I'm trying to set up a client server TCP program where the server has access to a MySQL database. The issue is how to send a QSqlQuery back from the server to the client. The communication server client is through struct data and pickle and I'm getting the expected exception "TypeError cannot pickle QSqlQuery object." I tried to create a custom class "class MyQuery(QSqlQuery)" but I could not make it work. Actually I cannot understand the “Pickling Class Instances” from the” https://docs.python.org/3/library/pickle.html” documentation. Finally I also looked into QNetworkAccessManager that does'nt seam to throw any additional possibility or advantage over socketserver.
The only work around I could figure out was to save the query values in a List and send the list back to the client.
Can somebody help me out. Is it possible to serialize a QSqlQuery? If so, how?. Is there a better way to send a QSqlQuery over a network?
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I want to receive data from an apache server to a client. I just need to receive a string, not a file, but I am curious about a simple way to implement it.
I tried to implement it in php, but it got complicated and gave up.
What is the difference between throw new Error and using Meteor.Error()? Is it simply that throw new Error will not be shown to the client, only on the server (the client will get a 500 Internal server error); and Meteor.Error will be sent to the client.
Are there any more differences? E.g. Does one break out of Fibers, stops downstream code?
The main thing with Meteor.Error is like you mentioned
A full stack trace (may not be given by Error always)
Possibility to send the error down to the client, in a limited non revealing form.
Hide the error from the server in certain cases (if its thrown in a method or publish method, and from hooks such as Accounts.onLoginAttempt)
The objects inside are EJSON serialised so a variety of data can be sent down to the client
When a Meteor.Error is thrown, because of the EJSON serialisation you get a bit more information on the server side.
Meteor displays the errors better.
Often you can get [Object object] as the reason to be displayed from ordinary errors when they come from ordinary Errors, from Meteor.wrapAsync
Theres not much else that's different, Meteor.Error is a a subclass of Error with the above changes.
So they'll both stop downstream code. When it comes to Fibers, if the ordinary one is thrown out of a Fiber in any way its likely to stop your app (on the server side & not in a method, startup, Meteor.setInterval, publish, etc)
Its definition is also quite small: https://github.com/meteor/meteor/blob/devel/packages/meteor/errors.js
I have a problem in delivering sensor data to the xively API via an Arduino Uno v3 and a Sparkfun WiFly shield. The problem is not in the hardware, or in the WiFly shield library since I can deliver the data to the Paraimpu server just fine.
The most fundamental problem is that the xively library will not work with the sparkfun WiFly library. The relevant declarations (suggested by xively in the documentation) are:
WiFlyClient client;
XivelyClient xivelyclient(client);
this will not work since the WiFlyClient declaration expects a server and port, hence I modified this to:
byte server[] = {173,203,98,29}; //api.xively.com IP address
WiFlyClient client(server,80);
XivelyClient xivelyclient(client);
This gives me an error on compilation of :
Xively_sketch2_aug20a:60: error: no matching function for call to 'XivelyClient::XivelyClient(WiFlyClient&)'
/Users/paultravers/Documents/Arduino/libraries/xively/XivelyClient.h:11: note: candidates are: XivelyClient::XivelyClient(Client&)
/Users/paultravers/Documents/Arduino/libraries/xively/XivelyClient.h:9: note: XivelyClient::XivelyClient(const XivelyClient&)
At this point I am stuck, and my attempts to modify the various libraries to try to reconcile this issue have come to no avail - mostly because it is above my skill level and I really don't know what I am doing.
To get round this, I have written the code to build the put request and send that to the API, using the template of the code that runs successfully to send data to Paraimpu.
I open a connection (either to api.xively.com or to 173.203.98.29; it makes no difference at this stage) and send the following :
PUT /v2/feeds/<feed ID redacted>.json
Host: api.xively.com
Content-Type: application/json
User-Agent : Xively-Arduino-Lib/1.0
X-ApiKey: < API key redacted >
Content-Length: 197
{"version":"1.0.0","datastreams" : [{"id":"TEMPERATURE_CHANNEL" , "current_value" : "29.00"},{"id":"LIGHT_SENSOR_CHANNEL","current_value":"541.00"},{"id":"ALARM_CHANNEL","current_value":"0.00"}]}
Terminating with a blank line.
