Class AbstractGraphRoundtripSupport is the abstract base class of both default roundtrip support classes provided by the server library. It defines the functionality that is common for both roundtrip support classes.

API Excerpt 7.1, “AbstractGraphRoundtripSupport graph reading and writing” lists the basic methods of the roundtrip support classes for deserializing GraphML data send from the client into a Graph instance and for sending the serialized Graph instance back to the client.

// Populate the given graph using the GraphML data passed as a parameter of the 
// given request.
boolean readGraph(HttpServletRequest request, Graph graph)

// Send the given graph instance as GraphML data using the given response.
void sendGraph(Graph graph, HttpServletResponse response)

Custom graph item attributes can be easily added for (de)serialization as shown in API Excerpt 7.2, “Adding Simple Attributes”. Adding custom graph item attributes for client-server roundtrips is discussed in detail in the corresponding knowledge base article.

// Add a custom attribute for GraphML (de)serialization
void addMapper(Object tag, String name, int graphMLType, int graphMLScope)

The methods listed in API Excerpt 7.3, “Configuring the roundtrip graph instance” can be used to create and configure the graph instance that is populated with the graph structure received from the client.

// Create the graph instance
abstract LayoutGraph createRoundtripGraph() 

// Configure the graph instance, e.g. by adding custom DataProviders
protected void configureRoundtripGraph( LayoutGraph layoutGraph ) 

If the native yFiles FLEX GraphML extension is used for client-server communication, a LayoutGraph instance should be used as the graph model on the server. To create and configure a LayoutGraph instance and to (de)serialize the LayoutGraph instance to/from GraphML data, the server library offers class GraphRoundtripSupport.

GraphML serialization and deserialization of Graph instances can be controlled by overriding the protected methods of GraphRoundtripSupport listed in API Excerpt 7.4, “Protected methods of GraphRoundtripSupport”.

// Configure the I/O handler for reading and writing Graph instances
protected void configureHandler(
  GraphMLLayoutGraphIOHandler layoutGraphIOHandler)

// Create the I/O handler instance for reading and writing graph instances.
protected GraphMLLayoutGraphIOHandler createHandler()

// Create the SerializerRegistry that stores all IDeserializer
// and ISerializer instances used for reading and writing the graph.
// This factory method can be overriden in order to register
// custom ISerializer and IDeserializer instances.
protected SerializerRegistry createSerializerRegistry()

API Excerpt 7.5, “Automatic label model conversion” shows the GraphRoundtripSupport option for automatic label model conversion. If setMapLabelModels is set to true, the I/O mechanism will try to convert between the client and yFiles Java label models. For edge labels, the conversion is possible for the slider- and free label models. Node label position can be mapped if the discrete node label model is used (exterior or interior node label model on the client).

The yFiles Java label position information will be committed to the label model parameters of yFiles FLEX client Label instances when the graph is written back to the client. The position information can also be comitted before, using method commitLabelLayouts(y.layout.LayoutGraph).

// Set whether client label models should be mapped to yFiles Java label models
// in order to transfer label positions in a client-server roundtrip.
void setMapLabelModels( boolean mapLabelModels )

If the yFiles Java GraphML extension is chosen for client-server communication, a a Graph2D instance will be used on the server to create and modifiy the graph structure and graph visualization information. Class Graph2DRoundtripSupport conveniently creates and configures a Graph2D instance for this purpose.

GraphML serialization and deserialization of Graph2D instances can be controlled by overriding the protected methods of Graph2DRoundtripSupport listed in API Excerpt 7.6, “Protected methods of Graph2DRoundtripSupport”.

// Configure the I/O handler for reading and writing Graph2D instances
protected void configureHandler(
  GraphMLIOHandler ioHandler)

// Create the I/O handler instance for reading and writing Graph2D instances.
protected GraphMLIOHandler createHandler()