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Question: Does Java support QoS (Quality of Service) for packets that
are sent over the Internet?
Answer: Yes, Java supports although it also depends on network
Paths through the Internet vary widely in the quality of service they provide.
Some paths are more reliable than others. Some impose high call setup or
per-packet charges, while others do not do usage-based charging. Throughput and
delay also vary widely. Often there are tradeoffs: the path that provides the
highest throughput may well not be the one that provides the lowest delay or the
lowest monetary cost. Therefore, the "optimal" path for a packet to follow
through the Internet may depend on the needs of the application and its user.
Because the Internet
itself has no direct knowledge of how to optimize the path for a particular
application or user, the IP protocol provides a (rather limited) facility for
upper layer protocols to convey hints to the Internet Layer about how the
tradeoffs should be made for the particular packet. This facility is the "Type
of Service" facility, abbreviated as the "TOS facility" here.
Although the TOS facility has been a part of the IP specification since the
beginning, it has been little used in the past. However, the Internet host
specification now mandates that hosts use the TOS facility. Additionally,
routing protocols (including OSPF and Integrated IS-IS) have been developed
which can compute routes separately for each type of service. These new routing
protocols make it practical for routers to consider the requested type of
service when making routing decisions.
So, in Java you can try
use the method setTrafficClass(int tc) of Socket class. As the underlying
network implementation may ignore this value applications should consider it a
For Internet Protocol v4 the value consists of an octet with precedence and TOS
fields as detailed in RFC 1349. The TOS field is bitset created by
bitwise-or'ing values such the following:-
read more in RFC 1349 and Java API
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