public class JsonConfigurationStore extends Component
This component provides a store for an application’s configuration backed by a JSON file. The JSON object described by this file represents the root directory. If an entry does not start with a slash, it represents the key of a key value pair. If it does starts with a slash, the value is another JSON object that describes the respective subdirectory.
The component reads the initial values from File passed
to the constructor. During application bootstrap, it
intercepts the Start event using a handler with priority
999999. When receiving this event, it fires all known preferences
values on the channels of the start event as a
InitialPreferences event, using a new EventPipeline
and waiting for its completion. Then, allows the intercepted
Start event to continue.
Components that depend on configuration values define handlers
for ConfigurationUpdate events and adapt themselves to the values
received. Note that due to the intercepted Start event, the initial
preferences values are received before the Start event, so
components’ configurations can be rearranged before they actually
start doing something.
Besides initially publishing the stored preferences values,
the component also listens for ConfigurationUpdate events
on its channel and updates the JSON file (may be suppressed).
Channel.Default| Constructor and Description |
|---|
JsonConfigurationStore(Channel componentChannel,
File file)
Creates a new component with its channel set to the given
channel and the given file.
|
JsonConfigurationStore(Channel componentChannel,
File file,
boolean update)
Creates a new component with its channel set to the given
channel and the given file.
|
| Modifier and Type | Method and Description |
|---|---|
void |
onConfigurationUpdate(ConfigurationUpdate event)
Merges and saves configuration updates.
|
void |
onStart(Start event)
Intercepts the
Start event and fires a
ConfigurationUpdate event. |
channel, component, defaultCriterion, isEligibleFor, setNameactiveEventPipeline, addHandler, attach, children, componentPath, componentVertex, detach, fire, initComponentsHandlers, iterator, name, newEventPipeline, newEventPipeline, newSyncEventPipeline, parent, registerAsGenerator, root, toString, unregisterAsGeneratorclone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitcriterionToString, toString, toStringforEach, spliteratorpublic JsonConfigurationStore(Channel componentChannel, File file) throws IOException
Creates a new component with its channel set to the given channel and the given file.
componentChannel - the channelfile - the file used to store the JSONorg.jdrupes.json.JsonDecodeExceptionIOExceptionpublic JsonConfigurationStore(Channel componentChannel, File file, boolean update) throws IOException
Creates a new component with its channel set to the given channel and the given file.
componentChannel - the channelfile - the file used to store the JSONorg.jdrupes.json.JsonDecodeExceptionIOException@Handler(priority=999999, channels=Channel.class) public void onStart(Start event) throws BackingStoreException, InterruptedException
Intercepts the Start event and fires a
ConfigurationUpdate event.
event - the eventBackingStoreException - the backing store exceptionInterruptedException - the interrupted exception@Handler(dynamic=true) public void onConfigurationUpdate(ConfigurationUpdate event) throws IOException
Merges and saves configuration updates.
event - the eventIOException - Signals that an I/O exception has occurred.