[maemo-developers] Application Manager scripting, second try

[From: Marius Vollmer]

Hi,

here is my second try at implementing some new features for the
.install files.  It is almost exclusively based on the feedback from
this list.  Thanks everybody for not letting me get away with my first
try! 

This time, I don't try to be more general than needed.  I hope that
this version is a nice incremental improvement to the existing way of
doing things.

To put things into context, let me briefly list the new features:

- You can have more than one catalogue in the .install file.
- Catalogue names can be localized.
- There is a special mode for installing stuff from a memory card.

(I removed backup/restore from the discussion since it uses .install
files (if at all) only as an implementation detail and we don't need
to cater to its needs.  I can still use my horrible XML scheme for
backup/restore since it all happens automatically.)


    http://hildon-app-mgr.garage.maemo.org/install.html

## Controlling the Hildon Application Manager

The Application Manager can be 'scripted' in a very limited way.  This
ability is used to implement the "Single Click" install feature as
used on the maemo Application Catalogue and when installing
applications from a memory card.

### Overview

The Application Manager offers some pre-defined 'interaction flows'
that can be controlled with a ".install" file.  Such a .install file
is a text file following the GKeyfile format, as defined by glib.

The following interaction flows are available:

- Adding catalogues 

  The .install file can contain a list of catalogues that will be
  added to the catalogues that are used by the Application Manager.

- Installing a package from the network catalogues

  The .install file can specify one package to be installed from the
  catalogues.  The .install file can also list the catalogues that are
  needed for this package to be installed successfully and they will
  be added first, similar to the "Adding catalogues" scenario.

- Installing packages from a memory card

  The .install file can be stored on a memory card and it can list the
  packages that are installable from the memory card.  It can also
  list a number of catalogues that are added after the installation
  has been completed.  This might be useful to provide updates later
  via these catalogues.

A GKeyFile consists of a number of groups, and each group contains
key/value pairs.  Each interaction flow has its own group; for example
the "Installing a package" interaction flow uses the group with the
name "install" as the main 'entry point'.  Other groups are used to
provide additional information, mostly about catalogues.  When none of
the supported entry points is found in the file, it is declared
incompatible with the current IT OS release.

For example, the following file will offer to install the `maemofoo`
package from the Foobar catalogue:

    [install]
    catalogues = foobar
    package = maemofoo

    [foobar]
    name = Foobar Catalogue
    name[en_GB] = Foobar Catalogue
    name[de_DE] = Foobar Katalog
    uri = http://foobar.com/repository
    components = main

As explained below, omitting the "dist" key means that the 'current'
distribution will be used.

### Catalogues

All of the interaction flows deal with catalogues.  They do that by
referring to groups in the .install file by name, such as "foobar" in
the example above.  Those names can be arbitrary but must be unique of
course.

A group describing a catalogue can contain the following keys:

 - `name`

 This key gives the display name of the catalogue as shown to the user
 in the "Tool > Application catalogues" dialog.  This key can be
 localised by following the GKeyFile conventions.  If you omit this
 key, the catalogue will have an empty name.

 - `uri`

 The URI part of the `deb` line that will be added to `sources.list`
 for this catalogue.  This key is required for all catalogues except
 those used with the "card_catalogues" key.

 - `file_uri`

 When using `file_uri` instead of `uri`, the URI part of the `deb`
 line will use the "file://" method and the `file_uri` gives the
 actual pathname, relative to the location of the .install file.  This
 key is required for all catalogues that are used with the
 "card_catalogues" key.

 - `dist`

 The distribution of the `deb` line that will be added to
 `sources.list` for this catalogue.  If you omit it, it will default
 to the distribution corresponding to the IT OS release on the device.

 The fact that the distribution should be selected automatically is
 remembered by the Application Manager.  For example, if you make a
 backup that contains a catalogue with automatic distribution
 selection and restore it on a different IT OS release, the
 distribution for the new version will be used automatically.

 - `components`

 The components part of the `deb` line that will be added to
 `sources.list` for this catalogue.  If you omit it, the components
 part will be empty.

