Nginx-Clojure

Nginx-Clojure is a Nginx module for embedding Clojure or Java programs, typically those Ring based handlers.

There are some core features :

1. Compatible with Ring and obviously supports those Ring based frameworks, such as Compojure etc.

2. One of benifits of Nginx is worker processes are automatically restarted by a master process if they crash

3. Utilizes lazy headers and direct memory operation between Nginx and JVM to fast handle dynamic contents from Clojure or Java code.

4. Utilizes Nginx zero copy file sending mechanism to fast handle static contents controlled by Clojure or Java code.

5. Supports Linux x64, Win32 and Mac OS X

6. Installation =============

The lastest version is 0.1.0.

1.1 Installation by Binary

1. First you can download the latest one from here. The zip file includes Nginx-Clojure binaries about Linux x64, Win32 and Mac OS X.
2. Unzip the zip file downloaded then rename the file nginx-${os-arc} to nginx, eg. for linux is nginx-linux-x64

1.2 Installation by Source

Nginx-Clojure may be compiled successfully on Linux x64, Win32 and Mac OS X x64.

1. First download from nginx site or check out nginx source by hg from http://hg.nginx.org/nginx. For Win32 users MUST check out nginx source by hg because the zipped source doesn't contain Win32 related code.

2. Check out Nginx-Clojure source from github OR download the zipped source code from https://github.com/xfeep/nginx-clojure/releases

3. If you want to use Http SSL module, you should install openssl and openssl dev first.

4. Setting Java header include path in nginx-clojure/src/c/config

   #eg. on ubuntu
   JNI_HEADER_1="/usr/lib/jvm/java-7-oracle/include"
   JNI_HEADER_2="${JNI_HEADER_1}/linux"

5. Add Nginx-Clojure module to Nginx configure command, here is a simplest example without more details about InstallOptions

   #If nginx source is checked out from hg, please replace ./configure with auto/configure
   $./configure \
   	--add-module=nginx-clojure/src/c
   $ make
   $ make install

6. Create the jar about Nginx-Clojure

   $ cd nginx-clojure
   $ lein jar

   Then you'll find nginx-clojure-${version}.jar (eg. nginx-clojure-0.1.0.jar) in the target folder.

7. Configurations =================

2.1 JVM Path , Class Path & Other JVM Options

Setting JVM path and class path within http { block in nginx.conf

    #for win32,  jvm_path maybe "C:/Program Files/Java/jdk1.7.0_25/jre/bin/server/jvm.dll";
    #for macosx, jvm_path maybe "/Library/Java/JavaVirtualMachines/1.6.0_65-b14-462.jdk/Contents/Libraries/libserver.dylib";
    #for linux,  jvm_path maybe "/usr/lib/jvm/java-7-oracle/jre/lib/amd64/server/libjvm.so";
    
    jvm_path "/usr/lib/jvm/java-7-oracle/jre/lib/amd64/server/libjvm.so";
    
    #jvm_options can be repeated once per option.
    #for win32, class path seperator is ";",  jvm_options maybe "-Djava.class.path=jars/nginx-clojure-0.1.0.jar;jars/clojure-1.5.1.jar";
    jvm_options "-Djava.class.path=jars/nginx-clojure-0.1.0.jar:jars/clojure-1.5.1.jar";
    
    #for memory setting
    #jvm_options "-Xms256m"
    #jvm_options "-Xmx256m"
    
    #for engble java remote debug uncomment next two lines
    #jvm_options "-Xdebug";
    #jvm_options "-Xrunjdwp:server=y,transport=dt_socket,address=8400,suspend=n";

Now you can start nginx and access http://localhost:8080/clojure, if some error happens please check error.log file.

2.2 Threads Number for Request Handler Thread Pool on JVM

Within http { block in nginx.conf jvm_workers is a directive about threads number for request handler thread pool on JVM, default is 0. ONLY IF you cann't resolve your performance problems by increasing worker_processes or reducing single request-response time, you can consider the way.

eg.

jvm_workers 8;

Now Nginx-Clojure will create a thread pool with fixed eight threads per JVM instance/Nginx worker to handle requests.

2.3 Ring Handler for Location

Within location block, directive clojure is an enable flag and directive clojure_code is used to setting a Ring handler.

###2.3.1 Inline Ring Handler

       location /clojure {
          clojure;
          clojure_code ' 
						(fn[req]
						  {
						    :status 200,
						    :headers {"content-type" "text/plain"},
						    :body  "Hello Clojure & Nginx!" 
						    })
          ';
       }

###2.3.2 Reference of External Ring Handlers

(ns my.hello)
(defn hello-world [request]
  {:status 200
   :headers {"Content-Type" "text/plain"}
   :body "Hello World"})

You should set your clojure JAR files to class path, see [2.1 JVM path & class path](#2.1 JVM path & class path) .

       location /myClojure {
          clojure;
          clojure_code ' 
          (do
               (use \'[my.hello])
                 hello-world))
          ';
       }

For more details and more useful examples for Compojure which is a small routing library for Ring that allows web applications to be composed of small, independent parts. Please refer to https://github.com/weavejester/compojure

###2.3.3 Pure Java Handler

package my;

import nginx.clojure.Constants;
import clojure.lang.AFn;
import clojure.lang.IPersistentMap;
import clojure.lang.PersistentArrayMap;

public class HelloHandler extends AFn {
	
	@Override
	public Object invoke(Object r) {
		IPersistentMap req = (IPersistentMap)r;
		
		//get some info from req. eg. req.valAt(Constants.QUERY_STRING)
		//....
		
		//prepare resps, more details about Ring handler on this site https://github.com/ring-clojure/ring/blob/master/SPEC
		Object[] resps = new Object[] {Constants.STATUS, 200, 
				Constants.HEADERS, new PersistentArrayMap(new Object[]{Constants.CONTENT_TYPE.getName(),"text/plain"}),
				Constants.BODY, "Hello Java & Nginx!"};
		return new PersistentArrayMap(resps);
	}
	
}

In nginx.conf, eg.

	location /java {
          clojure;
          clojure_code ' 
               (do (import \'[my HelloHandler]) (HelloHandler.) )
          ';
       }

You should set your JAR files to class path, see [2.1 JVM path & class path](#2.1 JVM path & class path) .