responsibility of LISA service

LISA component is part of RDK DAC framework on STB and is an abbreviation for Local Inventory & Storage Manager of DAC Apps. Its responsibility is:

• to offer service through API towards a controlling app - typically the operator resident app - to install or uninstall DAC Apps locally and to get list of local installed DAC apps and their metadata.
• on request perform the retrieval (download) and local storage (aka install) of the oci bundle and metadata associated with a DAC application. It also exposes progress of the retrieval and notifies when installation is finished
• allocate/segregate/manage local storage for installing App oci bundles but also segregated persistent storage area for corresponding Apps.
• on request perform uninstall (delete) of the app (on condition it is not indicated as "locked"). Give the ability to controlling app to mark specific app as locked or unlocked (default).  Use case for marking app as "locked" is to prevent app from being uninstalled when it is in use 

Lisa is implemented as Thunder out-of-process plugin.  Can be run in a separate container

Source code

current git repo location :  https://github.com/rdkcentral/LISA

Yocto recipe location : https://code.rdkcentral.com/r/plugins/gitiles/components/generic/rdk-oe/meta-cmf-video/+/refs/heads/rdk-next/recipes-extended/rdkservices/rdkservice-lisa.bb

License : Apachev2

API

API of LISA is available in https://github.com/rdkcentral/ThunderInterfaces/blob/R2/interfaces/ILISA.h

More details on API design of LISA is available here. However it was somewhat over-engineered compared to what we need as Minimum Viable Product (MVP) and hence not all api's from design were implemented.

In next section you see what is implemented as MVP and beyond 

What is implemented, what NOT, development phasing

Not everything of api design has been implemented in LISA code so far. Focus has been mainly on Minimum Viable Product

Everything marked in italic is implemented so far,  text in grey is not implemented

• Phase 1: MVP (Minimal Viable Product):
  • initialization with basic recovery on errors (removal of all data)
  • installation
    • libcurl HTTP get with HTTPS and TLS session resumption
    • HTTP code 202 back-off
    • persistent storage creation
    • untarring downloaded bundle
    • no authentication
    • no full metadata support (i.e. auxmetadata and resources)
    • handling of multiple versions of the same application
    • timeout is excluded
  • uninstall
    • full wipeout (both App bundle and associated persistent storage)
  • operationStatus
    • basic status Success/Error
  • getStorageDetails
    • no params (overall) Request payload: {}
    • single installed application Request payload: {"type":"application/vnd.rdk-app.dac.native", "id":"<string>", "version":"<string>"}
  • getList:
    • no filters
    • single app  {"type":"application/vnd.rdk-app.dac.native", "id":"<string>", "version":"<string>"}
  • getMetadata
    • single app Request payload: {"type":"application/vnd.rdk-app.dac.native", "id":"<string>", "version":"<string>"}
  • getProgress
  • auth module API interface + stub library
  • Configure logical storages on all plaforms
  • Locking support (lock, unlock, getLockInfo) to prevent app from being removed while in use. LISA API Extension (Locking mechanism)
• Phase 2: whole API
  • full initialization with cleanup and maintenance added (already done)
  • cleanup and maintenance after each operation (already done for install and uninstall)
  •  installation
    • full metadata
    • configurable download timeout implementation
  • persistent storage management (full)
    • creation/deletion/reset
    • quota management and enforcing (TBD how and where)
    • usage reporting: per app, overall
  • download  (download api method : for downloading app metadata, not implemented, confusion method name by the way)
  • reset
    • "storage"
    • "full"
    • "resources"
  • getStorageDetails
    • single installed application Request payload: {"type":"application/vnd.rdk-app.dac.native", "id":"<string>"}
  •  getList
    • filtering (already done)
  • setAuxMetada (already done)
  • cancel (already done)
  • Configure quotas in AS/FSM
  • Review logical storages requirements
    • separately for all platforms
      
