I'm going to implement aodv protocol as a linux module for a research project, and I need to implement it on Android later.I wonder if I could compile my codes into the android kernel and have my module work as in Linux (kernel 2.6 up).
Any suggestions would be greatly appreciated.
(P.S. There are already some aodv implementations on Android, such aodv-on-android and UoB JAdhoc, however, those are implemented in Java, not involving kernels)
The tagline goes: Android is Linux, so anything (portable) you do on Linux should be simple to make happen on Android.
This is mostly true, however there are a few things you'll want to keep in mind:
Portability: If you're writing your implementation on x86 and then moving the module to ARM for Android, be careful not to use any capabilities that don't exist on both. However, for something like a network protocol, you probably won't be running into a lot of these. The only one that comes to mind is the NIC.
Dalvik: Generic Linux distributions tend to run fairly close to the OS, meaning they regularly make system calls or libc calls, and the semantics of interactions with the kernel mostly carry over to the application. Android, however, has essentially a Java environment build on top of that, and the majority of applications only interact with that framework. For you, this means you will want to be aware of the possible need to modify the Android framework in order to make changes visible to applications.
The above point depends on your use case, however. If you plan on augmenting routing for existing applications to use aodv, then you'll want to hack around with Dalvik. If you'll be writing one proof of concept application, then you can write the portions that interact with aodv in C using the NDK, and avoid having to modify the application framework.
You probably already know this, but the kernel built system is sophisticated enough that you should be able to get away with writing your module once and compiling it for two architectures or platforms just by changing your configuration.
Hope this helps.
Related
I am currently planning the development of a multiplatform app, and I am not sure wich way to do it fits my requirements best, since all possibilties I could think of failed to satisfy me.
First I want to write an app for android, which should feel like a normal typical android app. So I want to use the standard actionbar and android design look and feel in my other gui elements. After finishing the android app I am planning on developing an ios app, which should have a different design, so i am going to redevelop the gui for this anyway.
But I don´t want to rewrite the other code wich represents the intelligence of the app, independent from the gui. I came up with the following possibilities:
1. Java GUI With native library
Here I abstract all the code of my app in a C++ library (since as far as I know ios supports the usage of c++ libraries too) and develop the gui android typically in java. The library would than have a function to start and would inform the gui about every change via callback functions.
Pro
I can reuse all the code that would be the same on both platforms. I just would implement the gui seperately
The design of the android gui is straightforward as I want it to be. It looks like typical android because it is typical android.
Cons
I dislike the usage of JNI very much. Especially the signature and names of the callback functions (calling java functions from c++) are not checked at compile time and require a lot of manual work. If I rename a function and forget to rework the native part I only notice this mistake at runtime.
2. Build the GUI on the native side
Here I had difficulties finding out what is possible, especially for 2.2
2.1 Use Qt
I have only a few first step experiences with Qt in general but as far as I understood i would have the following pros and cons:
Pro
Reuse most parts of the code for ios and Android. I would than redesign the gui for each platform to make them feel natural. I can´t evaluate how much qt may even assists me at doing that
Cons
I have to copy the android gui by using other qt widgets. This is more effort and I don´t know if one can replicate the android gui elements (like the actionbar) so that the user wouldn´t notice it.
2.2 Using the android framework from the native side
I dont know if this is possible at all, I wasn´t able to find this information. Can I use the class "NativeActivity" and use the android framework to build the gui and use e.g. the actionbar? If this is possible somehow it would have the pros from 1. and maybe wouldn´t have it cons?
Do you have any feedback to my ideas or maybe even new approaches I didn´t think of? How do other multiplatform apps like WhatsApp solve this problem? Do they have redundant code for each platform?
Thank you,
Tobi
I would say that it depends very much on your application requirements. By my opinion, a better solution is to develop a separate application for each platform using recommended SDK's for that platform, and implement in native C++ only the time consuming data processing algorithms.
Application runtime on mobile platforms is not so straightforward as on desktop platforms. You should take into account background and foreground processing, specific application life cycling, accessing system resources such as network, file system, etc. And all these issues do differ on iOS and Android.
Regarding possibilities that you listed.
Qt/QML is ok only in case two requirements are met:
1.1 Your application is a foregroud application without any background operations.
1.2 You purchase a commercial Qt license because only commercial Qt can be submitted to Apple iTunes app store (even GPL apps are under
question).
Using NDK Native Activities on Android with cross-platform C/C++ backend. Android NDK API offers much less API then Android Java SDK, so a lot of things you will have to implement or wrap manually. It is a hard road.
Mixing Java code and C/C++ using JNI gives you more of Android SDK API. But you should remember that an Android activity's life cycle is not somewhat that you're used to deal with when developing on C/C++.
Approach that we are using
We've been developing an application with a huge amount of cross platform functionality that should work on Windows/Linux/Mac OSx/Android/iOS. We're using the approach as follows.
Cross-platform core is written in pure C++.
We have adaptors to GUI interface for each platform.
On desktop we use Qt as it reaches all desktop platforms with minor adapting to each platform.
On iOS the GUI is built using iOS SDK with Objective-C and C++ core is linked as a Framework. Still, we had to patch our core in some way for iOS background requirements and so.
On Android we wrap our C++ core in a background process and build all the GUI using only Android Java SDK. Foreground GUI activities interact with the core via local sockets, so we don't need to bother with activities life cycling in our C++ core. But the adaptor is a litle bit complicated.
Nevertheless, both mobile platforms often require workarounds and adaptations in C++ core which add a number of #ifdef'ed branches in code for each platform.
I've been working on a writing a game for Android. Until now I've been using Java instead of the NDK, but I've decided to port my code to C++ (for performance, memory management and industry standards reasons).
