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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 17:57:27 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 17:57:27 +0000
commit6f0f7d1b40a8fa8d46a2d6f4317600001cdbbb18 (patch)
treed423850ae901365e582137bdf2b5cbdffd7ca266 /doc/api
parentInitial commit. (diff)
downloadgnome-software-6f0f7d1b40a8fa8d46a2d6f4317600001cdbbb18.tar.xz
gnome-software-6f0f7d1b40a8fa8d46a2d6f4317600001cdbbb18.zip
Adding upstream version 43.5.upstream/43.5upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r--doc/api/gnome-software-docs.xml778
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-rw-r--r--doc/api/gs-example-installed.pngbin0 -> 106482 bytes
-rw-r--r--doc/api/gs-example-search.pngbin0 -> 24934 bytes
-rw-r--r--doc/api/meson.build11
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diff --git a/doc/api/gnome-software-docs.xml b/doc/api/gnome-software-docs.xml
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--- /dev/null
+++ b/doc/api/gnome-software-docs.xml
@@ -0,0 +1,778 @@
+<?xml version="1.0"?>
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
+ "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd"
+[
+ <!ENTITY % local.common.attrib "xmlns:xi CDATA #FIXED 'http://www.w3.org/2003/XInclude'">
+]>
+<book id="index">
+ <bookinfo>
+ <title>GNOME Software Reference Manual</title>
+ </bookinfo>
+
+ <reference id="tutorial">
+ <title>GNOME Software Plugin Tutorial</title>
+ <partintro>
+ <para>
+ GNOME Software is a software installer designed to be easy to use.
+ </para>
+
+ <section>
+ <title>Introduction</title>
+ <para>
+ At the heart of gnome software the application is just a plugin loader
+ that has some GTK UI that gets created for various result types.
+ The idea is we have lots of small plugins that each do one thing and
+ then pass the result onto the other plugins.
+ These are ordered by dependencies against each other at runtime and
+ each one can do things like editing an existing application or adding a
+ new application to the result set.
+ This is how we can add support for things like firmware updating,
+ GNOME Shell web-apps and flatpak bundles without making big
+ changes all over the source tree.
+ </para>
+ <para>
+ There are broadly 3 types of plugin methods:
+ </para>
+ <itemizedlist>
+ <listitem>
+ <para><emphasis role="strong">Actions</emphasis>: Do something on a specific GsApp</para>
+ </listitem>
+ <listitem>
+ <para><emphasis role="strong">Refine</emphasis>: Get details about a specific GsApp</para>
+ </listitem>
+ <listitem>
+ <para><emphasis role="strong">Adopt</emphasis>: Can this plugin handle this GsApp</para>
+ </listitem>
+ </itemizedlist>
+ <para>
+ In general, building things out-of-tree isn't something that I think is
+ a very good idea; the API and ABI inside gnome-software is still
+ changing and there's a huge benefit to getting plugins upstream where
+ they can undergo review and be ported as the API adapts.
+ I'm also super keen to provide configurability in GSettings for doing
+ obviously-useful things, the sort of thing Fleet Commander can set for
+ groups of users.
+ </para>
+ <para>
+ However, now we're shipping gnome-software in enterprise-class distros
+ we might want to allow customers to ship their own plugins to make
+ various business-specific changes that don't make sense upstream.
+ This might involve querying a custom LDAP server and changing the
+ suggested apps to reflect what groups the user is in, or might involve
+ showing a whole new class of applications that does not conform to the
+ Linux-specific <emphasis>application is a desktop-file</emphasis> paradigm.
+ This is where a plugin makes sense.
+ </para>
+
+ <para>
+ The plugin needs to create a class derived from <type>GsPlugin</type>,
+ and define the vfuncs that it needs. The
+ plugin name is taken automatically from the suffix of the
+ <filename>.so</filename> file. The type of the plugin is exposed to
+ gnome-software using <function>gs_plugin_query_type()</function>, which
+ must be exported from the module.
