I am building a websocket client in q with the aim of connecting to cryptocurrency exchanges to receive public market data feeds in json for parsing into kdb. At this point, using this guide from KX's official knowledge base, I have managed to create a persistent websocket connection from my q process to the Kraken exchange by using stunnel as verified by a successful connection/upgrade response. My q script just defines .z.ws to show incoming messages, then connects to my local port running stunnel.
.z.ws:{0N!.j.k(x);}
h:(`:ws://127.0.0.1:5103)"GET / HTTP/1.1\r\nHost: ws.kraken.com\r\n\r\n"
My stunnel configuration looks like this:
[kraken]
client = yes
sni = ws.kraken.com
accept = 127.0.0.1:5103
connect = 104.16.212.191:443
It all seems to work because as mentioned before, my q process receives the following successfull system status confirmation.
`connectionID`event`status`version!(9.223372e+18;"systemStatus";"online";"1.7.2")
The guide says "If successful it will return a 2-item list of (handle;HTTP response)" which I also do recieve. They look like this:
(6i ;"HTTP/1.1 101 Switching Protocols\r\nDate: Mon, 08 Feb 2021 22:52:53 GMT\r\nConnection: upgrade\r\nSet-Cookie: __cfduid=d8179f7ef5db4e4e7a164dd75a492c2141612824773; expires=Wed, 10-Mar-21 22:52:53 GMT; path=/; domain=.kraken.com;HttpOnly; SameSite=Lax\r\nUpgrade: websocket\r\nSec-WebSocket-Accept: HSmrc0sMlYUkAGmm5OPpG2HaGWk=\r\nuWebSockets:17\r\nCF-Cache-Status: DYNAMIC\r\ncf-request-id: 082..)
I really thought that would be the tough part and I'm feeling somewhat proud to have succeeded thus far, but now I'm finding myself stuck again.
How do I interact with the websocket now? I want to send more messages ie. subscribe/unsubscribe to specific endpoints?
The guide cited above says very clearly "To send messages, use
q)neg[handle]"text" / a char vector"
but whenever I try
q)neg[6i].j.j(`ping)
I get the following error
'Cannot write to handle 6. OS reports: Bad file descriptor
I suspect maybe I need to subscribe to certain endpoints somehow in my initial GET request, but I'd still like to be able to subscribe and unsubscribe from different endpoints freely after having connected to the websocket.
Thanks for reading, and any insight is much appreciated. This is my first time posting on stackoverflow.
Best Regards,
Ross
That error could be related to your message getting rejected. I had a quick look at the python example and it looks to expect json like this:
{"event": "ping"}
So you'd need to send something like this:
q).j.j(1#`event)!1#`ping
"{\"event\":\"ping\"}"
https://support.kraken.com/hc/en-us/articles/360022327631-WebSocket-API-Public-Feeds-Python-Code-Examples
Aqua Q has a Crypto add-on for their TorQ kdb framework which could be useful:
https://www.aquaq.co.uk/q/torq-crypto-released/
https://github.com/AquaQAnalytics/TorQ-Crypto
(Disclaimer, I work for Aqua Q)
I have an Electron application that uses Kibana iframes in it. I am using a splash screen to wait for Kibana before showing my program interface, so that user will not see the "Kibana server not ready yet" text. I am trying to send GET request to "http://localhost:5601/status" to check if it returns 200 as status code. Doing this in a loop until I get 200 response and when I got the 200 code I close splash screen and show my program interface. However Kibana iframes still shows Kibana server not ready yet error. What is the reason behind this? Is there any other API URL that I can check to determine Kibana is completely ready? Please help
There is no 200 in the response. I think you are looking at whether the call to http://localhost:5601/status was successful which returns a 200. which means Kibana is up but probalbly not ready yet or is "warming up"
However, you should capture the response and make sure the overall status is green
This also sends statuses which shows status of each individual plugin, so if you dont care about certain plugin, you can iterate and check status only for required plugins.
I'm trying to do JMeter script for an application with Signalr protocol.
I'm able to identify connection-token, bearer-token, connection-id and co relate with request using long polling transport and receive message, but after third polling I could not receive the correct response, i'm getting response but not the expected and full response.
Could you please help me what could be the issue here?
