I'm using Play Framework 2.2.1 and it's WS library to upload a file. This file can be huge and I'd like to know how far into the upload I am. I can't find anything to make it possible (like progress callbacks, anything) but maybe there's some trick to that?
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I am developing an web application using the Play framework in Scala language. In my application I have to access the native methods which is written in C++ and converted into .so by using swig.
My aim is to call the native method which is in .so file from the Controller class. I have searched in the internet, but I didn't get any documentation for this.
I have seen some links which is used by scala language.
https://code.google.com/p/scala-native-access/
https://code.google.com/p/bridj/wiki/Download#Specialized_subsets_(smaller_JARs_!)
https://github.com/xudongyang/scala-native-access
But they didn't mention how exactly use this in the Play framework.
Can anybody have the documentation for Play scala native access?
Can anybody have the sample applcation for the same?
Like in any JVM language, JNA/JNI gives you native access. Be aware that because of Play's use of class loaders, you'll need to make sure you access from the same class. See fail to load a native library using activator (Play Framework)
This is hard to answer in general. Play! is just a Scala library and framework, some any tool that allows you to use native calls in Scala will work similarly with play. From the first link that you pointed to, there are instructions to integrate with SBT (the Scala Build Tool) which also manages your Play framework. You will need to make the changes they mention to your build.sbt file which you can find in the top level of your Play project folder.
I have a final project abount database design this semester. And my teacher gives us many tasks for alternatives, such as Student Information Management System, Airline Reservation System and so on. However, I want to design such a player that it allows users to upload their own works and share together. Of course it also provides download service. I'm a sophomore this year. I'm familiar with c++ programming, but do not know much about network programming. Furthermore, I learnt T-SQL this semester and also did some works on MySQL in java(course in this semester, too). My idea is here (I have drew a picture):http://tmjfzy.blog.163.com/blog/static/66447025201242553045/
I need some advice about network programming. Could you give me some to help me realize my imagination? Thank you :-).
So, you're basically reinventing YouTube but with dedicated client?
Actually it's very easy to start without any clients or C++ : all you need is a server with MySQL, Apache and PHP. I recommend WAMP server if you're on Windows. FlowPlayer is a flash video player quite easy to integrate, but today using HTML5 video features should be a better idea. I believe you can have the reference Web system up and running in about 3 to 6 days.
(I'm also a C++ programmer and I had no problem with learning enough HTML, PHP and JavaScript to do very similar thing ).
Once you have a system up and running (possibly with limitation on video file format) you can design and implement API. From server side it's nothing more than PHP files, just returning data in your format of choice (eg. JSon, XML) instead of generating HTML.
With server-side API done, you can start working on client. Registration, login, upload from file and download to file should go first. Once the client can get the video files, you can implement a player. A streaming player goes next. If you encounter problems with playing back the video files, this is good moment to break compatibility with web version and change video file format. Now that you know what playback formats are supported, you might implement converting before upload. (Conversion makes sense if you want to have all files on server in one format. Otherwise it's not really usefull: if a client can convert a video, it should be able to play it back. This means all other clients also should understand the format and be able to play it back.)
At this point you can consider rewriting the server. Or other student can be writing the server in the same time as you're busy with client.
Having working Apache-PHP reference all the time makes such parallelism a breeze.
All the above requires using HTTP as underlying protocol. I think Qt has built in support. If not you can use some library (like cURL) or implement it from scratch on sockets.
Eventually streaming, like RTP+RTSP, can be added for playback.
If you feel really adventurous, you can start designing your own protocol, but this is the very last step, after having both own client and own server working flawlessly on hand-implemented HTTP.
Can I use OpenCV with Ruby on Rails? If so, how can I do that? Or, what resources do you recommend for that?
Thanks.
There is also an open CV gem, fwiw -- https://github.com/ruby-opencv/ruby-opencv.
Sure you can!
It just depends on what do you need as there is no "one" silver bullet.
If you want to create an online home surveillance, for example, then you would probably have least effort by writing:
C++ image-processing command-line application on top of OpenCV that would write the surveillance events and/or images to SQLite database.
Read the database directly from Rails.
For anything more complex, you'd need a more complex architecture.
Whatever you do, pick the best tools for the purpose:
Let OpenCV do what it is best at (image processing)
Let Rails to it's magic (simple, less demanding online access to some resources)
In order to link OpenCV and Ruby together, you could create a dedicated Ruby-to-C++ bridge because none of the existing ones can match diverse needs and most frameworks will do for a few specialized (i.e. designed by you) function-calls through your bridge.
This link would be a good start to pick a framework for a bridge - just go for one and see what comes out.
You could write a program using OpenCV in C++, and then just process your data with it, by using CGI (Common Gateway Interface http://en.wikipedia.org/wiki/Common_Gateway_Interface). I don't think you can bind native code to Ruby like you can do in Java (JNI)
I'm working on a Django app, the objective of which is to collect data on video media, process/normalize/categorize and then display it within a site.
I'm wondering if I should open up the data through an API or not.
Are there any advantages in doing so?
usually you provide APIs when you want some external services/programs to use it.
other reason to have nice APIs is to have a AJAX code which will use extensively your backend. but a big disclaimer, in most of the cases standard (specialized) views are enough (and they be a 'lite' version of the API)
so at the end is question do you need it from start, or you can add this later-on when it will be needed/requested.
I'm thinking of creating an application that can use Firefox as a download manager. Is there any way to control Firefox (add downloads, start/stop downloads, etc) from an external program in C/C++?
If that is not possible, then perhaps an extension that can do that? If an extension is the only way, then how do I communicate with the extension from outside of Firefox?
You're starting with a solution, not a problem. The easier idea is to use XulRunner, the platform on which FireFox is built. You'd effectively implement your own application as a XulRunner plugin and use Necko (the network layer of XulRunner and FireFox) from there.
First of all I suggest that you familiarize yourself with developer.mozilla.org
As far as I understand, most Mozilla platform functions are available through a cross language API known as XPCOM. There's also a plugin API but it's primary aim is to visualize stuff (used by Flash, etc.).
Take a look at Gecko API. It allows third party developers to use the same technology as found in Mozilla.
For downloading files no need to use Firefox. Consider using libcurl.
Take a look at wget.