Cookie usernameCookie = new Cookie ("username", attributeUsername);
usernameCookie.setMaxAge(24*60*60);
response.addCookie(usernameCookie);
A cookie is created in the server in this way and it is added to the HttpServletResponse .
Then why is it that , a HttpServletRequest Header contain cookies ??
Cookies are transmitted per request, example use case:
The first client request does not contain cookies
Server sets cookie A, it is transmitted back to the client in HTTP header Set-Cookie; this is what response.addCookie does.
The second client request sends HTTP header Cookie containing a list of all matching cookies (including cookie A)
Cookies are part of the HTTP protocol. Wikipedia provides a fine overview: http://en.wikipedia.org/wiki/HTTP_cookie
Related
I try to emulate the access to the webservice of my company using a dart file.
Here is my request where I try to send the jsessionid cookie to the server :
taches = await http.post(
Uri.parse('https://test1.beotic.net/beop3server62/p3servicejson'),
headers: ({
"content-type": "application/json-rpc",
"set-cookie": setcookie
}),
body: body
);
The recuperate the setcookie variable is from the response header of a previous request that I sent to the server with an authentication token, what's inside setcookie look like this : JSESSIONID=01D68460B589F3B34A9C3208FA6CEA51; Path=/beop3server62; Secure
But it seems that the setcookie variable is never sent to the server as the response to this last request always contains a different jsessionid cookie in its headers and the body is :
{"jsonrpc":"2.0","id":"10","error":{"code":0,"message":"The user is
not
authentified","data":{"exceptionTypeName":"com.beotic.apps.p3.exception.AuthentificationException","message":"The
user is not authentified"}}}
I'm quite lost with all this as I tried many different things and none of them seem to work.
Thanks for helping !
Set-Cookie is a response header, not a request header.
Clients should read the Set-Cookie header, use the information in it to store data in their internal cookie jars, then generate Cookie request headers from the cookie jars when making subsequent requests to the same host.
I'm trying to send a request with a session cookie, but when the request is sent the value for that cookie changes.
Here is how the cookie looks:
Here is how it looks after the request has been sent:
What is happening ?
Sorry for the late answer to this question. The only reason I see for the cookie to change is if the server sends back a Set-Cookie header in the response.
Paw will behave like web browsers by sending by default a Cookie header with the cookies stored for this domain, and will store new cookies when the server sends back a Set-Cookie header.
You can see all cookies stored in Paw by going to the left panel > Sessions > Manage:
Also, please note that you have the ability to disable cookie sending and/or cookie saving for each request in the Request > Options tab:
When you set a cookie, you set the raw cookie data, and some metadata. This metadata includes the path for where the cookie is valid, the expiration time of the cookie, and so on.
When a browser performs a request, what exactly will the browsers send with it? Will it send the full cookie, with all the "metadata"? Or only the actual data of the cookie, without the metadata?
No only the value of the cookie is returned in subsequent requests, the other metadata stays on the client.
When you define a cookie on the server a Set-Cookie header is created in the response carrying the name, value and other metadata about the cookie. Multiple Cookies will create multiple Set-Cookie headers in the response.
When the browser makes subsequent requests it checks its "database" of available cookies to see which cookies are appropriate for the path being requested. It then creates a single Cookie header in the request that carries just a series of name/value pairs of the qualifying cookies.
Its important to keep tight control on the number of cookies and the size of the data otherwise you may find that the weight of cookie data being sent for each and every request can be deterimental to performance. This would be much worse if the metadata were returned with the cookies as well.
The server sets the cookie with the "Set-Cookie" header. This contains the metadata (path and expiry), if specified. The client (browser) only sends the cookie itself in a "Cookie" header.