I'm afraid no one will be able to help without seeing at least:
Anticipated response
Actual response
Reference requests sequence from i.e. real browser captured with a sniffer tool like Wireshark or Fiddler
The same as point 3 but for JMeter instead of the real browser.
Basically you need to execute points 3 and 4 and compare the generated network requests - they must be the same apart from the dynamic parameters (tokens, connection-id, etc.). Given requests are the same - you should be getting the same responses.
Another option is using While Controller in order to continue polling unless response matches your expectation.
I am making a request to a CGI program using AJAX. The response sends me content-length. My purpose is to dynamically exhibit the response progress. For that I need to start a function on onreadystate value of XHR object to be 3. But the request doesn't seems to acquire that status number. Instead it goes directly from state 1 to state 4.
What am I missing?
The response could be going so quickly that you just don't notice it at state 3. Especially if you are running it on localhost, the response could be transmitted very quickly. You could try setting an alert when it gets to stage 3 to test whether it's actually getting there. Also, I belive internet explorer says that it is a mistake to access the response in stage 3 so there could be compatibility issues.
If you're running on localhost, then probably the browser is never getting a chance to run between the time it sends the request and the time it gets the response...
browser opens connection, sets readyState to 1
browser sends packet to server process
server process receives packet, gets priority from scheduler
server returns data to browser, and yields control of the CPU. Browser continues execution.
browser sees all data has been received, sets readyState to 4.
Long story short: don't count on going into the "receiving" state.
A customer sometimes sends POST requests with Content-Length: 0 when submitting a form (10 to over 40 fields).
We tested it with different browsers and from different locations but couldn't reproduce the error. The customer is using Internet Explorer 7 and a proxy.
We asked them to let their system administrator see into the problem from their side. Running some tests without the proxy, etc..
In the meantime (half a year later and still no answer) I'm curious if somebody else knows of similar problems with a Content-Length: 0 request. Maybe from inside some Windows network with a special proxy for big companies.
Is there a known problem with Internet Explorer 7? With a proxy system? The Windows network itself?
Google only showed something in the context of NTLM (and such) authentication, but we aren't using this in the web application. Maybe it's in the way the proxy operates in the customer's network with Windows logins? (I'm no Windows expert. Just guessing.)
I have no further information about the infrastructure.
UPDATE: In December 2010 it was possible to inform one administrator about this, incl. links from the answers here. Contact was because of another problem which was caused by the proxy, too. No feedback since then. And the error messages are still there. I'm laughing to prevent me from crying.
UPDATE 2: This problem exists since mid 2008. Every few months the customer is annoyed and wants it to be fixed ASAP. We send them all the old e-mails again and ask them to contact their administrators to either fix it or run some further tests. In December 2010 we were able to send some information to 1 administrator. No feedback. Problem isn't fixed and we don't know if they even tried. And in May 2011 the customer writes again and wants this to be fixed. The same person who has all the information since 2008.
Thanks for all the answers. You helped a lot of people, as I can see from some comments here. Too bad the real world is this grotesque for me.
UPDATE 3: May 2012 and I was wondering why we hadn't received another demand to fix this (see UPDATE 2). Looked into the error protocol, which only reports this single error every time it happened (about 15 a day). It stopped end of January 2012. Nobody said anything. They must have done something with their network. Everything is OK now. From summer 2008 to January 2012. Too bad I can't tell you what they have done.
UPDATE 4: September 2015. The website had to collect some data and deliver it to the main website of the customer. There was an API with an account. Whenever there was a problem they contacted us, even if the problem was clearly on the other side. For a few weeks now we can't send them the data. The account isn't available anymore. They had a relaunch and I can't find the pages anymore that used the data of our site. The bug report isn't answered and nobody complaint. I guess they just ended this project.
UPDATE 5: March 2017. The API stopped working in the summer of 2015. The customer seems to continue paying for the site and is still accessing it in February 2017. I'm guessing they use it as an archive. They don't create or update any data anymore so this bug probably won't reemerge after the mysterious fix of January 2012. But this would be someone else's problem. I'm leaving.
Internet Explorer does not send form fields if they are posted from an authenticated site (NTLM) to a non-authenticated site (anonymous).