 - `filter_dist`

 This catalogue will be ignored when the distribution corresponding to
 the IT OS release on the device doesn't match.

When catalogues are compared, they are considered equal when their
`uri`, `dist` and `components` fields are equal.

### Adding catalogues.

This interaction flow is controlled by the "catalogues" group.  This
group has one mandatory key, "catalogues", and no optional ones.  The
"catalogues" key is a list of strings that refer to the catalogue
groups that describe the catalogues to be added.

Catalogues are filtered according to their `filter_*` keys.  When all
of the listed catalogues are filtered out, the .install file is
declared to be incompatible with the current IT OS release.

Each catalogue is considered in turn and the user is asked whether to
add it or not.  When it should be added and a catalogue is already
configured in the Application Manager that is equal to the one
considered, the configured catalogue is removed first.  When the user
declines the adding, the next catalogue is considered.

After considering every catalogue, the user is asked whether to
"Refresh the list of applications".

Example:

    [catalogues]
    catalogues = extras; sdk

    [extras]
    name = maemo Extras catalogue
    uri = http://repository.maemo.org/extras
    components = free non-free

    [sdk]
    name = maemo SDK catalogue
    uri = http://repository.maemo.org/
    components = free non-free

### Installing a package

This interaction flow is controlled by the "install" group.  This
group has one mandatory key, "package", and a optional one,
"catalogues".

The "package" key gives the name of the package to install.

The "catalogues" key, when present, is just like the "catalogues" key
for the "Adding catalogues" case.  The catalogues are handled a bit
differently, tho:

Each catalogue is considered in turn and when it there isn't already a
catalogue configured that is equal to it, the user is informed that it
needs to be added and is asked for confirmation.  Alternatively, when
a catalogue is already present but disabled, the user is informed that
it needs to be enabled and is asked for confirmation.  When the user
confirms, the catalogue is added and processing continues.  When s/he
declines, processing of the .install file stops and the changes to the
configured catalogues that have been made for it are reverted.

After the catalogues have been handled, the a "Refresh list of
applications" operation is performed without asking.  Processing
continues regardless of whether it fails or not.

Then, the given package is offered to the user for installing, as if
s/he had requested this from the "Browse installable applications"
view.

### Installing from a memory card

This interaction flow is controlled by the "card_install" group.  It
has two mandatory keys, "packages" and "card_catalogues", and a
optional one, "permanent_catalogues".

The "packages" key lists the names of packages that can be installed
from the memory card, using the "card_catalogues".

Installation of the packages happens in a temporary environment: in
this environment, the normally configured catalogues are not
available, only the catalogues listed by the "card_catalogues" key are
configured.  All of these catalogues must use "file_uri" instead of
"uri".

The packages are installed in this temporary environment.  The user
gets to select them from a list.  Only packages that are not already
installed or are not uptodate are offered.  When the offered list
would be empty, processing stops with an appropriate note.

When the user cancels the confirmation dialog or confirms with an
empty selection, processing stops.  Otherwise, each selected package
is installed in turn, one after the other.  If one of the
installations fails, an error message is displayed and processing
stops.

When all selected packages have been installed successfully, the
"permanent_catalogues" will be offered to the user for addition as
with the "Adding catalogues" case.

### Compatibility with IT OS 2007.

In addition to the format described above, the Hildon Application
Manager also understands the old .install files from IT OS 2007.

A file like this:

    [install]
    repo_name = NAME
    repo_deb = DEB
    repo_deb_3 = DEB_3
    package = PACKAGE

is interpreted as if it were

    [install]
    catalogues = repo; repo_3
    package = PACKAGE
    
    [repo]
    filter_dist = mistral
    name = NAME
    uri = URI
    dist = DIST
    components = COMPONENTS

    [repo_3]
    filter_dist = bora
    name = NAME
    uri = URI_3
    dist = DIST_3
    components = COMPONENTS_3

where URI, DIST, and COMPONENTS are parsed out of DEB, as
appropriate.

If the "package" key is omitted in the "install" group, it is treated
as a "catalogues" group.