The document discusses Concierge, an OSGi framework designed for embedded devices. It has the following key points: 1. Concierge is an implementation of the OSGi dynamic module system that aims to have a small footprint suitable for embedded devices while maintaining compatibility with the OSGi specification. 2. Experiments show Concierge has a footprint of only 245kB, much smaller than other OSGi frameworks, while still supporting full OSGi R5 compatibility. 3. Concierge is designed to have usability in mind for embedded systems, staying close to OSGi standards with limited additional functionality and good integration between application behavior and framework events.

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IoT Virtual Meetup
June 2nd 2016
Concierge – Bringing OSGi
(back) to Embedded Devices
Jan S. Rellermeyer

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Embedded Devices
Typically fixed-function devices
Limited user interface
ISA
OS
Software typically closely tied to the hardware
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Embedded Devices Are Evolving
We see a new class of embedded systems emerging
Advanced processors
Larger set of capabilities
Enhanced user interface / user experience
Open platforms for a software ecosystem
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OSGi
Dynamic Module System for the Java Runtime
Original domain: Home Gateway
Multiple software packages need to co-exist on the same machine
Long-running software
Periodic maintenance and updates requires
Ideally with minimal downtime and no interruption of unrelated software packages
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• Java on the Embedded Device
• Pros:
• bridges heterogeneity
• can run the same code in the cloud or on the device
• Cons:
• updates and maintenance

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Module Management
Traditional Java: The mystical class path
java –cp commons‐X.jar:foo.jar:bar.jar my.application.MainClass
Which module contains the main class?
What are the dependencies between foo.jar and bar.jar?
What happens if bar.jar is upgraded to bar-1.01.jar?
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OSGi Module Layer
Modules are called Bundles
JAR files with additional metadata
Runtime system: The Framework
Lifecycle management
Bundles implement isolation and locality
Interaction between bundles is limited
Shared code through package imports
Every bundle is loaded through a separate classloader
Monitoring system state through events
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Concierge
Question: What is the (minimum) overhead of OSGi?
The “old” Concierge:
OSGi R3 core implementation developed during my PhD at ETH Zurich
optimized for mobile and embedded devices, has a footprint of only 86kB
People found the source code readable and understandable: 7 Java classes + 7
inner classes.
[J.S. Rellermeyer and G. Alonso: Concierge – A Service Platform for Resource-Constrained Devices. In: EuroSys 2007].
Image: http://www.linksys.com
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Eclipse Concierge
Goals:
 Full OSGi core R5 compatibility
 Keep a small footprint to work well on
embedded devices
 Remain “readable”
 Remain backwards-compatible
 Java 5
 Java 1.4?
 Being a sandbox for innovation around OSGi
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Experiments
Beaglebone Rev A5
• AM335x 720MHz ARM Cortex-A8
• 256 MiB DDR2 RAM
• 4 GiB microSD card
• Angstrom Linux
• Java SE Embedded 1.7.0_21-b11 and
• Java SE Embedded build 1.8.0_06-b23 compact1
Raspberry Pi B
• ARM1176JZF-S 700 MHz ARM 11
• 512 MiB SDRAM (shared with GPU)
• 8 GiB SDHD card
• Raspbian Linux
• Java SE build 1.8.0-b132
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OSGi Frameworks
Eclipse Equinox
• version 3.10.101.v20150820-1432
• 1.3 MiB
• (R6 framework)
Apache Felix
• version 5.4.0
• 675 kiB
Knopflerfish
• version 7.2.0
• 609kiB / 320kiB compact
Concierge
• version 5.0.0
• 245kiB
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Resolver
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Generate 1000 “random bundles”
• Can either import or export up to 5 packages
• Choice of 50 packages in total
• For exports: generate a random package version from [1.0.0-21.0.0)
• For import: generate a random import range from the interval.
Install all 1000 bundles
Resolve the bundles
Benchmark turned out to be rather volatile…

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Usability
What does Usability mean for an OSGi framework?
Don’t be annoying…
Stay close to the (core) standard
Every OSGi framework has some extra functionality
Concierge has a built-in log service
Discrepancies between compile time and run time behavior is what makes OSGi
challenging
Log service in the framework => correlate application behavior with framework events
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XargsFileLauncher
$ java -jar framework/org.eclipse.concierge-5.0.0.*.jar samples/demo.xargs
# demo.xargs
-Dorg.osgi.framework.system.packages.extra+=javax.xml.parsers
# -Drepo=http://www.us.apache.org/dist/felix
-Drepo=localRepo
# load bundles, use wildcard notation for local files, not for URLs
-istart bundles/org.eclipse.concierge.shell-5.0.0.*.jar
-istart bundles/org.eclipse.concierge.service.startlevel-5.0.0.*.jar
-istart bundles/org.eclipse.concierge.service.packageadmin-5.0.0.*.jar
-istart ${repo}/org.apache.felix.httplite.complete-0.1.4.jar
-istart ${repo}/org.apache.felix.webconsole-4.2.14-all.jar
• Concierge supports Knopflerfish styled xargs file for startup
• Enhanced property (variable replacement) and install notation (wildcard support)
• Supports start level in scripts (-level <n>)
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Remote Management
RESTful interface
• Exposing the framework and its internal state as resources
• Bundles
• Services
• Easy management of OSGi deployments through REST
• Command line tools
• Web interfaces
• Application-level
• REST service implementation will appear in Concierge 5.1
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What’s next?
Several work streams
• R6 compatibility
• More auxiliary bundles
• EventAdmin
• Remote services?
• Remote management based on REST interface
• Help other projects with transitioning to Concierge

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