{"id":255698,"date":"2017-01-12T10:32:03","date_gmt":"2017-01-12T02:32:03","guid":{"rendered":"http:\/\/blog.zhenglei.net\/?p=255698"},"modified":"2017-01-12T16:01:27","modified_gmt":"2017-01-12T08:01:27","slug":"web-development-in-c","status":"publish","type":"post","link":"https:\/\/blog.zhenglei.net\/?p=255698","title":{"rendered":"Web development in C"},"content":{"rendered":"

davidmoreno\/onion<\/a><\/p>\n

kore<\/a><\/p>\n

klone<\/a><\/p>\n

nxweb<\/a><\/p>\n

 <\/p>\n

fast C HTTP server library comparison & wishlist<\/span><\/strong><\/h1>\n

Hi,<\/p>\n

Trying to choose an embeddable HTTP server library for a project, and
\nalso considering writing my own special-purpose code, I came up with
\nthe following comparison of libonion vs. other C libraries that include
\nhigh-performance HTTP support and are currently maintained.<\/p>\n

Licenses:<\/p>\n

libevhtp+libevent – 3-clause BSD
\nlibmicrohttpd – LGPL 2.1
\nlibonion – Apache 2 (except for some examples) or GPLv2+
\nmongoose – GPLv2 (and commercial)<\/p>\n

Build environment:<\/p>\n

libevhtp+libevent – cmake+autotools
\nlibmicrohttpd – autotools
\nlibonion – cmake
\nmongoose – none (one large file, like SQLite)<\/p>\n

Code size (“text” as reported by the size(1) command on the library or
\non a tiny sample program if statically linked, on Scientific Linux 6.6
\non x86_64):<\/p>\n

libevhtp+libevent – ~500 KB, or ~200 KB without unicode.c.o and reg*.c.o
\nlibmicrohttpd – ~100 KB default, ~55 KB with most .\/configure –disable-*
\nlibonion – ~100 KB with most ONION_USE_* set to false
\nmongoose – ~100 KB including JSON-RPC<\/p>\n

For the smaller builds of libmicrohttpd and libonion, I kept threads
\nsupport enabled, but disabled pretty much everything else that could be
\ndisabled without patching the code. \u00a0It looks like libmicrohttpd wins
\nthis test. \u00a0Maybe there’s more code in libonion to disable (make into
\ncompile-time options) – I haven’t checked yet.<\/p>\n

Built-in JSON support:<\/p>\n

libevhtp+libevent – none
\nlibmicrohttpd – none
\nlibonion – JSON builtin, JSON-RPC in Apache 2 licensed example
\nmongoose – JSON-RPC builtin (simple JSON parser not exported?)<\/p>\n

All of this is for current versions on GitHub or in recent release
\ntarballs as of a few days ago.<\/p>\n

Maybe someone else will find this useful. \u00a0I’d appreciate corrections.
\nIt is very likely that I overlooked something.<\/p>\n

On a related note, I found the list of alternate implementations on the
\nlibmicrohttpd homepage very helpful. \u00a0That’s classy. \u00a0Thanks.<\/p>\n

My wishlist:<\/p>\n

A processes (pre-fork) + [e]poll mode, like nginx has. \u00a0Processes have
\npros and cons vs. threads: more reliable, faster malloc\/free (no lock
\ncontention risk), but OTOH slower context switches (if running process
\ncount exceeds number of logical CPUs). \u00a0I would likely prefer this mode,
\nbut all four libraries appear to be missing it.<\/p>\n

Ability to accept not only HTTP, but also raw TCP connections, and
\nhandle them in application code along with the library-handled HTTP.
\nSuch as for implementing JSON-RPC directly over TCP, while also having
\nit over TCP+HTTP, and without having to manage an own\/separate
\nthreads\/processes pool. \u00a0Do any of the four have this? \u00a0I found no such
\nexamples with any of them.<\/p>\n

