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| =Overview= | | =Overview= |
| The current extension manager API is focussed on managing XPI style add-ons and is currently very limited forcing the UI and other callers to rely on direct access to the RDF datastore to glean certain required information about add-ons. | | The current extension manager API is focussed on managing XPI style add-ons and is currently very limited forcing the UI and other callers to rely on direct access to the RDF datastore to glean required information about add-ons. |
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| The main goals of this rewrite are: | | The main goals of this rewrite are: |
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| * Removing direct access to the datastore and providing API to replace that. | | * Support a wider range of add-on types managed through the same API |
| * Becoming a more general manager for add-ons to support different types of add-ons through the same interface such as search plugins, content plugins, jetpack, personas etc. | | * Allow application/extension developers to be able to easily query the state of installed items |
| | * Make it easier for applications to replace the add-ons UI with their own implementation by making all necessary information available through the defined API |
| | * Remove direct access to the datastore |
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| =Add-on states= | | =High Level View= |
| The new APIs represent add-ons in a number of states but these can broadly be split into two types, Local add-ons and Available add-ons. The API objects representing these add-ons are considered live views of the add-on. As operations are performed (disabling, downloading etc.) the properties of the object will update to reflect the new state. The objects represent add-on instances however. If I have an object representing the installed add-on "foo", then the user uninstalls and then reinstalls "foo" then the object still represents the old uninstalled instance of "foo". It is undefined whether retrieving the same add-on from the API twice will give two references to the same object or two separate objects that have the same properties. | | The new API is accessed through a global [[Extension Manager:API Rewrite:API#AddonManager|AddonManager]] object that is included in a JavaScript module. There will also be a limited amount of access provided through an XPCOM component but this is intended for platform integration only. The API makes no assumptions about what different types of add-ons do and how they are used, it does make some basic assumptions about the information available about them and the install process. Users of the API can register to receive events about all add-ons and installs. |
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| ==Local add-ons== | | ==Add-on Providers== |
| Local add-ons are add-ons that have been installed, or are installed but pending an application restart to be activated.
| | Underneath the manager (and essentially invisible through the API) are a set of add-on providers. Each one manages a set of types of add-on, for example there can be a provider for XPI style add-ons, a provider for plugins, a provider for lightweight themes, etc. There will probably be a hardcoded set of providers for the application and then some means for add-ons to register their own providers. It is up to the providers to maintain their lists of installed add-ons, perform installation and uninstallation and send appropriate notifications out to registered listeners. |
| <center>[[File:ExtIAddon.png]]</center>
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| The majority of the fields available are expected to be self explanatory however a couple deserve special mention:
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| ; isActive : This indicates whether the add-on is currently active in the application. For XPI style add-ons this cannot change without a restart, for other add-ons it may change instantly as the add-on is enabled/disabled.
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| ; availableUpdate : When an update to the add-on has been detected this is set to the information about the updated verson.
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| ; pendingUpdate : When an updated version of the add-on has been downloaded and installed, but the install requires a restart, this will give a reference to the new version.
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| ; pending* : Whenever an operation is waiting for an application restart to complete one of these flags may be set.
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| ; checkCompatibility : This method is similar to isCompatible however it allows checking compatibility with a particular version of the application. This is necessary for the application update system to determine whether new versions of add-ons are necessary before an application update.
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| It is expected that certain types of add-ons will implement an additional interface to provide specific methods/attributes. For example XPI add-ons will need to expose a method to get access to the installation files as we currently do through the <code>nsIInstallLocation</code> interface. | | ==Addon== |
| | The [[Extension Manager:API Rewrite:API#Addon|Addon]] object represents an add-on that is installed on the local system. This is a loose term since it also includes add-ons that have been downloaded and will be installed when the application is restarted. It is possible that the API will hand out multiple instances of Addon for the same underlying add-on. There are a set of properties that will be available for all types of add-ons and then each type of add-on may have additional properties. The same goes for operations that can be performed on the add-on. |
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| ==Available add-ons==
| | Certain add-ons may have restrictions over what operations can be performed. These restrictions could be just down to the nature of the add-on (themes cannot be disabled normally) or down to system policies (users may not have access to uninstall some add-ons for example). Each Addon has a permissions property that indicates what operations can currently be performed. |
| Available add-ons are add-ons that are known to be available somewhere. This may include:
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| * Add-ons offered for install by a website
| | Some types of add-ons may require restarts for certain operations. XPI style extensions for example require restarts for almost all operations. The API exposes the operations that are pending in the pendingOperations property. Pending operations can make it hard to tell what state an actual add-on is in. To help solve this the isActive property indicates whether the add-on is currently active. This is separate to and may be different to the various userDisabled, isCompatible and other properties that indicate whether an add-on can be active or not. |
| * Updated versions of add-ons detected by the update system
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| * Add-ons on the local filesystem the user is trying to install
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| Available add-ons also go through a number of states between simply being known as available, through downloading and on to installing.
| | Addon objects are live views of the underlying add-on. The properties are always guaranteed to be up to date. |
| <center>[[File:ExtIInstall.png]]</center>
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| The fields of the <code>extIInstall</code> interface are filled out depending on the available information. Some install methods for example do not give any information about the name or version of the add-on being installed.
