View source for Migration Guidelines from 0.4.4 to 0.5

gCore <code>0.5.0RC</code> requires or supports the following changes to practices and implementations that are compliant with gCore 0.4.4:

==== Changes Related to the gHN ====

:* ''package change in <code>ResultSet</code> components''
::The inclusion of the <code>ResultSet</code> service and related components in gCore has coincided with a refactorisation of their package structure. In particular, fully qualified names that begun with <code>org.gcube.searchservice</code> begin now with <code>org.gcube.common.searchservice</code>.

:* ''new log files and log file location.''
:: All gCore logs are now located in <code>$GLOBUS_LOCATION/logs</code>, while <code>nohup.out</code> remains in <code>$GLOBUS_LOCATION</code> (now regardless of where the <code>$GLOBUS_LOCATION/bin/gcore-start-container</code> is run from). The gHN's logs remains the same (<code>container.fulllog</code>, <code>container.log</code>), but the local services have dedicated log files (<code>ghnmanager.log</code>,<code>deployer.log</code>, <code>delegation.log</code>, <code>rs.log</code>). Globus logs are now collected in a separate log file <code>globus.log</code> and do not propagate to the contatainer's log files (default log level for globus is <code>WARN</code>). Developers are recommended to configure service-specific logs during development. For this purpose,  the configuration for local services in <code>$GLOBUS_LOCATION/container-log4j.properties</code> can be used as templates.

:* ''new lower bound on memory requirement for gHNs.''
:: The gHN now requires the allocation of '''1GB''' of heap space to the JVM in which it runs. This is a production-level requirement and can be disabled or corrected during development by editing the script <code>$GLOBUS_LOCATION/bin/gcore-start-container</code> (<code>START_OPTIONS</code> variable).

:* ''new gHN configuration file for offline use.''
:: gCore ships with a clone of <code>$GLOBUS_LOCATION/config/GHNConfig.xml</code> called <code>$GLOBUS_LOCATION/config/GHNConfig.client.xml</code>. The latter can diverge arbitrarily from the former so as to decouple offline and online use of the gHN.

:* ''(optional) configuration of free port range for the gHN.''
::Administrators and developers can now specify a <code>portRange</code> environment in <code>$GLOBUS_LOCATION/configs/GHNConfig.xml</code>' (or <code>$GLOBUS_LOCATION/configs/GHNConfig.client.xml</code> if useful). The value of the environment can be specified as in the following example:

:<pre><environment  name="portRange" value="60000-61000"  type="java.lang.String" /></pre>

:: Do note the following:
::* The configuration does not imply that the ports are actually 'open', only that they can be bound.
::* The gHN management interface (see below) depends on the existence of this configuration.
::* The first free port in this range can be obtained by invoking the method <code>getFreePort()</code> om the <code>GHNContext</code>. See the Javadoc documentation for details of the signature.

:* ''(optional) use of the JMX management interface.''
:: The gHN now binds a JMX managemenet interface to the port that it finds free in the configured range (see above). The bound port is shown in the gHN logs:

:<pre>...GHNContext: INITIALISED MANAGEMENT INTERFACE AT service:jmx:rmi:///jndi/rmi://localhost:60000</pre>

:: The interface can then be used with <code>jconsole</code>, a graphical JMX client that ships with the JDK:

:<pre>jconsole localhost:60000</pre>

::gHN-specific and RI-specific information and operations can be found in the <code>MBeans</code> tabbed pane under <code>org.gcube</code>. In the same tabbed pane, logger and appender information and operations can be found under <code>log4j</code>.

==== Changes Related to Services ====

:* '''<code>org.gcube.common.core.resources.GCUBETransformationProgram</code> and <code>org.gcube.common.core.resources.GCUBEVRE</code> are no longer available.'''
::These types were not in use as the corresponding resources are modelled with <code>org.gcube.common.core.resources.GCUBEGenericResource</code>.

:* '''the methods <code>org.gcube.common.core.state.GCUBEStatefulResource.isRemoved()</code> and <code>org.gcube.common.core.state.GCUBEStatefulResource.remove()</code> are no longer available.'''
::<code>isRemoved()</code> was intended primarily for internal usage and has been made redundant by the [[#locking|new locking mechanism]], which should now be used by developers. <code>remove()</code> was thread-unsafe as all removal operations should pass for the method <code>org.gcube.common.core.state.GCUBEResourceHome.remove()</code>.

:* '''the method <code>org.gcube.common.core.state.GCUBEStatefulResource.getPersistenceDelegate()</code> is now <code>deprecated</code> and will be removed in the next minor/major release.'''
::Exposing persistence delegates is no longer necessary and in fact dangerous. Resource load must be handled transparently by the home associated with the resource, and resource storage can be triggered by invoking directly the method <code>org.gcube.common.core.state.GCUBEStatefulResource.store()</code>.

:* '''the method <code>org.gcube.common.core.utils.events.GCUBEProducer.registerTopics()</code> was already <code>deprecated</code> and is now no longer available.'''
::The registration of topics is now performed implicitly at the notification of the first event in a given topic.

:* '''the method <code>org.gcube.common.core.context.GCUBEServiceContext.getConfigFile()</code> is now <code>deprecated</code> and will be removed in the next minor/major release.'''
:: The method is replaced by <code>org.gcube.common.core.context.GCUBEServiceContext.getFile()</code>. See [[#filemanagement|below]] for furter information.