Easily and cleanly embeddable into an application’s source tree, while
\nalso allowing easy updates to new upstream versions. \u00a0mongoose almost
\nachieves this, but at the expense of sacrificing meaningful separation
\ninto multiple translation units within the library itself. \u00a0I think we
\ndon’t have to pay this price. \u00a0We could have multiple files (10 or so?),
\nin a subdirectory, which are also easy to list in a project’s Makefile.
\nMaybe I’d do that for libonion, freeing it from cmake, but then updating
\nto new upstream versions would be harder. \u00a0Do I really have to bite the
\ncmake or\/and autotools bullet for something as simple as accepting HTTP?<\/p>\n

I’d prefer a more permissive license like 2-clause BSD or MIT. \u00a0But I
\nguess I’ll have to settle on Apache 2 or such. \u00a0mongoose’ use of GPLv2
\nis understandable – need to make money – but is otherwise a disadvantage
\n(even for a commercial project that could pay, and even when publishing
\nany source code changes is not a problem and would be planned anyway; we
\njust don’t want to put our time into something that we would not always
\nbe able to reuse in other projects).<\/p>\n

Optional JSON from the same upstream is a plus, ideally exported both as
\na generic JSON parser and as JSON-RPC support. \u00a0Looks like only libonion
\nsort of delivers both (but the code might not be production quality).<\/p>\n

Ability to exclude more of the functionality – for example, to include
\nonly the POST method (and not compile in code for the rest). \u00a0I am
\nconcerned not so much about code size per se, as I am about attack
\nsurface, and about ease of code reviews (not having to determine if some
\ncompiled-in code is actually dead code in a given case, but to know
\nreliably that it’s not compiled in).<\/p>\n

On a related note, David’s use of Coverity for libonion is commendable,
\nbut it looks abandoned since 2014, and many “defects” (even if false
\npositives) remained unfixed back then.<\/p>\n

Mark’s use of Coverity for libevhtp is also commendable… and looks
\nabandoned since May 10, 2015. \u00a0It shows “48,919 Lines of Code Analyzed”,
\nonly “4 Total defects” and “0 Outstanding” – I guess it means that
\neverything detected by Coverity before (which must have been many more
\n“defects”) had been eliminated prior to that run. \u00a0That’s impressive.
\nBut we don’t know how many new “defects” may have appeared in the 9
\nmonths that passed. \u00a0Also, I haven’t looked into whether libevent has
\nbeen subjected to similar static analysis or not (although being
\ninitially written by Niels Provos speaks in its favor, given Niels’
\nother work), and accepting TCP connections isn’t as much risk as parsing
\nHTTP and JSON.<\/p>\n

I don’t give a lot of weight to the Coverity results for my
\ndecision-making, but it shows whether the maintainers care, and there
\nare few other somewhat-meaningful metrics I could use before having
\nspent time to analyze and try to use the code myself.<\/p>\n

Why am I posting this to the onion mailing list specifically? \u00a0I find it
\nlikely that libonion wins for me, although not by a large margin (and
\nthere’s a lot that I dislike about it). \u00a0This is not a final decision
\nyet. \u00a0I might as well end up reverting to writing special-purpose code
\nfrom scratch.<\/p>\n

Thanks,<\/p>\n

Alexander<\/p>\n","protected":false},"excerpt":{"rendered":"

davidmoreno\/onion kore klone nxweb &nbsp … \u7ee7\u7eed\u9605\u8bfb →<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[13,2,18],"tags":[345,344],"class_list":["post-255698","post","type-post","status-publish","format-standard","hentry","category-html","category-linux","category-software-download","tag-c","tag-web"],"_links":{"self":[{"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=\/wp\/v2\/posts\/255698","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=255698"}],"version-history":[{"count":4,"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=\/wp\/v2\/posts\/255698\/revisions"}],"predecessor-version":[{"id":255704,"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=\/wp\/v2\/posts\/255698\/revisions\/255704"}],"wp:attachment":[{"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=255698"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=255698"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=255698"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}