This is feature for challange-response situations (NTLM- or Kerberos- secured web sites) where IE can expect that the first POST request immediately leads to an HTTP 401 Authentication Required response (which includes a challenge), and only the second POST request (which includes the response to the challange) will actually be accepted. In these situations IE does not upload the possibly large request body with the first request for performance reasons. Thanks to EricLaw for posting that bit of information in the comments.
This behavior occurs every time an HTTP POST is made from a NTLM authenticated (i.e. Intranet) page to a non-authenticated (i.e. Internet) page, or if the non-authenticated page is part of a frameset, where the frameset page is authenticated.
The work-around is either to use a GET request as the form method, or to make sure the non-authenticated page is opened in a fresh tab/window (favorite/link target) without a partly authenticated frameset. As soon as the authentication model for the whole window is consistent, IE will start to send form contents again.
Definitely related: http://www.websina.com/bugzero/kb/browser-ie.html
Possibly related: KB923155
Full Explanation: IEInternals Blog – Challenge-Response Authentication and Zero-Length Posts
This is easy to reproduce with MS-IE and an NTLM authentication filter on server side. I have the same issue with JCIFS (1.2.), struts 1. and MS-IE 6/7 on XP-SP2. It was finally fixed. There are several workarounds to make it up.
change form method from POST (struts default setting) to GET.
For most pages with small sized forms, it works well. Unfortunately i have possibly more than 50 records to send in HTTP stream back to server side. IE has a GET URL limit 2038 Bytes (not parameter length, but the whole URL length). So this is a quick workaround but not applicable for me.
send a GET before POST action executing.
This was recommended in MS-KB. My project has many legacy procedures and i would not take the risk at the right time. I have never tried this because it still needs some extra authentication processing when GET is received by filter layer based on my understanding from MS-KB and I would not like to change the behavior with other browsers, e.g. Firefox, Opera.
detecting if POST was sent with zero content-length (you may get it from header properties hash structure with your framework).
If so, trigger an NTLM authentication cycle by get challenge code from DC or cache and expect an NTLM response.
When the NTLM type2 msg is received and the session is still valid, you don't really need to authenticate the user but just forward it to the expected action if POST content-length is not zero. BTW, this would increase the network traffics. So check your cache life time setting and SMB session soTimeOut configuration before applying the change plz.
Or, more simple, you may just send a 401-unauthorized status to MS-IE and the browser shall send back POST request with data in reply.
MS-KB has provided a hot-fix with KB-923155 (I could not post more than one link because of a low reputation number :{ ) , but it seems not working. Would someone post a workable hot-fix here? Thanks :) Here is a link for reference, http://www.websina.com/bugzero/kb/browser-ie.html
We have a customer on our system with exactly the same problem. We've pin pointed it down to the proxy/firewall. Microsoft's IAS. It's stripping the POST body and sending content-length: 0. Not a lot we can do to work around however, and down want to use GET requests as this exposes usernames/passwords etc on the URL string. There's nearly 7,000 users on our system and only one with the problem... also only one using Microsoft IAS, so it has to be this.
There's a good chance the problem is that the proxy server in between implements HTTP 1.0.
In HTTP 1.0 you must use the Content-Length header field: (See section 10.4 here)
A valid Content-Length is required on
all HTTP/1.0 POST requests. An
HTTP/1.0 server should respond with a
400 (bad request) message if it cannot
determine the length of the request
message's content.
The request going into the proxy is HTTP 1.1 and therefore does not need to use the Content-Length header field. The Content-Length header is usually used but not always. See the following excerpt from the HTTP 1.1 RFC S. 14.13.
Applications SHOULD use this field to
indicate the transfer-length of the
message-body, unless this is
prohibited by the rules in section
4.4.
Any Content-Length greater than or
equal to zero is a valid value.
Section 4.4 describes how to determine
the length of a message-body if a
Content-Length is not given.
So the proxy server does not see the Content-Length header, which it assumes is absolutely needed in HTTP 1.0 if there is a body. So it assumes 0 so that the request will eventually reach the server. Remember the proxy doesn't know the rules of the HTTP 1.1 spec, so it doesn't know how to handle the situation when there is no Content-Length header.
Are you 100% sure your request is specifying the Content-Length header? If it is using another means as defined in section 4.4 because it thinks the server is 1.1 (because it doesn't know about the 1.0 proxy in between) then you will have your described problem.
