Development Team/Low-level Activity API: Difference between revisions

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<noinclude>{{Developers~~}}{{TOCright~~}}</noinclude>

<noinclude>{{Developers}}</noinclude>__TOC__

Sugar activities are usually written in Python using the [http://api.sugarlabs.org/ Python Activity API]. This page documents the underlying mechanism that all activities need to conform to. Activities can be written in any language, as long as it can connect to D-Bus and provide an X11 interface. The discussion below tries to be language-agnostic.

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This can be used to, e.g., open a URL (create a URL object in the journal then call this) or to view source code (store the source code as text file, then call ShowObject() on it).

Note: since Sugar 0.84, you also can give the full path to an existing file instead of an object id. If the user resumes that file, it will be copied to the Journal first and ~~the~~ opened using the chosen activity. <i>This seems to be of limited usefulness and is documented here just for completeness</i>

Note: since Sugar 0.84, you also can give the full path to an existing file instead of an object id. If the user resumes that file, it will be copied to the Journal first and then opened using the chosen activity. <i>This seems to be of limited usefulness and is documented here just for completeness</i>

<s>To focus on multiple objects: <code>org.laptop.Journal.FocusSearch(query)</code></s> ''Removed in Sugar 0.83''

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;$SUGAR_ACTIVITY_ROOT/data/: This directory is used similar to a traditional home directory, for persistent activity data such as configuration files. Make sure files in there are group readable and writable (see [[#Users and Groups|users and groups]]). The directory itself is group-writable. Files stored here will survive reboots and OS upgrades.

;$SUGAR_ACTIVITY_ROOT/tmp/: This directory is used similar to a /tmp directory, being backed by RAM. It may be as small as 1 MB. ~~This~~ directory is deleted when the activity exits (specifically, as soon as all children of the activity's first process die). This directory is ''only'' accessible to the activity and its children; not even to Sugar.

;$SUGAR_ACTIVITY_ROOT/tmp/: This directory is used similar to a /tmp directory, being backed by RAM if [[olpc:Rainbow|Rainbow]] is present. It may be as small as 1 MB. With [[olpc:Rainbow|Rainbow]], this directory is deleted when the activity exits (specifically, as soon as all children of the activity's first process die). This directory is ''only'' accessible to the activity and its children; not even to Sugar.

;$SUGAR_ACTIVITY_ROOT/instance/: This directory is used similar to a /var/tmp directory, being backed by flash rather than by RAM. It is unique per instance. It is used for transfer to and from the datastore (see [[#Keeping and Resuming|keeping and resuming]]). ~~This~~ directory is deleted when the activity exits (specifically, as soon as all children of the activity's first process die)

;$SUGAR_ACTIVITY_ROOT/instance/: This directory is used similar to a /var/tmp directory, being backed by flash rather than by RAM. It is unique per instance. It is used for transfer to and from the datastore (see [[#Keeping and Resuming|keeping and resuming]]). With [[olpc:Rainbow|Rainbow]], this directory is deleted when the activity exits (specifically, as soon as all children of the activity's first process die).

As of version 8.2, all the activity root directories are created in /home/olpc/isolation and can be examined there with the Terminal activity. However, activities MUST use the $SUGAR_ACTIVITY_ROOT variable because the isolation directory layout is expected to change.

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-<noinclude>{{Developers}}{{TOCright}}</noinclude>
+<noinclude>{{Developers}}</noinclude>__TOC__
 Sugar activities are usually written in Python using the [http://api.sugarlabs.org/ Python Activity API]. This page documents the underlying mechanism that all activities need to conform to. Activities can be written in any language, as long as it can connect to D-Bus and provide an X11 interface. The discussion below tries to be language-agnostic.
@@ Line 265: / Line 265: @@
 This can be used to, e.g., open a URL (create a URL object in the journal then call this) or to view source code (store the source code as text file, then call ShowObject() on it).
-Note: since Sugar 0.84, you also can give the full path to an existing file instead of an object id. If the user resumes that file, it will be copied to the Journal first and the opened using the chosen activity. <i>This seems to be of limited usefulness and is documented here just for completeness</i>
+Note: since Sugar 0.84, you also can give the full path to an existing file instead of an object id. If the user resumes that file, it will be copied to the Journal first and then opened using the chosen activity. <i>This seems to be of limited usefulness and is documented here just for completeness</i>
 <s>To focus on multiple objects: <code>org.laptop.Journal.FocusSearch(query)</code></s> ''Removed in Sugar 0.83''
@@ Line 312: / Line 312: @@
 ;$SUGAR_ACTIVITY_ROOT/data/: This directory is used similar to a traditional home directory, for persistent activity data such as configuration files. Make sure files in there are group readable and writable (see [[#Users and Groups|users and groups]]). The directory itself is group-writable. Files stored here will survive reboots and OS upgrades.
-;$SUGAR_ACTIVITY_ROOT/tmp/: This directory is used similar to a /tmp directory, being backed by RAM. It may be as small as 1 MB. This directory is deleted when the activity exits (specifically,  as soon as all children of the activity's first process die). This directory is ''only'' accessible to the activity and its children; not even to Sugar.
+;$SUGAR_ACTIVITY_ROOT/tmp/: This directory is used similar to a /tmp directory, being backed by RAM if [[olpc:Rainbow|Rainbow]] is present. It may be as small as 1 MB. With [[olpc:Rainbow|Rainbow]], this directory is deleted when the activity exits (specifically,  as soon as all children of the activity's first process die). This directory is ''only'' accessible to the activity and its children; not even to Sugar.
-;$SUGAR_ACTIVITY_ROOT/instance/: This directory is used similar to a /var/tmp directory, being backed by flash rather than by RAM. It is unique per instance. It is used for transfer to and from the datastore (see [[#Keeping and Resuming|keeping and resuming]]). This directory is deleted when the activity exits (specifically,  as soon as all children of the activity's first process die)
+;$SUGAR_ACTIVITY_ROOT/instance/: This directory is used similar to a /var/tmp directory, being backed by flash rather than by RAM. It is unique per instance. It is used for transfer to and from the datastore (see [[#Keeping and Resuming|keeping and resuming]]). With [[olpc:Rainbow|Rainbow]], this directory is deleted when the activity exits (specifically,  as soon as all children of the activity's first process die).
 As of version 8.2, all the activity root directories are created in /home/olpc/isolation and can be examined there with the Terminal activity. However, activities MUST use the $SUGAR_ACTIVITY_ROOT variable because the isolation directory layout is expected to change.