      • Phase 2: all supported platform
• review for all platforms: gaps
• Phase 3/later: 
  • TBD: authentication module
  • TBD: apps.db - authentication, antirollback, encryption
  • TBD: concurrent parallel downloads
  • TBD : Max quota per specific app? Not sure what is use case/expected behaviour config here

Example usage of LISA

logs of LISA in action in real DAC use case

DEMO video of app installation from DAC cloud using cli tool.  You can see in shell on button the logs of LISA in action.

https://drive.google.com/file/d/11QXXM9WBg8Sw76Eikg5FyodrpIfoBnkL/view

DAC_AWC_LISA.mp4

Example of application using LISA api

The refapp "resident App" that comes with RDK reference image  uses lisa for downloading DAC bundles. It is a consumer of LISA api.

Here are pointers to its code on where/how it uses LISA 

https://github.com/LibertyGlobal/refapp/search?q=LISA

TODO: Point to code where in resident UI of VA LISA is used (on RDK6.1 VA image) 

Detailed LISA design

comparison to RDK Packager

LISA is an alternative to the Packager Thunder Plugin used to retrieve ipkg packages, see https://github.com/rdkcentral/rdkservices/blob/master/Packager/doc/PackagerPlugin.md   

Data Types

LISA is able to handle the following data:

1. Application-specific:
   • Mandatory application metadata (type, id, version, source URL, name, category)
     • setting on installation request
     • getting
   • DAC bundles
     • downloading
     • deleting
   • Generic resources (files, e.g. icons)
     • downloading,
     • deleting
   • Auxiliary application metadata, dedicated API for:
     • setting
     • updating
     • getting
   • Persistent storage for application
     • creating
     • resetting
     • deleting
   • Storage/persistent storage usage checking
     • getting
2. Global
   • Storage usage checking
     • getting

API design

Before implementation, at the design stage, the following API in json schema has been defined LISA API .

In later design phase additional lock/unlock api allowing external application manager to signal LISA that a specific app from LISA database is in active use by End user and hence should not be deleted/upgraded at this moment, see description in  LISA API Extension (Locking mechanism)#APISchema

Actual Thunder interface definition/api is in defined in dual COM RPC / JSON- RPC interface in https://github.com/rdkcentral/ThunderInterfaces/blob/R2/interfaces/ILISA.h with annotations to automatically autogenerate* the JSON RPC api at build time

In section below we provide more explanation with the API methods.

API is to be exposed in JSON-RPC over WebSocket like other JSON-RPC thunder services 

For mat is of style :

{"jsonrpc":"2.0","id":{id},"method":"com.lgi.dac.lisa.1.methodName", "params":{payload}}

{id} - An identifier established by the Client that MUST contain a String, Number, or NULL value if included. If it is not included it is assumed to be a notification.

{payload} - A Structured value that holds the parameter values to be used during the invocation of the method. This member MAY be omitted.

Methods

• install 

Download the application bundle tarball from the given URL, unpack files to dedicated directory, create the db entries and persistent storage on success. Asynchronous operation, handle should be used for tracking the request. The id of an app is unique within the database. That means only one kind of (mime)type can be combined and saved with a specific app id.

Request payload: {"type":"application/vnd.rdk-app.dac.native", "id":"<string>", "version":"<string>", "url":"<string>", "appName":"<string>", "category":"<string>"}

Result payload: {"handle":"<string>"}

• uninstall

Uninstall the application: remove application files and - optionally - persistent storage and db entry. Non-blocking operation, handle should be used for tracking the request.

Request payload: {"type":"application/vnd.rdk-app.dac.native", "id":"<string>", "version":"<string>", "uninstallType":"<string>"}

Result payload: {"handle":"<string>"}

• download

Download arbitrary application's resource, e.g. icon. Resource are stored per application id/version. Asynchronous operation, handle should be used for tracking the request. If the resource of given resKey already exists it is replaced by the newly downloaded resource. If the resKey is unique, but the requested resource file already exists on the filesystem, the file should be stored under a different, unique filename, created by appending a suffix to the existing filename.

