gr.uoa.di.madgik.commons.state.store.data
Class StateStoreData

java.lang.Object
  gr.uoa.di.madgik.commons.state.store.data.StateStoreData

public class StateStoreData
extends Object

Class responsible of handling the persistency and retrieval of the actual state data clients want to persiste with the State Store Repository. This class dows not keep any internal state and is instanciated every time a new operation needs to be perofrmed on the repository payload data. The operations this class provides are not thread safe and even though it represents a shared resource it does not provide any kind of of resource locking policy. This is left to the wrapping class, StateManager. This class needs a value kith key EncodingCharset in the ConfigurationManager representing the charaset name to use during alphanumeric storage and retrieval through Put(gr.uoa.di.madgik.commons.state.store.registry.StateStoreRegistryKey, java.lang.String) and GetAlphanumeric(gr.uoa.di.madgik.commons.state.store.registry.StateStoreRegistryKey)

Author:

gpapanikos

Constructor Summary

StateStoreData(StateStoreInfo Info)
Creates a new instance

Method Summary

String	GetAlphanumeric(StateStoreRegistryKey Key) Retrieves the actual payload referenced by the provided metadata entry and returns it as the expected type.
byte[]	GetByteArray(StateStoreRegistryKey Key) Retrieves the actual payload referenced by the provided metadata entry and returns it as the expected type.
File	GetFile(StateStoreRegistryKey Key) Retrieves the actual payload referenced by the provided metadata entry and returns it as the expected type.
ISerializable	GetISerializable(StateStoreRegistryKey Key) Retrieves the actual payload referenced by the provided metadata entry and returns it as the expected type.
Serializable	GetSerializable(StateStoreRegistryKey Key) Retrieves the actual payload referenced by the provided metadata entry and returns it as the expected type.
File	MoveToClean(Map<String,StateStoreRegistryKey> registry) In case of deletes and updates in the registry and data file, there will be data kept in the file that are no longer needed but simply remain increrasing the size of the repository files.
void	Put(StateStoreRegistryKey Key, byte[] bytearray) Appends the provided payload to the repository data file.
void	Put(StateStoreRegistryKey Key, File file) Appends the provided payload to the repository data file.
void	Put(StateStoreRegistryKey Key, ISerializable obj) Appends the provided payload to the repository data file.
void	Put(StateStoreRegistryKey Key, Serializable obj) Appends the provided payload to the repository data file.
void	Put(StateStoreRegistryKey Key, String Alphanumeric) Appends the provided payload to the repository data file.

Methods inherited from class java.lang.Object

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

Constructor Detail

StateStoreData

public StateStoreData(StateStoreInfo Info)

Creates a new instance

Parameters:

Info - The repository persistency files information

Method Detail

Put

public void Put(StateStoreRegistryKey Key,
                String Alphanumeric)
         throws Exception

Appends the provided payload to the repository data file. The provided metadata StateStoreRegistryKey entry is updated with the offsets of the stored data

Parameters:

Key - The metadata entry representing the data.

Alphanumeric - The payload to store as a sequence of bytes using the configuration value with key EncodingCharset from the ConfigurationManager

Throws:

Exception - the store could not be performed

GetAlphanumeric

public String GetAlphanumeric(StateStoreRegistryKey Key)
                       throws Exception

Retrieves the actual payload referenced by the provided metadata entry and returns it as the expected type.

Parameters:

Key - The metadate entry referencing the data to retrieve

Returns:

The payload after decoding it using the value with key EncodingCharset from the ConfigurationManager back to a string from a byte array

Throws:

Exception - The retrieval could not be performed

Put

public void Put(StateStoreRegistryKey Key,
                byte[] bytearray)
         throws Exception

Appends the provided payload to the repository data file. The provided metadata StateStoreRegistryKey entry is updated with the offsets of the stored data

Parameters:

Key - The metadata entry representing the data.

bytearray - The payload to store as a sequence of bytes

Throws:

Exception - The store could not be performed

GetByteArray

public byte[] GetByteArray(StateStoreRegistryKey Key)
                    throws Exception

Retrieves the actual payload referenced by the provided metadata entry and returns it as the expected type.

Parameters:

Key - The metadate entry referencing the data to retrieve

Returns:

The payload

Throws:

Exception - The retrieval could not be performed

Put

public void Put(StateStoreRegistryKey Key,
                ISerializable obj)
         throws Exception

Appends the provided payload to the repository data file. The provided metadata StateStoreRegistryKey entry is updated with the offsets of the stored data

Parameters:

Key - The metadata entry representing the data.

obj - The object to store serializing it through ISerializable.Serialize()

Throws:

Exception - The store could not be performed

GetISerializable

public ISerializable GetISerializable(StateStoreRegistryKey Key)
                               throws Exception

Retrieves the actual payload referenced by the provided metadata entry and returns it as the expected type.

Parameters:

Key - The metadate entry referencing the data to retrieve

Returns:

The object instantiated with its default constructor and populated through the ISerializable.Deserialize(byte[])

Throws:

Exception - The retrieval could not be performed

Put

public void Put(StateStoreRegistryKey Key,
                Serializable obj)
         throws Exception

Appends the provided payload to the repository data file. The provided metadata StateStoreRegistryKey entry is updated with the offsets of the stored data

Parameters:

Key - The metadata entry representing the data.

obj - The object to store serializing it through an ObjectOutputStream

Throws:

Exception - The store could not be performed

GetSerializable

public Serializable GetSerializable(StateStoreRegistryKey Key)
                             throws Exception

Retrieves the actual payload referenced by the provided metadata entry and returns it as the expected type.

Parameters:

Key - The metadate entry referencing the data to retrieve

Returns:

The object retrieved using an ObjectInputStream

Throws:

Exception - The retrieval could not be performed

Put

public void Put(StateStoreRegistryKey Key,
                File file)
         throws Exception

Appends the provided payload to the repository data file. The provided metadata StateStoreRegistryKey entry is updated with the offsets of the stored data

Parameters:

Key - The metadata entry representing the data.

file - The file whose payload to retrieve and store

Throws:

Exception - The store could not be performed

GetFile

public File GetFile(StateStoreRegistryKey Key)
             throws Exception

Retrieves the actual payload referenced by the provided metadata entry and returns it as the expected type.

Parameters:

Key - The metadate entry referencing the data to retrieve

Returns:

The temporary file created where the payload is stored as it is retrieved by the repository data file

Throws:

Exception - The retrieval could not be performed

MoveToClean

public File MoveToClean(Map<String,StateStoreRegistryKey> registry)
                 throws Exception

In case of deletes and updates in the registry and data file, there will be data kept in the file that are no longer needed but simply remain increrasing the size of the repository files. This method reorganizes the data file into a new temporary file it creates that holds only the needed valid data records. During the process each entry that is valid as provided by the caller it is persisted in the new clean file. The metadata entries provided are also updated to point to the new offsets where their respective data are stored. This leaves the registry part of the repository in an inconsistend state until the file that the StateStoreInfo points to as the data repository file is deleted and replaced with the file that this method returns

Parameters:

registry - the in memeory structure holding the entries that should be kept from the data file

Returns:

The file created holding the new clean file to be used as the repository data file

Throws:

Exception - The clean operation could not be performed