Tuning serialization

The DataSerializer plug-ins expose metadata that tells WebSphere® eXtreme Scale which attributes it can and cannot directly use during serialization, the path to the data that will be serialized, and the type of data that is stored in memory. You can optimize object serialization and inflation performance so that you can efficiently interact with the byte array.

[Version 8.6 and later] [.net programming language only] You cannot define DataSerializer plug-ins for maps that are used by .NET applications.

Deprecated feature The ObjectTransformer interface has been replaced by the DataSerializer plug-ins, which you can use to efficiently store arbitrary data in WebSphere eXtreme Scale so that existing product APIs can efficiently interact with your data.

Overview

Copies of values are always made except when the NO_COPY mode is used. The default copying mechanism that is employed in eXtreme Scale is serialization, which is known as an expensive operation. The ObjectTransformer interface is used in this situation. The ObjectTransformer interface uses callbacks to the application to provide a custom implementation of common and expensive operations, such as object serialization and deep copies on objects. However, for improved performance in most cases, you can use the DataSerializer plug-ins to serialize objects. You must use either the COPY_TO_BYTES or COPY_TO_BYTES_RAW copy modes to use the DataSerializer plug-ins. For more information, see Serialization using the DataSerializer plug-ins.

An application can provide an implementation of the ObjectTransformer interface to a map, and eXtreme Scale then delegates to the methods on this object and relies on the application to provide an optimized version of each method in the interface. The ObjectTransformer interface follows:

public interface ObjectTransformer {
    void serializeKey(Object key, ObjectOutputStream stream) throws IOException;
    void serializeValue(Object value, ObjectOutputStream stream) throws IOException;
    Object inflateKey(ObjectInputStream stream) throws IOException, ClassNotFoundException;
    Object inflateValue(ObjectInputStream stream) throws IOException, ClassNotFoundException;
    Object copyValue(Object value);
    Object copyKey(Object key);
}

You can associate an ObjectTransformer interface with a BackingMap by using the following example code:

ObjectGrid g = ...;
BackingMap bm = g.defineMap("PERSON");
MyObjectTransformer ot = new MyObjectTransformer();
bm.setObjectTransformer(ot);

Tune object serialization and inflation

Object serialization is typically the most important performance consideration with eXtreme Scale, which uses the default serializable mechanism if an ObjectTransformer plug-in is not supplied by the application. An application can provide implementations of either the Serializable readObject and writeObject, or it can have the objects implement the Externalizable interface, which is approximately ten times faster. If the objects in the map cannot be modified, then an application can associate an ObjectTransformer interface with the ObjectMap. The serialize and inflate methods are provided to allow the application to provide custom code to optimize these operations, given their large performance impact on the system. The serialize method serializes the object to the provided stream. The inflate method provides the input stream and expects the application to create the object, inflate it using data in the stream and return the object. Implementations of the serialize and inflate methods must mirror each other.

The DataSerializer plug-ins replace the ObjectTransformer plug-ins, which are deprecated. To serialize your data in the most efficient way, use the DataSerializer plug-ins to improve performance in most cases. For example, if you intend to use functions, such as query and indexing, then you can immediately take advantage of the performance improvement that the DataSerializer plug-ins yield without making configuration or programmatic changes to your application code.