+ </para>
+ <example>
+ <title>A sample plugin</title>
+ <programlisting>
+/*
+ * Copyright (C) 2016 Richard Hughes
+ */
+
+#include &lt;glib.h&gt;
+#include &lt;gnome-software.h&gt;
+
+struct _GsPluginSample {
+ GsPlugin parent;
+
+ /* private data here */
+};
+
+G_DEFINE_TYPE (GsPluginSample, gs_plugin_sample, GS_TYPE_PLUGIN)
+
+static void
+gs_plugin_sample_init (GsPluginSample *self)
+{
+ GsPlugin *plugin = GS_PLUGIN (self);
+
+ gs_plugin_add_rule (plugin, GS_PLUGIN_RULE_RUN_BEFORE, "appstream");
+}
+
+static void
+gs_plugin_sample_list_apps_async (GsPlugin *plugin,
+ GsAppQuery *query,
+ GsPluginListAppsFlags flags,
+ GCancellable *cancellable,
+ GAsyncReadyCallback callback,
+ gpointer user_data)
+{
+ GsPluginSample *self = GS_PLUGIN_SAMPLE (plugin);
+ g_autoptr(GTask) task = NULL;
+ const gchar * const *keywords;
+ g_autoptr(GsAppList) list = gs_app_list_new ();
+
+ task = gs_plugin_list_apps_data_new_task (plugin, query, flags,
+ cancellable, callback, user_data);
+ g_task_set_source_tag (task, gs_plugin_sample_list_apps_async);
+
+ if (query == NULL ||
+ gs_app_query_get_keywords (query) == NULL ||
+ gs_app_query_get_n_properties_set (query) != 1) {
+ g_task_return_new_error (task, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
+ "Unsupported query");
+ return;
+ }
+
+ keywords = gs_app_query_get_keywords (query);
+
+ for (gsize i = 0; keywords[i] != NULL; i++) {
+ if (g_str_equal (keywords[i], "fotoshop")) {
+ g_autoptr(GsApp) app = gs_app_new ("gimp.desktop");
+ gs_app_add_quirk (app, GS_APP_QUIRK_IS_WILDCARD);
+ gs_app_list_add (list, app);
+ }
+ }
+
+ g_task_return_pointer (task, g_steal_pointer (&amp;list), g_object_unref);
+}
+
+static GsAppList *
+gs_plugin_sample_list_apps_finish (GsPlugin *plugin,
+ GAsyncResult *result,
+ GError **error)
+{
+ return g_task_propagate_pointer (G_TASK (result), error);
+}
+
+static void
+gs_plugin_sample_class_init (GsPluginSampleClass *klass)
+{
+ GsPluginClass *plugin_class = GS_PLUGIN_CLASS (klass);
+
+ plugin_class->list_apps_async = gs_plugin_sample_list_apps_async;
+ plugin_class->list_apps_finish = gs_plugin_sample_list_apps_finish;
+}
+
+GType
+gs_plugin_query_type (void)
+{
+ return GS_TYPE_PLUGIN_SAMPLE;
+}
+ </programlisting>
+ </example>
+
+ <para>
+ We have to define when our plugin is run in reference to other plugins,
+ in this case, making sure we run before <code>appstream</code>.
+ As we're such a simple plugin we're relying on another plugin to run
+ after us to actually make the GsApp <emphasis>complete</emphasis>,
+ i.e. loading icons and setting a localised long description.
+ </para>
+ <para>
+ In this example we want to show GIMP as a result (from any provider,
+ e.g. flatpak or a distro package) when the user searches exactly for
+ <code>fotoshop</code>.
+ </para>
+ <para>
+ We can then build and install the plugin using:
+ </para>
+ <informalexample>
+ <programlisting>
+gcc -shared -o libgs_plugin_example.so gs-plugin-example.c -fPIC \
+ $(pkg-config --libs --cflags gnome-software) \
+ -DI_KNOW_THE_GNOME_SOFTWARE_API_IS_SUBJECT_TO_CHANGE &amp;&amp; \
+cp libgs_plugin_example.so $(pkg-config gnome-software --variable=plugindir)
+ </programlisting>
+ </informalexample>
+
+ <mediaobject id="gs-example-search">
+ <imageobject>
+ <imagedata format="PNG" fileref="gs-example-search.png" align="center"/>
+ </imageobject>
+ </mediaobject>
+
+ </section>
+
+ <section>
+ <title>Distribution Specific Functionality</title>
+ <para>
+ Some plugins should only run on specific distributions, for instance
+ the <code>fedora-pkgdb-collections</code> plugin should only be used on
+ Fedora systems.
