Apache Tomcat Connectors :
http://tomcat.apache.org/connectors-doc/

JK?

• extend mod_jserv
• mod_jserv?
  - jserv : Servlet 컨테이너 (servlet 2.0 지원/jsp 지원 X)
  - jserv를 Apache HTTP Server에 연결하기 위한 모듈
• mod_jserv는 설정하고 사용하기에 “너무 복잡!”
  - 가장 큰 단점은 오직 Unix 플랫폼에서의 Apache HTTP Server만 지원
• 이러한 단점 극복하고자 개발한 것이 JK Connector!
  . 다양한 플랫폼 지원
  . Apache HTTP Server, iplanet, IIS 등 지원
  . SSL 지원
  . mod_jk, isapi, nsapi, dsapi

JK2 Connector

• JK Connector를 재구성(Refactoring)해서 만든 Connector
• Apache 2.0을 대상으로 설계 (1.3도 지원하긴 함)
• Multi Thread 형태 웹서버와 연동될 때 성능 향상
  - IIS, iPlanet, Apahce HTTP Server 2.x

Connector Source

ajp13 Protocol

• ajp13 : Apache JServ Protocol version 1.3
• packet-oriented
• Gal Shachor (original designer)
• Dan Milstein : cleaned up the Java code -> more readable!
• ajp12 -> ajp13
  - Increasing performance (speed, specifically)
  - Adding support for SSL

Download

Configuration

• Reference Guide :
  http://tomcat.apache.org/connectors-doc/reference/apache.html
• WebServer HOWTO : Apache
  http://tomcat.apache.org/connectors-doc/webserver_howto/apache.html

Error Case

• 연결 실패 시
  - connecting to tomcat failed

• message send 실패 시
  - all endpoints are disconnected
  - failed sending request
  - tomcat is probably not started

• message reply 실패 시
  - tomcat is down or refused connection
  - tomcat is down, stopped or network problem

• WEB mod_jk 모듈에서 Connection Error 발생
  - jk module이 back-end 서버 (WAS)로 부터 reply를 받지 못할 경우 출력

Tomcat is down or refused?connection. No response has been sent to the client (yet)

• WAS에서 Exception 발생
  - ajp listener가 request를 기다리거나 response를 보내려는 중에 socket이 close

read request stopped.cause: java.net.SocketException: Connection reset

• connecting to Tomcat failed
  - 소스 배포 등으로 WAS 다운 시 발생

• Apache/mod_jk/Tomcat cannot send the response to the client anymore, because basically the client is not there anymore.
  HOWTO
  - try “netstat ?an”
  - try “top” or “ps” to see what Apache processes are doing
  - look at the Apache access and error logs

[info] ajp_process_callback::jk_ajp_common.c (1788): Writing to client aborted or client network problems
[info] ajp_service::jk_ajp_common.c (2447): (node1) sending request to tomcat failed (unrecoverable), because of client write error (attempt=1)

JkLogLevel

JkLogLevel set the log level between :

• info log will contains standard mod_jk activity (default).
• error log will contains also error reports.
• debug log will contains all information on mod_jk activity

Bug