OSGi fundamentals

@MilenDyankov

OSGi Fundamentals

OSGi = Modularity

"When I use a word," Humpty Dumpty said,

in rather a scornful tone,

"it means just what I choose it to mean - neither

more nor less."

Modularity Maturity Modelproposed by Dr Graham Charters

at the OSGi Community Event 2011

Level 1 Ad Hoc nothing

Level 2 Modules decoupled from artifact

Level 3 Modularity decoupled from identity

Level 4 Loose-Coupling decoupled from implementation

Level 5 Devolution decoupled from ownership

Level 6 Dynamism decoupled from time

Level 1 Ad Hoc nothing

Level 2 Modules decoupled from artifact

Level 3 Modularity decoupled from identity

Level 4 Loose-Coupling decoupled from implementation

Level 5 Devolution decoupled from ownership

Level 6 Dynamism decoupled from time

Level 7 Peter Kriens only available to people who are Peter Kriens

Modularity Maturity Modelproposed by Dr Graham Charters

at the OSGi Community Event 2011

Modularity Maturity Modelproposed by Peter Kriens

in foreword to “Java Application Architecture”

Level 1 Ad Hoc

Level 2 Modules

Level 3 Modularity

Level 4 Loose-Coupling

Level 5 Devolution

Level 6 Dynamism

Unmanaged / chaos

Managing dependencies

Proper isolation

Minimize coupling

Service-oriented architecture

Level 1 Monolith

Level 2 Composite

Level 3 Containers

Level 4 Discovery

Level 5 JuServices

Buzzword compliant Modularity Maturity Model

Level 1 Monolith Unaware of own dependencies

Level 2 Composite Aware of infrastructural dependencies

Level 3 Containers Aware of functional dependencies

Level 4 Discovery Aware of functional requirements

Level 5 Adapts to changing requirementsJuServices

Buzzword compliant Modularity Maturity Model

Level 1 Monolith

Level 2 Composite

Level 3 Containers

Level 4 Discovery

Level 5 JuServices

Buzzword compliant Modularity Maturity Model

Level 1 Monolith

Level 2 Composite

Level 3 Containers

Level 4 Discovery

Level 5 JuServices

Buzzword compliant Modularity Maturity Model

Buzzword compliant Modularity Maturity Model

JuServices

Level 1 Monolith

Level 2 Composite

Level 3 Containers

Level 4 Discovery

Level 5

Buzzword compliant Modularity Maturity Model

JuServices

Level 1 Monolith

Level 2 Composite

Level 3 Containers

Level 4 Discovery

Level 5 OSGi

productintermediate

intermediate

material

Product

Entity

EntityEntity

Entity

Entity Entity

Offer

Offer

Offer

Offer

Offer

Offer

Offer

Offer

Offer

Offer

Offer

Application

Artifact

ArtifactArtifact

Artifact

Artifact Artifact

Export

Export

Export

Export

Export

Export

Export

Export

Export

Export

Export

Artifact

Level 2decoupled from

artifact

Foo

Level 2decoupled from

artifact

Manifest-Version: 1.0Bundle-ManifestVersion: 2Bundle-Name: Foo

Bundle-SymbolicName: com.fooBundle-Vendor: Foo, Inc.

Bundle-Version: 1.0.0. . .

Buzzword compliant Modularity Maturity Model

JuServices OSGi

Level 1 Monolith

Level 2 Composite

Level 3 Containers

Level 4 Discovery

Level 5

OK!

Level 3decoupled from

identity

Artifact

Export

Artifact

Level 3decoupled from

identity

Require-Bundle: com.fooFoo

Me

Level 3decoupled from

identity

Export-Package ::= export ( ',' export)*

List of packages (Java package + version) within this jarfile that external code is allowed to access!

Foo

Me

Level 3decoupled from

identity

Export-Package:\ com.standard.power.plugs;\

version=”1.0.0”,\com.foo.power.plugs.shop;\

version=”2.3.0”;\uses:=”com.standard.power.plugs”,\

...

Export-Package ::= export ( ',' export)*

List of packages (Java package + version) within this jarfile that external code is allowed to access!

Foo

Me

Level 3decoupled from

identity

Import-Package ::= import ( ',' import )*

List of packages (Java package + version-range) thatclasses in this jar file expect other bundles to provide!

Foo

Me

Level 3decoupled from

identity

Import-Package:\ com.standard.power.plugs;\

version=”[1,2)”,\com.foo.power.plugs.shop;\

version=”2.3.0”,\com.other.power.plugs.shop;\

version=”1.5.0”,\...

Foo

Me

Import-Package ::= import ( ',' import )*

List of packages (Java package + version-range) thatclasses in this jar file expect other bundles to provide!

Buzzword compliant Modularity Maturity Model

JuServices OSGi

Level 1 Monolith

Level 2 Composite

Level 3 Containers

Level 4 Discovery

Level 5

OK!

OK!

Level 4decoupled fromimplementation

Artifact

Artifact

RequirementNeed toconnectdevice to

power outlet!

CapabilityCan

connectdevice to

power outlet!

RESOLVER

Level 4decoupled fromimplementation

Artifact

Artifact

RequirementNeed toconnectdevice to

power outlet!

CapabilityCan

connectdevice to

power outlet!

RESOLVER

Require-Capability:power.supply;\

filter:=”(& (voltage>110)\(voltage<230))”,\

electrician;\filter:=”(& (price<50)\

(certified=yes))”

Level 4decoupled fromimplementation

Artifact

Artifact

RequirementNeed toconnectdevice to

power outlet!