+ This can be achieved with a simple runtime check using the helper
+ <code>gs_plugin_check_distro_id()</code> method or the <code>GsOsRelease</code>
+ object where more complicated rules are required.
+ </para>
+ <example>
+ <title>Self disabling on other distributions</title>
+ <programlisting>
+static void
+gs_plugin_sample_init (GsPluginSample *self)
+{
+ GsPlugin *plugin = GS_PLUGIN (self);
+
+ if (!gs_plugin_check_distro_id (plugin, "ubuntu")) {
+ gs_plugin_set_enabled (plugin, FALSE);
+ return;
+ }
+ /* set up private data etc. */
+}
+ </programlisting>
+ </example>
+
+ </section>
+
+ <section>
+ <title>Custom Applications in the Installed List</title>
+ <para>
+ Next is returning custom applications in the installed list.
+ The use case here is a proprietary software distribution method that
+ installs custom files into your home directory, but you can use your
+ imagination for how this could be useful.
+ The example here is all hardcoded, and a true plugin would have to
+ derive the details about the GsApp, for example reading in an XML
+ file or YAML config file somewhere.
+ </para>
+ <example>
+ <title>Example showing a custom installed application</title>
+ <programlisting>
+static void
+gs_plugin_sample_init (GsPluginSample *self)
+{
+ GsPlugin *plugin = GS_PLUGIN (self);
+
+ gs_plugin_add_rule (plugin, GS_PLUGIN_RULE_RUN_BEFORE, "icons");
+}
+
+static void
+gs_plugin_custom_list_apps_async (GsPlugin *plugin,
+ GsAppQuery *query,
+ GsPluginListAppsFlags flags,
+ GCancellable *cancellable,
+ GAsyncReadyCallback callback,
+ gpointer user_data)
+{
+ g_autofree gchar *fn = NULL;
+ g_autoptr(GsApp) app = NULL;
+ g_autoptr(GIcon) icon = NULL;
+ g_autoptr(GsAppList) list = gs_app_list_new ();
+ g_autoptr(GTask) task = NULL;
+
+ task = g_task_new (plugin, cancellable, callback, user_data);
+ g_task_set_source_tag (task, gs_plugin_custom_list_apps_async);
+
+ /* We’re only listing installed apps in this example. */
+ if (query == NULL ||
+ gs_app_query_get_is_installed (query) != GS_APP_QUERY_TRISTATE_TRUE ||
+ gs_app_query_get_n_properties_set (query) != 1) {
+ g_task_return_new_error (task, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
+ "Unsupported query");
+ return;
+ }
+
+ /* check if the app exists */
+ fn = g_build_filename (g_get_home_dir (), "chiron", NULL);
+ if (!g_file_test (fn, G_FILE_TEST_EXISTS)) {
+ g_task_return_pointer (task, g_steal_pointer (&amp;list), g_object_unref);
+ return;
+ }
+
+ /* the trigger exists, so create a fake app */
+ app = gs_app_new ("chiron.desktop");
+ gs_app_set_management_plugin (app, plugin);
+ gs_app_set_kind (app, AS_COMPONENT_KIND_DESKTOP_APP);
+ gs_app_set_state (app, GS_APP_STATE_INSTALLED);
+ gs_app_set_name (app, GS_APP_QUALITY_NORMAL, "Chiron");
+ gs_app_set_summary (app, GS_APP_QUALITY_NORMAL, "A teaching application");
+ gs_app_set_description (app, GS_APP_QUALITY_NORMAL,
+ "Chiron is the name of an application.\n\n"
+ "It can be used to demo some of our features");
+
+ /* these are all optional, but make details page looks better */
+ gs_app_set_version (app, "1.2.3");
+ gs_app_set_size_installed (app, GS_SIZE_TYPE_VALID, 2 * 1024 * 1024);
+ gs_app_set_size_download (app, GS_SIZE_TYPE_VALID, 3 * 1024 * 1024);
+ gs_app_set_origin_hostname (app, "http://www.teaching-example.org/");
+ gs_app_add_category (app, "Game");
+ gs_app_add_category (app, "ActionGame");
+ gs_app_add_kudo (app, GS_APP_KUDO_INSTALLS_USER_DOCS);
+ gs_app_set_license (app, GS_APP_QUALITY_NORMAL, "GPL-2.0+ and LGPL-2.1+");
+
+ /* use a stock icon */
+ icon = g_themed_icon_new ("input-gaming");