Request payload: {"type":"application/vnd.rdk-app.dac.native", "id":"<string>", "version":"<string>", "resKey":"<string>", "url":"<string>"}

Result payload: {"handle":"<string>"}

• reset

Deletes the content of the database and/or persistent storage and/or all resources for the application. Synchronous operation, returns response on success or failure. Optional parameters type, id, version are used to filter the applications on which the reset will be performed. If they are not given, the reset operation affects all the data. Synchronous operation, returns a response on success or failure. 

Request payload: {"type":"application/vnd.rdk-app.dac.native", "id":"<string>", "version":"<string>", "resetType":"<string>"}

Response payload: {"status":"<string>"}

• getStorageDetails

Returns information on the storage usage. Depending on provided parameters: overall storage usage, application id storage or application id/version storage. Synchronous operation, returns a response on success or failure. Notes on implementation:

• overall storage usage (for all apps) may be cached based on the data gathered in Initialization and Maintenance flows (see below), however, if returned value is not cached from Initialization and Maintenance flows, the actual value (including current size of the temporary storage) should be returned
• per app and per app/version storage usage should be estimated synchronously on the invocation of the method, temporary storage should not be included
• quota returned in storagePayload is an optional parameter, it is returned only when known to LISA.

Request payload: {"type":"application/vnd.rdk-app.dac.native", "id":"<string>", "version":"<string>"}

Result payload: {"storage":"<storagePayload>"}

• getList

Returns a list of installed applications filtered using optional filtering criteria: type, id, version, appName, category. Synchronous operation, returns a response on success or failure.

Request payload: {"type":"application/vnd.rdk-app.dac.native", "id":"<string>", "version":"<string>","appName":"<string>","category":"<string>"}

Resultpayload: {"apps":"<appsPayload>"}

• setAuxMetadata

Set an arbitrary key+value metadata for a given application. The existing metadata key is replaced (overwritten) by the provided key/value pair. Synchronous operation, returns a response on success or failure. 

Request payload: {"type":"application/vnd.rdk-app.dac.native", "id":"<string>", "version":"<string>","key":<string>,"value":<string>}

Result payload: {}

• getMetadata

Get all metadata stored for given application version. Synchronous operation, returns a response on success or failure. 

Request payload: {"type":"application/vnd.rdk-app.dac.native", "id":"<string>", "version":"<string>"}

Response payload: {"status":"<string>","metadata":}

• cancel

Cancel previous asynchronous request.

Request payload: {"handle":"<string>"}

Response payload: {"status":"<string>"}

• getProgress

Get estimated progress of an asynchronous operation.

Request payload: {"handle":"<string>"}

Response payload: {"status":"<string>", "progress":<number>}

Events

• operationStatus

Notification sent on the completion of asynchronous operation.

payload: {"handle":"<string>", "status":"<string>", "details":"<string>"}

Download progress tracking

Tracking of the download progress is implemented using:

• requesting for Content-Length HTTP header before actual transfer, to check for available space and to store the size of the resource
• updating the counter of downloaded bytes on the successful transfer of each data chunk (see libcurl CURLOPT_WRITEFUNCTION)
• returning the updated value of progress parameter on invocation of getProgress API.

Block diagram

Logical modules

LISA auth module

(is not IMPLEMENTED, was not required for MVP since bundles are encrypted and signed)

API to be implemented by the library:

• getAuthenticationMethod(appType, id, URL); returned value should indicate one of method:
  • NONE
  • BASIC_AUTH
  • API_KEY_IN_REQUEST
  • API_KEY_IN_HEADER
  • API_KEY_IN_COOKIE
  • CLIENT_CERT
  • BEARER_TOKEN (Oauth2)
• getAPIKey(appType, id, URL, *key, bufferSize); value returned in key buffer contains API key to be included to the request; returns 0 on success, 1 on error (buffer too small), 2 on other errors
• getCredentials(appType, id, URL, *user, *password, bufferSize); returns user/apssword; returns 0 on success, 1 on error (buffer too small), 2 on other errors
• getClientCertsFile(appType, id, URL, *privKeyFileName, *privKeyPassphrase, *clientCertFileName, bufferSize); returns certificate file names; returns 0 on success, 1 on error (buffer too small), 2 on other errors
• getToken(appType, id, URL, *token, bufferSize); returns bearer token; returns 0 on success, 1 on error (buffer too small), 2 on other errors

sqlite usage

sqlite database schema

Note:

