Package org.onosproject.ui
Class UiMessageHandler
- java.lang.Object
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- org.onosproject.ui.UiMessageHandler
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public abstract class UiMessageHandler extends java.lang.Object
Abstraction of an entity capable of processing JSON messages from the user interface client.The message structure is:
{ "event": "event-type", "payload": { arbitrary JSON object structure } }
Oninitialization
the handler will create and cacheRequestHandler
instances, each of which are bound to a particular event-type. Onarrival
of a new message, the event-type is determined, and the message dispatched to the corresponding RequestHandler'sprocess
method.For convenience the implementation includes methods to obtain JSON generating objects (mapper, objectNode, arrayNode) as well as a JsonCodecContext for preparing and digesting messages to the UI client.
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Constructor Summary
Constructors Constructor Description UiMessageHandler()
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description protected com.fasterxml.jackson.databind.node.ArrayNode
arrayNode()
Returns a freshly minted array node.void
cacheLionBundle(LionBundle bundle)
Invoked during initialization to cache any requested localization bundles in the handler's context, so that it may subsequently look up localization strings when composing data for the client.UiConnection
connection()
Returns the user interface connection with which this handler was primed.protected abstract java.util.Collection<RequestHandler>
createRequestHandlers()
Subclasses must create and return the collection of request handlers for the message types they handle.void
destroy()
Destroys the message handler context.ServiceDirectory
directory()
Returns the service directory with which this handler was primed.protected <T> T
get(java.lang.Class<T> serviceClass)
Returns an implementation of the specified service class.protected CodecContext
getJsonCodecContext()
Obtain a CodecContext to be used in encoding and decoding objects that have a registered JsonCodec for their class.protected LionBundle
getLionBundle(java.lang.String id)
Returns the localization bundle with the given identifier, if we requested to have it cached during initialization; null otherwise.void
init(UiConnection connection, ServiceDirectory directory)
Initializes the handler with the user interface connection and service directory context.java.util.Set<java.lang.String>
messageTypes()
Returns the set of message types which this handler is capable of processing.protected com.fasterxml.jackson.databind.node.ObjectNode
objectNode()
Returns a freshly minted object node.void
process(com.fasterxml.jackson.databind.node.ObjectNode message)
Processes a JSON message from the user interface client.java.util.Set<java.lang.String>
requiredLionBundles()
Returns the set of identifiers for localization bundles that the message handler would like injected into itself, so that it can use those bundles in composing localized data to ship to the client.protected void
sendMessage(com.fasterxml.jackson.databind.node.ObjectNode data)
Sends the specified data to the client.
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Method Detail
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createRequestHandlers
protected abstract java.util.Collection<RequestHandler> createRequestHandlers()
Subclasses must create and return the collection of request handlers for the message types they handle.Note that request handlers should be stateless. When we are
destroyed
, we will simply drop our references to them and allow them to be garbage collected.- Returns:
- the message handler instances
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messageTypes
public java.util.Set<java.lang.String> messageTypes()
Returns the set of message types which this handler is capable of processing.- Returns:
- set of message types
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process
public void process(com.fasterxml.jackson.databind.node.ObjectNode message)
Processes a JSON message from the user interface client.- Parameters:
message
- JSON message
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init
public void init(UiConnection connection, ServiceDirectory directory)
Initializes the handler with the user interface connection and service directory context.- Parameters:
connection
- user interface connectiondirectory
- service directory
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destroy
public void destroy()
Destroys the message handler context.
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connection
public UiConnection connection()
Returns the user interface connection with which this handler was primed.- Returns:
- user interface connection
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directory
public ServiceDirectory directory()
Returns the service directory with which this handler was primed.- Returns:
- service directory
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get
protected <T> T get(java.lang.Class<T> serviceClass)
Returns an implementation of the specified service class.- Type Parameters:
T
- type of service- Parameters:
serviceClass
- service class- Returns:
- implementation class
- Throws:
ServiceNotFoundException
- if no implementation found
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requiredLionBundles
public java.util.Set<java.lang.String> requiredLionBundles()
Returns the set of identifiers for localization bundles that the message handler would like injected into itself, so that it can use those bundles in composing localized data to ship to the client.This default implementation returns an empty set.
Subclasses that wish to have localization bundles injected should override this method and return the set of bundle identifiers.
- Returns:
- the set of identifiers of required localization bundles
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cacheLionBundle
public void cacheLionBundle(LionBundle bundle)
Invoked during initialization to cache any requested localization bundles in the handler's context, so that it may subsequently look up localization strings when composing data for the client.- Parameters:
bundle
- the bundle to cache
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getLionBundle
protected LionBundle getLionBundle(java.lang.String id)
Returns the localization bundle with the given identifier, if we requested to have it cached during initialization; null otherwise.- Parameters:
id
- the lion bundle identifier- Returns:
- the associated lion bundle
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objectNode
protected com.fasterxml.jackson.databind.node.ObjectNode objectNode()
Returns a freshly minted object node.- Returns:
- new object node
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arrayNode
protected com.fasterxml.jackson.databind.node.ArrayNode arrayNode()
Returns a freshly minted array node.- Returns:
- new array node
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sendMessage
protected void sendMessage(com.fasterxml.jackson.databind.node.ObjectNode data)
Sends the specified data to the client. It is expected that the data is in the prescribed JSON format for events to the client.- Parameters:
data
- data to be sent
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getJsonCodecContext
protected CodecContext getJsonCodecContext()
Obtain a CodecContext to be used in encoding and decoding objects that have a registered JsonCodec for their class. This method instantiates a private inner class which is returned on subsequent calls.- Returns:
- a CodecContext.
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