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Distributed Logging in Java
with Constrained Resource
Usage
Sunil Brown Varghese, Daniel Andresen
Dept. of Computing and Information Sciences
Kansas State University
Overview
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Introduction to Logging
Distributed Logging
Distributed Logging with RMI
Conclusions
Introduction
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Everyone logs in one way or other…
print(), out, System.out.print() are examples
of console logging
Large systems like aircraft monitoring
systems, transaction–based financial
processes may log into multiple targets
Advantages of Logging
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Feedback to developers during development
cycles
Provide system diagnostic alerts from
production systems
Provide information for statistical analysis of
working of a system
Delivery based on levels of importance could
improve efficiency in development cycle
Logging options
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The Log4J Project
Logging Toolkit for Java from IBM
Java 2 Standard Edition (v1.4.0 onward)
Distributed Logging
Distributed Logging
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Log4j has good support for sending log
messages to multiple log servers by TCP/IP
socket connections
J2SE provides the Java Logging framework
by default and supports distribution of log
messages by socket connections (though
listeners are left to the developer)
Java Logging Framework
Observation effects the Observed
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If generated at a high rate, distributed log
messages may swamp the processor and
the network connections whereby decreasing
system performance and the accuracy of the
log analysis
Solution: Limit the use of distributed log
messages to critical and non-repetitive
sections of code and buffer messages
Distributed Logging with RMI
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Transmission of Log messages with RMI
calls allows the log objects to be recorded at
remote sites as is
Log messages may be modified easily ( say
based on network load, exception objects
may be removed from log)
Representation
Extending the Java Logging
Framework
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RMI Handler extended from Handler class
ensuring compatibility with Logger and
security in-built into Java Logging
The logging levels may be varied
dynamically against bandwidth usage by
providing level information in an XML file
Class View – Client Side
Class View – Server Side
Sample Levels.xml file
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<?xml version='1.0'?>
<param-list>
<cutoff>1600</cutoff>
<cutoff>1400</cutoff>
<cutoff>1200</cutoff>
<cutoff>1000</cutoff>
<cutoff>800</cutoff>
<cutoff>600</cutoff>
<cutoff>500</cutoff>
</param-list>
RMI Log Server
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Instantiates a logger and assigns the RMI
Handler and other Handlers based on an
XML file
Server binds to the specified machine and
port (binding data from input XML file)
This framework allows a chain of RMI
Servers to be formed connected by RMI
Handlers in a tree fashion
Bandwidth Computation
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TCP/IP based weighted average method is
used to update bandwidth
Bandwidth is sampled for a Sampling Time
and it is reset for a fresh start
If there is no bandwidth updates for an
Inactivity Tolerance period, the Bandwidth is
reset
RMI Log Buffer
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The RMI Handler may buffer the log
messages so as to reduce the number of
RMI calls needed. This could dramatically
raise the efficiency of transmission
The RMI Buffer ensures message
transmission under normal RMI Handler
operation and abnormal termination
RMI Log Server GUI
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The GUI connects to RMI Log Server
and provides time graphs of bandwidth
statistics
The cutoffs along with bandwidth
variance are shown
RMI Log Server GUI
RMI Log Server GUI Connection
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As there isn’t a unique naming scheme for
RMI Handlers connected to a logger, the
URL and port information is used as RMI
Handler identifier
RMI Log Server GUI Connection
Limitations / Assumptions
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Leveling thresholds at the RMI Handler level
are to be set intuitively by the user
Log message sizes were taken as constants
for testing purposes
The overhead of making an RMI call is
heavier than sending data through TCP/IP
sockets
Conclusions
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RMI Logging allows the recreation of log
messages in remote sites as long as all
sub-components are serializable
Allows the exception objects to be stored in
remote repositories
RMI Handler can monitor its bandwidth
usage and discard log messages of low level
Future work
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RMI Handler may maintain a server list so
that if one RMI Log Server fails, it retransmits
to secondary servers
The GUI interface can be developed further
to remotely control RMI Log Servers
Questions ?