The 2 tables in the db schema (apps and installed_apps) are required to be able to correctly handle the case when the application is uninstalled, deleted because of corruption, deleted because of storage capacity issue, or not installed locally (launched from the cloud) but operator or user wants to keep persistent storage of given application intact (for later usage). In this case, an entry in apps table keeps tracking the persistent storage without introducing any other dirty hacks. This approach will also be useful for managing remote applications, for which we don't need to maintain the application's locally downloaded files, but persistent storage might be needed.

-- enable support for foreign keys, available since sqlite version 3.6.19 (2009-10-14)
PRAGMA foreign_keys = ON;

-- table for application ids and persistent storage
CREATE TABLE IF NOT EXISTS apps(
idx INTEGER PRIMARY KEY, -- unique index for the application type/id
type TEXT NOT NULL, -- MIME type 
app_id TEXT UNIQUE NOT NULL, -- unique id of app within given MIME type
data_path TEXT, -- path to app peristent storage, relative to [APPS_STORAGE]/{epoch}
created TEXT NOT NULL -- unix epoch timestamp of when the application entry was created 
);

-- table for installed applications in specific versions
CREATE TABLE IF NOT EXISTS installed_apps (
idx INTEGER PRIMARY KEY, -- unique index for the application type/id/version
app_idx INTEGER NOT NULL, -- reference to apps table, index of the application type/id
version TEXT NOT NULL, -- version of the application
name TEXT NOT NULL, -- name of the application
category TEXT, -- category
url TEXT, -- URL from which the application was downloaded
app_path TEXT, -- path to app files, realtive to [APPS]/{epoch}
created TEXT NOT NULL, -- unix epoch timestamp of when the application was installed
resources TEXT, -- json object with downloaded resources metadata
metadata TEXT, -- json object with auxiliary resources metadata
FOREIGN KEY(app_idx) REFERENCES apps(idx),
UNIQUE(app_idx, version)
);

sqlite quick startup 

1. print tables
SELECT sql FROM sqlite_master WHERE name = 'apps';
SELECT sql FROM sqlite_master WHERE name = 'installed_apps';

2. insert app id
INSERT INTO apps VALUES(NULL, 'application/vnd.rdk-app.dac.native', 'com.lgi.app3', 'dac.native/com.lgi.app3/data', strftime('%s','now'));

3. get app_id of given app
SELECT idx,type,app_id FROM apps WHERE type = 'application/vnd.rdk-app.dac.native' AND app_id = 'com.lgi.app3';

4. insert new application version
INSERT INTO installed_apps VALUES(NULL, <app_idx>, '1.0.0', 'Super-app', 'Game', 'http://download.com/bundle1.tgz', 'dac.native/com.lgi.app3/1.0.0/app', strftime('%s','now'), NULL, NULL, NULL);

5. SELECT app version
SELECT DISTINCT apps.type,apps.app_id,installed_apps.version,installed_apps.metadata FROM installed_apps,apps WHERE apps.type='application/vnd.rdk-app.dac.native' AND apps.app_id='com.lgi.app3' AND installed_apps.version="1.0.0";

6. set meatdata for given app/version
SELECT DISTINCT installed_apps.idx,installed_apps.metadata FROM installed_apps,apps WHERE apps.type='application/vnd.rdk-app.dac.native' AND apps.app_id='com.lgi.app3' AND installed_apps.version="1.0.0";
UPDATE installed_apps SET metadata = '{[{"description","New nice application."},{"parental":"5"}]}' WHERE idx=<idx>;

Storages for data

The logical storages: [APPS] and [APPS_STORAGE] should be defined per platform, to use concrete physical storages.

