Re: distribution issues - moving zlib into HDF5...

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I agree with Ed's concern about the netCDF library not being able to read netCDF files that are created using zlib. Same goes for HDF5 itself. However it's done, the libraries should have zlib available.

At first blush, Ed's solution seems to me like a good one.


At 03:17 PM 3/14/2006, Elena Pourmal wrote:

By default HDF5 tries to find zlib on the system and include it. Most of the systems will have zlib library installed.

Including zlib with the source code may do more harm than good because users may end up with multiple versions of the zlib library.

Let's see what other people will say.


At 02:37 PM 3/14/2006, Ed Hartnett wrote:
Elena Pourmal <epourmal@xxxxxxxxxxxxx> writes:

> Hi Ed,
> Zlib is optional for HDF5. We intentionally didn't put zlib with HDF5
> source as we did many years ago for HDF4.

Yes, I can see that.

> Are you talking about source code or binary distribution?

Source code.

> Would it be possible for you to make zlib optional for NetCDF-4? Could
> you explain more about shared libraries problem?

Would it be possible? Yes.

Would it be desirable? I don't think so.

The problem with making it optional is that then someone can easily
produce a netCDF-4 file that won't be readable is some places because
zlib is not built into netcdf-4 somewhere.

(That is, a user with zlib-enabled netCDF-4 can create the file, and
send it to someone without zlib in netCDF-4, who would then be unable
to read it. And would then send me a support email for me to
handle. In which I will tell him to build netCDF-4 with zlib. So why
not save all that trouble, and *always* build netCDF-4 with zlib?)

What is the benefit if *not* having zlib installed? It is tiny and
easy to include. Leaving it out gains nothing that I can see.

Right now, netCDF-4 *requires* that HDF5 be built with zlib. I am
trying to get a configuration tarball together to support that.

Unless someone can present a very good reason for doing so, I don't
see why there should be two versions of netCDF-4 out there, one with,
and one without zlib.

So the question becomes: how to get one tarball to work for netCDF-4,
including zlib. The easiest way would be in HDF5 included zlib, and I
may have to hack the HDF5 configuration to do this in the case of the
netCDF-4 master tarball.

But it would be so much easier if this was done at HDF5 HQ, instead of
my me in my garage...

Ed Hartnett  -- ed@xxxxxxxxxxxxxxxx

Elena Pourmal, HDF QA, Maintenance and Support Team Leader
NCSA University of Illinois at Urbana-Champaign
605 E. Springfield Ave.
Champaign, IL 61820

(217)333-0238 (office)
(217)244-1987 (fax)

Mike Folk, Scientific Data Tech (HDF)
NCSA/U of Illinois at Urbana-Champaign  Voice: 217-244-0647
1205 W. Clark St, Urbana IL 61801 Fax: 217-244-5521

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