Building LinkedIn's Next Generation Architecture with OSGi

OSGi Building LinkedIn's Next Generation Architecture with OSGI Yan Pujante Distinguished Software Engineer Member of the Founding Team @ LinkedIn ypujante@linkedin.com http://www.linkedin.com/in/yan

Background ■ LinkedIn created in 03/2003 • close to 30M members • proﬁtable with 5 revenue lines • HQ in Mountain View (400 employees) ■ Technologies • 2 datacenters (~ 600 machines) • SOA, java, tomcat, spring framework, http, Oracle, MySQL, servlets, jsp, graph, OSGi... • dev on MacOS X, prod on Solaris

Challenges ■ Growing engineering team on a monolithic code base (still modular) ■ Growing product team wanting more and more feature, faster ■ Growing operations team deploying more and more servers

Challenges (SOA in dev) Front-End Back-End X 1 3 webapp Z 2 Y webapp 4 M N webapp jetty (1) webapp P N R webapp webapp webapp tomcat jetty (2) ■ Front-end: many BL services in one webapp (in tomcat) ■ Back-end: many wars in 5 containers (jetty) with 1 service per war ■ Note that prod and dev are different

Container Challenge ■ 1 war with N services • does not scale for dev (conﬂicts, monolithic...) ■ N wars with 1 service • does not scale from a container point of view (no shared jars) ■ Can add containers but only 12Gb of RAM :(

Challenges (SOA in prod) ■ Upgrading back-end service to new version requires downtime • Hardware LB does not account for version ■ Upgrading front-end service to new version requires redeploy • N services in 1 war ■ Adding new back-end service painful • lots of manual conﬁguration (LB, front- end...)

Solution: OSGi ■ Belief that OSGi is one of the tools that will help us address those challenges Why OSGi?

OSGi intro ■ OSGi means “Open Services Gateway initiative” ■ OSGi is a spec with several implementations • Equinox (eclipse!) • Knoplerﬁsh • Felix (Apache)

OSGi intro (cont.) ■ OSGi has some very good properties • Smart class loading => multiple versions jars ok • Highly dynamic => deploy / undeploy built in • Services registry • Highly extensible / conﬁgurable ■ OSGi bundle = Jar File with OSGi manifests

OSGi bundle Specification-Title: Colorado Software Summit 2008 Hello Wolrd Client Bundle-Activator: com.linkedin.colorado.helloworld.client.HelloWorldClientActivator Import-Package: com.linkedin.colorado.helloworld.api;version=quot;[1.0.0,1.0.1)quot;, com.linkedin.colorado.helloworld.client;version=quot;[1.0.0,1.0.1)quot;, org.osgi.framework;version=quot;[1.4.0,1.4.1)quot; Export-Package: com.linkedin.colorado.helloworld.client;version=quot;1.0.0quot; Bundle-Version: 1.0.0 Bundle-Name: colorado-helloworld-client Bundle-ManifestVersion: 2 Bundle-SymbolicName: colorado-helloworld-client Bnd-LastModified: 1224557973403 Generated-On: 20081020 Tool: Bnd-<unknown version> Implementation-Version: DevBuild

BundleActivator ■ In a war: ServletContextListener public interface ServletContextListener extends EventListener { void contextInitialized(ServletContextEvent event); void contextDestroyed(ServletContextEvent event); } web.xml <listener> <listener-class>com.colorado.MyListener</listener-class> </listener> ■ In a Bundle: BundleActivator public interface BundleActivator { void start(BundleContext bundleContext) throws Exception; void stop(BundleContext bundleContext) throws Exception; } MANIFEST.MF Bundle-Activator: com.colorado.MyActivator

BundleContext ■ The bundle context is the entry point: • registerService / getServiceReference => to register / get services from registry • addBundleListener / addServiceListener => to listens / extends the framework • even installBundle ! • ... and more

Demo ■ Equinox demo... stay tuned...

Web Container JARs WAR ■ Services exported Services with Spring/RPC ■ Services in same war can see each other SpringRPC ■ Share the jars WEB Container VM HTTP

Web Container JARs JARs Services Services ■ Cannot share jars SpringRPC SpringRPC ■ Cannot talk directly WEB Container VM HTTP

OSGi container Bundles ■ Bundles (jars) shared Service Registry ■ Services shared ■ Dynamic replacement of bundles OSGi Container VM • OSGi solves the container challenge

Distributed OSGi ■ OSGi is currently container centric ■ Next version (4.2) will introduce distributed OSGi • What do we do in the meantime ?

LinkedIn distributed OSGi Bundles Service Service Registry Registry C1 VM ■ Service ‘red’ talks to service ‘green’ (local) • What happens if we move ‘green’ to a different container ?

