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Architecture introspection is required when the system doesn't work as expected. In this case, having a quick access to instances states and interconnection is a stringent requirement. The arch
command allows getting these data from the Felix Shell and , from the Equinox shell and Gogo.
Note : The Gogo commands are not yet released but are available from the iPOJO trunk.
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Download
The Felix command commands is available from the download page and in the arch
folder of the iPOJO trunk http://svn.apache.org/repos/asf/felix/trunk/ipojo/arch/.
The Equinox command sources are available http://svn.apache.org/repos/asf/felix/sandbox/clement/ipojo-utils/arch-equinox/. To compile sources, just launch the mvn clean install
and deploy the resulting bundle.
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Installation
Once you get the bundle, just install and start it in the OSGi Framework shell:
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start file:/BUNDLE_URL.jar
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| nonexmlnone |
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| xml |
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title | Equinox |
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install file:/BUNDLE_URL.jar
Bundle X installed
start X
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install file:/ARCH_GOGO_URL.jar
Bundle X installed
start X
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Equinox and Felix Shells
Then, you can use it to introspect the system by launching the arch
command.
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arch => displays instances name & state (equivalent to arch \-instances)
arch -instance $instance_name => displays complete information about the instance $instance_name
arch -factories => display the list of available factories
arch -factory $factory_name => display complete information about the factory $factory_name
arch -handlers => list available handlers
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Gogo Shell Commands
The set of commands available from Gogo is a little bit different:
ipojo:instances
(or just instances
) lists the instances and stateipojo:instance $instance_name
(or just instance $instance_name
) displays the complete information about the specified $instance_nameipojo:factories
(or just factories
) lists the available public factoriesipojo:factory $factory_name
(or just factory $factory_name
) displays complete information about the factory $factory_nameipojo:handlers
(or just handlers
lists available handlers
Reading instance architecture
When you launch the arch
command (or instances
on Gogo), the list of created instances (enabling architecture introspection) is displayed.
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-> arch
Instance ArchCommand -> valid
Instance spell.english.EnglishDictionary-0 -> valid
Instance spell.checker.SpellCheck-0 -> valid
Instance spell.gui.SpellCheckerGui-0 -> valid
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$ instances
Instance ArchCommand -> valid
Instance spell.english.EnglishDictionary-0 -> valid
Instance spell.checker.SpellCheck-0 -> valid
Instance spell.gui.SpellCheckerGui-0 -> valid
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To get more information on an instance, launch arch -instance the_instance_name
(or instance the_instance_name
on Gogo)
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-> arch -instance spell.checker.SpellCheck-0
instance component.type="spell.checker.SpellCheck" state="valid" bundle="8" name="spell.checker.SpellCheck-0"
handler state="valid" name="org.apache.felix.ipojo.handlers.dependency.DependencyHandler"
requires optional="false" aggregate="false" state="resolved" binding-policy="dynamic" specification="spell.services.DictionaryService"
handler state="valid" name="org.apache.felix.ipojo.handlers.providedservice.ProvidedServiceHandler"
provides service.id="36" state="registered" specifications="[spell.services.SpellChecker]"
property value="spell.checker.SpellCheck" name="factory.name"
property value="spell.checker.SpellCheck-0" name="instance.name"
handler state="valid" name="org.apache.felix.ipojo.handlers.architecture.ArchitectureHandler"
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$ipojo:instance spell.checker.SpellCheck-0
instance component.type="spell.checker.SpellCheck" state="valid" bundle="8" name="spell.checker.SpellCheck-0"
->
handler state="valid" name="org.apache.felix.ipojo.handlers.dependency.DependencyHandler"
requires optional="false" aggregate="false" state="resolved" binding-policy="dynamic" specification="spell.services.DictionaryService"
handler state="valid" name="org.apache.felix.ipojo.handlers.providedservice.ProvidedServiceHandler"
provides service.id="36" state="registered" specifications="[spell.services.SpellChecker]"
property value="spell.checker.SpellCheck" name="factory.name"
property value="spell.checker.SpellCheck-0" name="instance.name"
handler state="valid" name="org.apache.felix.ipojo.handlers.architecture.ArchitectureHandler"
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Instance architecture is organized as follows:
On the first line, are displayed the component type (i.e. factory), the instance state (valid
or invalid
), the bundle from which the instance is created, and the instance name.
Then, the information is organized handler by handler (a piece of container). For each handler plugged on the instance can participate to the instance architecture. For each handler its name (such as {{ org.apache.felix.ipojo.handlers.dependency.DependencyHandler}} for iPOJO service dependencies, {{ org.apache.felix.ipojo.handlers.providedservice.ProvidedServiceHandler}} for iPOJO service providing...) and the state (either valid
or invalid
are displayed. Remember that an instance is valid only and only if all plugged handlers are valid.
