I have an application that connect to an IP camera and that do HTTP request to get image and M-JPEG. For now it's ok because I have the camera in the developpement room. But in a few weeks, the cam will be out in production (they are very expensive cam) so I will not have them for testing and debugging my app.
What I want to know is what would be the best way to "mock" these cams? For now, my application is using 2 cams, let's say they are on http://192.168.88.1 and http://192.168.88.2. I have think of this:
In my application, I could encapsulate the functions that do the
http calls in a class that could do real http request when in
release and fake when in debug. The bad side of this is that it will
not reproduce real thing like occasional timeout and network
traffic.
Maybe there is a ip cam simulator somewhere that I can put on my
network and use?
Maybe create real http request to a real server that I will have
programmed to return fake picture? If so, how to procede?
Like you see, I have ideas but I'm not sure what's the best and what people out there are doing. With your answers, take in consideration that I might use it for unit testing as well as normal debugging while the camera is away.
Thanks!
Ad. 1: This is a good approach when unit testing - your code should not depend on external servers/devices/file systems. But you already see that this environment might be too idealized. However I would aim to externalize HTTP infrastructure code - this will both improve your testing capabilities and overall architecture.
Ad. 2: Never heard of such, sorry.
Ad. 3: I think this is the most feasible solution. If you've ever worked with servlets, just grab Tomcat or Jetty and write one. Then connect to your servlet under localhost:8080/war_name/servlet_name and return whatever you want from it. Here is a dead simple example.
If you've never heard about Java servlets and servlet containers - it's still worth to learn about them. But it might be faster to start an HTTP server built into the Sun JDK, see HttpServer API and an example.
If you want real images and have access to a webcam, you could create, in your solution, an ASP.Net webservice that takes a picture out of your webcam on request.
When you're in debug mode, configure your solution to start the webservice on the asp.net developpement server, so you don't have to configure a "real" web server
Here is a link to code to take a snapshot from c#
It's for winforms, but it should be adaptable for a web service
http://sites.google.com/site/webcamlibrarydotnet/winfrom-and-csharp-sample-code-and-download
I'd recommend creating a simple test harness using Sinatra. Sinatra is very simple to use to stub out any kind of basic web app like this.
For example, here's a real program written using Sinatra:
require 'sinatra'
get '/hi' do
"Hello World!"
end
This will run a simple web listener that will respond Hello World! if you hit the URI /hi.
Sinatra is a Ruby-based app and it's best if you know Ruby. If you don't or if you have a strong preference for another language, Sinatra's Wikipedia page lists 25+ similar apps that are written in all kinds of other languages, so there's likely an option you can use.
Use python build in http server
# sudo python -m http.server 80
Serving HTTP on 0.0.0.0 port 80 ...
123.123.12.1 - - [12/Feb/2018 11:34:02] "GET / HTTP/1.1" 200 -
Related
I've designed a desktop app using PyQt GUI toolkit and now I need to embed this app on my Django website. Do I need to clone it using django's own logic or is there a way to get it up on website using some interface. Coz I need this to work on my website same way it works as desktop. Do I need to find out packages in django to remake it over the web or is there way to simplify the task?
Please help.
I'm not aware of any libraries to port a PyQT desktop app to a django webapp. Django certainly does nothing to enable this one way or another. I think, you'll find that you have to rewrite it for the web. Django is a great framework and depending on the complexity of your app, it might not be too difficult. If you haven't done much with web development, there is a lot to learn!
If it seemed like common sense to you that you should be able to run a desktop app as a webapp, consider this:
Almost all web communication that you likely encounter is done via HTTP. HTTP is a protocol for passing data between servers and clients (often, browsers). What this means is that any communication that takes place must be resolved into discrete chunks. Consider an example flow:
You go to google in your browser.
Your browser then hits a DNS server (or cache) that resolves the name google.com to some IP address.
Cool, now your browser makes a request to that IP address and says "get me some stuff".
Google decides to send you back a minimal amount of HTML and lots of minified JavaScript in the page.
Your browser realizes that there are some image links in the HTML and so it makes additional requests to google to get each of the images so that it can display them.
