org.apache.derby.impl.sql.catalog

Class DD_Version

java.lang.Object

org.apache.derby.impl.sql.catalog.DD_Version

All Implemented Interfaces:

java.io.Externalizable, java.io.Serializable, Formatable, TypedFormat

public class DD_Version
extends java.lang.Object
implements Formatable

Generic code for upgrading data dictionaries. Currently has all minor version upgrade logic.

A word about minor vs. major upgraded. Minor upgrades must be backwards/forwards compatible. So they cannot version classes or introduce new classes. Major releases are only backwards compatible; they will run against an old database, but not the other way around. So they can introduce new classes, etc.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
DD_Version() Public niladic constructor needed for Formatable interface.

Method Summary

Modifier and Type	Method and Description
int	getTypeFormatId() Get the formatID which corresponds to this class.
void	readExternal(java.io.ObjectInput in) Read this object from a stream of stored objects.
java.lang.String	toString() Stringify this Version.
void	writeExternal(java.io.ObjectOutput out) Write this object to a stream of stored objects.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

DD_Version

public DD_Version()

Public niladic constructor needed for Formatable interface.

Method Detail

toString

public java.lang.String toString()

Stringify this Version.

Overrides:

toString in class java.lang.Object

Returns:

String representation of this Version.

getTypeFormatId

public int getTypeFormatId()

Get the formatID which corresponds to this class. Map to the 5.0 version identifier so that 5.0 will understand this object when we write it out in soft upgrade mode. CS 5.0 will de-serialize it correctly. When we are writing out a 5.1 version number we write out the 5.1 version just to ensure no problems.

Specified by:

getTypeFormatId in interface TypedFormat

Returns:

the formatID of this class

readExternal

public final void readExternal(java.io.ObjectInput in)
                        throws java.io.IOException

Read this object from a stream of stored objects. Set the minor version. Ignore the major version.

Specified by:

readExternal in interface java.io.Externalizable

Parameters:

in - read this.

Throws:

java.io.IOException - on error

writeExternal

public final void writeExternal(java.io.ObjectOutput out)
                         throws java.io.IOException

Write this object to a stream of stored objects. Write out the minor version which is bumped across minor release. Just to be safe, write out the major version too. This will allow us to do versioning of a specific Version impl in the future.

Specified by:

writeExternal in interface java.io.Externalizable

Parameters:

out - write bytes here.

Throws:

java.io.IOException - on error