Distributed Logging in Java with Constrained Resource Usage Sunil Brown Varghese, Daniel Andresen Dept. of Computing and Information Sciences Kansas State University

Overview Introduction to Logging Distributed Logging Distributed Logging with RMI Conclusions

Introduction 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 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 The Log4J Project Logging Toolkit for Java from IBM Java 2 Standard Edition (v1.4.0 onward)

Distributed Logging

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 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 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 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

RMI Log Server 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 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 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 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 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 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 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 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 ?