Log File Analyzer

A Java command-line application that analyzes mixed log files, classifies log entries (APM logs, Request logs, and Application logs), and outputs structured JSON summaries. The project is built using the Chain of Responsibility design pattern for scalable and modular log processing.

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Project Report

📄 Answers to Part 1 and the class diagram are available in:
202 answers individual project.pdf

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How to Run the Application

Build the JAR file

mvn clean package
mv target/logfileanalyzer-1.0-SNAPSHOT-jar-with-dependencies.jar log-analyzer.jar

Run with a sample input file

java -jar log-analyzer.jar --file sample_input_logs-1.TXT

The output files will be created inside the src/output/ directory.

Run Tests

mvn clean test

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Output Files

After execution, the following JSON files are generated:

• apm.json – Aggregates for metrics like CPU, memory, disk, etc.
• application.json – Counts of log levels (e.g., ERROR, INFO, DEBUG)
• request.json – API response time stats and status code summaries

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Design Pattern Used

The application uses the Chain of Responsibility pattern. Each handler (APMLogHandler, ApplicationLogHandler, RequestLogHandler, NullLogHandler) checks if it can process a log line and, if not, passes it to the next handler.

Each handler uses a corresponding aggregator:

• APMLogAggregator
• ApplicationLogAggregator
• RequestLogAggregator

These aggregators implement a shared interface: LogAggregator.

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Sample Input Log Lines

timestamp=2024-04-12T22:00:00Z metric=cpu_usage_percent value=72
timestamp=2024-04-12T22:00:01Z level=INFO message="Starting application"
timestamp=2024-04-12T22:00:02Z request_method=POST request_url="/api/update" response_status=200 response_time_ms=120

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👩‍💻 Developed by

Jahnavi Kedia
CMPE 202 – Individual Project
San Jose State University