[APPS] storage for Application bundle 

files of App in App oci bundle are stored in [APPS] storage. 

Paths:

• App's files: [APPS]/dac/images/{epoch}/{id}/{version}/
• App's auxiliary resources (e.g. icons), currently not implemented: [APPS]/dac/images/{epoch}{id}/{version}/res
• Temporary files storage (for downloaded files before unpacking), referred as [APPS_TMP]: 
  • [APPS_TMP] is located in [APPS]/dac/images/tmp
  • [APPS_TMP]/{id}/{version}/ - used for downloading application of given id and given version

Important, LISA's database can be located there eg :  [APPS]/dac/db/{epoch}/apps.db

[APPS_STORAGE]  persistent storage area an App can use:

Apps persistent storage is located in [APPS_STORAGE]. 

Paths:

Apps' persistent storage: [APPS_STORAGE]/dac/{epoch}/{id}/

Epoch

Epoch indicator {epoch} is used for easy invalidation of not supported or revoked format of apps on fundamental changes. May also be used for the antirollback (db authentication - TBD?)

LISA logic per use case

Initialization

Maintenance and Cleanup

Install

Uninstall

Download

Lisa Thunder plugin configuration

config schema

{
	"$schema": "plugin.schema.json",
    "jsonrpc":"2.0",
	"info": {
		"title": "Local Inventory & Storage Manager of DAC Apps (LISA) Plugin",
        "class": "Lisa",
		"callsign": "org.rdk.dac.lisa",
		"locator": "libWPEFrameworkLisa.so",
		"status": "alpha",
		"autostart": true,
		"description": "The Local Inventory & Storage Manager of DAC Apps (LISA) plugin allows authenticated downloading and management of DAC bundles from a remote server. It also manages the persistent storage of the DAC applications.",
		"version": "1.0"
	},
	"interface": {
		"$ref": "{interfacedir}/lisa.json#"
	},
	"configuration": {
		"type": "object",
		"properties": {
			"configuration": {
				"type": "object",
				"properties": {
					"network": {
						"type": "object",
						"required": [
							"timeout",
							"default_retryIn"
						],
						"properties": {
							"timeout": {
								"type": "number",
								"description": "Single resource downloading timeout in seconds"
							},
							"default_retryIn": {
								"type": "number",
								"description": "Default value of GET retry delay in seconds on HTTP/202, when no "Retry-After" header field is returned in the response."
							}
						}
					},
					"storages": {
						"type": "object",
						"required": [
							"apps",
							"apps_storage",
							"apps_tmp"
						],
						"properties": {
							"apps": {
								"type": "string",
								"description": "Path to the persistent storage for downloaded applications top dir"
							},
							"apps_storage": {
								"type": "string",
								"description": "Path to the persistent storage for downloaded applications persistent storage top dir"
							},
							"apps_tmp": {
								"type": "string",
								"description": "Path to the temporary storage for applications being downloaded"
							}
						}
					}
				},
				"required": [
					"timeout",
					"storages"
				]
			}
		}
	}
}

example lisa thunder plugin config

{
	"$schema": "plugin.schema.json",
	"jsonrpc":"2.0",
	"info": {
		"title": "Local Inventory & Storage Manager of DAC Apps (LISA) Plugin",
        "class": "Lisa",
		"callsign": "org.rdk.dac.lisa",
		"locator": "libWPEFrameworkLisa.so",
		"status": "alpha",
		"autostart": true,
		"description": [
			"The Local Inventory & Storage Manager of DAC Apps (LISA) plugin allows authenticated downloading and management of DAC bundles from a remote server. It also manages the persistent storage of the DAC applications."
		],
		"version": "1.0"
	},
	"interface": {
		"$ref": "{interfacedir}/lisa.json"
	},
	"configuration": {
		"storages": {
			"apps": "/mnt/apps",
			"apps_storage": "/mnt/apps_storage",
			"apps_tmp": "/mnt/apps_tmp"
		},
		"network": {
			"timeout": 1800,
			"default_retryIn": 300
		}
	}
}