This is the website of dronekit-python api.
http://python.dronekit.io/
I checked the examples and also online git repo, it seems all examples are built on top of mavproxy. and API itself doesn't have mavlink communication capability.
I wonder if there are any other use cases for droneapi.
and if I don't want to use mavproxy, does it mean I have to write my own mavlink layer?
Yes, using the current release implementation (1.x) everything is built on MAVProxy.
I understand that the intention is that in future you will not necessarily have to run your apps from within a MAVProxy console (I don't know if the actual dependency on MAVProxy is being removed - I supsect not!)
starting with v2 of dronekit-python we are MAVProxy free, please follow the migration guides http://python.dronekit.io/guide/migrating.html
dronekit-python doesn't need to run in mavproxy. You could use a custom mavlink communication layer to implement the API if you wanted.
(I find the implementation as a mavproxy module a little suboptimal for users in that it can be a bit confusing and a little bit weirder to write code that uses the API, but it does have the advantages of allowing the use of other mavproxy modules (maps, joystick control, whatever) along with basic mavproxy functionality like forwarding, and it can also be a faster path for development: It's probably easier to connect dronekit-python to mavproxy than to write a brand new, untested communication layer that does 50% of what mavproxy does. I'm guilty of doing the same thing to get something working fast.)
Related
I'm working on a project, implementing everything in C language. As a part of the project, we need to be able to control and configure firewalld, firewall of the current system.
firewalld is implemented in Python and an interface is available. However, we don't want to make Python calls from C or vice versa.
There are command line tools to configure firewalld (e.g. firewall-cmd) but we don't want to make such calls from C either.
I recently started working on firewalld, I don't know much about its internals. I've read that it uses D-Bus, I also don't know much about D-Bus.
There is a C library developed by Thomas Woerner: libfirewall.
However, it's been more than a year and a half since the last commit so it's not maintained. Other than libfirewall, I don't know any firewalld interface in C.
I gave libfirewall a shot. It got me some problems when both compiling and running the examples and I still have problems to resolve. Is it worth to continue with libfirewall? Should I use it?
Is there any other interface that I'm not aware of?
Possibly naive question due to lack of understanding of D-Bus: I thought, maybe, with a D-Bus interface, I can issue commands to firewalld. Can it be done? (i.e. Does D-Bus work like that?) Can we write a program that mimics, say firewall-cmd, and interacts with D-Bus in the same way and at the end allows us to control firewalld?
If this is possible, how to do it and what to use? libdbus and GDBus have relatively good documentation although libdbus requires good deal of effort. They even said "If you use this low-level API directly, you're signing up for some pain." in the documentation. In any case I'll be in need of examples or any kind of text demonstrating their usage.
How should I approach this problem?
Yes, you can issue commands to firewalld via D-Bus. I haven't checked but expect that firewall-cmd is itself implemented as a D-Bus client.
The D-Bus API is extensively documented: https://firewalld.org/documentation/man-pages/firewalld.dbus.html. The documentation should give you a rough idea what can be accomplished through the API. You could try the D-Bus debugger d-feet to interact with firewalld without any code.
GDBus is definitely the easiest way use D-Bus from C but it's still not trivial and firewalld is a fairly complex API: Using it may require some expertise (completely depending on what you need to do).
Iam working yet with C program on STM32 microproc, what contains a web server, accesible by the user via web gui(HTML and javascript files). The web gui part became more complex, and it needs higher level operations.
The questions: is it possible to embed a node.js program with some node modules? Does it work with the C webserver, or the node program have to make the webserver, and communicate with the C program?
Or there is an other solution what is better in this case?
This question maybe seems dumb, but i didnt find documentation about it.
After a research I found some solutions:
Node.js for Embedded Systems
The book can then guide you to jerryscript which:
is a lightweight JavaScript engine for resource-constrained devices
such as microcontrollers
You can find there that it's also used with the STM32-Discovery board.
Node.js on clientside
This article guides to Browserify which allows to run node on clientside.
Just make it simpler
You could use HTTPD implementation shipped with LwIP. There is a script called makefsdata which allows to convert html, js, css ... files into c-arrays. This implementation also supports POST method.
I am not finding documentation for custom protocol support.
From what I understand, Gatling has core engine that does scheduling, thread management etc, and protocol support is designed as an Actor ?
I am trying to develop a custom protocol (thats basically a shell script that will talk to an external service). The latest reference documentation does not seem to have any reference to how to do this ? Any pointers will be greatly appreciated.
