Friday, May 16, 2014

Sharing logging context across application boundaries

How do you share logging context across application boundaries? Let me try to illustrate the challenge.

Example: 2 applications (sender/receiver) exchanging requests and replies. How does the sender flag a specific request to be traced or tracked across both applications at runtime?

Well, today java developers who use log4j or any other logging framework would enable debug (you also need to know what categories to be debug enabled) on both applications and you get all kinds of messages in the log. Now you have to analyze the log and pick out entries that are only related to a set of specific request/reply pairs relevant to a specific exchange of interest.

TNT4J provides a facility to share context across applications called shared conditional logging. The idea is to establish a shared pool of tokens (key/value pairs) available to all applications a runtime. These tokens can be added, removed, updated on the fly and therefore logging context or any other context can be communicated to all applications at runtime.

This simple model allows sender applications set a token/value pair and pass it along (out of band) to the receiver. Both apps can check for trace levels on a specific token to determine whether logging is needed. The result is that only specific request/reply pairs are tracked across 2 or more applications.

This approach saves developer a ton of time, reduces the overhead associated with enabling debug mode for all, logs only what is needed and therefore reduces the amount of manual analysis, simplifies diagnostics phase.

I am using this framework in my own project and so far with great results.

Tuesday, May 13, 2014

Launched TNT4J -- Java Open Source Project for Tracking, Tracing Application Behavior

I am restarting my blog again after a few years of silence with a launch of a new java open source project (TNT4J) available @ GitHub The mission of the project is to deliver production quality logging framework that significantly outperforms existing simple logging frameworks such as log4j, syslog, etc.

Simple logging of severity/message combo is just not enough when it comes to truly distributed, concurrent applications. Frankly I was tired of going through log files and trying to figure out why apps behave they way they do. I created this framework to deal with 3 basic logging problems:

  • How do I log only what is needed and across applications, runtimes (is DebugEnabled()) simply is not enough and produced too much unrelated data across concurrent apps.
  • How do I correlate and relate log entries within and across logs that belong to a logical activity such as order process, request etc and across multiple threads, applications, runtimes. Logs are just simply a big mess.
  • How do I record important metrics and state of the app, business process? Many times I ask myself what else was going on when this error occured? What was GC, memory, my apps internal variables etc, etc. Much of this info is simply hidden and not available.
Of course one could say, "well use profilers and such, problem solved". The asnwer is simple, when you develop and deliver apps to the users and they have problems, what do you tell your end users? Go use a profiler, buy an application diagnostic tool, go debug the application YOU developed (mobile or otherwise). With many copies of your apps running across variety of devices, servers, desktops how do you troubleshoot your application running elsewhere? Most developers request logs and log analysis nightmare begins. 

Crash logs have too much system, runtime data and lack application specific data required to understand application logic. To troubleshoot application behavior or misbehavior one needs to know how application behaves and log that in addition to what the runtime is doing (stack, traces, VM info, memory, etc).

Most logs are simply useless and a mess -- either too much data, too much text, not enough context, not enough relations. TNT4J addresses this problem head on. I created this project to help myself with this problem. 

I think developers may find TNT4J very useful. Let me know what you think. I welcome feedback, collaborators and adopters. All Welcome.