Now all the content is loaded on your browser so it starts to execute the JavaScript code, and that code needs some more data from google so it starts sending requests to google too.
This is just a small example of how fundamentally different a web application operates than how a desktop application does. On a desktop app you have the added convenience that any operation doesn't need to be "packaged up" and sent, then have an action taken, etc (unless you're using a messaging architecture, but that's relatively uncommon outside of enterprise apps).
I am writing a backend web api for a mobile app. It should support HTTPS. Most of my experience in .NET, but for this one I want to use Go/Golang. I have a sample service ready, now I need to make sure that it is production ready.
In .NET I will just use IIS, but I have no clue what would be a good approach for Go.
Should I have nginx as reverse proxy, or I better use FastCGI ? And how to make sure that my go app is up and will run on system reboot ? should I use upstart or something similar ?
I've been using Nginx FastCGI with a Go webservice - they work well together. It's no harder to set up than HTTP reverse proxying - except for having to learn how to do it. The performance ought in principle to be a lot better, but I have no measurements to justify that hunch. My web service can work in both HTTP mode and FastCGI mode (one or other at a time), so I suppose I ought to do some benchmarking (note to self!).
If you want proper system startup (and you should), you need to learn how init scripts work. I sometimes cheat and start with an existing working script someone else wrote for a similar application and customise it to work with mine.
I've used nginx as a reverse proxy for my Go projects. I've found that it's a lot easier to set up useful server settings such as TLS, compression, etc., in nginx rather than as a pure Go server.
Keeping it alive on server reboot is a more complicated question. I would suggest learning how to write a script/whatever for your server's init daemon and just doing it that way.
Is it possible to communicate from a web browser(Loaded an HTM page from server) to an application running in the same server using AJAX. Need to send the request from browser using a button click and update the page with responses received from one another application running in the same server machine?
I am using HTML pages to create website and not using any PHP or ASP like server side scripting. In server machine data are manipulated using a C++ application.
I think you can use any sort of Javascript functions to do that. But you might need to use jQuery or similar frameworks to make your live easier. You might need to search for "Comet Programming" to know exactly how to do 2-way communication between client and server
Updated:
Well, this kind of stuff requires you to read a lot (if you have not already known). Basically, what you need is a server that can do long-polling (or eventsource, websockets). There are many open-source ones that might help you to get started. I can list a several good ones here. There are a lot more
http://www.ape-project.org/
http://cometd.org/
http://socket.io/
http://code.google.com/p/erlycomet/
http://faye.jcoglan.com/
So after you have the comet server up and running you will need to setup the client side (probably Javascript). For those listed projects, most of them come with the client side code to interact with the server (Except for erlycomet). Therefore, you can just use the examples provided and run a quick prototype. If you want to use your raspberry pi, you can use nodejs which provide a lot of ease for dealing with real-time communication (socket.io, faye). And lately, http://www.meteor.com/
I would think of the problem this way: you want to provide a web front end to an existing c++ application. To achieve this you need to think about how your web server communicates with your c++ application. Communication between the browser and web server can be thought of as a separate problem - as you say AJAX calls can be used, or maybe have a look at websockets.
Once you have your request in the web server you need to communicate it to the C++ application (and/or visa versa). This can be done a number of ways, e.g. sockets or RPC. I found this question here which has some good advice.
OK, this is impossible, but I will try to explain the situation here.
Let's say we have cases, that we need a fast setup of a web server in order to have a simple soap web service running (querying a db and so on).
In VS though, upon debugging a web project, it creates a quick ASP.NET development server without relying on the actuall IIS that might be installed on the PC.
Is there any project that does something like that?
This would be ideal for small projects, where a simple executable would get a server ready to go and would allow web services to be executed right away.
I have looked at some stuff over the net like http://msdn.microsoft.com/en-us/magazine/cc163879.aspx and http://mtaulty.com/CommunityServer/blogs/mike_taultys_blog/archive/2004/05/24/4479.aspx but they seem to be quite outdated and i am not sure how well they work (havent tested them thoroughly)
EDIT: I have build an application like the one you suggest. However, how can i implement HTTP GET/POST requests to the service using this method? I tried using WebGet after my operationcontract but it didnt work. For example, my service is at http://localhost:8080/Service and i would like to use it such as http://localhost:8080/Service/getMethod?x=2.