Firebug is a useful tool for Firefox to view all these headers. Similar tools should be available for other browsers.
only the cookie data is sent to server,other metadata is for the browser to perform some actions like cookie expiration
the user-agent will re-transmit the path, domain, and port attributes if the cookie was set under RFC2965 (via the Set-Cookie2 header) and if the attribute was specified by the server. a sample request might contain:
Cookie: $Version="1";
name="val"; $Path="/site"; $Domain=".example.com"; $Port="81";
name="val"; $Path="/site/dir"; $Domain=".example.com"; $Port="81"
if the cookie was specified using the original netscape Set-Cookie header, no attributes will be re-transmitted. if multiple cookies with the same name (but different paths) are valid for the request, all matching cookies will be supplied. an example request:
Cookie: name=val; name=val2
the full spec is here:
https://www.rfc-editor.org/rfc/rfc2965
the original netscape spec is here:
http://web.archive.org/web/20070805052634/http://wp.netscape.com/newsref/std/cookie_spec.html
Since HTTP is a stateless protocol, when a client makes a number of requests to the server, how does the server uniquely identify a particular client's requests over a period of time say t1, t2, t3..
I browsed the web and came across terms like session id, URL rewriting and cookies. But it would be great if someone explains it in a better way. Specifically which part of the HTTP request and response would be used for session tracking?
As you mentioned, common ways to implement HTTP session tracking include URL rewriting and cookies. Session tracking basically requires that a session ID is maintained across multiple requests to the server. This means that each time a given client makes a request to the server, it passes the same session ID. The server can use this ID to lookup the session information it maintains.
When using cookies, the server asks the client to store a cookie by setting the Set-Cookie HTTP response header. This cookie contains the unique session ID assigned to that client - in this example the string 'ABAD1D':
Set-Cookie: JSESSIONID=ABAD1D;path=/
The cookie is then sent back to the server by the client using the Cookie HTTP request header on each request and thus the server is informed on each request the session ID currently assigned to the client.
Cookie: JSESSIONID=ABAD1D
When using URL rewriting, this same session ID is instead sent somewhere in the URL. Again, the server extracts the session ID from the URL so that it can lookup the session for a particular client:
http://my.app.com/index.jsp;JSESSIONID=ABAD1D
However, the server must also make sure that any URLs in the web pages sent back to the client are also rewritten to contain that particular clients session ID. As the session ID is encoded in the URLs, this method of session tracking is transparent to the browser. Often a server will resort to URL rewriting if it finds it is unable to set a session cookie on the client - implying that the client does not support/allow cookies.
Note that sessions can expire. This means that if the server does not 'see' a given session ID for a period of time, it may remove the session data to preserve resources.
Specifically which part of the HTTP
request and response would be used for
session tracking?
In the HTTP response, the server can set a cookie. It does so with the Set-Cookie header. For example:
Set-Cookie: session=12345; path=/
The client then returns the value of all cookies that match the properties that were set along with the cookie, which can include path (as above) and domain, and that haven't expired yet.
The cookie is sent back to the server as part of the HTTP headers. For example:
Cookie: session=12345
None of the original property information is sent back with the cookie.
A unique cookie allows the server to associate a unique key with a particular browser instance. The server can then use that key as an index into a hash table or a database table that holds unique per-user state information.
Session tracking is a server side thing.
A web server issues some session identifier that is returned to the browser. Browser submits this session identifier along with each request.
This is probably done using cookies transparently for the user.
the session handling is in most case handled by sending a cookie to the client. that cookie would be sent back to the server on every request from that particular client.
The session id will be associated with some resources on server side (file,ram space) so the server by reading the session id in the cookie can find this resource and then know which client it was.
Find enough details here
HTTP Sessions are the recommended approach. A session identifies the requests that originate from the same browser during the period of conversation. All the servlets can share the same session. The JSESSIONID is generated by the server and can be passed to client through cookies, URL re-writing (if cookies are turned off) or built-in SSL mechanism. Care should be taken to minimize size of objects stored in session and objects stored in session should be serializable. In a Java servlet the session can be obtained as follows:
HttpSession session = request.getSession(); //returns current session or a new session
Sessions can be timed out (configured in web.xml) or manually invalidated.
HTTP Session allows web servers to maintain user identity and store user specific data during multiple request/response between client and we application
Given a URI which has headers for caching properly configured.
If two users make a request to the same URI but provide two different sets of credentials, will a proxy cache the response per user+URI, or per URI, or not at all?
The response will only be used for other users if the Cache-Control response header contains the public directive. Apart from that, the proxy must not cache a response to an authorized request.
Read the section Authorization of the HTTP 1.1 standard for all the details.