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| ; addon : This is an overloaded field. If the <code>extIInstall</code> represents an update to an existing add-on then the <code>addon</code> field references the old version of that add-on. After the available add-on has been downloaded and installed however the <code>addon</code> field references the installed add-on.
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| ; certificate : If the available add-on's code has been signed then this will hold the certificate. This may not be available until after downloading has begun/ended.
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| ''Consider splitting the <code>addon</code> field into two separate fields''
| | ==AddonInstall== |
| | The [[Extension Manager:API Rewrite:API#AddonInstall|AddonInstall]] object represents an add-on that is not yet installed or has just been installed. It may come from an update check to an existing add-on, a request to install a new add-on or a search for new add-ons. It tracks the high level progress of any necessary downloads, dependencies and installation of the add-on. |
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| =Management=
| | The AddonInstall goes through a set of states: |
| The global management interface is a lot simpler in this API. Essentially it only contains methods to start installs, list local add-ons and available add-ons, and adding various listeners to be notification about important events. | |
| <center>[[File:ExtIManager.png]]</center>
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| ''Need to decide whether pending installs and/or pending upgrades appear in <code>getAddons</code>. They have to be reachable somehow but presumably they are through <code>getInstalls</code> although indirectly.''
| | ;Available :Represents an add-on that is known to be available for install. Depending on where the AddonInstall came from there may be very little information about the add-on available. |
| | ;Downloading :This state is used to show that downloads are in progress for the add-on. During download progress information will be available but again very little information my be available about an add-on. |
| | ;Downloaded :This state is entered if installation does not proceed after downloading completes. At this point all information about an add-on is available. |
| | ;Installing :Here the add-on is being installed by its provider. This may cover file extraction etc. |
| | ;Installed :Here the add-on has been installed and its Addon object will appear in AddonManager.getAddons. The add-on itself however may not be active until after an application restart. |
| | ;Cancelled :If the install or download process is cancelled then the install object goes into a Cancelled state and cannot be restarted. |
| | ;Failed :There are failure states for download and install, once in these states the install cannot be restarted. |
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| Additionally there is a need for a private interface to the manager. This is only to be used by the platform and other internal components in order to facilitate add-on loading and blocklisting. The actual content of this is likely not as it stands here, this is just a copy of the existing internal methods from <code>nsIExtensionManager</code>
| | Once the install process for an AddonInstall is started with <code>install</code> it will move through all of the states naturally sending out notifications at each transition and some progress events in between until either an error is encountered or the install is stopped by an install listener returning <code>false</code> from one of the notifications. |
| <center>[[File:ExtIManagerInternal.png]]</center>
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| =Listeners=
| | Certain types on installs may skip steps. Installing an add-on from the file system for example may jump straight to the Downloaded state since there is no need to download it. |
| In order for the UI to be kept up to date with the state of add-ons and installs there are a number of listeners that can be registered for. These are split into three types.
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| ==Local add-on events== | | ==Dependencies and Bootstrapping== |
| These events are focused on local add-ons and allows the UI to change state as the add-ons are enabled/disabled/etc.
| | It is anticipated that at some time automatic downloading of dependencies and bootstrap add-ons will be implemented. This is intended to happen in the AddonInstall Downloading and Checking states. Once the initial file for an add-on is downloaded the AddonManager checks to see if a repository is installed to handle it. |
| <center>[[File:ExtIAddonListener.png]]</center>
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| ''I think there are additional events we are going to need here.''
| | If there is a repository to handle the add-on then it is used to check for compatibility, updates and dependency information. And dependent items will be downloaded before the AddonInstall moves to the Downloaded state, allowing the item to be installed and usable with minimal delay after that point. |
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| ==Available add-on events==
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| These events cover the progress of detecting, downloading and installing available add-ons.
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| <center>[[File:ExtIInstallListener.png]]</center>
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| ==Update check events==
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| When performing an update check the following listener will receive events about the progress of the check.
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| <center>[[File:ExtIUpdateCheckListener.png]]</center>
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| ; onUpdateAvailable : This will indicate an available add-on that is compatible with the application version that the update check was performed for.
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| ; onCompatibilityUpdates : This indicates that the local add-on that an update check was performed for received a compatibility update during the check.
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| ; onUpdateFinished: This is always called at the end of the check and indicates whether there was a success or failure.
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| ''We might consider having onUpdateAvailable be called for every available add-on, callers could then decide which of the available new versions to install.''
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| =Implementation=
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| It is expected that the extension manager code will be split into multiple parts consisting of a central manager that doesn't have very much functionality and then a number of separate components to manage different types of add-ons. It's not defined how the manager will interact with the separate components but presumably we will either make them separate xpcom components with a well defined interface, or use jsm modules. Presumably the separate components will need their own datastores for their own specific needs, however we might consider having them all share a single sqlite database.
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| The central management code will have to be written, likely mostly from scratch but this is just a thin wrapper around the separate components. The existing XPI management code can be reused to make up the separate component handling XPI add-ons. The UI will also have to be rewritten to use the new API rather than the RDF datastore.
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