Offer BundleContext#registerService without HashTable

[bjhargrave]

Original bug ID: BZ#239
From: Lars Vogel <lars.vogel@vogella.com>
Reported version: R7

[bjhargrave]

Comment author: Lars Vogel <lars.vogel@vogella.com>

The synchronized data structure HashTable is not recommened to be used, by several tools, e.g. Sonar shows this as warning. Would be nice if we could register services without creating warnings in our code.

Example:

Dictionary<String, String> props = new Hashtable<>();
	props.put(Constants.SERVICE_VENDOR, "Eclipse"); //$NON-NLS-1$
	props.put(Constants.SERVICE_PID, SimpleConfiguratorConstants.TARGET_CONFIGURATOR_NAME);
	ServiceFactory<?> configurationFactory = new SimpleConfiguratorFactory(context);
	configuratorRegistration = context.registerService(Configurator.class.getName(), configurationFactory, props);

---

[HannesWell]

Comment author: Lars Vogel <lars.vogel@vogella.com>

The synchronized data structure HashTable is not recommened to be used, by several tools, e.g. Sonar shows this as warning.

Even the Java-doc of Dictionary says that Map should be used instead.

Dictionary is referenced in the following classes (at least in the eclipse implementation org.eclipse.osgi) :

• org.osgi.framework.Bundle
• org.osgi.framework.BundleContext
• org.osgi.framework.Constants
• org.osgi.framework.Filter
• org.osgi.framework.FrameworkUtil
• org.osgi.framework.ServiceEvent
• org.osgi.framework.ServiceReference
• org.osgi.framework.ServiceRegistration
• org.osgi.service.condpermadmin.Condition

Some of them define API using Dictionary, some only consume it. But all of them should be considered when Dictionary is replaced some day.

[bjhargrave]

See the new FrameworkUtil.asDictionary(Map) helper method which can be used here. This method was recently added as a bridge from Maps to the OSGi API.

---

Map<String, String> props = new HashMap<>();
	props.put(Constants.SERVICE_VENDOR, "Eclipse"); //$NON-NLS-1$
	props.put(Constants.SERVICE_PID, SimpleConfiguratorConstants.TARGET_CONFIGURATOR_NAME);
	ServiceFactory<?> configurationFactory = new SimpleConfiguratorFactory(context);
	configuratorRegistration = context.registerService(Configurator.class.getName(), configurationFactory, FrameworkUtil.asDictionary(props));

---

[stbischof]

I can see your problems with the dictionary. But in most cases of using dictionaries it might be better to use newer patterns.
e.g. use @ Component and other ComponentPropertType annotations and do not try to register everything by hand in the BundleActivator.

The only way i really use an dictionary is in tests. But there I use the powerfully Dictionaries class. Maybe more of the functionally should be available in the framework package.

Btw.
The javadoc does not say that you should use maps instead of dictionarys. It says only to not do new implementations.

New implementations should implement the Map interface, rather than extending this class.