CapabilityCan

connectdevice to

power outlet!

RESOLVER

Require-Capability:power.supply;\

filter:=”(& (voltage>110)\(voltage<230))”,\

electrician;\filter:=”(& (price<50)\

(certified=yes))”

org.osgi.framework.system.capabilities.extra= power.supply;voltage:Long=220

Level 4decoupled fromimplementation

Artifact

Artifact

RequirementNeed toconnectdevice to

power outlet!

CapabilityCan

connectdevice to

power outlet!

RESOLVER

Require-Capability:power.supply;\

filter:=”(& (voltage>110)\(voltage<230))”,\

electrician;\filter:=”(& (price<50)\

(certified=yes))”

org.osgi.framework.system.capabilities.extra= power.supply;voltage:Long=220

Provide-Capability:electrician;price:Long=10;certified=yes

Buzzword compliant Modularity Maturity Model

JuServices OSGi

Level 1 Monolith

Level 2 Composite

Level 3 Containers

Level 4 Discovery

Level 5

OK!

OK!

OK!

Level 5

decoupled fromownership & time

JuServices

Artifact

Artifact

REGISTRY

Service

Service

Service

Service

Level 5

decoupled fromownership & time

JuServices

Artifact

Artifact

REGISTRY

Service

Service

Service

Service

manifestmanifest

OSGi service registry

REGISTER

REGISTER

manifest

Interface

Service 1

. . .

Service N

Level 5

decoupled fromownership & time

JuServices

Artifact

Artifact

REGISTRY

Service

Service

Service

Service

manifestmanifest

OSGi service registry

REGISTER USE

manifest

Interface

Service 1

. . .

Service N

REGISTER

Level 5

decoupled fromownership & time

JuServices

Artifact

Artifact

REGISTRY

Service

Service

Service

Service

OSGi service registry

SERVLET

SERVLET

GET GET

REGISTER

REGISTER

HTTPServiceImpl

HTTPService

HTTPServiceImpl

REGISTER

manifest

Level 5

decoupled fromownership & time

JuServices

Artifact

Artifact

REGISTRY

Service

Service

Service

Service

manifest

OSGi service registry

HTTPServlet

REGISTER

SERVLET

SERVLETGET(when needed)

HTTPServiceImpl

Servlet1 (path=”/1”)

Servlet2 (path=”/2”)

REGISTER

Level 5

decoupled fromownership & time

JuServices

Artifact

Artifact

REGISTRY

Service

Service

Service

Service

Register OSGI service (manually) SINGLETON

PROPERTIES CONTRACT

Level 5

decoupled fromownership & time

JuServices

Artifact

Artifact

REGISTRY

Service

Service

Service

Service

Use an OSGI service (manually)

DONE WITHTHE SERVICE

START USINGTHE SERVCE

FINDA SERVCE

Level 5

decoupled fromownership & time

JuServices

Artifact

Artifact

REGISTRY

Service

Service

Service

Service

Declarative servicesand

Service Component Runtime (SCR)

Level 5

decoupled fromownership & time

JuServices

Artifact

Artifact

REGISTRY

Service

Service

Service

Service

/OSGI-INF/MyComponent.xml file:<?xml version="1.0" encoding="UTF-8"?>

<scr:component name=”MyComponent”xmlns:scr=”http://www.osgi.org/xmlns/scr/v1.2.0”>

<implementation class=”com.liferay.MyComponent”/></scr:component>

Manifest header:Service-Component: OSGI-INF/MyComponent.xml

Level 5

decoupled fromownership & time

JuServices

Artifact

Artifact

REGISTRY

Service

Service

Service

Service

@Component(configurationPid=”hello.component.pid”,configurationPolicy=ConfigurationPolicy.OPTIONAL,enabled=true,immediate=true,name=”HelloComponent”,property={

”vendor.name=Liferay”, ”other.property=value”

},service={HelloService.class, OtherService.class})

public class HelloComponent implements MultiService { . . .

Level 5

decoupled fromownership & time

JuServices

Artifact

Artifact

REGISTRY

Service

Service

Service

Service

@Activatevoid open(Map<String,?> properties) { }

@Deactivatevoid close() {}

@Modifiedvoid modified(Map<String,?> properties) {}

Level 5

decoupled fromownership & time

JuServices

Artifact

Artifact

REGISTRY

Service

Service

Service

Service

@Reference(cardinality=ReferenceCardinality.MANDATORY,name = “LogService”,policy = ReferencePolicy.STATIC,policyOption=ReferencePolicyOption.RELUCTANT,service = LogService.class,target = “(vendor.name=Liferay)”,unbind = “unsetLog”,updated = “updatedLog”

)void setLog( LogService log) {}void unsetLog( LogService log) { }void updatedLog( Map<String,?> ref ) { }

Buzzword compliant Modularity Maturity Model

JuServices OSGi

Level 1 Monolith

Level 2 Composite

Level 3 Containers

Level 4 Discovery

Level 5

OK!

OK!

OK!

OK!

The essence ofmodularity is

Not knowing

The essence ofmodularity is

Not knowing

Which enforcesoptimization forPredictability

Which results inapplicationAgility

The essence ofmodularity is

Not knowing

Which enforcesoptimization forPredictability

milen.dyankov@liferay.com@MilenDyankov

http://www.liferay.com@Liferay