+ gs_app_add_icon (app, icon);
+
+ /* return new app */
+ gs_app_list_add (list, app);
+
+ g_task_return_pointer (task, g_steal_pointer (&amp;list), g_object_unref);
+}
+
+static GsAppList *
+gs_plugin_custom_list_apps_finish (GsPlugin *plugin,
+ GAsyncResult *result,
+ GError **error)
+{
+ return g_task_propagate_pointer (G_TASK (result), error);
+}
+ </programlisting>
+ </example>
+ <para>
+ This shows a lot of the plugin architecture in action. Some notable points:
+ </para>
+ <itemizedlist>
+ <listitem>
+ <para>
+ Setting the management plugin means we can check for this string
+ when working out if we can handle the install or remove action.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ Most applications want a kind of <code>AS_COMPONENT_KIND_DESKTOP_APP</code>
+ to be visible as an application.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ The origin is where the application originated from — usually
+ this will be something like <emphasis>Fedora Updates</emphasis>.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ The <code>GS_APP_KUDO_INSTALLS_USER_DOCS</code> means we get the
+ blue "Documentation" award in the details page; there are many
+ kudos to award to deserving apps.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ Setting the license means we don't get the non-free warning —
+ removing the 3rd party warning can be done using
+ <code>GS_APP_QUIRK_PROVENANCE</code>
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ The icon will be loaded into a pixbuf of the correct size when
+ needed by the UI. You must ensure that icons are available at
+ common sizes. For icons of type <code>GsRemoteIcon</code>, the
+ <code>icons</code> plugin will download and cache the icon
+ locally.
+ </para>
+ </listitem>
+ </itemizedlist>
+ <para>
+ To show this fake application just compile and install the plugin,
+ <code>touch ~/chiron</code> and then restart gnome-software.
+ To avoid restarting <filename>gnome-software</filename> each time a
+ proper plugin would create a <code>GFileMonitor</code> object to
+ monitor files.
+ </para>
+
+ <mediaobject id="gs-example-installed">
+ <imageobject>
+ <imagedata format="PNG" fileref="gs-example-installed.png" align="center"/>
+ </imageobject>
+ </mediaobject>
+
+ <para>
+ By filling in the optional details (which can also be filled in using
+ <code>refine_async()</code> you can also make the details
+ page a much more exciting place.
+ Adding a set of screenshots is left as an exercise to the reader.
+ </para>
+
+ <mediaobject id="gs-example-details">
+ <imageobject>
+ <imagedata format="PNG" fileref="gs-example-details.png" align="center"/>
+ </imageobject>
+ </mediaobject>
+
+ </section>
+
+ <section>
+ <title>Downloading Metadata and Updates</title>
+
+ <para>
+ The plugin loader supports a <code>refresh_metadata_async()</code> vfunc that
+ is called in various situations.
+ To ensure plugins have the minimum required metadata on disk it is
+ called at startup, but with a cache age of <emphasis>infinite</emphasis>.
+ This basically means the plugin must just ensure that
+ <emphasis role="strong">any</emphasis> data exists no matter what the age.
+ </para>
+ <para>
+ Usually once per hour, we'll call <code>refresh_metadata_async()</code> but
+ with the correct cache age set (typically a little over 24 hours) which
+ allows the plugin to download new metadata or payload files from remote
+ servers.
+ The <code>gs_utils_get_file_age()</code> utility helper can help you
+ work out the cache age of a file, or the plugin can handle it some other
+ way.