LinkedIn distributed OSGi Bundles Service Registry Bundles C2 Service Registry VM Bundles C1 VM Service Registry C3 VM

LinkedIn distributed OSGi Bundles Service Registry Bundles 2 C2 Service Registry VM 2 Bundles C1 VM Service Registry C3 VM

LinkedIn distributed OSGi Bundles Service Registry Bundles 2 C2 Service Registry VM 2 3 Bundles C1 VM Service Registry 3 C3 VM

LinkedIn distributed OSGi ■ no more N-1 / 1-N problem • libraries and services can be shared in 1 container (mem. footprint smaller) • services shared across containers ■ transparent location to clients • no more conﬁgurations to change when adding/removing/moving services ■ software load balancer • much more ﬂexible (handle version)

LB and version Bundles Bundles Service Registry Service Registry 2 2 C2 VM 3 Bundles C1 VM Service Registry 3 C3 VM

Everything is perfect... ■ ...Not really • OSGi has some problems

OSGi problems ■ OSGi is great, but tooling is not quite there yet ■ Not every lib is a bundle ■ OSGi was designed for embedded devices => using it for server side is recent (but very active)

OSGi problems ■ OSGi is quite low level => but there is some work to ‘hide’ the complexity • spring DM (spring dynamic module) • multiple vendors containers ■ Spring DM Server, Glassfish, Infiniflow ■ OSGi is container centric, but next version will add distributed OSGi (although no support for LB)

OSGi problems (cont.) ■ version management can be nightmarish • Import-Package: com.linkedin.util;version=1.0.0 ■ version=1.0.0 means [1.0.0, ∞) ■ should use at least: version=[1.0.0,2.0.0) ■ runtime is dynamic and can result in untested code being executed!

Runtime version problem ■ client1 and client2 uses Service 3.0.0 ■ Dependencies are ‘loose’: [3.0.0, 4.0.0)

Runtime version problem ■ We upgrade client1 and service ■ client2 starts using green bundles ■ => Most likely untested

Runtime version solutions ? ■ A solution is to lock version: • [1.0.0,1.0.0] => no slack • [1.0.0,1.0.1) => tiny bit of slack for emergency mode ■ Does it really work ? spring 2.5.5 imports hibernate version [3.1,∞) ■ Can OSGi even resolve with everything locked down ?

Runtime version problem ■ With maximal lock-down, client2 cannot use the new service

Runtime version solutions ? ■ Services cannot talk to each other directly => need serialization for backward compatible services (dynamic proxy)

Despite problems... ■ ...OSGi and community moving in the right direction

Where are we ? ■ Bundle repository (big amount of work... in progress) ■ Use ivy/bnd for generating bundles ■ Evaluating container • Inﬁniﬂow (from Paremus) most likely the one • LinkedIn spring / SCA to deploy composites ■ Work on the load balancer/distribution (in progress) ■ Work on tooling / build integration (Sigil from Paremus) ■ Much much more to do...

Conclusion ■ Using OSGi... deﬁnitely! ■ But we do not want application developers to have to deal with it.

More information ■ Check my posts on the LinkedIn blog (OSGi series). More to come...

http://java.dzone.com	2839
http://www.javaplex.com	847
http://singztechmusings.wordpress.com	434
http://blog.linkedin.com	195
http://michaelsheen.sinaapp.com	98
http://heeha.wordpress.com	54
http://osgi.dzone.com	44
http://www.slideshare.net	44
http://www.scoop.it	44
http://architects.dzone.com	30
https://wiki.ecmc.hu	13
http://jisi.dreamblog.jp	13
http://bouraouibilel.blogspot.com	11
http://linkedin.typepad.com	9
http://bouraouibilel.blogspot.fr	6
http://webcache.googleusercontent.com	3
http://www.techgig.com	3
http://www.schoox.com	2
http://www.schoox.com	2
http://bouraouibilel.blogspot.jp	2
http://translate.googleusercontent.com	2
https://confluence.ecmc.hu	1
http://bouraouibilel.blogspot.com.ar	1
http://bouraouibilel.blogspot.pt	1
http://bouraouibilel.blogspot.de	1
https://singztechmusings.wordpress.com	1
http://www.dzone.com	1
http://paper.li	1
http://jmmiddleware.wordpress.com	1
http://64.233.183.104	1
http://static.slideshare.net	1
http://bouraouibilel.blogspot.sk	1

Building LinkedIn's Next Generation Architecture with OSGi

by LinkedIn on Oct 28, 2008

Accessibility

Categories

Upload Details

Usage Rights

32 Embeds 4,706

Statistics

Building LinkedIn’s Next Generation Architecture with OSGi Presentation Transcript