Perhaps you can use HTTP GET instead to bypass the problem.
This is a known problem for Internet explorer 6, but not for 7 that I know of. You can install this fix for the IE6 KB831167 fix.
You can read more about it here.
Some questions for you:
Do you know which type of proxy?
Do you know if there is an actual body sent in the request?
Does it happen consistently every time? Or only sometimes?
Is there any binary data sent in the request? Maybe the data starts with a \0 and the proxy has a bug with binary data.
If the user is going through an ISA proxy that uses NTLM authentication, then it sounds like this issue, which has a solution provided (a patch to the ISA proxy)
http://support.microsoft.com/kb/942638POST requests that do not have a POST body may be sent to a Web server that is published in ISA Server 2006
I also had a problem where requests from a customer's IE 11 browser had Content-Length: 0 and did not include the expected POST content. When the customer used Firefox, or Chrome the expected content was included in the request.
I worked out the cause was the customer was using a HTTP URL instead of a HTTPS URL (e.g. http://..., not https://...) and our application uses HSTS. It seems there might be a bug in IE 11 that when a request gets upgraded to HTTPS due to HSTS the request content gets lost.
Getting the customer to correct the URL to https://... resulted in the content being included in the POST request and resolved the problem.
I haven't investigated whether it is actually a bug in IE 11 any further at this stage.
Are you sure these requests are coming from a "customer"?
I've had this issue with bots before; they sometimes probe sites for "contact us" forms by sending blank POST requests based on the action URI in FORM tags they discover during crawling.
Presence and possible values of the ContentLength header in HTTP are described in the HTTP ( I assume 1/1) RFC:
http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.13
In HTTP, it SHOULD be sent whenever the message's length can be determined prior to being transferred
See also:
If a message is received with both a
Transfer-Encoding header field and a Content-Length header field,
the latter MUST be ignored.
http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.4
Maybe your message is carrying a Transfer-Encoding header?
Later edit: also please note "SHOULD" as used in the RFC is very important and not equivalent to "MUST":
3. SHOULD This word, or the adjective "RECOMMENDED", mean that there
may exist valid reasons in particular circumstances to ignore a
particular item, but the full implications must be understood and
carefully weighed before choosing a different course.
Ref: http://www.ietf.org/rfc/rfc2119.txt
We had a customer using same website in anonymous and NTLM mode (on different ports). We found out that in our case the 401 was related to Riverbed Steelhead application used for http optimization. The first signal pointing us into that direction was a X-RBT-Optimized-By header. The issue was the Gratuitous 401 feature:
This feature can be used with both per-request and per-connection
authentication but it‘s most effective when used with per-request
authentication. With per-request authentication, every request must be
authenticated against the server before the server would serve the
object to the client. However, most browsers do not cache the server‘s
response requiring authentication and hence it will waste one
round-trip for every GET request. With Gratuitous 401, the client-side
Steelhead appliance will cache the server response and when the client
sends the GET request without any authentication headers, it will
locally respond with a ―401 Unauthorized‖ message and therefore saving
a round trip. Note that the HTTP module does not participate in the
actual authentication itself. What the HTTP module does is to inform
the client that the server requires authentication without requiring
it to waste one round trip.
Google also shows this as an IE (some versions, anyway) bug after an https connection hits the keepalive timeout and reconnects to the server. The solution seems to be configuring the server to not use keepalive for IE under https.
Microsoft's hotfix for KB821814 can set Content-Length to 0:
The hotfix that this article describes implements a code change in Wininet.dll to:
Detect the RESET condition on a POST request.
Save the data that is to be posted.
Retry the POST request with the content length set to 0. This prevents the reset from occurring and permits the authentication process to complete.
Retry the original POST request.
curl sends PUT/POST requests with Content-Length: 0 when configured to use HTTP proxy. It's trick to overcome required buffering in case of first unauthorized PUT/POST request to proxy. In case of GET/HEAD requests curl simply repeats the query. The scheme for PUT/POST is like:
Send first PUT/POST request with Content-Length set to 0.
Get answer. HTTP status code of 407 means we have to use proxy
authorization. Prepare headers for proxy authentication for send request.
Send request again with filled headers for proxy authentication and real data to POST/PUT.