Package org.jgroups.protocols
Class FRAG2
java.lang.Object
org.jgroups.stack.Protocol
org.jgroups.protocols.FRAG2
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 (200 bytes).
- Version:
- $Id: FRAG2.java,v 1.36.2.1 2008/07/22 11:51:22 belaban Exp $
- Author:
- Bela Ban
-
Field Summary
-
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionFragment a packet if larger than frag_size (add a header).int
final String
getName()
long
long
long
long
int
void
init()
Called after instance has been created (null constructor) and before protocol is started.void
void
setFragSize
(int s) void
setOverhead
(int o) boolean
setProperties
(Properties props) Setup the Protocol instance acording to the configuration stringIf event is a message, if it is fragmented, re-assemble fragments into big message and pass up the stack.Methods inherited from class org.jgroups.stack.Protocol
destroy, downThreadEnabled, dumpStats, enableStats, getDownProtocol, getProperties, getProtocolStack, getThreadFactory, getTransport, getUpProtocol, printStats, providedDownServices, providedUpServices, requiredDownServices, requiredUpServices, setDownProtocol, setPropertiesInternal, setProtocolStack, setUpProtocol, start, statsEnabled, stop, upThreadEnabled
-
Constructor Details
-
FRAG2
public FRAG2()
-
-
Method Details
-
getName
-
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
Setup the Protocol instance acording to the configuration string- Overrides:
setProperties
in classProtocol
-
init
Description copied from class:Protocol
Called after instance has been created (null constructor) and before protocol is started. Properties are already set. Other protocols are not yet connected and events cannot yet be sent. -
resetStats
public void resetStats()- Overrides:
resetStats
in classProtocol
-
down
Fragment a packet if larger than frag_size (add a header). Otherwise just pass down. Only add a header if framentation is needed ! -
up
If event is a message, if it is fragmented, re-assemble fragments into big message and pass up the stack.
-