I have a servlet hosted in the glassfish server. i want to communicate with it using telnet to understand what is going on behind the scenes when using html form get method.
What should i give in the Host field of the HTTP request?
Get /WebApplication1/NServlet HTTP/1.1
Host: localhost
If i want to send custom properties in the HTTP request as below, is it possible to extract their value using request.getAttribute() method.
Get /WebApplication1/NServlet HTTP/1.1
Host: localhost
Custom-Attribute: xyz
Another doubt is that is javax.servlet package not a part of java SE sdk. i had to install java ee to get it running.
The Host field is just the hostname part of the URL, e.g. Host: google.com for http://google.com/
Custom-Attribute: xyz would be exposed in the HttpServletRequest using getHeader(), not getAttribute().
If you want to use HTTP for your protocol (as you've suggested in your comments), check out HttpClient. As the name suggests, it's the client-side of the client/server HTTP implementation, and it should be relatively easy to determine what to set on the client side such that you see it on the server.
There's a great tutorial here. I would perhaps get a simple page working in the servlet first, and check it via the browser, and then implement the client side.
Based on your question, I don't there's enough information for anyone to answer you. Tomcat/Jetty/etc are basically web servers that contain servlets (and therefore JSP/JSF/Wicket etc etc) processors for dynamically generating content.
So, what is it you're trying to figure out, and why?
Related
So I have two Java applications, a server and a client. They are simple programs no GUI elements just console applications. They work just fine running on my machine, and I have a client version that can even connect to the server via the internet.
Instead of hosting the Server on my local machine I would like to host it from a site like Openshift. Which I already have a HTML site up at using Tomcat 7. I would also like to be able to go to a page on the web server and have that page act as the client program.
I want to embedded the client program into the web server but....
How do I make the connection between the two servers? Pretty much how do I get the Web Page to reach out to the other server and make the connection(I am using sockets)? Do I need to be using a servlet, JSP, or something like Jquery?
If you feel like you need to see either the server program or the client let me know and I will post them.
I would like to host a client version on the web page.
Your JSP or servlet would be the client in that case, it would open a socket to the server process. Have a look at HttpServlet and its doGet method, this is basically what you would implement, and where you would place much of your client code, like opening a socket to your server process and returning data. You'll find tons of examples on the internet, see for instance
how to write hello world servlet Example
Browsing to the servlet's URL will invoke the doGet method and execute your client code. It should be stateless though, i.e. take whatever parameters are in the HttpServletRequest, do its thing based on that, and return as soon as possible. If your clients need to retain their connection to the server process, it will be a different story, and you may need for instance websockets (I have insufficient experience with that but it would sound like a good fit in that case).
For an assignment, I have written a server that services HTML files and I am supposed to use my web browser as a test client. I am also told that if there is a request for a file that doesn't exist i should send the following
HTTP/1.1 404 Not Found\r\n\r\n and if anything else goes wrong
HTTP/1.1 500 Internal Server Error\r\n\r\n"
I have run tests that should cause those to be sent, but nothing occurs in my browser window? Should I be getting any visual feedback from sending such a request?
In an HTML response there should only be one CRLF (carriage return and line feed) after each line. So you can first remove the extra \r\n.
Also on the second line you can send an HTML response back to the client saying what the error was if you want to show an error. This is normally what a typical web server does where it has its default error page if one is not defined. If you are not sending any HTTP headers, then you can insert the HTML body you want to send back such as <h1> No page found</h1> as the second line.
To include an "entity" in an http response
HTTP/1.1 404 Not Found
Content-Type: text/html
Content-Length: 10
01234576789
each line is ended by CRLF. Be sure to count the Content-Length correctly.
I see that this is a learning exercise, and understand that you may have been told to implement the server this way. But bearing that in mind ...
This is the wrong way to implement a web server / service. The right way is to find an existing implementation and build your service on top of that.
You could use a Java EE web container; i.e. something that implements the Servlets spec.
You could use a non-servlet framework (like Grizzly).