+ </para>
+ <para>
+ For the Flatpak plugin we just make sure the AppStream metadata exists
+ at startup, which allows us to show search results in the UI.
+ If the metadata did not exist (e.g. if the user had added a remote
+ using the command-line without gnome-software running) then we would
+ show a loading screen with a progress bar before showing the main UI.
+ On fast connections we should only show that for a couple of seconds,
+ but it's a good idea to try any avoid that if at all possible in the
+ plugin.
+ Once per day the <code>gs_plugin_get_updates()</code> method is called,
+ and then <code>gs_plugin_download_app()</code> may be called if the
+ user has configured automatic updates.
+ This is where the Flatpak plugin would download any ostree trees (but
+ not doing the deploy step) so that the applications can be updated live
+ in the details panel without having to wait for the download to complete.
+ In a similar way, the fwupd plugin downloads the tiny LVFS metadata with
+ <code>refresh_metadata_async()</code> and then downloads the large firmware
+ files themselves when <code>gs_plugin_download()</code> or
+ <code>gs_plugin_download_app()</code> is called.
+ </para>
+ <para>
+ Note, if the downloading fails it's okay to return <code>FALSE</code>;
+ the plugin loader continues to run all plugins and just logs an error
+ to the console. We'll be calling into <code>refresh_metadata_async()</code>
+ again in only another hour, so there's no need to bother the user.
+ For actions like <code>gs_plugin_app_install</code> we also do the same
+ thing, but we also save the error on the GsApp itself so that the UI is
+ free to handle that how it wants, for instance showing a GtkDialog
+ window for example.
+ </para>
+ <example>
+ <title>Refresh example</title>
+ <programlisting>
+static void progress_cb (gsize bytes_downloaded,
+ gsize total_download_size,
+ gpointer user_data);
+static void download_file_cb (GObject *source_object,
+ GAsyncResult *result,
+ gpointer user_data);
+
+static void
+gs_plugin_example_refresh_metadata_async (GsPlugin *plugin,
+ guint64 cache_age_secs,
+ GsPluginRefreshMetadataFlags flags,
+ GCancellable *cancellable,
+ GError **error)
+{
+ const gchar *metadata_filename = "/var/cache/example/metadata.xml";
+ const gchar *metadata_url = "https://www.example.com/new.xml";
+ g_autoptr(GFile) file = g_file_new_for_path (metadata_filename);
+ g_autoptr(GTask) task = NULL;
+ g_autoptr(SoupSession) soup_session = NULL;
+
+ task = g_task_new (plugin, cancellable, callback, user_data);
+ g_task_set_source_tag (task, gs_plugin_example_refresh_metadata_async);
+
+ soup_session = gs_build_soup_session ();
+
+ /* is the metadata missing or too old? */
+ if (gs_utils_get_file_age (file) &gt; cache_age_secs) {
+ gs_download_file_async (soup_session,
+ metadata_url,
+ file,
+ G_PRIORITY_LOW,
+ progress_cb,
+ plugin,
+ cancellable,
+ download_file_cb,
+ g_steal_pointer (&amp;task));
+ return;
+ }
+
+ g_task_return_boolean (task, TRUE);
+}
+
+static void
+progress_cb (gsize bytes_downloaded,
+ gsize total_download_size,
+ gpointer user_data)
+{
+ g_debug ("Downloaded %zu of %zu bytes", bytes_downloaded, total_download_size);
+}
+
+static void
+download_file_cb (GObject *source_object,
+ GAsyncResult *result,
+ gpointer user_data)
+{
+ GsPlugin *plugin = GS_PLUGIN (source_object);
+ g_autoptr(GTask) task = g_steal_pointer (&amp;user_data);
+
+ if (!gs_download_file_finish (result, &amp;local_error)) {
+ g_task_return_error (task, g_steal_pointer (&amp;local_error));
+ } else {
+ g_debug ("successfully downloaded new metadata");
+ g_task_return_boolean (task, TRUE);
+ }
+}
+
+static gboolean
+gs_plugin_example_refresh_metadata_finish (GsPlugin *plugin,
+ GAsyncResult *result,
+ GError **error)
+{
+ return g_task_propagate_boolean (G_TASK (result), error);
+}
+ </programlisting>
+ </example>
+ </section>
+
+ <section>
+ <title>Adding Application Information Using Refine</title>
+
+ <para>
+ As previous examples have shown it's very easy to add a new
+ application to the search results, updates list or installed list.
