I am using Apache server for redirecting the secure request to our web server [tomcat], we had also use the Apache server for load balancing.
and further I describe that, we pass the file object to server for the processing.
so at server side we get the file object null every-time when we use the load balancing server technique, this happen when we work with the load balancing environment.
if any body having idea and knowledge in it that please share it with us?
What is the issue with this null pointer exception?
Related
I've been researching how to connect Tomcat and apache http server because I will have my web application written in angular deployed in apache http server 2.2 (currently succesfully tested on my own computer, local), and my REST service written in java deployed in Tomcat v6,
and what I want now is that when some component is clicked, to make a http request (like this http://localhost:8080/rest/getCars/20130505) that connects with the servlet and use the json provided to use the information provided in another component.
So I have created my own url/json to test the web application on itself, but as I said, it is possible to make the same thing but with a real http URI like it can be seen here: https://angular.io/docs/ts/latest/guide/server-communication.html#!#cors
They use:
let wikiUrl = 'http://en.wikipedia.org/w/api.php';
And I use, as of right now:
private datesUrl = 'src/example.json'; // URL to web API
#Injectable()
getDates(): Observable<Date[]> {
return this.http.get(this.datesUrl)
.map(this.extractData)
.catch(this.handleError);
}
So I believe my next step would be to change that datesUrl and write the http written above: http://localhost:8080/rest/getCars/20130505, so that it connects to Tomcat.
But my problem is that I don't know if this is going to work without any connection done between apache http server and tomcat. I've seen there are connectors, like mod_jk and mod_proxy http://httpd.apache.org/docs/2.2/mod/mod_proxy.html#proxypass
and so on. I would like to know if, in my case, if I need to use this modules for apache http server or it's not necessary, since I have never seen any of this and install the modules is proving to be a challenge. The end game objective I have is to go from local to a real server, but as far as I know there is no need for anyone from the outside to use the webpage, it's only for the business itself, so with access to the server/machine I could still access localhost, same as I do when I test it locally.
You don't need any special connection between the PHP server and the Tomcat server: it's a plain-old HTTP request. Tomcat doesn't care if your PHP script made that request, or if it came from the open internet.
In the case of the PHP script making the request, it's making its standard HTTP call, and doesn't care that you are running a Tomcat server locally or whatever. Just go ahead and do it. If Tomcat is already responding to HTTP requests on that URL, then calling it from PHP requires no further configuration.
I’m looking to run Apache as a cache server for static images. If requited image is missed locally on the server the server should download it from the third-part server and store it locally prior to responding to the request.
So when client sends request
http://myserver/static/images/image1.jpg
and the image is missed locally (i.e /var/www/static/images/image1.jpg is missed) the server
Download the image from the another server
http://third-partserver/static/images/image1.jpg
Store it locally at /var/www/static/images/image1.jpg
Return the image to the client
Is there any way to make it possible by using existed Apache modules and configurations only without writing any specific code?
I got a query regarding a response from cluster of managed server (Weblogic) behind load balancer.
During a request to server (though load balancer) if server crashes then does response goes back to client OR load balancer re-route the request to another running server in that cluster (stateful request)
so the workflow is something like this:
Client request -> server1 -> crashed in between processing request -> reponse back to app -> send back to server -> load balancing-> to another running server.
does it go to client in case of crash server response
OR
Load Balancer handles the response and see that server crash response received and hence it re-request (without even client letting know about this whole crashing scene)
Depends on the Load Balancer, depends on the vendor, depends on the module and method. Your question is vague. This is what a load balancer should be configured to do. It comes built in for some load balancers like Apache and might have to be specifically configured for some others.
The load balancer should probe your application page, for example if you have an application running on http://example.com:9101/index.html, then every 15 seconds(say) it will probe the page and ensure the application is up and send traffic to it. If not, it will send it to the other members defined. So if the server crashes, it will know and stop sending. Most commercial and free load balancers have to option to be configured to do so, so does the weblogic load balancer.
Without more information, this is the most general answer I can provide.
Doesn't have to be Apache, but that's just the only HTTP server I know of (Actually could you guys recommend alternatives that I could look into as well?)
Anyways, so I have been messing around with Amazon Web Services and I created an EC2 server instance with an Amazon Linux Image. On that, (Following guides and examples) I installed Apache and now when I make a GET request to my public IP, it returns to me the HTML files I created on my server.
My question is, what if I never installed Apache, and then made an HTTP request to my public IP? For no reason really, the question just came up in my head and I'm curious. I'd rather not figure out how to uninstall Apache or create a new instance to figure it out, so I was wondering if somebody could weigh in as well as tell me a little more about what it is exactly apache does on a server. My understanding is that it is a layer you can install on your server OS that will create a socket listener to port 80 (HTTP), and when a request is made on that port, Apache will return web pages? Also I think I read somewhere you could configure Apache to forward a port to something like a python server script?
Thanks in advance for your time!
could you guys recommend alternatives that I could look into as well?)
nginx is a popular alternative to apache. It's much more efficient.
what if I never installed Apache, and then made an HTTP request to my public IP?
Your browser would get a "connection reset" because there is nothing on port 80. Your browser would display a message (Chrome says "This webpage is not available"). You would NOT get a "404" because that requires an HTTP server to send HTTP codes.
If your server was firewalled instead, you'd bet a busy wait for a while, then a message about the server not responding.
Also I think I read somewhere you could configure Apache to forward a port to something like a python server script?
Yes, that is called "reverse proxy" mode. It's essential to any application website if you want to scale. The web server(s) can distribute traffic to one or more backends running the application. The web server is useful for filtering bad requests (since your backend in Ruby/Python will be 1000's of times slower than the reverse proxy.)
Well, if you want to test what will happen if Apache isn't installed, you can always just stop the Apache service by typing:
sudo service apache2 stop
or
sudo service httpd stop
depending on your version. Then if you visit your site's webpage you'll get a 404 error or something similar.
There are ways to use python scripts to run simple servers, but in general it's easier to just let Apache handle that and use a framework like Ruby on Rails or Django to control the display and creation of content for your server.
I'm using Jmeter to load test my web application. I have two web servers and we are using HAProxy for load balance. All my tests are running fine and configured correctly. I have three jmeter remote clients so I can run my tests distributed. The problem I'm facing is that ALL my jmeter requests are only being processed by one of the web servers. For some reason it's not balancing and I'm having many time outs, and huge response times. I've looked around a lot for a way to make these requests being balanced, but I'm having no luck so far. Does anyone know what can be the cause of this behavior? Please let me know if you need to know anything about my environment first and I will provide the answers.
Check your haproxy configuration:
What is it's load balancing policy, if not round-robin is it based on ip source or some other info that might be common to your 3 remote servers?
Are you sure load balancing is working right? Try testing with browser first, if you can add some information about the web server in response to debug.
Check your test plan:
Are you sure you don't have somewhere in your requests a sessionid that is hardcoded?
How many threads did you configure?
In your Jmeter script by default the HTTP Request "Use KeepAlive" header option is checked.
Keep-Alive is a header that maintains a persistent connection between
client and server, preventing a connection from breaking
intermittently. Also known as HTTP keep-alive, it can be defined as a
method to allow the same TCP connection for HTTP communication instead
of opening a new connection for each new request.
This may cause all requests to go to the same server. Just uncheck the option and save, stop your script and re-run.