If you need to stress test something that is implemented in a shell script, then Gatling probably isn't the best fit. Gatling is designed for stress testing networking protocols. So unless you can duplicate what your shell script is doing in Gatling expressed in networking protocols, you then might want to use something else.
Secondly, if you did implement it, I would check with the core developers of Gatling if it's something that they would consider including (use a github issue to ask). Since the applications of this might not be widespread, they may choose to not include it in their project. If that's the case you would have to either run your own fork with the implementation or add some sort of plugin architecture to Gatling for 3rd part extensibility.
So my suggestions are:
Decompose your shell script into the specific network protocol parts you're interested in stress testing implementing in Gatling.
Use a different tool that's designed to running multiple shell scripts at once for stress testings. Something like GNU Parallel if you're on a Linux box.
Implement it yourself. There's no documentation on how to do this. However a good starting example would be the JMS Protocol Implementation to give you an idea of all that's involved.
I want to build a restful (CoAP) web service which can execute c code to handle events.
Therefore I'm searching a lib which provides me with a rest api in C and cgi similar to
restcgi which is sadly in c++ or CGI-Simple which is in perl.
The server is running on a embedded device so it has very limited resources and the services will be accessed only by machines.
Thank you very much.
You may be interested in Raphters framework and its architecture. It's pretty small, so you can examine the code, the framework itself can be used as a FastCGI backend for some web server, e.g. for nginx.
I have recently came across one quite interesting CoAP library which uses libevent. You will aslo want to check Klone embeddable HTTP server by the same guys at KoanLogic. I have previously looked at libcoap, but it didn't find it very usable at the time. You may also wish to try using either libuv, libev or libevent. But I guess it's probably gonna be much easier to adopt some of the code from WT repository and get your CoAP/HTTP server done.
Say I have fancy new algorithm written in C,
int addone(int a) {
return a + 1;
}
And I want to deploy as a web application, for example at
http://example.com/addone?a=5
which responds with,
Content-Type: text/plain
6
What is the best way to host something like this? I have an existing setup using Python mod_wsgi on Apache2, and for testing I've just built a binary from C and call as a subprocess using Python's os.popen2.
I want this to be very fast and not waste overhead (ie I don't need this other Python stuff at all). I can dedicate the whole server to it, re-compile anything needed, etc.
I'm thinking about looking into Apache C modules. Is that useful? Or I may build SWIG wrappers to call directly from Python, but again that seems wasteful if I'm not using Python at all. Any tips?
The easiest way should be to write this program as a CGI app (http://en.wikipedia.org/wiki/.cgi). It would run with any webserver that supports the Common Gateway Interface.
The output format needs to follow the CGI rules.
If you want to take full advantage of the web server capabilities then you can write an Apache module in C. That needs a bit more preparation but gives you full control.
Maybe this tiny dynamic webserver in C to be used with C language can help you.. it should be easy to use and self-contained.
Probably the fastest solution you can adopt according to the benchmarks shown on their homepage!
This article from yesterday has a good discussion on why not to use C as a web framework. I think an easy solution for you would be to use ctypes, it's certainly faster than starting a subprocess. You should make sure that your method is thread safe and that you check your input argument.
from ctypes import *
libcompute = CDLL("libcompute.so")
libcompute.addone(int(a))
I'm not convinced that you're existing general approach might not be the best one. I'm not saying that Apache/Python is necessarily the correct one but there is something compelling about separating the concerns in your architecture being composed of highly focused elements that are specialists in their functions within the overall system.
Having your C-based algorithm server being decoupled from the HTTP server may give you access to things like HTTP scalability and caching facilities that might otherwise have to be in-engineered (or reinvented) within your algorithm component if things are too tightly coupled.
I don't think performance concerns in of themselves are always the best or only reasons when designing an architecture. For example the a YAWS deployment with a C-based driver could be a very performant option.
I have just setup a web service using libmicrohttpd and have had amazing results. On a quad core I've been handling 20400 requests a second and the CPU is running only at 58%. This is probably going to be deployed on a server with 8 cores, so I'm expecting much better results. A very simple C service will be even faster!
I have tried GWAN, it is very good, but it's closed, and doesn't play well with virtual environments. I will give #Gil kudos being good at supporting it here though. We just had a few issues and found LibMicroHttpd works better for our needs.
If you go here, you may need to update your openssl if you're using CentOs from axivo
rpm -ivh --nosignature http://rpm.axivo.com/redhat/axivo-release-6-1.noarch.rpm
yum --disablerepo=* --enablerepo=axivo update openssl-devel
You can try Duda I/O, it only requires a Linux host: http://duda.io