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Another piece of a puzzle...
Authored by: Xenex on Mar 21, '03 10:38:16AM

A friend of mine recommended a PDF browser plugin from Schubert-it to me the other day, which works quite well. I looked around the rest of the site, and came across something called Disk Image Browser Plugin 0.1 (Proof of Concept Release).

Very intrigued, I downloaded it and read the ReadMe. I'll save you the trouble of downloading the file:

Disk Image Browser Plugin

Background

The default installation method on OS X is via a Disk Image. This has some decisive advantages, as preserving both HFS and UNIX metadata, compression without the need of proprietary software etc. On the other hand the installation process is a little bit awkward. You have to download the disk image, double-click it to mount it using Disk Copy, bear its icon bouncing, after installation trash the Disk Image file etc. This is where the Disk Image Browser Plugin comes to play.

What is this?

The Disk Image Browser Plugin is a browser plugin that automatically mounts the disk image whenever you click a link to one without the need to download the disk image file first. That means you can browse the disk or read a Readme before downloading the whole image, and install software right from the remotely mounted image. No image file remains to trash after you're done with it.

How is it installed?

Download the Disk Image Plugin from

http://www.schubert-it.com/download/diskimage-plugin.sit

and move it into the folder /Library/Internet Plug-Ins/
Restart your browser.

Why proof of concept release?

The Disk Image Browser Plugin currently appears to work reliably only with software distributed as part of a ".Mac" subscription. Other server's configuration often seem to be not suited for remote mounting of disk images. It is therefore not intended for general adoption. It demonstrates a more convenient way of distributing software on OS X though.

This software is provided as is without any guarantee. Copyright ©2002 Manfred Schubert.

I assume this is what the 'mysterious' Internet-enabled setting is for.

Now, perhaps Apple are releasing their Disk Image files on .Mac in this Internet-enabled format, but most others are not. It will be very interesting to see if this "mount online" idea is the way Apple want to go in the future in distributing software.

---
It's what's not there that makes what's there what it is.

[ Reply to This | # ]

How to get Apache to serve like this
Authored by: David on Mar 21, '03 12:33:29PM

This is \0\0\0\0\0\0\0\0how Apache serves the .dmg files so that this plug-in works.
There is a setting in /etc/http/mime.types. The line is:

application/octet-stream bin dms lha lzh exe class so dll dmg

So, the plug-in basically takes an octet-stream from the server and
then
translates it into a .dmg file. It looks like the plug-in stores the .dmg file
in cache.

---
www.AcornWebDesigns.com
Quality websites for inexpensive prices (Is that an oxymoron?)



[ Reply to This | # ]
How to get Apache to serve like this
Authored by: mech_filter on Mar 22, '03 07:59:06AM

Hmm. Would that have any negative effect for people who didn't have
this plugin installed?



[ Reply to This | # ]
Another piece of a puzzle...
Authored by: daniel_steffen on Mar 22, '03 12:04:12AM

This has nothing to do with "internet-enabled" disk images, it uses a capability of hdid that has existed at last since 10.1: mounting disk images over http.

I've certainly used this sucessfully to mount disk images from my own apache server, so it's not restricted to .mac accounts at all, but you may have to configure apache settings to get good performance, as detailed in the hdid manpage:

Mounting Images via HTTP
       In  addition  to mounting image files from local or remote
       mounted filesystems, one can also mount image  files  from
       HTTP  servers.   For  flat  image  files  (UDIF images, or
       AppleSingle/MacBinary encoded NDIF image files) mounting a
       image is a matter of passing the http:// URL to hdid:

              hdid http://server.company.com/Images/stuff.dmg

       If  the  image  file  to be served via HTTP is a dual fork
       NDIF image that is not encoded  into  a  flat-file  format
       such as AppleSingle, and the HTTP server is running on Mac
       OS X, dual fork files may be detected and supported.  Such
       dual-fork  files must be moved or copied using the Finder,
       ditto -rsrcFork, or some other  resource-fork-aware  tool.
       Properly  copied  dual-fork  files  on a UFS volume have a
       ._filename file in addition to the filename you see in the
       Finder (i.e.  stuff.img would also have ._stuff.img in the
       same directory).

       In either case, one would specify  the  URL  to  the  data
       fork, and hdid will determine if it is necessary to access
       the secondary file.

       Accessing dual fork files on HFS+ filesystems via HTTP  is
       only supported if the HTTP server is on a Mac OS X system.
       It is possible that some options on the web  server  could
       disable access to the resource fork on an HFS+ volume, but
       no such options have yet been found.

       Browsing images via HTTP is  much  more  pleasant  if  the
       server  settings  are  modified  to  be  more  friendly to
       highly-persistent clients.  In particular for Apache, Max-
       KeepAliveRequests should be increased significantly beyond
       100 or set to 0 (unlimited) and KeepAliveTimeout should be
       boosted  to  at least 30 (seconds).  Increasing the number
       of simultaneous clients may also be desirable  because  of
       the  increased  delay  before clients are forcibly discon-
       nected.

       While it is not directly related to mounting via  hdid(1),
       informing  your  web  server  that '.dmg' (and others) are
       extensions  associated  with  the   MIME   type   applica-
       tion/octet-stream  will allow web browsers to download the
       files rather than try to display them.   For  apache,  you
       add   the   extensions   to   the   appropriate   line  in
       /etc/httpd/mime.types.


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