---------------------------------------------------------------------------
    M i n e r v a   S o f t w a r e   T e c h n i c a l   R e l e a s e

   Number: 016/Update                                    Baring Crescent
   Date:   10/09/92                                               Exeter
   Author: MK                                                      Devon
   Pages:  02                                                    EX1 1TL     

               Updating RISC OS applications with new versions
-----------------------------------------------------------------------------

When updating applications there are two classifications of application to
consider:

 (a) Applications which are fully self contained and invariable. This
     describes the majority of applications.

 (b) Applications which may vary in content. This includes such things as
     !System and !Fonts. There are other examples, such as the Minerva
     Business Accounts; this one application may contain any combination of
     the individual ledger modules.

Updating applications needs care because applications are not single files
although the filer treats them as such. An application is actually a
directory, identified to the filer as an application by the fact that the
first character in its name is an exclamation mark (!). Note that the
'files' created by some applications are also applications, usually
described as 'pseudo applications.' This includes the files generated by
programs such as Genesis and Impression. These pseudo applications usually
fall into class (a) above.

Class (a) applications are easy to update. You need simply to delete the old
version and replace it with the new. Note that deleting the old version is
important; simply copying the new version over the old will not always work
correctly for two reasons:

 (1) The application is actually a directory. If the new version contains
     a different selection of files from the old one, you will end up with a
     combination of the two applications on the disc. Although this is not
     necessarily harmful, it is wasteful of space.

 (2) If your filer is not configured correctly, it will not overwrite files
     during a copy and it will not tell you that it has not done so. This
     means the application will not actually be updated and you will not be
     able to tell since you cannot see the files inside the application. This
     also applies to individual file updates, eg when making a backup of a
     file from hard disc to floppy disc.

So, to update applications in class (a), DELETE THE OLD VERSION FIRST.



--01---016/Update----------------------------------------------------------
With class (b) applications, deleting the old version first may be
disasterous as the update may not contain everything that was in the old
version. Eg, if you were updating your !Fonts to get a new font, deleting
the old !Fonts first would result in all the existing fonts being lost and
the new font becoming the only font available. To avoid this, the
applications should be merged by copying the new one on top of the old one.
However, this invokes problem (2), above. To overcome this you need to
configure your filer so that it can overwrite existing files:

   * Click MENU over any directory display window.
   * In the 'Options' submenu, ensure that the 'Confirm' option is ticked.
   * Update the application by dragging the new one onto the old one.
   * You will be asked to confirm overwrites of any existing files.
   * Answer Yes to overwrite in all cases.
   * Re-configure the options for your filer if desired.

This procedure will update the application correctly. Note that in the case
of !System, there is a special application called !SysMerge which will
update your !System correctly. If you have a copy of this you should use it
instead of the procedure described above. To find out more about !SysMerge,
read its help file.

--02---016/Update----------------------------------------------------------