+ Some plugins don't want to add more applications, but want to modify
+ existing applications to add more information depending on what is
+ required by the UI code.
+ The reason we don't just add everything at once is that for
+ search-as-you-type to work effectively we need to return results in
+ less than about 50ms and querying some data can take a long time.
+ For example, it might take a few hundred ms to work out the download
+ size for an application when a plugin has to also look at what
+ dependencies are already installed.
+ We only need this information once the user has clicked the search
+ results and when the user is in the details panel, so we can save a
+ ton of time not working out properties that are not useful.
+ </para>
+ <example>
+ <title>Refine example</title>
+ <programlisting>
+static void
+gs_plugin_example_refine_async (GsPlugin *plugin,
+ GsAppList *list,
+ GsPluginRefineFlags flags,
+ GCancellable *cancellable,
+ GAsyncReadyCallback callback,
+ gpointer user_data)
+{
+ g_autoptr(GTask) task = NULL;
+
+ task = g_task_new (plugin, cancellable, callback, user_data);
+ g_task_set_source_tag (task, gs_plugin_example_refine_async);
+
+ /* not required */
+ if ((flags &amp; GS_PLUGIN_REFINE_FLAGS_REQUIRE_LICENSE) == 0) {
+ g_task_return_boolean (task, TRUE);
+ return;
+ }
+
+ for (guint i = 0; i &lt; gs_app_list_length (list); i++) {
+ GsApp *app = gs_app_list_index (list, i);
+
+ /* already set */
+ if (gs_app_get_license (app) != NULL) {
+ g_task_return_boolean (task, TRUE);
+ return;
+ }
+
+ /* FIXME, not just hardcoded! */
+ if (g_strcmp0 (gs_app_get_id (app, "chiron.desktop") == 0))
+ gs_app_set_license (app, "GPL-2.0 and LGPL-2.0+");
+ }
+
+ g_task_return_boolean (task, TRUE);
+}
+
+static gboolean
+gs_plugin_example_refine_finish (GsPlugin *plugin,
+ GAsyncResult *result,
+ GError **error)
+{
+ return g_task_propagate_boolean (G_TASK (result), error);
+}
+ </programlisting>
+ </example>
+ <para>
+ This is a simple example, but shows what a plugin needs to do.
+ It first checks if the action is required, in this case
+ <code>GS_PLUGIN_REFINE_FLAGS_REQUIRE_LICENSE</code>.
+ This request is more common than you might expect as even the search
+ results shows a non-free label if the license is unspecified or
+ non-free.
+ It then checks if the license is already set, returning with success
+ if so.
+ If not, it checks the application ID and hardcodes a license; in the
+ real world this would be querying a database or parsing an additional
+ config file.
+ As mentioned before, if the license value is freely available without
+ any extra work then it's best just to set this at the same time as
+ when adding the app with <code>gs_app_list_add()</code>.
+ Think of refine as <emphasis>adding things that cost time to
+ calculate only when really required</emphasis>.
+ </para>
+ <para>
+ The UI in gnome-software is quite forgiving for missing data, hiding
+ sections or labels as required.
+ Some things are required however, and forgetting to assign an icon or
+ short description will get the application vetoed so that it's not
+ displayed at all.
+ Helpfully, running <code>gnome-software --verbose</code> on the
+ command line will tell you why an application isn't shown along with
+ any extra data.
+ </para>
+
+ </section>
+
+ <section>
+ <title>Adopting AppStream Applications</title>
+
+ <para>
+ There's a lot of flexibility in the gnome-software plugin structure;
+ a plugin can add custom applications and handle things like search and
+ icon loading in a totally custom way.
+ Most of the time you don't care about how search is implemented or how
+ icons are going to be loaded, and you can re-use a lot of the existing
+ code in the <code>appstream</code> plugin.
