Andy Seaborne created JENA-1029:
-----------------------------------
Summary: Add a Jena-wide subsystem lifecycle
Key: JENA-1029
URL: https://issues.apache.org/jira/browse/JENA-1029
Project: Apache Jena
Issue Type: Improvement
Affects Versions: Jena 3.0.0
Reporter: Andy Seaborne
A subsystem lifecyclefor Jena would provide the hook for:
* basic wiring together e.g. wiring RIOT into Jena core
* initialization e.g. {{TDB.init()}} becomes redundant
* starting and stopping in large systems, e.g. starting and stopping Fuseki2
when in a Tomcat server
This proposal is as simple as possible. It is for system bootstrap and basic
lifecycle. It is not intended to work for a mixture of jars from different Jena
releases.
*Sub-system Interface*
{code:title=JenaSubsystemLifecycle|borderStyle=solid}
public interface JenaSubsystemLifecycle {
public void start() ;
public void stop() ;
}
{code}
{{stop}} would not be called normally as part of JVM exit (code can do that
itself anyway). It is in support of start-stop-(re)start and only called if
there is a hook for such a cycle. {{stop}} is more of a placeholder for the
moment.
*Registry*
There is a single registry:
{code:title=JenaSubsystemRegistry|borderStyle=solid}
public class JenaSubsystemRegistry {
public static void add(JenaSubsystemLifecycle module) ;
public static boolean isRegistered(JenaSubsystemLifecycle module) ;
public static void remove(JenaSubsystemLifecycle module) ;
public static int size() ;
public static boolean isEmpty() ;
public static void forEach(Consumer<JenaSubsystemLifecycle> action) ;
}
{code}
*Ensuring initialization*
Jena core provides a "system init" that is cheap to call if initialization has
already occurred. It should attempt the first call as early as possible.
When initializing, it runs a {{ServiceLoader}} cycle to discover any
{{JenaSubsystemLifecycle}} implementations described in a
{{META-INF/services/...}} file and populates the registry. Then the registry is
used to call {{start()}} in some unspecified order.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
