException if an I/O error occurs while accessing the children datasets.
* @throws IllegalStateException if this dataset is not a collection, the isCollection() method should be used to check.
*/
public List listDatasets(CrawlableDatasetFilter filter) throws IOException;
/**
* Returns the size in bytes of the dataset, -1 if unknown.
* @return the size in bytes of the dataset, -1 if unknown.
*/
public long length();
/**
* Returns the date the dataset was last modified, null if unknown.
* @return the date the dataset was last modified, null if unknown.
*/
public Date lastModified(); // or long milliseconds?
}