+ To do this you just save an AppStream-format XML file in either
+ <filename>/usr/share/swcatalog/xml/</filename>,
+ <filename>/var/cache/swcatalog/xml/</filename> or
+ <filename>~/.local/share/swcatalog/xml/</filename>.
+ GNOME Software will immediately notice any new files, or changes to
+ existing files as it has set up the various inotify watches.
+ </para>
+ <para>
+ This allows plugins to care a lot less about how applications are
+ going to be shown.
+ For example, the <code>flatpak</code> plugin downloads AppStream data
+ for configured remotes during <code>refresh_metadata_async()</code>.
+ </para>
+ <para>
+ The only extra step a plugin providing its own apps needs to do
+ is to implement the <code>gs_plugin_adopt_app()</code> function.
+ This is called when an application does not have a management plugin
+ set, and allows the plugin to <emphasis>claim</emphasis> the
+ application for itself so it can handle installation, removal and
+ updating.
+ </para>
+ <para>
+ Another good example is the <code>fwupd</code> that wants to handle
+ any firmware we've discovered in the AppStream XML.
+ This might be shipped by the vendor in a package using Satellite,
+ or downloaded from the LVFS. It wouldn't be kind to set a management
+ plugin explicitly in case XFCE or KDE want to handle this in a
+ different way. This adoption function in this case is trivial:
+ </para>
+
+ <informalexample>
+ <programlisting>
+void
+gs_plugin_adopt_app (GsPlugin *plugin, GsApp *app)
+{
+ if (gs_app_get_kind (app) == AS_COMPONENT_KIND_FIRMWARE)
+ gs_app_set_management_plugin (app, plugin);
+}
+ </programlisting>
+ </informalexample>
+ </section>
+
+ <section>
+ <title>Using The Plugin Cache</title>
+
+ <para>
+ GNOME Software used to provide a per-process plugin cache,
+ automatically de-duplicating applications and trying to be smarter
+ than the plugins themselves.
+ This involved merging applications created by different plugins and
+ really didn't work very well.
+ For versions 3.20 and later we moved to a per-plugin cache which
+ allows the plugin to control getting and adding applications to the
+ cache and invalidating it when it made sense.
+ This seems to work a lot better and is an order of magnitude less
+ complicated.
+ Plugins can trivially be ported to using the cache using something
+ like this:
+ </para>
+ <informalexample>
+ <programlisting>
+ /* create new object */
+ id = gs_plugin_flatpak_build_id (inst, xref);
+- app = gs_app_new (id);
++ app = gs_plugin_cache_lookup (plugin, id);
++ if (app == NULL) {
++ app = gs_app_new (id);
++ gs_plugin_cache_add (plugin, id, app);
++ }
+ </programlisting>
+ </informalexample>
+ <para>
+ Using the cache has two main benefits for plugins.
+ The first is that we avoid creating duplicate GsApp objects for the
+ same logical thing.
+ This means we can query the installed list, start installing an
+ application, then query it again before the install has finished.
+ The GsApp returned from the second <code>list_apps()</code>
+ request will be the same GObject, and thus all the signals connecting
+ up to the UI will still be correct.
+ This means we don't have to care about <emphasis>migrating</emphasis>
+ the UI widgets as the object changes and things like progress bars just
+ magically work.
+ </para>
+ <para>
+ The other benefit is more obvious.
+ If we know the application state from a previous request we don't have
+ to query a daemon or do another blocking library call to get it.
+ This does of course imply that the plugin is properly invalidating
+ the cache using <code>gs_plugin_cache_invalidate()</code> which it
+ should do whenever a change is detected.
+ Whether a plugin uses the cache for this reason is up to the plugin,
+ but if it does it is up to the plugin to make sure the cache doesn't
+ get out of sync.
+ </para>
+ </section>
+
+ </partintro>
+ </reference>
+
+ <reference id="api">
+ <partintro>
+ <para>
+ This documentation is auto-generated.
+ If you see any issues, please file bugs.
