org.jboss.aerogear.sync.server

Class ServerSyncEngine<T,S extends Edit<? extends Diff>>

java.lang.Object

org.jboss.aerogear.sync.server.ServerSyncEngine<T,S>

Type Parameters:

T - The data type data that this implementation can handle.

S - The type of Edits that this implementation can handle.

public class ServerSyncEngine<T,S extends Edit<? extends Diff>>
extends Object

The ServerSyncEngine is responsible for driving the main differential synchronization algorithm.

During construction the engine gets injected with an instance of ServerSynchronizer which takes care of diff/patching operations, and an instance of ServerDataStore for storing data.

A synchronizer in AeroGear is a module that serves two purposes which are closely related. One, is to provide storage for the data type, and the second is to provide the patching algorithm to be used on that data type. The name synchronizer is because they take care of the synchronization part of the Differential Synchronization algorithm. For example, one synchronizer might support plain text while another supports JSON Objects as the content of documents being stored. But a patching algorithm used for plain text might not be appropriate for JSON Objects.

To construct a server that uses the JSON Patch you would use the following code:

 
 final JsonPatchServerSynchronizer synchronizer = new JsonPatchServerSynchronizer();
 final ServerInMemoryDataStore<JsonNode, JsonPatchEdit> dataStore = new ServerInMemoryDataStore<JsonNode, JsonPatchEdit>();
 final ServerSyncEngine<JsonNode, JsonPatchEdit> syncEngine = new ServerSyncEngine<JsonNode, JsonPatchEdit>(synchronizer, dataStore);
 

Constructor Summary

Constructors

Constructor and Description
ServerSyncEngine(ServerSynchronizer<T,S> synchronizer, ServerDataStore<T,S> dataStore) Sole constructor.

Method Summary

Modifier and Type	Method and Description
PatchMessage<S>	addSubscriber(Subscriber<?> subscriber, Document<T> document) Adds a subscriber for the specified document.
void	connectSubscriber(Subscriber<?> subscriber, String documentId) Connects a subscriber to an already existing document.
S	diff(String documentId, String clientId) Performs the server side diff which is performed when the server document is modified.
Document<T>	documentFromJson(com.fasterxml.jackson.databind.JsonNode json) Converts the JsonNode into a Document instance.
PatchMessage<S>	getPatchMessage(String documentId, String clientId) Returns the PatchMessage for the specified documentId and clientId.
Set<Subscriber<?>>	getSubscribers(String documentId) Returns all the subscribers for the specified document.
void	notifySubscribers(PatchMessage<S> patchMessage) Performs the server side patching for a specific client and updates all subscribers to the patched document.
PatchMessage<S>	patch(PatchMessage<S> patchMessage) Performs the server side patching for a specific client.
PatchMessage<S>	patchMessageFromJson(String json) Creates a {link PatchMessage} by parsing the passed-in json.
void	removeSubscriber(Subscriber<?> subscriber, String documentId) Removes the specified Subscriber.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ServerSyncEngine

public ServerSyncEngine(ServerSynchronizer<T,S> synchronizer,
                        ServerDataStore<T,S> dataStore)

Sole constructor.

Parameters:

synchronizer - an instance of ServerSynchronizer that will take care for the diff/patching

dataStore - an instance of ServerDataStore to store the document/objects

Method Detail

addSubscriber

public PatchMessage<S> addSubscriber(Subscriber<?> subscriber,
                                     Document<T> document)

Adds a subscriber for the specified document. A server does not create a new document itself, this would be created by a client and a first revision is added to this synchronization engine by this method call.

Parameters:

subscriber - the subscriber to add

document - the document that the subscriber subscribes to. Will be added to the underlying datastore if it does not already exist in the datastore.

Returns:

PatchMessage for the Document. Will either be an PatchMessage with an empty diff, if this is the initial addition of the document, or if the document already exists in the underlying datastore the patch message will contain a diff to bring the document up to date.

connectSubscriber

public void connectSubscriber(Subscriber<?> subscriber,
                              String documentId)

Connects a subscriber to an already existing document.

Parameters:

subscriber - the Subscriber to add

documentId - the id of the document that the subscriber wants to subscribe.

removeSubscriber

public void removeSubscriber(Subscriber<?> subscriber,
                             String documentId)

Removes the specified Subscriber.

Parameters:

subscriber - the Subscriber to remove

documentId - the document id that the subscriber subscribes to

getSubscribers

public Set<Subscriber<?>> getSubscribers(String documentId)

Returns all the subscribers for the specified document.

Parameters:

documentId - the id of the document for which all subscribers should be returned.

Returns:

Set all the Subscribers

diff

public S diff(String documentId,
              String clientId)

Performs the server side diff which is performed when the server document is modified. The produced Edit can be sent to the client for patching the client side document.

Parameters:

documentId - the document in question.

clientId - the clientId for whom we should perform a diff and create edits for.

Returns:

Edit The server edits, or updates, that were generated by this diff .

patch

public PatchMessage<S> patch(PatchMessage<S> patchMessage)

Performs the server side patching for a specific client.

Parameters:

patchMessage - the changes made by a client.

Returns:

PatchMessage to allow method chaining

notifySubscribers

public void notifySubscribers(PatchMessage<S> patchMessage)

Performs the server side patching for a specific client and updates all subscribers to the patched document.

Parameters:

patchMessage - the changes made by a client.

patchMessageFromJson

public PatchMessage<S> patchMessageFromJson(String json)

Creates a {link PatchMessage} by parsing the passed-in json.

Parameters:

json - the json representation of a PatchMessage

Returns:

PatchMessage the created {code PatchMessage}

documentFromJson

public Document<T> documentFromJson(com.fasterxml.jackson.databind.JsonNode json)

Converts the JsonNode into a Document instance.

Parameters:

json - the JsonNode to convert

Returns:

Document the document representing the contents of the JsonNode instance.

getPatchMessage

public PatchMessage<S> getPatchMessage(String documentId,
                                       String clientId)

Returns the PatchMessage for the specified documentId and clientId.

Parameters:

documentId - the document identifier

clientId - the client identifier

Returns:

PatchMessage for the current document/client combination