org.orekit.data
Class NetworkCrawler

java.lang.Object
  org.orekit.data.NetworkCrawler

All Implemented Interfaces:

DataProvider

public class NetworkCrawler
extends Object
implements DataProvider

Provider for data files directly fetched from network.

This class handles a list of URLs pointing to data files or zip/jar on the net. Since the net is not a tree structure the list elements cannot be top elements recursively browsed as in DirectoryCrawler, they must be data files or zip/jar archives.

The files fetched from network can be locally cached on disk. This prevents too frequent network access if the URLs are remote ones (for example original internet URLs).

If the URL points to a remote server (typically on the web) on the other side of a proxy server, you need to configure the networking layer of your application to use the proxy. For a typical authenticating proxy as used in many corporate environments, this can be done as follows using for example the AuthenticatorDialog graphical authenticator class that can be found in the tests directories:

   System.setProperty("http.proxyHost",     "proxy.your.domain.com");
   System.setProperty("http.proxyPort",     "8080");
   System.setProperty("http.nonProxyHosts", "localhost|*.your.domain.com");
   Authenticator.setDefault(new AuthenticatorDialog());
 

Gzip-compressed files are supported.

Zip archives entries are supported recursively.

This is a simple application of the visitor design pattern for list browsing.

Author:

Luc Maisonobe

See Also:

DataProvidersManager

Field Summary

Fields inherited from interface org.orekit.data.DataProvider

GZIP_FILE_PATTERN, ZIP_ARCHIVE_PATTERN

Constructor Summary

NetworkCrawler(URL... urls)
Build a data classpath crawler.

Method Summary

boolean	feed(Pattern supported, DataLoader visitor) Feed a data file loader by browsing the data collection.
void	setTimeout(int timeout) Set the timeout for connection.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

NetworkCrawler

public NetworkCrawler(URL... urls)

Build a data classpath crawler.

The default timeout is set to 10 seconds.

Parameters:

urls - list of data file URLs

Method Detail

setTimeout

public void setTimeout(int timeout)

Set the timeout for connection.

Parameters:

timeout - connection timeout in milliseconds

feed

public boolean feed(Pattern supported,
                    DataLoader visitor)
             throws OrekitException

Feed a data file loader by browsing the data collection.

The method crawls all files referenced in the instance (for example all files in a directories tree) and for each file supported by the file loader it asks the file loader to load it.

If the method completes without exception, then the data loader is considered to have been fed successfully and the top level data providers manager will return immediately without attempting to use the next configured providers.

If the method completes abruptly with an exception, then the top level data providers manager will try to use the next configured providers, in case another one can feed the data loader.

Specified by:

feed in interface DataProvider

Parameters:

supported - pattern for file names supported by the visitor

visitor - data file visitor to use

Returns:

true if some data has been loaded

Throws:

OrekitException - if the data loader cannot be fed (read error ...)