C/C++ HTTP Client Library for Embedded Projects

Question

So I have trawled through pages and pages of search results on StackOverflow and Google and I have come across very few C/C++ HTTP client libraries suitable for a resource-constrained, embedded environment (e.g. an ARM). I have however come across quite a few that are suitable for desktop-class applications.

Essentially, I am after a simple, easy-to-use and convenient API to make HTTP GET, POST and HEAD calls (with support for authentication, download resume and payload compression). It would be ideal if it had a small footprint (i.e. no or minimal external dependencies) and is open-source (with a permissive license).

Here's a list of what I've come across so far and why they are not suitable -

• curl - too heavyweight
• poco - too heavyweight
• neon - GPL
• qlibc - relies on POSIX libraries
• cpp-netlib - relies on Boost libraries
• serf - relies on the Apache Portable Runtime library
• urdl - relies on Boost libraries
• HTTP Client C API - promising but requires a C++ wrapper

Are there any libraries out there that I am unaware of or am I better off rolling my own?

Solution 1

Have you taken a look at the HTTPClient on mbed? Looks like there are lots of forks of an original from a few years ago that wasn't maintained. I haven't used this...

http://mbed.org/users/WiredHome/code/HTTPClient/

Solution 2

I can just describe what I used for those tasks.

curl - if you are lazy, you can just download in built binary and have nothing to do more, it has very simple headers and a lot of examples. You will need 3-4 already built libraries and header. With no external dependencies. So, I would count it as too low-level, but not heavyweight at all.

boost.asio - very interesting paradigm of realization, quite easy and clean. But I would say it is low-level too. Harder then curl. And needs to use boost, that is external dependency you want to avoid, I guess.

poco - best solution for http server. It's high level, after you joined it to your application, you just need to implement few virtual functions, having all other work (and thread management) done. Poco gives a lot of stuff for application management, thread/process management and it is very simple and easy, I would even say it has java-like interface. Yes, there is external dependency to poco, but I would look at this as a chance to learn perfect library. Still, for http clients it is really heavy.

That is all my C++ experience with HTTP. Counting you need just client and don't need dependencies, I would offer you to look at libcurl library. It's cross-platform, easy, no dependencies and low-level enough to get all you need with network. And if you will have time - look at Poco, really, I believe you will fell in love with this library as I did. Hope that will be helpful.

Solution 3

I found another one, which just needs to be packed into a lib. didn't test it, but may be worth a look:

https://github.com/reagent/http.git

Comments

[thegreendroid]

Thanks for the answer! These libraries really are too heavyweight for the project I am working on though, I just can't justify pulling in such a huge library.

[thegreendroid]

That looks promising! I'll try that out, thanks!

[thegreendroid]

This one is definitely usable with a few tweaks, thanks!

[weberc2]

I was Googling around for something like this, and it turns out the author works in the same building as me...