# READMORE.txt (2004-02-29, 03-10, 03-14, 04-20, 05-21, 06-18, 07-13,
# 2005-01-21, 01-23)
# L. Zhao <writebear \at yahoo \dot com>

So you want to know more of JWebPresenter! I'm happy to see that :-).

Introduction

  This is part of the JWebPresenter project. It is the "simple
  solution". An advanced solution which supports something like
  MC (motion compensation) is being considered (oh! I found MC
  is not useful for presentaions, so don't expect 2005-01-23).

Change log

  2004-02-29, ver 1.0,  finally I chose the GPLv2 as the license.
  2004-03-10, ver 1.01, remove the useless mcMode test.
  2004-03-14, ver 1.02, document improvement.
  2004-04-20, ver 1.1,  major enhancement (Swing code, popup menu)
  2004-05-21, ver 1.2,  major change (dynamic URL, new menu, etc)
  2004-06-18, ver 1.21, minor enhancement (Reset function)
  2004-07-13, ver 1.22, minor enhancement (document improvement)
  2005-01-21, ver 1.23, minor enhancement (pre-defined window size)
  2005-01-21, ver 1.3,  major enhancement (embeded applet mode)

Technical details

  You already know that JWebPresenter is based on bitmap images:
  server (presenter) changes the slide image at pre-defined URL,
  while client (audience) fetches the image periodically. This
  basically works, and is the default behavior of JWebPresenter.

  However, in practice, it is better to tell the client the next:
   1) presentation protocol,
   2) sequence number,
   3) the next fetch time,
   4) 2004-05-21 the slide URL
   5) 2004-05-21 the next ctlURL (see follows)

  By 1), client can know how to treat the presenting.

  By 2), client can know the sequence number of slide. I know that
  there is a "Last-Modified" header in the HTTP protocol, but it
  does not always work, at least in my preliminary test, due to
  implementation difference and the cache mechanism of browsers
  or Java VMs. So I decided to use a separate control message --
  presented at the "ctlURL". This can maximize the compatibility:
  a minimal HTTP server works well; an FTP server also works fine.
  The troubles due to cache problem can be avoided too.

  By 3), client can have a hint of how fast the presenting is. This
  may help client to arrange the slide fetch process.

  By 4), client can know where to fetch the slide, and by 5), client
  can know where to get the next control message. In the versions
  before 1.2, I used two static URLs (i.e., slideURL and ctlURL are
  invariant), which sometimes get in trouble due to the cache mechanism
  of Browser, Proxy or Java VM. Therefore, from version 1.2, I decided
  to use dynamic slideURL and ctlURL. For new clients, I still keep a
  link from initial slideURL and ctlURL to the current ones. Besides,
  for slow clients, a list of presented slides is kept during presenting
  (they can be skipped though).

  Hence JWebPresenter client fetches control message from ctlURL,
  then extract slide URL and next ctlURL from the fetched messages.
  Currently, I simply skip the fetch of image if the "Seq" parameter
  did not change. But a more clever client can use its own cache to
  do things more efficiently.

  For more implementation details, please read the sources --
  Believe me, they are not difficult and are well commented.
  If you modified the Java program source, new jar file can be
  obtained by "jar cvfm jwp.jar MANIFEST *.class" after compile.

  If you are interested in more details, contact me please!

Multiple sources

  JWebPresenter has no limit on the maximum number of concurrent
  presentations (notice that it does not mean the maximum number
  of concurrent clients). In such a case, you can define slideURL
  and ctlURL as many as the number of concurrent presentations.
  For this, you first need to prepare your presentation in images
  name them slide-1-1.png, ..., slide-1-n.png for the first source;
          ...
          slide-n-1.png, ..., slide-n-m.png for the nth source.
  The number of slides in a source needs not to be same. Mixed
  image types are also OK, actually the file with minimal size is
  chosen automatically if there are several ones of the same name
  except the extension! More details can be find in slideshow.pl.

Question/suggestion/advice

  If you have questions, suggestions, advices or, even more,
  want to help me in developing this project, please feel free
  to contact me. Thanks. I'm not a crazy programmer, yet I like
  programming. Your feedback could improve JWebPresenter!

Thank you!