uk.ac.starlink.hapi

Class ChunkStreamer

java.lang.Object

uk.ac.starlink.hapi.ChunkStreamer

public class ChunkStreamer
extends Object

Handles reading HAPI data streams in chunks to cope with data requests that encounter service errors with the status 1408 "Bad Status - too much time or data requested".

Since:

26 Jan 2024

Author:

Mark Taylor

Constructor Summary

Constructors

Constructor and Description
ChunkStreamer(HapiService service, int chunkLimit, IOConsumer<String> limitCallback) Constructor.

Method Summary

Modifier and Type	Method and Description
int	getChunkLimit() Returns the largest number of chunks that this streamer is prepared to request for a given download.
InputStream	openMultiChunkStream(URL requestUrl) Returns an input stream corresponding to the supplied HAPI data request URL, but which may be assembled from the concatenation of multiple actual requests to the service.

Methods inherited from class java.lang.Object

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

Constructor Detail

ChunkStreamer

public ChunkStreamer(HapiService service,
                     int chunkLimit,
                     IOConsumer<String> limitCallback)

Constructor.

A limit must be supplied for the maximum number of chunks that will be retrieved for a given request. If this limit is exceeded, the supplied callback object, if any, will be called and the stream will terminate. If the callback throws an IOException, it will be encountered by the code reading the stream.

Parameters:

service - service to which requests will be made

chunkLimit - maximum number of chunks that a data stream will include

limitCallback - called with a failure message if chunk limit is exceeded; may be null

Method Detail

getChunkLimit

public int getChunkLimit()

Returns the largest number of chunks that this streamer is prepared to request for a given download.

Returns:

chunk limit

openMultiChunkStream

public InputStream openMultiChunkStream(URL requestUrl)
                                 throws IOException

Returns an input stream corresponding to the supplied HAPI data request URL, but which may be assembled from the concatenation of multiple actual requests to the service.

Parameters:

requestUrl - data request URL

Returns:

input stream containing all data in requested range, subject to chunk limit

Throws:

IOException