OSGi Service Platform Compendium

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OSGi Service PlatformCompendium

• IONA Dublin August 2007
• Peter Kriens
• aQute
• OSGi Fellow

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Contents

• Context Diagram
• OSGi System Services
• OSGi Services
• OSGi Utils
• OSGi Security Layer

3
OSGi Context
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Context Diagram
Deployer
Operator
Developer
OSGi Environment
Device
End User
5
OSGi Environment
6
Core OSGi Layering

• Execution Environment
• All APIs are compatible with CDC and J2SE
• CLDC possible with VM specific extensions
• Module layer introduces Bundles
• Class loading rules
• Modularization
• Life Cycle Layer provides an API for managing
  bundles
• Services Layer provides a dynamic component model
  with communication ports called services
• Security layer provides a comprehensive
  permission model with dynamic management

Bundle E
Bundle F
get
register
n
m
service
7
OSGi System Services
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Package Admin

• Provided by the Framework
• Shows information about packages
• Import/Export
• Stale
• Used and Usedby
• Provides information about bundles
• Require Bundle
• Fragments
• Used mainly by management agents

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Permission Admin Service

• Framework uses Permission Admin Service to
  administer permissions
• Permissions associated with bundle location
• Allows setting before bundle is downloaded
• Synchronous Bundle Listener added so that a
  Management Bundle
• Set the permissions Just In Time
• (Simple) Serializable format for permissions

10
Start Level Service

• Allows Management Agent to control
  startup/shutdown sequence of installed bundles
• Supports many levels
• System service, implemented by Framework

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URL Handling
System Bundle

• Manages the URLStreamHandlerFactory and
  URLContentHandlerFactory of Java
• These factories can only be set once so the
  Framework must manage them
• Bundles can register a URLStreamHandlerService or
  ContentHandler
• The Framework will automatically add these to the
  standard set

URL Content Handler Factory
URL Stream Handler Factory
Provides Protocol Handler for URLs
Provides Content handler
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Conditional Permission

• Provide a flexible policy management for a
  delegated management model
• An Operator must be able to sell a device to an
  Enterprise and be assured the enterprise can not
  do anything the Operator does not want
• The Enterprise administrator must be able to give
  the device to a person and restrict the
  possibilities further
• Bundles must be restricted to only the
  permissions they need

Management domain
Operator
Enterprise
Sales
Bundle
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Conditional Permissions

• Signing based on Public Key Cryptography
• Operator signs signing certificate of Deployer
• Developer adds a local permissions file to the
  bundle
• Easy to read
• The local permissions are audited by the Deployer
• Deployer signs the bundle
• The bundle gets deployed on a Service Platform
• The permissions of the bundle are the
  intersection of
• Local permissions
• System permissions for that signer
• Operator remains in full control at all times

Bundle A
local permissions
signature
controls
OSGi Service Platform
system permissions
S
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Conditional Permissions
client

• Conditional Permission Admin provides granting of
  permissions based on conditions
• Bundle signed by X
• Bundle from location Y
• Prompted
• Logged into network
• Java 2 does not provide a mechanism for this
• Very flexible and powerful model

server
checkPermission
JVM
implies
Permission Table
Cond. Perm. Admin
Conditional Permission Admin
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OSGi Compendium Services
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Log Service
LogReaderService
Log Service impl
log reader

• Simple Service to log message to a log
• Dispatches messages between the logging bundles
  and bundles interested in log information
• Severity
• Debug, Info, Warning, Error, Custom
• Automatically handles time, date, source bundle
• Has buffer of undefined length

LogService
Logging bundle
Logging bundle
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Http Service
Http Service impl

• Provides Simple Access to a local web server
• Uses Servlet 2.1 Standard
• Allows simplified access to resources in bundles
• Very popular
• Also usable for web services, UPnP, etc.

Web server
HttpService
Servlet requests And resources
Servlet Provider
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Device Access
Domain service
Device Driver
installs

• Dynamic device driver download model
• Plug Play
• Plugged in devices identify themselves
• Device Manager will download appropriate bundle
• Matching process for best driver
• Extendable
• Driver Selector, Driver locator

Device Access
Device Service
Driver Locator
Driver Selector
Base Driver
Driver Locator Impl
Driver Selector Impl
External Device Controller
External Device
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Device Access
Device Manager
IEEE 1394B
Network bundle
Driver Locator
Device
Driver Locator
Interface
Driver
10. Show camera on TV
Sony CCD654
TV bundle
TV
Camera
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Configuration Admin
Configuration Listener Service
Configuration Admin
Config. Listener Impl

• Configures bundles
• At startup, or any later moment
• Maintains a repository of configurations
• Local
• Management system
• Configurations are key/value pairs
• Typed with Meta Types
• Can be extended with plugins
• Managed Services
• Provide a single set of properties
• Managed Service Factories
• Provide creation and deletion of any number of
  sets of properties
• Supports filter based searches

Managed Service
Managed Factory Service
Variable number of records
A bundle
Another Bundle
One record
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Preferences Service

