org.dspace.app.xmlui.utils

Class DSpaceValidity

java.lang.Object

org.dspace.app.xmlui.utils.DSpaceValidity

All Implemented Interfaces:

Serializable, org.apache.excalibur.source.SourceValidity

public class DSpaceValidity
extends Object
implements org.apache.excalibur.source.SourceValidity

This is a validity object specifically implemented for the caching needs of DSpace, Manakin, and Cocoon.

The basic idea is that, each time a DSpace object is rendered by a Cocoon component, the object and everything about it that makes it unique should be reflected in the validity object for the component. By following this principle, if the object has been updated externally then the cache will be invalidated.

This DSpaceValidity object makes this processes easier by abstracting out the processes of determining what is unique about a DSpace object. A class is expected to create a new DSpaceValidity object and add() to it all DSpaceObjects that are rendered by the component. This validity object will serialize all those objects to a string, take a hash of the string and compare the hash of the string for any updates.

Author:

Scott Phillips

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected long	assumedValidityDelay The length of time that a cache is assumed to be valid
protected long	assumedValidityTime The time when the validity is no longer assumed to be valid
protected CollectionService	collectionService
protected CommunityService	communityService
protected boolean	completed Simple flag to note if the object has been completed.
protected long	hash A hash of the validityKey taken after completion
protected ItemService	itemService
protected StringBuffer	validityKey The validityKey while it is being build, once it is completed.

Fields inherited from interface org.apache.excalibur.source.SourceValidity

INVALID, UNKNOWN, VALID

Constructor Summary

Constructors

Constructor and Description
DSpaceValidity()
DSpaceValidity(String initialValidityKey) Create a new DSpace validity object.

Method Summary

Methods

Modifier and Type	Method and Description
void	add(Context context, DSpaceObject dso) Add a DSpace object to the validity.
void	add(String nonDSpaceObject) Add a non-DSpaceObject to the validity, the object should be serialized into a string form.
DSpaceValidity	complete() Complete this validity object.
int	isValid() Determine if the cache is still valid
int	isValid(org.apache.excalibur.source.SourceValidity otherObject) Determine if the cache is still valid based upon the other validity object.
void	setAssumedValidityDelay(long milliseconds) Set the time delay for how long this cache will be assumed to be valid.
void	setAssumedValidityDelay(String delay) Set the time delay for how long this cache will be assumed to be valid.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

validityKey

protected StringBuffer validityKey

The validityKey while it is being build, once it is completed.

completed

protected boolean completed

Simple flag to note if the object has been completed.

hash

protected long hash

A hash of the validityKey taken after completion

assumedValidityTime

protected long assumedValidityTime

The time when the validity is no longer assumed to be valid

assumedValidityDelay

protected long assumedValidityDelay

The length of time that a cache is assumed to be valid

communityService

protected transient CommunityService communityService

collectionService

protected transient CollectionService collectionService

itemService

protected transient ItemService itemService

Constructor Detail

DSpaceValidity

public DSpaceValidity(String initialValidityKey)

Create a new DSpace validity object.

Parameters:

initialValidityKey - The initial string

DSpaceValidity

public DSpaceValidity()

Method Detail

complete

public DSpaceValidity complete()

Complete this validity object. After the completion no more objects may be added to the validity object and the object will return as valid.

Returns:

this.

setAssumedValidityDelay

public void setAssumedValidityDelay(long milliseconds)

Set the time delay for how long this cache will be assumed to be valid. When it is assumed valid no other checks will be made to consider its validity, and once the time has expired a full validation will occur on the next cache hit. If the cache proves to be validated on this hit then the assumed validity timer is reset.

Parameters:

milliseconds - The delay time in millieseconds.

setAssumedValidityDelay

public void setAssumedValidityDelay(String delay)

Set the time delay for how long this cache will be assumed to be valid.

This method takes a string which is parsed for the delay time. The string must be of the following form: "<integer> <scale>" where scale is days, hours, minutes, or seconds.

Examples: "1 day" or "12 hours" or "1 hour" or "30 minutes"

Parameters:

delay - The delay time in a variable scale.

See Also:

setAssumedValidityDelay(long)

add

public void add(Context context,
       DSpaceObject dso)
         throws SQLException

Add a DSpace object to the validity. The order in which objects are added to the validity object is important, ensure that objects are added in the *exact* same order each time a validity object is created. Below are the following transitive rules for adding objects, i.e. if an item is added then all the item's bundles and bitstreams will also be added.

Communities -> logo bitstream
Collection -> logo bitstream
Item -> bundles -> bitstream
Bundles -> bitstreams
EPeople -> groups

Parameters:

context - session context.

dso - The object to add to the validity.

Throws:

SQLException - passed through.

add

public void add(String nonDSpaceObject)
         throws SQLException

Add a non-DSpaceObject to the validity, the object should be serialized into a string form. The order in which objects are added to the validity object is important, ensure that objects are added in the *exact* same order each time a validity object is created.

Parameters:

nonDSpaceObject - The non-DSpace object to add to the validity.

Throws:

SQLException - passed through.

isValid

public int isValid()

Determine if the cache is still valid

Specified by:

isValid in interface org.apache.excalibur.source.SourceValidity

Returns:

SourceValidity.VALID, SourceValidity.UNKNOWN, or SourceValidity.INVALID.

isValid

public int isValid(org.apache.excalibur.source.SourceValidity otherObject)

Determine if the cache is still valid based upon the other validity object.

Specified by:

isValid in interface org.apache.excalibur.source.SourceValidity

Parameters:

otherObject - The other validity object.

Returns:

SourceValidity.VALID or SourceValidity.INVALID.