The org.apache.felix.ipojo.handlers.dependency.DependencyHandler
provides data on service dependencies and more precisely on the state of service dependencies. In the previous example, the dependency on {{ spell.services.DictionaryService}} was resolved. On the following example, the same dependency is no more resolved:
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Notes that, the instance also becomes invalid and that the provided service is unregistered.
If the provider comes back, the dependency becomes resolved
and the instance becomes valid
If an instance begins to use a service, the bound providers are described in the instance architecture:
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-> arch -instance spell.checker.SpellCheck-0
instance component.type="spell.checker.SpellCheck" state="valid" bundle="8" name="spell.checker.SpellCheck-0"
object name="spell.checker.SpellCheck@e222eb"
handler state="valid" name="org.apache.felix.ipojo.handlers.dependency.DependencyHandler"
requires optional="false" aggregate="false" state="resolved" binding-policy="dynamic" specification="spell.services.DictionaryService"
uses service.id="41" instance.name="spell.english.EnglishDictionary-0"
handler state="valid" name="org.apache.felix.ipojo.handlers.providedservice.ProvidedServiceHandler"
provides service.id="42" state="registered" specifications="[spell.services.SpellChecker]"
property value="spell.checker.SpellCheck" name="factory.name"
property value="spell.checker.SpellCheck-0" name="instance.name"
handler state="valid" name="org.apache.felix.ipojo.handlers.architecture.ArchitectureHandler"
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$instance spell.checker.SpellCheck-0
instance component.type="spell.checker.SpellCheck" state="valid" bundle="8" name="spell.checker.SpellCheck-0"
object name="spell.checker.SpellCheck@e222eb"
handler state="valid" name="org.apache.felix.ipojo.handlers.dependency.DependencyHandler"
requires optional="false" aggregate="false" state="resolved" binding-policy="dynamic" specification="spell.services.DictionaryService"
uses service.id="41" instance.name="spell.english.EnglishDictionary-0"
handler state="valid" name="org.apache.felix.ipojo.handlers.providedservice.ProvidedServiceHandler"
provides service.id="42" state="registered" specifications="[spell.services.SpellChecker]"
property value="spell.checker.SpellCheck" name="factory.name"
property value="spell.checker.SpellCheck-0" name="instance.name"
handler state="valid" name="org.apache.felix.ipojo.handlers.architecture.ArchitectureHandler"
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In the previous case, the dependency on {{ spell.services.DictionaryService}} use the service 41 from the iPOJO instance named {{ spell.english.EnglishDictionary-0}}
You can also check created POJO objects (implementation class objet). Here, only one object was created (spell.checker.SpellCheck@e222eb
).
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To list available factories (i.e. component types), launch the arch -factories
command (or factories
on Gogo):
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-> arch -factories
Factory spell.checker.SpellCheck (VALID)
Factory spell.gui.SpellCheckerGui (VALID)
Factory spell.english.EnglishDictionary (VALID)
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$factories
Factory spell.checker.SpellCheck (VALID)
Factory spell.gui.SpellCheckerGui (VALID)
Factory spell.english.EnglishDictionary (VALID)
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For each available (public) factories,the name and the sate are displayed. A factory is valid if and only if all required handlers are available. To get more information on a factory launch the arch -factory factory_name
(or factory factory_name
on Gogo) command:
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factory implementation-class="spell.english.EnglishDictionary" state="valid" bundle="7" name="spell.english.EnglishDictionary"
provides specification="spell.services.DictionaryService"
missinghandlers list="[]"
requiredhandlers list="[org.apache.felix.ipojo:provides, org.apache.felix.ipojo:architecture]"
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On the first line, you get the implementation class of the type, the state of the factory, the bundle declaring the type and the name of the type. Then you You also get the list of required and missing handlers.
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You can also list available handlers with the arch -handlers
(or handlers
on Gogo) command.
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-> arch -handlers
Handler org.apache.felix.ipojo:controller (VALID)
Handler org.apache.felix.ipojo:callback (VALID)
Handler org.apache.felix.ipojo:requires (VALID)
Handler org.apache.felix.ipojo:provides (VALID)
Handler org.apache.felix.ipojo:properties (VALID)
Handler org.apache.felix.ipojo:architecture (VALID)
Handler org.apache.felix.ipojo.handler.whiteboard:wbp (VALID)
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$handlers
Handler org.apache.felix.ipojo:controller (VALID)
Handler org.apache.felix.ipojo:callback (VALID)
Handler org.apache.felix.ipojo:requires (VALID)
Handler org.apache.felix.ipojo:provides (VALID)
Handler org.apache.felix.ipojo:properties (VALID)
Handler org.apache.felix.ipojo:architecture (VALID)
Handler org.apache.felix.ipojo.handler.whiteboard:wbp (VALID)
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Handlers with the org.apache.felix.ipojo
namespace (section before :
) are core handlers (provided by the iPOJO bundlecore bundles). Others are external handlers (provided by others bundles).
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