Class RecordHandler - deepstreamHub Java SDK RecordHandler

The factory method's for deepstreamHub's realtime datastore concepts, such as getRecord(recordName), getList(listName), provider functionality such as listen(eventName,listener) and single requests like snapshot(recordName)

Methods

Record getRecord(String recordName)

Returns an existing record or creates a new one. If creating a new one the record will not be in a ready state till it is loaded from the server.

Show example...

Record record = client.record.getRecord("users/A");

List getList(String listName)

Returns an existing List or creates a new one. A list is a specialised type of record that holds an array of recordNames.

Show example...

Record record = client.record.getList("users");

AnonymousRecord getAnonymousRecord()

Returns an AnonymousRecord. An anonymous record is effectively a wrapper that mimicks the API of a record, but allows for the underlying record to be swapped without losing subscriptions etc. This is particularly useful when selecting from a number of similarly structured records. E.g. a list of users that can be choosen from a list. The only API differences to a normal record is an additional setName(name) method.

SnapshotResult snapshot(String recordName)

Retrieves a SnapshotResult with the current record data. Using this doesn't subscribe the client to changes the way getRecord(name) does.

Show example...

SnapshotResult result = client.record.snapshot("user/B");

boolean has(String recordName) throws DeepstreamError

Returns a HasResult that shows whether or not the record exists.

Show example...

HasResult result = client.record.has("user/C");

void listen(String pattern, ListenListener listenCallback)

Allows to listen for record subscriptions made by this or other clients. This is useful to create "active" data providers, e.g. providers that only provide data for a particular record if a user is actually interested in it.

You can only listen to a pattern once, and if multiple listeners match the same pattern only a single one will be notified.

Show example...

client.event.listen("users/", new ListenListener() {
  @Override
  public boolean onSubscriptionForPatternAdded(String subscription) {
    if (/ can provide */) {
      return true;
    } else {
      return false;
    }
  }



  @Override
  public void onSubscriptionForPatternRemoved(String subscription) {
    // handle unsubscription
  }
});

void unlisten(String pattern)

Remove the listener added via listen(pattern,listener). This will remove the provider as the active provider and allow another provider to take its place.

Show example...

client.record.unlisten("users/*", listener);