You could build on top of a server-side HTTP protocol stack; e.g. using Apache the HttpComponent library.
Building a web server from the ground up is a lot of work if you are going to do it properly. And the chances that you won't do it properly; i.e. you won't implement your service according how the HTTP spec says a server should behave. You will leave things out, do things the wrong way, etc.
Please don't do it. There are already too many broken (i.e. non-compliant) web servers out there. We don't need more.
And if you DO decide to implement HTTP from the ground up, then you (YOU) need to thoroughly read and understand the HTTP spec. And you (YOU) need to do your own basic research on how browsers implement the client side of the spec ... and what you therefore need to do on the server side to make browsers behave "normally".
i have to design a localhost application that one code at other project returns one url that follows like this..
http://localhost:8080/MyProject?id="somevalue"
now my task to implements the https( the url that is generated by the other project is hard coded.So we can have the https url also....as the other project is also one of my projects but after the task is over it will return url with id as parameter)
So let us have the url of the type
https://localhost:8443/MyProject?id="somevalue"
my design things are as follows.
1. i have to use https
2.i have to use RSA bit length of 512 bits
3.i have to be able to read the value id with request.getParameter()
4.How https coding will be different from http in servlets..
can we use the same coding of http in https..
i do not need the complex implementation. what i need is just it has to appear https and In the servlet implementation i want to use http coding...
Is it possible..
Thank you..
Your code shouldn't be affected if you are moving from Non SSL to SSL, assuming you are using tomcat, please read documentation to configure SSL
I have a java app on my server and I can access it with my browser by going to server.com:8080/app.
I've been trying to get my application to access this weblet but because of XSS jQuery.post() gives me errors. Both the app and weblet are on the same server, but since I have to access the weblet through port 8080 Javascript thinks it's another server.
My question: Is there a way to avoid this XSS issue?
I don't want to use a PHP proxy or .htaccess. I also don't want to use the $.getJSON(url + '&callback?') method.
I'm looking for any other solutions.
Thanks in advance.
It' SOP(Same Origin Policy) that's stopping you here, not XSS. XSS is a security vulnerability, which breaks SOP. And yes it limits access so both pages have to run on the same protocol, port and domain.
Can you use a reverse proxy from the webserver on port 80 to 8080? If not you could take a look at easyXDM. Another alternative is to have the 8080 service return rhe access control header mentioned in one of your comments, but this is not supported in older browsers.
Is there anything in the Servlet spec, Tomcat, or Wicket that will allow a webapp running behind mod_proxy to determine the non-proxied URL of the request?
We need to send out emails with links in them. I had been using the following bit of Wicket to construct URLs to specific pages in the app:
String relURL = RequestCycle.get().getRequest().getRelativePathPrefixToWicketHandler();
RequestUtils.toAbsolutePath(relURL);
Since the emails don't go back out through the proxy, of course the URLs don't get re-written, and end up looking like http://localhost/....
Right now the best I can do is to hard-code the URLs to our production server, but that's setting us up for some debugging headaches when running on dev/test machines.
Using InetAddress.getLocalHost().getHostName() isn't really a solution, since that's likely to return prod1.mydomain.com or somesuch, rather than mydomain.dom, from which the request likely originated.
As answered for the question Retain original request URL on mod_proxy redirect:
If you're running Apache >= 2.0.31 then you might try to set the
ProxyPreserveHost directive as described here .
This should pass the original Host header trough mod_proxy into your
application, and normally the request URL will be rebuild there (in
your Servlet container) using the Host header, so the schema location
should be build using the host and path infos from "before" the proxy.
Is there anything in the Servlet spec, Tomcat, or Wicket that will allow a webapp running behind mod_proxy to determine the non-proxied URL of the request?
No. If the reverse proxy doesn't put the information that you require into the message headers before passing them on, there's no way to recover it.
You need to look at the Apache Httpd documentation to figure out how to get the front-end to put the information that you need into the HTTP request headers on the way through. (It can be done. I just can't recall the details.)