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author | Sebastien Douheret <sebastien.douheret@iot.bzh> | 2017-06-19 16:52:06 +0200 |
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committer | Sebastien Douheret <sebastien.douheret@iot.bzh> | 2017-06-19 18:13:44 +0200 |
commit | d1b49a7d26bf344d9f00ae12144cbcc7d930b08b (patch) | |
tree | 58d5276d2b6097e535fe90f447f336b72c4c12e3 /docs/1-afm-daemons.md | |
parent | a07557a06366d5c5ed6e62cd91beb48ae478de1a (diff) |
Re-order doc chapters
Change-Id: I44cf2054fa06816480e26fc19b45c6f8a464a708
Signed-off-by: Sebastien Douheret <sebastien.douheret@iot.bzh>
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diff --git a/docs/1-afm-daemons.md b/docs/1-afm-daemons.md new file mode 100644 index 0000000..6d31e34 --- /dev/null +++ b/docs/1-afm-daemons.md @@ -0,0 +1,613 @@ +The application framework daemons +================================= + +Foreword +-------- + +This document describes application framework daemons +FCS (Fully Conform to Specification) implementation is still under development. +It may happen that current implementation somehow diverges with specifications. + +Introduction +------------ + +Daemons ***afm-user-daemon*** and ***afm-system-daemon*** handle applications +life. Understand that they will manage operations like: + + - ***installation*** + - ***uninstallation*** + - ***running*** + - ***suspend*** + - ***inventory*** + - ... + +In addition, they ensure that operations use the security framework as needed +and that applications are executed in the correct context. + +***D-Bus*** is in charge of transmitting orders to the appropriate daemon +depending upon ***D-Bus*** destination. + +The figure below summarizes the situation of both **afm-system-daemon** and +**afm-user-daemon** in the system. + +![afm-daemons][afm-daemons] + +The D-Bus interface +------------------- + +### Overview of the dbus interface + +The ***afm daemons*** takes theirs orders from the session instance +of D-Bus. The use of D-Bus is great because it allows to implement +discovery and signaling. + +The dbus session is by default addressed by environment +variable *DBUS_SESSION_BUS_ADDRESS*. Using **systemd** +variable *DBUS_SESSION_BUS_ADDRESS* is automatically set for +user sessions. + +They are listening with the destination name ***org.AGL.afm.[user|system]*** +at the object of path ***/org/AGL/afm/[user|system]*** on the interface +***org.AGL.afm.[user|system]*** for the below detailed members for the +***afm-system-daemon***: + + - ***install*** + - ***uninstall*** + +And for ***afm-user-daemon***: + + - ***runnables*** + - ***detail*** + - ***start*** + - ***once*** + - ***terminate*** + - ***pause*** + - ***resume*** + - ***runners*** + - ***state*** + - ***install*** + - ***uninstall*** + +D-Bus is mainly used for signaling and discovery. Its optimized +typed protocol is not used except for transmitting only one string +in both directions. + +The client and the service are using JSON serialization to +exchange data. Signature of any member of the D-Bus interface is +***string -> string*** for ***JSON -> JSON***. This is the normal case, if there +is an error, current implementation returns a dbus error that is a string. + +Here are examples using *dbus-send*, here to install an application from a +widget file: + + dbus-send --session --print-reply \ + --dest=org.AGL.afm.system \ + /org/AGL/afm/system \ + org.AGL.afm.system.install 'string:"/tmp/appli.wgt" + + +And here, to query data on installed applications that can be run: + + dbus-send --session --print-reply \ + --dest=org.AGL.afm.user \ + /org/AGL/afm/user \ + org.AGL.afm.user.runnables string:true + +### The protocol over D-Bus + +On all following sub-chapters we assume that we talk about either +***afm-system-daemon*** or ***afm-user-daemon***. Method and D-Bus parameters +are considered as self-explanatory. + +The D-Bus interface is defined by: + + * **DESTINATION**: org.AGL.afm.[user|system] + + * **PATH**: /org/AGL/afm/[user|system] + + * **INTERFACE**: org.AGL.afm.[user|system] + +#### Method org.AGL.afm.system.install + +**Description**: Install an application from a widget file. + +When an application with the same *id* and *version* already exists. Outside of +using *force=true* the application is not reinstalled. + +Applications are installed the subdirectories of applications common directory. +If *root* is specified, the application is installed under the +sub-directories of the *root* defined. + +Note that this methods is a simple accessor method of +***org.AGL.afm.system.install*** from ***afm-system-daemon***. + +After the installation and before returning to the sender, +***afm-system-daemon*** sends a signal ***org.AGL.afm.system.changed***. + +**Input**: The *path* of the widget file to install and, optionally, +a flag to *force* reinstallation, and, optionally, a *root* directory. + +Either just a string being the absolute path of the widget file: + + "/a/path/driving/to/the/widget" + +Or an object: + + { + "wgt": "/a/path/to/the/widget", + "force": false, + "root": "/a/path/to/the/root" + } + +"wgt" and "root" must be absolute paths. + +**output**: An object with the field "added" being the string for +the id of the added application. + + {"added":"appli@x.y"} + +--- + +#### Method org.AGL.afm.system.uninstall + +**Description**: Uninstall an application from its id. + + +Note