• Simple hierarchical model like Windows Registry
• Uses simple hierarchical names
• /bundle/121/httpport81
• Different trees
• Multiple named trees per bundle
• One system tree
• Storage can be local or on management system

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org.osgi.service.prefs v1.0Preferences Service
Named or System
root
/c2
c2
c1
/c1/d2
d1
d2
foo8 bar9 lexacme
properties /c1/d2
d1
/c1/d2/d1/d2
d1
d2
foo8 bar9 lexacme
properties /c1/d2/d1/d2
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User Admin Service

• Repository of users
• Maintains data for authentication and other
  purposes
• Private keys, passwords, bio-profile, User
  Preferences
• Does not authenticate self
• Powerful role based authorization model
• Users, group of users, and groups of groups
• Administrative functions

User Admin Listener
User Admin
User Admin Listener Impl
User Admin
User Admin Listener Impl
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Wire Admin Service
Producer Impl

• Connects Producer services to Consumer services
  via Wire object
• Wire objects have properties for configuration
• Matches classes flexible
• Fully Dynamic
• Secure

Producer
Wire Admin
Wire Admin Controller
Wire Admin
Consumer
Consumer Impl
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IO Connector Service
IO Connector Impl

• Standard feature in CLDC and CDC VM profiles to
  access protocols instead of URLs
• Adds dynamic addition and removal or protocols
• Supports streams and message based protocols

Javax. Io. connector
IOConnector
Protocol Provider
http, ftp, sms, etc
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Initial Provisioning

• Provides a model for provisioning a service
  platform with its first configuration
• Allows service platforms to be delivered from the
  factory in a single configuration
• When positioned at the customer premises, the
  platform retrieves its configuration (bundles
  data) from the management host
• Only uses a single unique id
• Secure protocol (RSH) and normal HTTP

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Declarative Services

• Classic OSGi model based on startup
  initialization
• Startup time
• Many services not needed until much later, if
  ever
• Lazy Initialization is much better
• The service model provides hooks so that a bundle
  is not initialized until it is needed
• Bundles declare their requirements and
  capabilities declaratively in a bundle resource
• The Service Component Runtime
• Tracks bundles
• Calculate dependencies
• Initialize a declarative service when it is
  needed
• Bundles that are not activated do not consume
  resources in the system

component.xml
bundle A
SCR
bundle B
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Event Manager Service

• The Event Manager is a simple publish and
  subscribe model
• Events have
• A Topic string
• Properties
• Events are posted through the Event Admin
  service, either synchronous or asynchronous
• Clients can register an Event Listener and
  receive events
• Can use a filter for further selection
• Event delivery is protected by an Topic
  Permission

Event Listener
Event Manager
Event Manager
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Topic Permission

• The TopicPermission class allows fine-grained
  control over which bundles may post events to a
  given topic and which bundles may receive those
  events.
• Matching algorithm.
• For example, a name of "a.b." implies "a.b.c"
  but not "x.y.z" or "a.b".
• There are two available actions "publish" and
  "subscribe".

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Standard Properties

• bundle - Bundle A bundle object
• bundle.id - Long A bundle's ID
• bundle.symbolicName - String A bundle's symbolic
  name
• event - Object The actual event object. Used
  when rebroadcasting an event that was sent via
  some other event mechanism.
• exception - Throwable An exception or error
• exception.class - String Must be equal to
  exception.getClass().getName()
• exception.message - String Must be equal to
  exception.getMessage()
• message - String A human-readable message
• objectClass - String A service's objectClass
• service - ServiceReference A service
• service.id - Long A service's ID
• service.pid - String A service's persistent
  identity
• timestamp - Long The time when the event
  occurred, as reported by System.currentTimeMillis(
  )

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XML Parser Service

• Allows different bundles to register an XML
  parser
• Supports finding best parser for a specific
  application
• Based on standard Java JAR service, but then in
  bundles

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Dmt Admin

• Based on a tree model
• A Node maps to specific device aspect, e.g.
  current start level
• Nodes on the tree are implemented by plugins
• Plugins are services
• Meta Model extended
• Transactional
• Session based
• Good interface to native device
• From native to Java
• From Java to native
• Alerts
• Security
• Java 2 Permission model (also remote managers)
• ACLs

Deploy Admin
.
Appl. Manager
DmtExecPlugin
DmtAdmin
Event Admin
Dmt Admin
DmtDataPlugin
Config Admin
Monitor
Native State

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Monitoring

• Monitoring
• Monitorable services
• Any Monitorable service can provide multiple
  Status Variables
• Status Variables available through the DMT
• Monitoring jobs can be scheduled
• Report a set of Status Variables to the
  management System

DmtDataPlugin
MonitorAdmin
Monitor
EventAdmin
Monitorable
Appl
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Deployment

• Deployment Admin provides the possibility to
  install and update Deployment Packages
• Deployment Packages are
• A set of bundles with associated Resource
  Processor
• Transactional
• No sharing with other Deployment Packages
• Resource Processors provide the semantics for the
  bitsof the resources in the JAR file
• Process (install)
• Drop (uninstall)
• Security based on the permissions associated with
  the signer of the Deployment Package

