W3C home > Mailing lists > Public > www-lib@w3.org > July to September 2000

RE: Request for thoughts on libwww

From: Dillenberger, William D. <Dillenberger@wcom.net>
Date: Wed, 2 Aug 2000 12:55:05 -0400
Message-ID: <910F402DBBD5D311AC5B00508B6F1A1E05BF1266@wcomexch2.wcom.net>
To: "'Taylor Gautier'" <tgautier@scale8.com>, "'Kerry DeZell'" <kdezell@bluemountain.com>, www-lib@w3.org
	I am using libwww to write an http1.1 SSL client posting
	I have built the OpenSSL 95a and use it with libwww pre-5.3.0.
	i have a client that does ssl posting successfully but only for
	i can echo Taylor's comments on timers, posting being broken, and 
	the general difficulty of correcting problems. The SSL portion of
	application, although the libwww SSL wrappers were added as an 
	after thought, has not been a problem.  I have been wrestling with 
	libwww about a month. I still don't have a handle on all the
            complexities. My application has required that i go into the
	code and make changes to the HTTP and Event state machines.
            Unlike the OpenSSL maillist, the libwww maillists are rather
Bill Dillenberger

> -----Original Message-----
> From:	Taylor Gautier [SMTP:tgautier@scale8.com]
> Sent:	Wednesday, August 02, 2000 12:03 PM
> To:	'Kerry DeZell'; www-lib@w3.org
> Subject:	RE: Request for thoughts on libwww
> Kerry -
> We used libwww for quite a while.  I finally had to remove it, for a
> variety
> of reasons.
> These are:
> 1) Difficult to use.  I found little to no real documentation on how to
> use
> it.  Mostly just examples that sometimes worked, but most of the time were
> just slightly not enough.  Every time I had to add functionality it was a
> struggle to figure out which calls to make, which objects to use, and
> usually ended up in deep searches in the source tree.
> 2) Pipelining requests.  No one on the list seems to agree with me (well
> maybe they do, but no one responded to my posts), but pipelining requests
> to
> a load-balanced web server farm is a *BAD* idea.  Libwww does not seem to
> care if you set max pipelined requests to 1 (in fact the code outright
> rejects it) and this does not make me feel good right from the start.  In
> addition, we decided since we had invested so much time in using libwww
> that
> we could just "fix" this issue.  In short, we did (hacked the code).  But
> in
> the long run we didn't.  There seems to be no capability to say "ok, to
> this
> host, I want to pipeline.  To this other host, I don't".  The host
> structures and setup are all pretty murky.
> 3) Managing and setting up timeouts was a pain.  Based on the code I was
> pretty sure I could call the global api to set timeouts at the right time
> to
> make it do the right thing.  But this is pretty weird.  Say you are
> talking
> to 10 hosts.  Doesn't it seem to make sense that you might want a global
> default timeout, but then have the ability to modify that on an individual
> basis?  Well the only way to do it is to modify the global timeout at
> *just*
> the right time when the host object copies the global var to a local var.
> (Hint: you have to do this from a callback)
> 4) More on the timeouts:  the timeout code for posting data is broken.
> Another tweak I had to add was to reset the timeout every time a chunk of
> data was transferred.  Otherwise the timeout applies to the overall
> transfer
> time and this is no good if your sets of data are large (well, frankly
> it's
> just plain incorrect.  You don't want to timeout a server after 10 seconds
> if every 1 second you have successfully transferred say 10kb)
> 4) If you start to use libwww for a great length of time you will notice
> that it wants to control your program, not the other way around.   It
> should
> not be called libwww, it should be called Appwww.  It is quite literally
> it's own application, and the code/logic that you are writing it considers
> more or less a plugin.  Fighting this proved to be exhausting, I finally
> gave up.
> 5) We were running in a threaded environment.  Even more difficult to
> manage
> libwww just right, though I do think I did it correctly.  It took a good
> solid week to get all the synchronization issues worked out.
> On the plus side, libwww does seem to support HTTP 1.1 (byte-ranged gets),
> a
> very nice debug/tracing utility, good error messages, and overall seemed
> to
> work pretty well, once you put in a heap of work to tweak it just right.
> In the end, it seemed, it was not a good fit for us.
> (FYI, I never used the XML parsing from libwww, I always just took the
> data
> and ran it through libxerces)
> Taylor Gautier
> Senior Software Engineer
> -----Original Message-----
> From: Kerry DeZell [mailto:kdezell@bluemountain.com]
> Sent: Tuesday, August 01, 2000 8:34 PM
> To: www-lib@w3.org
> Subject: Request for thoughts on libwww
> Hello,
> My name is Kerry and I work for Blue Mountain Arts (the electronic
> greeting card website). We are doing more and more programattic website
> to website communication as we integrate new attachments and
> functionality into our cards. Unfortunately, to date this has been done
> in a piecemeal fashion but I would like to consolidate using a single
> library (either public domain such as libwww, custom built, or purchased
> if necessary). Since the majority of our CGI's are written in C and I am
> not big on reinventing the wheel, I am interested in the C version of
> libwww.
> As we begin to add more attachments to our cards that require purchases,
> i.e. chocolates, our need for SSL support is also growing.
> I have obtained the latest versions of libwww and open SSL and have been
> playing with some simple applications. So far the non-SSL applications
> have been easy to use and haven behaved as expected. I was also able to
> create a simple SSL application as well. However, when I started doing
> multiple https requests, the application core dumps deep in the SSL
> write functionality (in perusing mail lists this morning it looks like
> this may have been found by others as well and fixed already).
> This made me wonder how stable the SSL baseline is and whether anyone is
> using it and libww extensively (e-groups mail list shows only 22
> members). I would also be interested in knowing if anyone has any
> benchmarks on the speed and stability of w3c as a whole. (i.e. has it
> been checked for memory leaks, profiled for inefficient code, how often
> are common interfaces changed/deprecated etc.)
> Lib w3c seems like a pretty good framework but it is unclear from the
> website how many users are actually using it, whether any of these uses
> are for other than experimental purposes or in house tools, or how
> actively the baseline is being maintained (most of the CVS activity
> seems to be months old and the last news item on the website is a year
> old though the SSL fix seemed to happen fairly quickly once noticed).
> Before I recommend that Blue Mountain use this technology I'd like to
> get a better feel for how the library is being used, if the SSL portion
> is being used by anyone for actual e-commerce implementatinos, and what
> people think of C libwww and its SSL interface. I would also be
> interested in knowing if anyone is actively using the XML parsing
> portion of the library as more of our interfaces to other websites seem
> to be headed in that direction.
> Any information that you could provide would be greatly appreciated. If
> we do decide to use the technology we may be able to assist in
> furthering the product.
> Thanks
> Kerry DeZell
> Blue Mountain Arts
Received on Wednesday, 2 August 2000 13:00:28 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 6 January 2015 21:33:53 UTC