Porting my application shouldn't be a problem (I've written my fair share of C++ applications), but I've been using RoboGuice as a dependency injection framework because otherwise my object graph would become too complex rather quickly.
I've been looking around, but I haven't found any resources about using a dependency injection framework in combination with the Android NDK.
Can someone tell me if there any such franeworks available. If so, which one would you recommend?
If you have a C++11 compiler for Android you could use several frameworks (I wrote Infectorpp) but there are others available. You should note that DI is quite limited in C++ due to the lack of reflection so you should make some compromises as not everything you did in RoboGuice would still be possible.
By doing a quick search seems that C++11 is possible on Android. I don't have an Android device and still not needed to emulate it, but if you have any feedback it will be wellcome (private message here or support ticket on google code is enough), the library is headers only so no special build stuff is required for it, apart enabling c++11 on your compiler wich is just one extra option by command line. If that will works good on Android then it will be definitely good also for PC. (Do not misunderstand please, I'm using it heavily, but seems very few people is interested in DI in C++ and so I get very little feedback)
There was also a nice framework cpp-resolver: a little awkard to use because you explicitly register factory functions for injecting ALL parameters, but very scalable, especially for server applications.. (decouple object lifetime management and works with plain old C++).
The most complete framework is probably wallaroo
If you search something really easy to use Infectorpp is a good choice
If you need control over lifetime (mostly servers): Cpp-resolver is perfect
If you need exotic features and configuration files: wallaroo
As side note, run-time configuration is possible also with frameworks that do not explicitly support it:
You just need a Factory that istantiate a different type based on a configuration file you could read through a class that you add as dependency to factories (Probably you don't need to know that since you were already using DI frameworks, but still good to know for occasional readers)
Wikipedia says "Anything between the kernel and the applications is known as middleware". Now, if we look at the android architecture, it consists of:
Applications
Application Framework
Libraries and Runtime
Linux kernel
so, my simple question is what is middleware in case of android architecture? Is it Libraries+Runtime or is it Libraries+Runtime+Application Framework. I read somewhere that it consists of Libraries and Runtime. If that's true then why Application Framework is not considered as a part of middleware, because according to the middleware's definition, Application Framework is also between kernel and user applications.
I'd say it's either:
Application Framework and
Libraries and Runtime
Or:
Libraries and Runtime
I would not say there is only one right opinion, this is a question of interpretation.
I believe its the Libraries and Runtime together.
As middle-ware is the interface between the applications and operating system.
In Android- kernel is operating system and app+app framework is applications.
Then Libraries and Android Runtime together is said to be middle-ware as per my analysis.please correct me if I'm wrong...
In computer science, definitions and later categorization of components to those definitions are sometimes hazy. There is no perfect bucketing of components :-)
Middleware: In practice, these are set of libraries that make it convenient for programmers to access OS or hardware primitives.
In Android, the libraries definitely form middleware. I would not classify the Runtime(read virtual machine) as a middleware.
More specifically, Middleware in Android development, using Redux approach, is a program layer for asynchronous tasks, their managing, scheduling and subscribing. You use it for API requests, logs, analytics, persistence, other time-consuming operations that you want to execute on a separate thread (to free-up the UI Thread, for example).
ReactiveX is a popular Middleware library and approach you can use in your project. Its Android framework is RxAndroid.
I am getting into making my own embedded system and I wanted to use an open source OS to run on it but I can't seem to find any information for making a completely customized GUI (Meaning desktop Icons, Menus, and windows). Would anyone know how to go about doing this? Or could point me into the right direction to research?
You've got quite a vague question there :
Here is an article on how to port Android to an embedded system
Information for making a completely customized GUI (Meaning desktop Icons, Menus, and windows)
You can start by learning android development.
Developers have full access to the same framework APIs used by the core applications. The application architecture is designed to simplify the reuse of components; any application can publish its capabilities and any other application may then make use of those capabilities (subject to security constraints enforced by the framework). This same mechanism allows components to be replaced by the user.
Have you picked out a development kit for this yet? If you get a Beagleboard or something with a TI processor, there are great resources for getting started with Android or Linux. The beagleboard would be a particularly good choice, due to a rather active community.
Freescale also has good support, particularly with its Linux builder LTIB.
I am not entirely familiar with how one would go about re-inventing a GUI for Android, but in Linux a good place to start might be with GTK+ or Qt libraries.
I'm doing some initial research on smart phone development, and I noticed that Android and Windows Mobile both support c++ for application development. I was curious if anyone had any experience trying to manage shared files between both Android and Windows Mobile, and to what extent that code can be shared? e.g. no user interface can be shared, but web service and business logic classes can be shared, etc.
I can't speak to the WinMo side of things, but on the Android side you should really really really avoid using native code for anything except performance-critical processing algorithms. JNI/NDK stuff does not play nicely with the normal Dalvik lifecycle and can be a source of all sorts of ugly unpleasant bugs and memory leaks. From what I understand there also aren't on-board NDK libraries for more complex high-level functionality like HTTP (just more basic/performance-oriented libs like libz and OpenGL), so you'd probably have to compile that stuff and ship it with the app as well. I would definitely not recommend coding your web service classes in C++, even if it's technically possible; it'll be less buggy and nicer to write C#/Java and you should be able to make mostly the same architectural decisions for consistency.
That said, if you have a performance-critical bit of image processing code or the like, it actually can be fairly straightforward to get that working across Android to other platforms (I've seen it done quite well with some image-processing C code used in an iPhone app and then used via the NDK in an Android app).
Check the documentation on the NDK for details on what it can (and can't) do, and see similar SO threads like this one.