DmtDataPlugin
DeploymentAdmin
Depl. Admin
EventAdmin
Resource Processor
Rrsrc. Proc.
Autoconf
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Deployment
Global section

• Deployment Package
• Based on JAR Format
• Manifest describes the resources and associates
  them with a Resource Processor
• Fix Packages
• Provide only updated contents

Name bundle-A.jar SHA1-Digest
RTasyyasi987iasj Bundle-SymbolicName
com.acme.a Bundle-Version 2.1
manifest.mf
signer.sf
Name certificates.cr SHA1-Digest
lkMjUasm87asjjasloe DP-ResourceProcessor
com.acme.c509
signer.rsa
bundle-A.jar
bundle-B.jar
autoconf.xml
certificates.cer
Resource Processor
Certificate Processor
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Deployment

• Customizers
• A Deployment Package can contain its own Resource
  Processor bundle
• This customizer is installed and started before
  other bundles in the Deployment Package
• It registers a Resource Processor service
• The Deployment Admin will only allow only
  contents from the correct DP to be processed by
  the customizer
• The customizer gets access to the private data
  area of its related bundles

Customizer
DP
Depl. Admin
bundle A
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Application Model

• A generic model that is intended to abstract
  different application models so they can be
  treated as one
• Screen Manager
• Provides access to icons and descriptive
  localized information for each application
• Can monitor the state of running instances
• Applications can be scheduled for later execution
  when a specific event arrives
• Application Descriptor and Application Handle
  services are provided as vendor specific base
  classes
• Interacts with JSR 211

Screen manager
Application Descriptor
Application Handle
Native Container
MIDP Container
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UPnP

• Popular UPnP specifications adapted to OSGi
  Service Platform
• Makes it very easy to write a UPnP control point
  or device
• Involves registering a simple UPnPDevice service

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OSGi Compendium Utils
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Service Tracker

• Takes the pain out of the dynamics
• Tracks the coming, modification, and going of
  services
• Hides the difference between services already
  registered and services that are going to be
  registered
• Can be used with an interface or through
  sub-classing

• Object addingService(ServiceReference)
• void modifiedService(Object, ServiceReference)
• void removedService(Object, ServiceReference)

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Position, Measurement, State

• Support classes for Wire Admin
• Position
• Supports GPS like position
• Measurement
• SI measurement system to prevent calculation
  errors
• Error calculations
• Timestamp
• State

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OSGi Security Layer
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Security Layer Benefits

• Possibility to run not fully trusted code on a
  device
• Deployer can mitigate its risk when signing a
  bundle
• Local Permissions
• Delegated responsibility
• Less frustration at Users and Deployers because
  they are more independent
• Less staff required at Operator
• Operator always maintains fully in control
• A change of mind is instantaneous

44
Security Layer

• Security Architecture based on 4 roles
• Operator
• Deployer
• End User
• Developer
• The OSGi Framework provides a (optional)
  comprehensive security model
• Based on Java 2 Permissions
• Signing or location based authentication

Deployer
Operator
developer
Bundle B
Bundle A
Bundle D
Bundle E
Bundle F
Framework
Device
end user
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Security Layer

• Provide a flexible policy management for a
  delegated management model
• An Operator must be able to sell a device to an
  Enterprise and be assured the enterprise can not
  do anything the Operator does not want
• The Enterprise administrator must be able to give
  the device to a person and restrict the
  possibilities further
• Bundles must be restricted to only the
  permissions they need

Management domain
Operator
Enterprise
Sales
Bundle
46
Security Layer
Enterprise
Developer

• Signing based on Public Key Cryptography
• Operator signs signing certificate of Deployer
• Developer adds a local permissions file to the
  bundle
• Easy to read
• The local permissions are audited by the Deployer
• Deployer signs the bundle
• The bundle gets deployed on a Service Platform
• The permissions of the bundle are the
  intersection of
• Local permissions
• System permissions for that signer
• Operator remains in full control at all times

Bundle A
local permissions
signature
Operator
controls
OSGi Service Platform
system permissions
S
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Security Layer

• Permissions can be assigned based on
• Signer
• Location (Channel)
• Custom Condition
• Multiple signers are possible
• Bundle gets union of signer permissions
• No partial signing, all signers must sign all
  content
• Flexible management API for permissions
• Dynamic
• changes take effect immediately
• Compatible with standard Java 2 VMs
• Take advantage of optimizations

Bundle A
Location, signer, custom
OSGi Service Platform
system permissions

local permissions
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Security Layer

• Signer requires coarse grained
• Must work for all bundles from that signer
• Bundle can use very fine grained
• A specific bundle can require specific
  permissions
• Standard Permissions
• FilePermission
• RuntimePermission
• SocketPermission
• Framework permissions
• AdminPermission
• ServicePermission
• PackagePermission
• BundlePermission
• Service Permissions
• ConfigurationPermission
• EventPermission
• ApplicationPermission

Fine grained local permissions
Coarse grained system permissions
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