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.
Related
I'm start learning java programming, and I want make a simple server application. I read about com.sun.net.httpserver.HttpServer and find a good example on this link: https://github.com/imetaxas/score-board-httpserver-corejava.
I understand how to do Get-request in url, but I don't know how POST works. I think it must be sent a form or data on the server.
I attach the link of project, which I'm learning, in readme the author wrote http://localhost:8081/2/score?sessionkey=UICSNDK - it's not working...
I wrote in url and get sessionkey: "localhost:8081/4711/login --> UICSNDK"
I wrote in url this for Post request: "localhost:8081/2/score?sessionkey=UICSNDK" - not working and in chrome return 404 bad request
3.wrote in url this:"localhost:8081/2/highscorelist"
Please help me, I am beginner.
The difference between GET and POST is that with a GET request the data you wish to pass to the endpoint is done by modifying the url itself by adding parameters to it.
With a POST any data you wish to send to the endpoint must be in the body of the request.
The body of a request is arbitrary data that comes after a blank line in the header The reqiest has the request line, following by any number of header attributes, then a blank line.
The server would need to know what the format of the body of the request was and parse it as appropriate.
Of course 'modern' frameworks like jax-rs allow you to automatically convert request data to objects, so that it is much simpler.
I am trying to read Jira issue data using a webhook that posts the data to my servlet.
When I travserve the request parameters map, I don't find anything in it.
But the content lenght shows as "8876" which means webhook is sending the data. Somehow I am not able to read/retrieve the data in my servlet.
Also checked, content-type returns as "application/json".
Does anyone know how to read Jira webhook post data?
You have to read the response body, not the parameters map. For that purpose you can use
request.getInputStream();
or
request.getReader();
method.
PS: You can configure the web hook to post data to http://requestb.in/ so you can easily analyze the request parameters, the request body, the headers, etc.
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Possible Duplicate:
Servlets: doGet and doPost
I know doGet() request is appended to the request URL in a query string.But I don't know the concept of doPost() request.how does doPost request posting information to the server.
Please Guide me to get the working concept of doPost request...
Post requests are used usually for sending data to Server, and get request for reading data from server. In Post request data is sent in http request body, so data size can be very large compared to Get. If a browser fires an POST request (usually a form submit) doPost of the mapping Servlet will be called. There is another overloaded method (service()) which is called for both GET and POST
In doPost() the data is not appended in the URL.
It can handle large amount of data compared to the doGet() method.
Filling of form and submitting is done through doPost(), it's secure to use doPost() during submission of the username and password.
There is also differnce in the doGet() and doPost() header and body structure.
The main conceptual difference GET and POST is that, GET is used for getting the data from the server, and POST is used for updating the data to the server.
In general POST has the following properties:
The data is x-www-form-urlencoded . Which means, the request parameters are sent as request body. And the server has to parse the request body for parameters.
By default, when no content-length header is present, the default value for GET is 0 whereas for POST it is till end of stream.
GET is Idempotent whereas POST is Non-Idempotent. i.e, Proxies on failures for GET they retry. But, for POST they do not retry.
doGet() can be used when client request doesn't intend to change stored data.
I am trying to simulate HTTP requests in Java with the URL class and the HttpURLConnection class, the GET requests are easy to simulate while some POST requests seem harder because most POST request need Cookie in the request header. Some cookies were set by the HTTP response in the Set-Cookie field and I can get them by the function provided by HttpURLConnection, but I found that other cookies may be set by JavaScript and I have no way to handle them, so I wonder is there any packaged tool to simulate HTTP requests in Java?
try Apache commons Httpclient:
http://hc.apache.org/httpclient-3.x/
Why do you need to generate HTTP requests? Do you want to perform some stress tests?
I'd advise using something like JMeter (you can find a brief tutorial here).
Hope this helps something, it's better to avoid reinventing the wheel (if you need something like this, but it wasn't clear for me from your question).
For the cookie set with Javascript, you could try to parse the HTTP response, extract the cookie information and set it for your next request
For example, lets say, the response has code which calls a setCookie() function (setCookie is user-defined javascript function),
...
//some javascript code
setCookie("username", "johndoe");
//some more javascript
...
then you would extract the line setCookie() and the parse it for the name and value
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.