Nginx implements long connection application

Whether you are doing web backend, app backend, or SOA service, long connection is a good choice. On the one hand, it saves the resource consumption of establishing a connection every time. On the other hand, it allows timely response to messages. Improved experience.

Here is a way to implement long connections through the Nginx module. This method is a long connection on the http protocol. Strictly speaking, the http protocol itself is a request-response type, and there is no strict long connection. The so-called long connection This means that when there is no response, you can hold it until there is a response, and then immediately re-establish the connection.

Let’s talk about how to achieve it.

1. First download NGiNX_HTTP_Push_Module and Nginx, these two tar files;

2. Copy these two tar files to the linux system and execute them in the nginx directory:

  ./configure --add-module=path/to/nginx_http_push_module ... 
	make
	make install

3. Middle It is possible that the pcre module cannot be found. If you are using a Centos system, use yum -y install pcre-devel openssl openssl-devel to install it
After installation, continue to install nginx

4. Wait for nginx to be installed. Finally, configure a long connection:

In the nginx.conf file
in /use/local/nginx/conf
Add:

  location /publish { 
    set $push_channel_id $arg_id; 
    push_publisher; 
    push_store_messages on; 
    push_message_timeout 2h; 
    push_max_message_buffer_length 10; 
} 
location /activity { 
    push_subscriber; 
    set $push_channel_id $arg_id; 
    push_subscriber_concurrency broadcast; 
    default_type text/plain; 
}

5. Restart ngnix and visit http://yourIP:port/activity?id =Your Channel, if the browser keeps waiting,
Then, you write a piece of code to publish a message. If the browser can receive it, it means the installation is successful!

    public void testNginx(){
        String http = "http://172.16.4.108/publish?id=my";
        PostMethod postMethod = new PostMethod(http);
        RequestEntity requestEntity = new StringRequestEntity("444");
        postMethod.setRequestEntity(requestEntity);
        try{
            int status =this.client.executeMethod(postMethod);
            if (status == HttpStatus.SC_OK) {
                String text = postMethod.getResponseBodyAsString();
                System.out.println(text);
            }
        }catch (Exception e){
            e.printStackTrace();
        }
    }

6. After the above is installed, we can start our own logic

The following is the listening end. Here is a simple implementation. We need to always record a lastModified on the listening end. This time represents The time of the last new message he received

private static String etag = "";
    private static String lastModified = "";
    public static void main(String[] args){
        while (true) {
            HttpClient httpClient = new HttpClient();
            String http = "http://172.16.4.108/activity?id=my";
            GetMethod getMethod = new GetMethod(http);
            getMethod.setRequestHeader("Connection","keep-alive");
            getMethod.setRequestHeader("If-None-Match", etag);
            getMethod.setRequestHeader("If-Modified-Since", lastModified);
            try {
                int status = httpClient.executeMethod(getMethod);
                if(getMethod.getResponseHeader("Etag") != null) {
                    etag = getMethod.getResponseHeader("Etag").getValue();
                }
                if(getMethod.getResponseHeader("Last-Modified") != null) {
                    lastModified = getMethod.getResponseHeader("Last-Modified").getValue();
                }
                System.out.println("etag=" + etag + ";lastmodif=" + lastModified + ";status=" + status);
                if (status == HttpStatus.SC_OK) {
                    String text = getMethod.getResponseBodyAsString();
                    System.out.println(text);
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

The following is the message sending end: It is the same as the code we used during testing

        public void testNginx(){
        String http = "http://172.16.4.108/publish?id=my";
        PostMethod postMethod = new PostMethod(http);
        RequestEntity requestEntity = new StringRequestEntity("444");
        postMethod.setRequestEntity(requestEntity);
        try{
            int status =this.client.executeMethod(postMethod);
            if (status == HttpStatus.SC_OK) {
                String text = postMethod.getResponseBodyAsString();
                System.out.println(text);
            }
        }catch (Exception e){
            e.printStackTrace();
        }
    }

At this point, our solution is completed.

The above has introduced Nginx to implement long connection applications, including aspects of the application. I hope it will be helpful to friends who are interested in PHP tutorials.

🎜