Standard set of libs

• Guava - Google Common Libraries
• slf4j - Simple logging facade for Java
  • Introduction
• log4j - Apache Logging Services
• Apache Commons - The Apache Commons
• freemarker - Java Template Engine
• Hibernate - Java ORM Library
• dom4j - Old XML Library

Executor

Executor

Notes

A way to embed clean up operations into long running systems.

Runtime.getRuntime().addShutdownHook(Thread)

HttpServlet

What is the lifetime/timeline of a HttpServlet?

It seems as if the lifetime is dependent on the web container. Tomcat is different from WebSphere for example.

It is possible to spawn services via

<servlet>
    <servlet-name>Master Servlet</servlet-name>
    <servlet-class>com.example.ServiceSpawn</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>

ArrayBlockingQueue

Perform an experiment with the ArrayBlockingQueue.

How would the mechanism be used to implement:

• Synchronous Service Processes
• Asynchronous Event Processes
• Supervisor Processes

All concurrent processes would have its own queue that would be able to receive responses if a process thread, a request if a service thread, or a message if an event thread.

Supervisor threads are a special type of event thread. The concept is that if a subordinate worker (event or service) thread crashes or has any information to relay then a message would just be sent to the supervisor and the appropriate action would be taken.

• Exit on subordinate crash
• Respawn on subordinate crash
• Log message

Message types

• put() for event receivers
• put(timeout) for service receivers?
• poll() when receiving events
• poll(timeout) when receiving responses

Process class would be an extension of the Runnable interface.

class Process extends Runnable {
  protected Thread thread;
  protected BlockingQueue<Message> queue;
  protected Process supervisor;
};

Simple Java Framework for Tomcat

What would be the components of a simple Java MVC framework?

Notes

ServerSocket the accept()ing socket

Socket the connect()ing socket

StringBuffer quickly append string fragments

BufferedReader get readLine()

InetSocketAddress build connection/bind address

java.nio.ByteBuffer general purpose buffer