I believe that the development server used by Visual Studio is based off of the Cassini code base (of which there is a fork here). I also found this article on hosting the asp.net runtime. It was also created a while back (2004), but has been updated since (2008). I think a lot of the core concepts are probably still the same.
Another approach would be a roll-your-own web server using the HttpListener class. This could take some work if you want to use it for hosting asmx type services, but if you were doing RESTful services, it isn't too bad of an option (this is actually how RavenDB works if you are not hosting it under IIS).
A WCF service can be hosted in almost any kind of application, including a Windows Service or a console application. There is no need for a web server at all.
Alright,
i've done it so im posting it here to help anyone who has issues with similar problems.
Create your WCF Service file as usual and then by using ServiceHost (or WebServiceHost) you can easily create a WCF service.
In order to use GET http requests to make it simple to communicate with mobile devices (such as iphone) you can use WebGet above your service methods and make sure you manually add a service endpoint using WebHttpBinding for WebServiceHost or WebHttpBinding with an WebHttpBehavior for ServiceHost.
Then you can call your service methods such as http://localhost:port/webhttpendpointaddress/mymethod?x=2.
for one of my applications I'd like to provide a minimal web interface. This core application is written in C++ and uses Qt4 as a framework. Since I'm also using some libraries I wrote to calculate some things and do some complex data management, I'd like to use this existing code as a backend to the web interface.
Idea 1: Using an embedded web server
The first thing I tried (and which worked to some degree) was using an embedded web server (mongoose). As you can imagine, it is just a very thin library and you have to implement a lot of things yourself (like session management, cookies, etc.).
Idea 2: Using a normal web server and adding a fcgi/cgi/scgi backend to my application
The next thing that came to my head was using a mature but compact web server (for instance, lighttpd) and simple provide a fcgi/scgi/cgi backend to it. I could write the web application using a good framework, like Pylons, PHP, or RoR, (...) and simply have an URL prefix, like /a/... which allows me to directly talk to the backend.
I tried to implement the libfcgi into my application, but it looks messier than needed (for instance you'd have to implement your own TCP/IP sockets to pass on data between your app and the web server and tunnel it through the FCGI library, meh)
Idea 3: Creating a command line version of my application which does the most basic things and use a normal web server and framework to do the rest
This is the third idea that came to my head. It is basically about creating a web application using a traditional way (PHP, RoR, etc.) and using a command line version of my application to process data and return it when needed.
I've got some experience with creating web applications, but I never had to do something like this, so I'd like to hear some ideas or suggestions. I'd like to use JavaScript on the browsers (AJAX, that is) and pass some JSON constructs between web browser and server to make the user experience a bit smoother.
So what are your suggestions, ideas on this? I don't want to re-invent the wheel, honestly.
I would never expose a custom written application to the net as front-end, for that servers like apache or lighthttp are build. They give you some serious security out of the box.
As for interaction of your app with that webserver, it depends a bit on the load and what kind of experience you have with writing software in PHP, python or other languages supported by your web server (via interpreter of course).
A slight load, and a command line tool accessed from PHP might do perfectly well.
A more heavy load and you might wish to implement a simple (SOAP?) server with Qt and access that from a python (or php) script.
That way you don't need to do layout in you app, and you also don't need to implement security all that much.
I'm currently researching a similar situation (custom web app backend using Qt), and the least bad option is FastCGI. Found something you might be interested in. Not production ready without some serious testing, but this might be a good starting point for Qt - FastCGI interop: FastCGIQt
I've used the FastCGI Protocol Driver library for a similar project (also a Qt application), the download link is at the end of that page [Libfastcgi]. Integration with the application turned out actually comparatively easy. Lighttpd + mod_fastcgi was used as web server. Can't say anything about FastCGIQt, though.
You Wt works well to provide a web interface to Qt based applications. Both have a similar programming style, and there's an example that demonstrates the integration with Qt.
Here is example of embedded QML-server: https://github.com/ncp1402/ql-server