that this methods is a simple method accessor of +***org.AGL.afm.system.uninstall*** from ***afm-system-daemon***. + +After the uninstallation and before returning to the sender, +***afm-system-daemon*** sends a signal ***org.AGL.afm.system.changed***. + +**Input**: the *id* of the application and optionally the application *root* path. + +Either a string: + + "appli@x.y" + +Or an object: + + { + "id": "appli@x.y", + "root": "/a/path/to/the/root" + } + +**output**: the value 'true'. + +--- + +#### Method org.AGL.afm.user.detail + + +**Description**: Get details about an application from its id. + +**Input**: the id of the application as below. + +Either just a string: + + "appli@x.y" + +Or an object having the field "id" of type string: + + {"id":"appli@x.y"} + +**Output**: A JSON object describing the application containing +the fields described below. + + { + "id": string, the application id (id@version) + "version": string, the version of the application + "width": integer, requested width of the application + "height": integer, resqueted height of the application + "name": string, the name of the application + "description": string, the description of the application + "shortname": string, the short name of the application + "author": string, the author of the application + } + +--- + +#### Method org.AGL.afm.user.runnables + +**Description**: Get the list of applications that can be run. + +**Input**: any valid json entry, can be anything except null. + +**output**: An array of description of the runnable applications. +Each item of the array contains an object containing the detail of +an application as described above for the method +*org.AGL.afm.user.detail*. + +--- + +#### Method org.AGL.afm.user.install + +**Description**: Install an application from its widget file. + +If an application of the same *id* and *version* exists, it is not +reinstalled except when *force=true*. + +Applications are installed in the subdirectories of the common directory +reserved for applications. +If *root* is specified, the application is installed under +sub-directories of defined *root*. + +Note that this methods is a simple accessor to the method +***org.AGL.afm.system.install*** of ***afm-system-daemon***. + +After the installation and before returning to the sender, +***afm-user-daemon*** sends the signal ***org.AGL.afm.user.changed***. + +**Input**: The *path* of widget file to be installed. Optionally, +a flag to *force* reinstallation and/or a *root* directory. + +Simple form a simple string containing the absolute widget path: + + "/a/path/driving/to/the/widget" + +Or an object: + + { + "wgt": "/a/path/to/the/widget", + "force": false, + "root": "/a/path/to/the/root" + } + +***wgt*** and ***root*** MUST be absolute paths. + +**output**: An object containing field "added" to use as application ID. + + {"added":"appli@x.y"} + +--- + +#### Method org.AGL.afm.user.uninstall + +**Description**: Uninstall an application from its id. + + +Note that this methods is a simple accessor to +***org.AGL.afm.system.uninstall*** method from ***afm-system-daemon***. + +After the uninstallation and before returning to the sender, +***afm-user-daemon*** sends the signal ***org.AGL.afm.user.changed***. + +**Input**: the *id* of the application and, optionally, the path to +application *root*. + +Either a string: + + "appli@x.y" + +Or an object: + + { + "id": "appli@x.y", + "root": "/a/path/to/the/root" + } + +**output**: the value 'true'. + +--- + +#### Method org.AGL.afm.user.start + +**Description**: + +**Input**: the *id* of the application and, optionally, the +start *mode* as below. + +Either just a string: + + "appli@x.y" + +Or an object containing field "id" of type string and +optionally a field mode: + + {"id":"appli@x.y","mode":"local"} + +The field "mode" is a string equal to either "local" or "remote". + +[Currently the mode is not available in the systemd version] + +**output**: The *runid* of the application launched. *runid* is an integer. + +--- + +#### Method org.AGL.afm.user.once + +**Description**: + +**Input**: the *id* of the application + +Either just a string: + + "appli@x.y" + +Or an object containing field "id" of type string. + + {"id":"appli@x.y"} + +**output**: The *state* of the application retrieved or launched. +See *org.AGL.afm.user.state* to get a description of the returned +object. + +--- + +#### Method org.AGL.afm.user.terminate + +**Description**: Terminates the application attached to *runid*. + +**Input**: The *runid* (an integer) of running instance to terminate. + +**output**: the value 'true'. + +--- + +#### Method org.AGL.afm.user.stop + +Obsolete since 8th November 2016 (2016/11/08). +Kept for compatibility. + +Use **org.AGL.afm.user.pause** instead. + +--- + +#### Method org.AGL.afm.user.continue + +Obsolete since 8th November 2016 (2016/11/08). +Kept for compatibility. + +Use **org.AGL.afm.user.resume** instead. + +--- + +#### Method org.AGL.afm.user.pause + +[Currently not available in the systemd version] + +**Description**: Pauses the application attached to *runid* until terminate or resume. + +**Input**: The *runid* (integer) of the running instance to pause. + +**output**: the value 'true'. + +--- + +#### Method org.AGL.afm.user.resume + +[Currently not available in the systemd version] + +**Description**: Resumes the application attached to *runid* previously paused. + +**Input**: The *runid* (integer) of the running instance to resume. + +**output**: the value 'true'. + +--- + +#### Method org.AGL.afm.user.state + +**Description**: Get informations about a running instance of *runid*. + +**Input**: The *runid* (integer) of the running instance inspected. + +**output**: An object describing instance state. It contains: +the runid (integer), the pids of the processes as an array starting +with the group leader, the id of the running application (string), +the state of the application (string either: "starting", "running", "paused"). + +Example of returned state: + + { + "runid": 2, + "pids": [ 435, 436 ], + "state": "running", + "id": "appli@x.y" + } + +--- + +#### Method org.AGL.afm.user.runners + +**Description**: Get the list of currently running instances. + +**Input**: anything. + +**output**: An array of states, one per running instance, as returned by +the method ***org.AGL.afm.user.state***. + +Starting **afm daemons** +---------------------- + +***afm-system-daemon*** and ***afm-user-daemon*** are launched as systemd +services attached to system and user respectively. Normally, service files are +locatedat */lib/systemd/system/afm-system-daemon.service* and +*/usr/lib/systemd/user/afm-user-daemon.service*. + +### ***afm-system-daemon*** options + +The options for launching **afm-system-daemon** are: + + -r + --root directory + + Set the root application directory. + + Note that the default root directory is defined + to be /usr/share/afm/applications (may change). + + -d + --daemon + + Daemonizes the process. It is not needed by sytemd. + + -q + --quiet + + Reduces the verbosity (can be repeated). + + -v + --verbose + + Increases the verbosity (can be repeated). + + -h + --help + + Prints a short help. + +### ***afm-user-daemon*** options + +The options for launching **afm-user-daemon** are: + + -a + --application directory + + [Currently not available in the systemd version] + + Includes the given application directory to + the database base of applications. + + Can be repeated. + + -r + --root directory + + [Currently not available in the systemd version] + + Includes root application directory or directories when + passing multiple rootdir to + applications database. + + Note that default root directory for + applications is always added. In current version + /usr/share/afm/applications is used as default. + + -m + --mode (local|remote) + + [Currently not available in the systemd version] + + Set the default launch mode. + The default value is 'local' + + -d + --daemon + + Daemonizes the process. It is not needed by sytemd. + + -q + --quiet + + Reduces the verbosity (can be repeated). + + -v + --verbose + + Increases the verbosity (can be repeated). + + -h + --help + + Prints a short help. + +Tasks of **afm-user-daemon** +---------------------------- + +### Maintaining list of applications + +At start **afm-user-daemon** scans the directories containing +applications and load in memory a list of avaliable applications +accessible by current user. + +When **afm-system-daemon** installs or removes an application. +On success it sends the signal *org.AGL.afm.system.changed*. +When receiving such a signal, **afm-user-daemon** rebuilds its +applications list. + +**afm-user-daemon** provides the data it collects about +applications to its clients. Clients may either request the full list +of avaliable applications or a more specific information about a +given application. + +### Launching application + +**afm-user-daemon** launches application by using systemd. +Systemd builds a secure environment for the application +before starting it. + +Once launched, running instances of application receive +a runid that identify them. To make interface with systemd +evident, the pid is the runid. + +### Managing instances of running applications + +**afm-user-daemon** manages the list of applications +that it launched. + +When owning the right permissions, a client can get the list +of running instances and details about a specific +running instance. It can also terminate a given application. + +### Installing and uninstalling applications + +If the client own the right permissions, +**afm-user-daemon** delegates that task +to **afm-system-daemon**. + +Using ***afm-util*** +-------------------- + +The command line tool ***afm-util*** uses dbus-send to send +orders to **afm-user-daemon**. This small scripts allows to +send command to ***afm-user-daemon*** either interactively +at shell prompt or scriptically. + +The syntax is simple: it accept a command and when requires attached arguments. + +Here is the summary of ***afm-util***: + + - **afm-util runnables **: + + list the runnable widgets installed + + - **afm-util install wgt **: + + install the wgt file + + - **afm-util uninstall id **: + + remove the installed widget of id + + - **afm-util detail id **: + + print detail about the installed widget of id + + - **afm-util runners **: + + list the running instance + + - **afm-util start id **: + + start an instance of the widget of id + + - **afm-util once id **: + + run once an instance of the widget of id + + - **afm-util terminate rid **: + + terminate the running instance rid + + - **afm-util state rid **: + + get status of the running instance rid + + +Here is how to list applications using ***afm-util***: + + afm-util runnables + + +[afm-daemons]: pictures/afm-daemons.svg |