+ </para>
+ </partintro>
+ <title>GNOME Software Plugin API</title>
+ <xi:include href="xml/gs-app.xml"/>
+ <xi:include href="xml/gs-app-collation.xml"/>
+ <xi:include href="xml/gs-app-list.xml"/>
+ <xi:include href="xml/gs-app-query.xml"/>
+ <xi:include href="xml/gs-appstream.xml"/>
+ <xi:include href="xml/gs-category.xml"/>
+ <xi:include href="xml/gs-category-manager.xml"/>
+ <xi:include href="xml/gs-debug.xml"/>
+ <xi:include href="xml/gs-desktop-data.xml"/>
+ <xi:include href="xml/gs-download-utils.xml"/>
+ <xi:include href="xml/gs-external-appstream-utils.xml"/>
+ <xi:include href="xml/gs-fedora-third-party.xml"/>
+ <xi:include href="xml/gs-icon.xml"/>
+ <xi:include href="xml/gs-ioprio.xml"/>
+ <xi:include href="xml/gs-key-colors.xml"/>
+ <xi:include href="xml/gs-metered.xml"/>
+ <xi:include href="xml/gs-odrs-provider.xml"/>
+ <xi:include href="xml/gs-os-release.xml"/>
+ <xi:include href="xml/gs-plugin.xml"/>
+ <xi:include href="xml/gs-plugin-event.xml"/>
+ <xi:include href="xml/gs-plugin-helpers.xml"/>
+ <xi:include href="xml/gs-plugin-job-list-apps.xml"/>
+ <xi:include href="xml/gs-plugin-job-list-categories.xml"/>
+ <xi:include href="xml/gs-plugin-job-list-distro-upgrades.xml"/>
+ <xi:include href="xml/gs-plugin-job-refine.xml"/>
+ <xi:include href="xml/gs-plugin-job-refresh-metadata.xml"/>
+ <xi:include href="xml/gs-plugin-job.xml"/>
+ <xi:include href="xml/gs-plugin-loader-sync.xml"/>
+ <xi:include href="xml/gs-plugin-loader.xml"/>
+ <xi:include href="xml/gs-plugin-types.xml"/>
+ <xi:include href="xml/gs-plugin-vfuncs.xml"/>
+ <xi:include href="xml/gs-remote-icon.xml"/>
+ <xi:include href="xml/gs-test.xml"/>
+ <xi:include href="xml/gs-worker-thread.xml"/>
+ <xi:include href="xml/gs-utils.xml"/>
+ </reference>
+
+</book>
diff --git a/doc/api/gnome-software.types b/doc/api/gnome-software.types
new file mode 100644
index 0000000..5f0a7b0
--- /dev/null
+++ b/doc/api/gnome-software.types
@@ -0,0 +1,6 @@
+gs_app_get_type
+gs_app_list_get_type
+gs_category_get_type
+gs_os_release_get_type
+gs_plugin_event_get_type
+gs_plugin_get_type
diff --git a/doc/api/gs-example-details.png b/doc/api/gs-example-details.png
new file mode 100644
index 0000000..88c29e4
--- /dev/null
+++ b/doc/api/gs-example-details.png
Binary files differ
diff --git a/doc/api/gs-example-installed.png b/doc/api/gs-example-installed.png
new file mode 100644
index 0000000..0cd424a
--- /dev/null
+++ b/doc/api/gs-example-installed.png
Binary files differ
diff --git a/doc/api/gs-example-search.png b/doc/api/gs-example-search.png
new file mode 100644
index 0000000..77611bd
--- /dev/null
+++ b/doc/api/gs-example-search.png
Binary files differ
diff --git a/doc/api/meson.build b/doc/api/meson.build
new file mode 100644
index 0000000..2ccab7b
--- /dev/null
+++ b/doc/api/meson.build
@@ -0,0 +1,11 @@
+gnome.gtkdoc(
+ 'gnome-software',
+ src_dir : join_paths(meson.project_source_root(), 'lib'),
+ main_xml : 'gnome-software-docs.xml',
+ html_assets : [
+ 'gs-example-details.png',
+ 'gs-example-installed.png',
+ 'gs-example-search.png'
+ ],
+ install : true
+)