:* '''<code>org.gcube.common.core.porttypes.GCUBEStartupPortType</code> is now <code>deprecated</code> and will be removed in the next minor/major release.'''
::Derive now ''all'' port-type implementations from <code>org.gcube.common.core.porttypes.GCUBEPortType</code>, regardless of the value set in their deployment descriptors for <code>loadOnStartup</code>. Do note that:
::* The requirement that <code>loadOnStartup</code> be set to <code>true</code> for at least one port-type implementation does remain.
::* The requirements to derive <code>GCUBEPortType</code> are the same requirements to derive <code>GCUBEStartupPortType</code> (i.e. implement the method <code>getServiceContext()</code>).
:: Note also that <code>GCUBEStartupPortType</code> is recast as a subclass of <code>GCUBEPortType</code> for this release only.
:: See also the Primer for more information [[The_Development_Cycle#A_Simple_Implementation|on this requirement]].

:* ''New port-type and home callbacks on RI lifetime.''
:: <code>org.gcube.common.core.porttypes.GCUBEPortType</code> defines callbacks for all the states of RI lifetime: <code>onInitialisation()</code>, <code>onInitialisation()</code>onReady()</code, <code>onFailure()</code>, <code>onUpdate()</code>,<code>onStateChange()</code>. The same callbacks are now also defined for <code>org.gcube.common.core.state.GCUBEResourceHome.remove()</code>. See the Developer's Guide for specific information on the [[Contexts#Lifetime_Management_2|lifetime of the RI]].

<div id="filemanagement"></div>
:* ''New file management methods on service contexts.''
::Service contexts offer two methods to write and read files from the file system: <code>getFile()</code> and <code>getPersistentFile()</code>. The usage model and difference between the two methods are described in detail in the Developer's Guide, first [[Contexts#Common_Facilities|here]] and then [[Contexts#Configuration_and_File_Management|here]] . Do notice that, changes to persistent files must be explicitly notified to the persistence manager (see below), if one is configured for the service.

:* ''(Optional) configuration of remote backup/recovery.''
:: Services that wish to take advantage of the new facility for remote backup and recovery can do so by adding the a <code>persistenceManagerProfile</code> resource to their <code>deploy-jndi-xml</code>, as follows:

<pre>
<resource name="persistenceManagerProfile" type="org.gcube.common.core.persistence.GCUBERIPersistenceManagerProfile">
   <resourceParams>	
	<parameter><name>factory</name><value>org.globus.wsrf.jndi.BeanFactory</value></parameter>	
	<parameter><name>className</name><value>org.gcube.common.smspersistence.GCUBESMSPersistenceManager</value>
         </parameter><parameter><name>monitoringInterval</name><value>...value in seconds...</value></parameter>               
    </resourceParams>
</resource>
</pre>

:: Do note the following:
::* <code>className</code> specifies the class of the only SMS-based persistence manager that ships with gCore
::* <code>monitoringInterval</code> measures ''in seconds''  how often  the persistent manager will backup the RI state, if and only if this has changed since the last backup.
::* changes to persisted WS-Resources are automatically detected by the persistence manager. Changes to other files below the storage root of the service must be explicitly flagged by invoking the method <code>org.gcube.common.core.context.GCUBEServiceContext.notifyStateChange()</code>. 
:: See also the release notes for an [[Release_Notes|overview of remote persistence]].

:* ''New ''<code>org.gcube.common.core.informationsystem.client.ISClient</code>'' interface.''
:: The <code>ISClient</code> interface now supports query by reference. See the Primer for examples [[/Advanced_Topics#ISClient_interface|on usage]].

:* ''New ''<code>org.gcube.common.core.informationsystem.notifier.ISNotifier</code>'' interface.''
:: ['''Please summarise and point to primer section similarly to entry above'''].

:* ''New persistence modes for'' <code>org.gcube.common.core.state.GCUBEResourceHome</code>.
:: Resource homes can now be configured to support additional modes of persistence. See the Primer for an explanation of the [[Adding_State#Persistence_Modes|available modes and configuration details]].

<div id="locking"></div>
:* ''New locking mechanism for resources.''
:: <code>org.gcube.common.core.state.GCUBEStatefulResource</code> now defines a method <code>getLock()</code> that returns a new <code>org.gcube.common.core.state.GCUBEReadWriteLock</code> that can be used by cooperating threads (including gCF's of course) to synchronise their access to the resource. <code>GCUBEReadWriteLock</code> is an extension of Java's [http://java.sun.com/j2se/1.5.0/docs/api/java/util/concurrent/locks/ReadWriteLock.html <code>ReadWriteLock</code>] which supports ''pre-emptive'' write locks (if one thread succeeds the others waiting for the lock are interrupted). This should be of limited interest to the vast majority of developers as the pre-emptive behaviour is used transparently by gCF on removal operations. Do use <code>GCUBEReadWriteLock</code> as a standard read-write lock otherwise.

:* ''New interface for sychronous consumers.''
::The tagging interface <code>org.gcube.common.core.utils.events.GCUBESynchronousConsumer</code> is now available for consumers that wish producers to block in their delivery of events.