org.jgroups.protocols
Class FRAG2
java.lang.Object
org.jgroups.stack.Protocol
org.jgroups.protocols.FRAG2
- public class FRAG2
- extends Protocol
Fragmentation layer. Fragments messages larger than frag_size into smaller packets.
Reassembles fragmented packets into bigger ones. The fragmentation number is prepended
to the messages as a header (and removed at the receiving side).
Each fragment is identified by (a) the sender (part of the message to which the header is appended),
(b) the fragmentation ID (which is unique per FRAG2 layer (monotonically increasing) and (c) the
fragement ID which ranges from 0 to number_of_fragments-1.
Requirement: lossless delivery (e.g. NAK, ACK). No requirement on ordering. Works for both unicast and
multicast messages.
Compared to FRAG, this protocol does not need to serialize the message in order to break it into
smaller fragments: it looks only at the message's buffer, which is a byte[] array anyway. We assume that the
size addition for headers and src and dest address is minimal when the transport finally has to serialize the
message, so we add a constant (1000 bytes).
- Version:
- $Id: FRAG2.java,v 1.20 2005/08/11 12:43:47 belaban Exp $
- Author:
- Bela Ban
Fields inherited from class org.jgroups.stack.Protocol |
down_handler, down_prot, down_queue, down_thread, down_thread_prio, log, observer, props, stack, stats, trace, up_handler, up_prot, up_queue, up_thread, up_thread_prio, warn |
Constructor Summary |
FRAG2()
|
Methods inherited from class org.jgroups.stack.Protocol |
destroy, downThreadEnabled, dumpStats, enableStats, getDownProtocol, getDownQueue, getProperties, getUpProtocol, getUpQueue, handleSpecialDownEvent, init, isTrace, isWarn, passDown, passUp, printStats, providedDownServices, providedUpServices, receiveDownEvent, receiveUpEvent, requiredDownServices, requiredUpServices, setDownProtocol, setObserver, setPropertiesInternal, setProtocolStack, setTrace, setUpProtocol, setWarn, start, startDownHandler, startUpHandler, statsEnabled, stop, stopInternal, upThreadEnabled |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
FRAG2
public FRAG2()
getName
public final java.lang.String getName()
- Specified by:
getName
in class Protocol
getFragSize
public int getFragSize()
setFragSize
public void setFragSize(int s)
getOverhead
public int getOverhead()
setOverhead
public void setOverhead(int o)
getNumberOfSentMessages
public long getNumberOfSentMessages()
getNumberOfSentFragments
public long getNumberOfSentFragments()
getNumberOfReceivedMessages
public long getNumberOfReceivedMessages()
getNumberOfReceivedFragments
public long getNumberOfReceivedFragments()
setProperties
public boolean setProperties(java.util.Properties props)
- Setup the Protocol instance acording to the configuration string
- Overrides:
setProperties
in class Protocol
resetStats
public void resetStats()
- Overrides:
resetStats
in class Protocol
down
public void down(Event evt)
- Fragment a packet if larger than frag_size (add a header). Otherwise just pass down. Only
add a header if framentation is needed !
- Overrides:
down
in class Protocol
up
public void up(Event evt)
- If event is a message, if it is fragmented, re-assemble fragments into big message and pass up
the stack.
- Overrides:
up
in class Protocol
Copyright ? 1998-2005 Bela Ban. All Rights Reserved.