I want to setup a proxy or a standalone aplication where a "server A" can do some POST request to this proxy and turn the POST request to a GET request to "server B".
Then the GET response must be redirected to "server A" which is waiting a response for the POST.
¿Is it possible?
What I want to get from the request is a static pdf.
Any idea how to do it would be great
Thanks
You should not do this as the semantics are different.
GET requests are designed to be cached (i.e. usually static stuff). POST on the other hand is more dynamic and is not cached.
You are very likely to get undesired behaviour if you do this.
Related
I am using Java servlets using Apache tomcat.
I've configured a threadpool and am dealing with each request.
My page is taking in many GET requests at the same time, I'm wondering if I can respond to the server after each get request before any of the logic happens?
So server gives me a request -> I respond with either 'good send another' or 'bad send another' before I start my queueing.
Any help would be much appreciated!
EDIT
Sorry that was terribly written :(
What I'm asking for is a way to send a Header to the client (in this case it's a server which sends me lots of requests). The response would just be 200 or error based on the information I get sent.
What my program is doing:
My servlet gets sent lots of GET requests from one client. (over 100,000) Which I am using tomcat to queue and put into a threadpool. It is then assigned to a worker thread which processes it and puts it into a database.
I've been told to do is send a request back to that server saying 'ok received it'. I think I can use a header response but I don't have the URL of that client (and the client can change for different campaigns). So was wondering what the best way would be to send that response.
After doing some more research I think what I'm looking for is ServletOutputStream.
response.setContentType("text/html");
ServletOutputStream output = response.getOutputStream();
output.flush();
output.close();
Using servlet output stream where do I set the <head><body> tag? and insert the header response afterwards.
The simple answer is "sure".
If these are get requests from a web page for a web page, include a refresh timer and send back some token that can be used to identify the difference between a first-time-request and an I-requested-earlier-are-you-done request. In this case the refresh timer can be set via a meta refresh tag.
If the get requests are part of a REST API then you can define "got it and I'm working" into the protocol. For instance, return a 202 to indicate "got it but not done" and return 200 to indicate "done". As with the html page, consider sending some token back with the 202 that identifies the pending request.
I have a small REST-ful Java back-end that some clients written in C connect to. There is a certain POST method they call where they send some information, I save that to a database and respond with 200 OK, if all goes well. Basic structure shown below.
#POST
#Path("/mypath")
#Produces("text/html")
public Response processMessage(final String message, #Context final HttpServletRequest request) throws IOException {
.....
return Response.ok().build();
}
My issue is that on this response, I get the following error in the log:
javax.ws.rs.NotAllowedException: No resource method found for , return 405 with Allow header
I understand what this error means in circumstances when let's say you try to execute a GET on an endpoint that is supposed to be a POST, for example. I can't understand though why I would get this after my response goes out, and it clearly shows that the request type is empty.... so odd.
Some additional info - the code on the client side has been buggy with incorrect HTTP code... but what would have to be wrong on the client side to cause this kind of response? (I do not have access to the client side code).
Also, there is no client side code in my app, if you are wondering if there is some other code making a call out of my webapp.
Thanks for any ideas!
The issue is most likely on the client side, so without seeing that code it is difficult to offer more detailed information -- but my expectation would be that this is a result of your client attempting to do something like POST or PUT credentials, or something along that line.
Your only recourse is to enable verbose request logging, log the requests that are generating 405 errors, and report it to the client developers.
Worth noting, however, that any publicly-exposed APIs will generate piles of 405s and 404s because "hackers" will try to execute things like WordPress hacks and so on against any known URL.
Is it possible to send HTTP POST request to a webserver and retrieve just headers of response or read just few bytes of the body, so the rest won't be downloaded at all (so it won't consume traffic)? If yes, how?
I know that there is a HEAD method for this, but I need to achieve it by POST method .. well, I am not sure if I need the POST method, I just need to post the data. Maybe if the webserver isn't secured well enough (it doesn't check what method it's used - it's just directly access the post data), is it possible to send "post data" by HEAD request?
There is no built-in HTTP mechanism for this, and HTTP HEAD requests do not allow content in the body. If however you are the one writing the server code then anything is possible.
If this is the case, I would suggest a URL parameter that triggers this behavior. For example:
POST /myURL - This would return the whole response
POST /myURL?body=minimal - Returns the reduced size response that you are looking for.
And you would have to code your server method to construct and return the appropriate response based on the URL parameter.
Is it possible to make GET & POST requests in Java or another language such that you don't care about what is returned?
As in just sending the requests but not wanting to receive any responses?
Whether you care about the response or not, it will be sent. The HTTP protocol specifications say that it must be.
If you don't care about the response, your client could just close the connection immediately after sending the request. But the chances are that you do want to know that the request was processed (i.e. the response status) even if you don't want to look at the contents of the response message.
So maybe you could send the request and request body, and read the response status and then close the connection without reading the response body. However, this has a downside. It means that you can't reuse the HTTP connection to make further requests. The next request to the same server has to open a new connection.
You could use anynchronous HTTP requests if you don't care about the responses (that way your worker thread will not have to wait for the response to come back). See http://www.javaworld.com/javaworld/jw-03-2008/jw-03-asynchhttp.html for some details on Asynchronous/Synchronous HTTP queries in Java. Then you can control if the anychronous thread does or does not handle the response (or any failure flagged on the communication) - as long as there were no TCP level failures on the request the connection will still be opened.
You can't control whether or not the server returns a response. Your code is free to ignore any response it receives.
It's pretty hard to not get responses because they're part of the HTTP protocol. but you can certainly ignore the responses.
im writing a java application that sends a post request to a server and expect a json from the server. Now when i need to get the response from the server do i only need to get it from the inputStream when the http code is 200 (HTTP OK) or is there any other cases ? , example :
//...
if (urlConn.getResponseCode() == HttpURLConnection.HTTP_OK) {
// only here try to get the response
}
//...
It depends on how the server is implemented. Check the API, if the server has one. If it's internal, ask your server guy.
Generally speaking, if your response code is either 2xx or 3xx, I would check the response anyway...
If the server your communicating with is following the spec then either 200 or 201 responses are valid to contain an entity. A 204 response is successful but has no data in the response.
See section 9.5 here: http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html#sec9.5 for details of acceptable responses to a POST. Extract below:
The action performed by the POST method might not result in a resource
that can be identified by a URI. In this case, either 200 (OK) or 204
(No Content) is the appropriate response status, depending on whether
or not the response includes an entity that describes the result.
If a resource has been created on the origin server, the response
SHOULD be 201 (Created) and contain an entity which describes the
status of the request and refers to the new resource, and a Location
header (see section 14.30).
There are three things to consider:
All 2xx codes denote success of some sort. But depending on the exact code, your reading code might be different. (204 for example means success but no content.)
There are redirecting codes (3xx). These are usually automatically followed by the http client library but you can also set them not to, in which case you need to have custom code that handles these cases.
There can be valuable information returned in the stream even if you get a code that denotes an error. Whether you want to process it depends on your exact needs.