Needless to say I have set up channels in xively with those names. But this does not work - I don't get the expected return, and the channels don't update. If I read the returning input on the connection it is just a long string of numbers. Can anyone see anything wrong in the format of this request?
i might take a look at WiFlyClient's documentation...maybe you need to set the port/etc in some other way...than extend WiFlyClient
class WiFlyClient2 : public WiFlyClient {
WiFlyClient2(int[] ip,int port) : WiFlyClient() {
//setup up your parent by calling it's functions here
}
}
then it should work like:
byte server[] = {173,203,98,29}; //api.xively.com IP address
WiFlyClient client(server,80);
XivelyClient xivelyclient(client);
note: i never use wifly/etc, i just use arduino...and i run into troubles like this too :)
I don't have a WiFly shield to test with. But as you said in your comment to Zoltan, I don't think that the WiFly client works in the same way that the Arduino Ethernet or Wifi do. This means that the Xively library likely does not work with the WiFly client.
This means that your approach of writing your own HTTP request is probably the way to go. I looked through your request and it looks exactly correct to me. Does anything show up in the Xively Workbench Request Log when you send the request?
One thing you could try is to use the CSV format instead. This can be better for testing since you avoid the possibility of a minor JSON error causing your entire request to not work. To do this change your .json to .csv and then simply make your body a comma separated list of datastream,value. Your body should look something like this:
TEMPERATURE_CHANNEL,29.00
LIGHT_SENSOR_CHANNEL,541.00
ALARM_CHANNEL,0.00
If this does not work it would be helpful if you could post what the return is, that would help us help you. Good luck!
One thing I noticed in your code is that you don't send the HTTP version in your request.
You should try sending:
PUT /v2/feeds/<feed ID redacted>.json HTTP/1.1
I was getting 405 errors when writing to Xively because I incorrectly had HTTP/1.0 as the version in my put requests.
There's also an example from SparkFun's WiFly library that shows writing to Thingspeak which is helpful to make sure you're using the WiFlyClient instance correctly.
I want to build a wcf web service so that the client and the server would be able to transfer files between each other. Do you know how I can achieve this? I think I should turn it into a byte array but I have no idea how to do that. The file is also quite big so I must turn on streamed response.
It sounds like you're on the right track. A quick search of the interwebz yielded this link: http://www.codeproject.com/Articles/166763/WCF-Streaming-Upload-Download-Files-Over-HTTP
Your question indicates that you want to send a file from a java client to a WCFd endpoint, but the contents of your question indicate that this should be a bidirectional capability. If this is the case, then you'll need to implement a service endpoint on your client as well. As far as that is concerned, I cannot be of much help, but there are resources out there like this SO question: In-process SOAP service server for Java
As far as practical implementation, I would think that using these two links you should be able to produce some code for your server and client.
As far as reading all bytes of a file, in C# you can use: File.ReadAllBytes It should work as in the following code:
//Read The contents of the file indicated
string fileName = "/path/to/some/file";
//store the binary in a byte array
byte[] buffer = File.ReadAllBytes(fileName);
//do something with those bytes!
Be sure to use the search function in the future:
I am writing a iOS client for a an existing product that uses a legacy SOAP webservice. I got the proper URL to send my SOAP/XML messages too and even have some samples. However, none of them seem to work...
I always get a 404 error with the following error text "Predicate mismatch for View"
I am using an ASIFormDataRequest for the actual request and apending the data (SOAP XML in this case) via [someFormRequest appenData:myData].
I am flat out of ideas here and am wondering what, if anything I am doing wrong. Or should I ping one of the back end guys? Could this error be a result of something on the server side?
This is an error message spit out by the pyramid web framework when attempting to access a URL without supplying all of the required parameters. You definitely want to double check that the URL you are using has all of the required params (headers, query string options, request body, etc) and if you're convinced that what you are sending is correct then but your backend guys because it's definitely a miscommunication or a bug between the two of you.