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Oracle® Coherence Java API Reference
Release 3.7.0.0

E18683-01


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Interface Evolvable

All Known Subinterfaces:
EvolvablePortableObject
All Known Implementing Classes:
AbstractEvolvable

public interface Evolvable

The Evolvable interface is implemented by classes that require forwards- and backwards-compatibility of their serialized form. An Evolvable class has an integer version identifier n, where n >= 0. When the contents and/or semantics of the serialized form of the Evolvable class changes, the version identifier is increased. Two versions identifiers, n1 and n2, indicate the same version iff n1 == n2; the version indicated by n2 is newer than the version indicated by n1 iff n2 > n1.

The Evolvable interface is designed to support the evolution of classes by the addition of data. Removal of data cannot be safely accomplished as long as a previous version of the class exists that relies on that data. Modifications to the structure or semantics of data from previous versions likewise cannot be safely accomplished as long as a previous version of the class exists that relies on the previous structure or semantics of the data.

When an Evolvable object is deserialized, it retains any unknown data that has been added to newer versions of the class, and the version identifier for that data format. When the Evolvable object is subsequently serialized, it includes both that version identifier and the unknown future data.

When an Evolvable object is deserialized from a data stream whose version identifier indicates an older version, it must default and/or calculate the values for any data fields and properties that have been added since that older version. When the Evolvable object is subsequently serialized, it includes its own version identifier and all of its data. Note that there will be no unknown future data in this case; future data can only exist when the version of the data stream is newer than the version of the Evolvable class.

Since:
Coherence 3.2
Author:
cp/jh 2006.07.14

Method Summary
 int getDataVersion()
          Obtain the version associated with the data stream from which this object was deserialized.
 Binary getFutureData()
          Return all the unknown remainder of the data stream from which this object was deserialized.
 int getImplVersion()
          Determine the serialization version supported by the implementing class.
 void setDataVersion(int nVersion)
          Set the version associated with the data stream with which this object is being deserialized.
 void setFutureData(Binary binFuture)
          Store the unknown remainder of the data stream from which this object is being deserialized.

 

Method Detail

getImplVersion

int getImplVersion()
Determine the serialization version supported by the implementing class.
Returns:
the serialization version supported by this object

getDataVersion

int getDataVersion()
Obtain the version associated with the data stream from which this object was deserialized. If the object was constructed (not deserialized), the data version is the same as the implementation version.
Returns:
the version of the data used to initialize this object, greater than or equal to zero

setDataVersion

void setDataVersion(int nVersion)
Set the version associated with the data stream with which this object is being deserialized.
Parameters:
nVersion - the version of the data in the data stream that will be used to deserialize this object; greater than or equal to zero
Throws:
java.lang.IllegalArgumentException - if the specified version is negative
java.lang.IllegalStateException - if the object is not in a state in which the version can be set, for example outside of deserialization

getFutureData

Binary getFutureData()
Return all the unknown remainder of the data stream from which this object was deserialized. The remainder is unknown because it is data that was originally written by a future version of this object's class.
Returns:
future data in binary form

setFutureData

void setFutureData(Binary binFuture)
Store the unknown remainder of the data stream from which this object is being deserialized. The remainder is unknown because it is data that was originally written by a future version of this object's class.
Parameters:
binFuture - future data in binary form
Throws:
java.lang.IllegalStateException - if the object is not in a state in which the data can be set, for example outside of deserialization

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Oracle® Coherence Java API Reference
Release 3.7.0.0

E18683-01


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