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Work-in-progress. Completed page will be linked into the Tutorials and Walkthroughs page. |
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While we use a Provider in this tutorial, the procedure described here is also applicable to applications.
As in the case of other tutorials, ${ONOS_ROOT} refers to the project root directory of ONOS, and ${KARAF_ROOT} refers to the installation location of Apache Karaf.
Modifications
1. Modify the component POM file.
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// new imports import static com.google.common.base.Strings.isNullOrEmpty; import org.osgi.service.component.ComponentContext; import org.apache.felix.scr.annotations.Modified; import java.util.Dictionary; // ...<snip>... public class NullLinkProvider extends AbstractProvider implements LinkProvider { private final Logger log = getLogger(getClass()); // Attention - we need register and unregister our Class (NullLinkProvider), // before and after we load the config file @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY) protected ComponentConfigService componentConfigService; // The Manager serving as communication point between the ONOS core and this Provider @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY) protected LinkProviderRegistry providerRegistry; // The interface that defines how this Provider can interact with the core private LinkProviderService providerService; public NullLinkProvider() { // ProviderId is used by the core to identify this Provider // The schema "null" and FQDN of the Null southbound comprise this ID super(new ProviderId("null", "org.onosproject.provider.nil")); } @Activate public void activate(ComponentContext context) { //Attention - register for system-wide configurations componentConfigService.registerProperties(getClass()); providerService = providerRegistry.register(this); deviceService.addListener(linkProvider); // launch exactly one LinkDriver if (!modified(context)) { log.info("Using defaults: flicker={}, eventRate={}", FLICKER, DEFAULT_RATE); linkDriver.submit(new LinkDriver()); } log.info("started"); } @Deactivate public void deactivate(ComponentContext context) { //Attention - just unregister when deactivate our Class componentConfigService.unregisterProperties(getClass(),false); // ... } // The method called when configuration changes are made @Modified public boolean modified(ComponentContext context) { return false; } // ...<snip>... } |
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ComponentContext context: Used to pass around information read from a configuration file@Modified: Annotation indicating that themodified()method should be called when configuration changes are made.
We call modified() from activate()so that the configuration file is read at module startup. Afterwards, the @modified annotation causes modified() to be called whenever the file is changed.
3. Annotate the tunable parameters.
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// new imports
import org.apache.felix.scr.annotations.Property;
// ...<snip>...
public class NullLinkProvider extends AbstractProvider implements LinkProvider {
// ...<snip>...
// Default values for tunable parameters
private static final boolean FLICKER = false;
private static final int DEFAULT_RATE = 3000;
@Property(name = "flicker", boolValue = FLICKER,
label = "Setting to flap links")
private boolean flicker = FLICKER;
@Property(name = "eventRate", intValue = DEFAULT_RATE,
label = "Duration between Link Event")
private int eventRate = DEFAULT_RATE;
// ...<snip>... |
4. Add file-parsing code.
Next, we implement modifymodified() to parse out the values set for these parameters.
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@Modified
public boolean modified(ComponentContext context) {
// if there's no file, fall back to defaults
if (context == null) {
log.info("No configs, using defaults: flicker={}, eventRate={}",
FLICKER, DEFAULT_RATE);
return false;
}
Dictionary<?, ?> properties = context.getProperties();
boolean flickSetting;
int newRate;
// try to extract values keyed on the parameters' names
try {
String s = (String) properties.get("flicker");
flickSetting = isNullOrEmpty(s) ? flicker : Boolean.valueOf(s.trim().equals("true");
s = (String) properties.get("eventRate");
newRate = isNullOrEmpty(s) ? eventRate : Integer.valueOfparseInt(s.trim());
} catch (Exception e) {
log.warn(e.getMessage());
flickSetting = flicker;
newRate = eventRate;
}
if (flicker != flickSetting) {
flicker = flickSetting;
}
// launch a LinkDriver with the new values, if they were changed
if (flicker) {
if (eventRate != newRate) {
eventRate = newRate;
}
linkDriver.submit(new LinkDriver());
log.info("Using settings: flicker={}, eventRate={}", flicker,
eventRate);
return true;
}
return false;
} |
5
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. Verification
We can now rebuild the Null Providers to test the configurability of this Provider.
6. Modifying the cfgdef file
Use your favorite editor to modify $ONOS_HOME/providers/null/link/target/classes/org/onosproject/provider/nil/link/impl/NullLinkProvider.cfgdefThe configurations associated with tunable components are added to ${ONOS_ROOT}/tools/package/etc/ . The files are named by the FQDN of the component. For the NullLinkProvider, this would be org.onosproject.provider.nil.link.impl.NullLinkProvider.cfg. The contents of the file are simple, a list of parameter names and their values:
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# SampleThis configurationsfile foris the NullLinkProvider. # # If enabled, generates LinkDetected and LinkVanished events # to make the link appear to be flapping. # # flicker = true # # If enabled, sets the time between LinkEvent generation, # in milliseconds. # # eventRate = 2000 |
Verification
We can now rebuild the Null Providers to test the configurability of this Provider.
auto-generated by onos-maven-plugin
flicker|BOOLEAN|false|Setting to flap links
eventRate|INTEGER|3000|Duration between Link Event |
You can modify one or both parameters and watch for the impact.