DCIM: Distributed Cache
Invalidation Method for Maintaining Cache Consistency In Wireless Mobile
Networks
ABSTRACT:
This paper proposes distributed cache invalidation
mechanism (DCIM), a client-based cache consistency scheme that is implemented
on top of a previously proposed architecture for caching data items in mobile
ad hoc networks (MANETs), namely COACS, where special nodes cache the queries
and the addresses of the nodes that store the responses to these queries. We
have also previously proposed a server-based consistency scheme, named SSUM,
whereas in this paper, we introduce DCIM that is totally client-based. DCIM is
a pull-based algorithm that implements adaptive time to live (TTL),
piggybacking, and prefetching, and provides near strong consistency
capabilities. Cached data items are assigned adaptive TTL values that
correspond to their update rates at the data source, where items with expired
TTL values are grouped in validation requests to the data source to refresh
them, whereas unexpired ones but with high request rates are prefetched from
the server. In this paper, DCIM is analyzed to assess the delay and bandwidth
gains (or costs) when compared to polling every time and push-based schemes.
DCIM was also implemented using ns2, and compared against client-based and
server-based schemes to assess its performance experimentally. The consistency
ratio, delay, and overhead traffic are reported versus several variables, where
DCIM showed to be superior when compared to the other systems.
EXISTING SYSTEM:
The cache consistency mechanisms in the
literature can be grouped into three main categories: push based, pull based,
and hybrid approaches. Push-based mechanisms are mostly server-based, where the
server informs the caches about updates, whereas Pull-based approaches are client-based,
where the client asks the server to update or validate its cached data.
Finally, in hybrid mechanisms the server pushes the updates or the clients pull
them
DISADVANTAGES
OF EXISTING SYSTEM:
·
The major issue that faces client cache
management concerns the maintenance of data consistency between the cache
client and the data source. All cache consistency algorithms seek to increase
the probability of serving from the cache data items that are identical to
those on the server.
·
However, achieving strong consistency,
where cached items are identical to those on the server, requires costly
communications with the server to validate (renew) cached items, considering
the resource limited mobile devices and the wireless environments they operate
in.
PROPOSED SYSTEM:
In this paper, we propose a pull-based
algorithm that implements adaptive TTL, piggybacking, and prefetching, and
provides near strong consistency guarantees. Cached data items are assigned
adaptive TTL values that correspond to their update rates at the data source.
Expired items as well as nonexpired ones but meet certain criteria are grouped
in validation requests to the data source, which in turn sends the cache
devices the actual items that have changed, or invalidates them, based on their
request rates. This approach, which we call distributed cache invalidation
mechanism (DCIM), works on top of the COACS cooperative caching architecture.
ADVANTAGES
OF PROPOSED SYSTEM:
Ø TTL
algorithms are popular due to their simplicity, sufficiently good performance,
and flexibility to assign TTL values to individual data items.
Ø Also,
they are attractive in mobile environments because of limited device energy and
network bandwidth and frequent device disconnections.
Ø TTL
algorithms are also completely client based and require minimal server
functionality. From this perspective, TTL-based algorithms are more practical
to deploy and are more scalable.
Ø This
is the first complete client side approach employing adaptive TTL and achieving
superior availability, delay, and traffic performance.
SYSTEM ARCHITECTURE:
Overview
of DCIM basic design.
Interactions
between nodes in a DCIM system.
ALGORITHMS USED:
ü Algorithm
1- Decision flow at the server.
ü Algorithm
2- Inner loop and outer loop (shaded part) functions.
Decision
flow at the server.
Inner
loop and outer loop (shaded part) functions.
SYSTEM CONFIGURATION:-
HARDWARE CONFIGURATION:-
ü Processor - Pentium –IV
ü Speed - 1.1
Ghz
ü RAM - 256
MB(min)
ü Hard Disk -
20 GB
ü Key Board -
Standard Windows Keyboard
ü Mouse - Two
or Three Button Mouse
ü Monitor - SVGA
SOFTWARE CONFIGURATION:-
ü Operating System : Windows XP
ü Programming Language :
JAVA
ü Java Version :
JDK 1.6 & above.
REFERENCE:
Kassem Fawaz, Student Member, IEEE, and
Hassan Artail, Senior Member, IEEE-“DCIM: Distributed Cache Invalidation Method
for Maintaining Cache Consistency in Wireless Mobile Networks”- IEEE TRANSACTIONS ON MOBILE COMPUTING VOL.
12, NO. 4, APRIL 2013.
