org.mmbase.core.util
Class StorageConnector

java.lang.Object
  org.mmbase.core.util.StorageConnector

public class StorageConnector
extends Object

A StorageConnector object is associated with a specific builder. It provides methods for loading nodes from the cloud (using the search query classes), either individual nodes or nodelists.

Since:

MMBase-1.8

Version:

$Id: StorageConnector.java 45315 2011-02-18 20:23:11Z michiel $

Author:

Pierre van Rooden

Field Summary

protected MMObjectBuilder	builder
protected int	maxNodesFromQuery Maximum number of nodes to return on a query (-1 means no limit, and is also the default)

Constructor Summary

StorageConnector(MMObjectBuilder builder)

Method Summary

void	addIndex(Index index)
void	addIndices(List<Index> indexList)
protected void	addSubResult(NodeSearchQuery query, List<Integer> subResult, List<MMObjectNode> result)
void	addToIndex(String key, Field field)
protected boolean	assertSizes(Collection<MMObjectNode> virtuals, Collection<MMObjectNode> result)
int	count(SearchQuery query) Counts number of nodes matching a specified constraint.
boolean	created() Check whether the table is accessible.
Index	createIndex(String key)
MMObjectBuilder	getBuilderForNode(int number)
protected QueryResultCache	getCache(SearchQuery query) Returns the Cache which should be used for the result of a certain query.
Index	getIndex(String key)
Map<String,Index>	getIndices()
MMObjectNode	getNode(int number, boolean useCache) Retrieves a node based on it's number (a unique key).
List<MMObjectNode>	getNodes() Returns all the nodes from the associated builder.
List<MMObjectNode>	getNodes(Collection<MMObjectNode> virtuals) Convert virtual nodes to real nodes based on their otype Normally a multirelations-search will return virtual nodes.
List<MMObjectNode>	getNodes(SearchQuery query) Returns nodes matching a specified constraint.
List<MMObjectNode>	getNodes(SearchQuery query, boolean useCache) Returns nodes matching a specified constraint.
int	getNodeType(int number) Retrieves an object's type.
NodeSearchQuery	getSearchQuery(String where) Creates search query that retrieves nodes matching a specified constraint.
boolean	isInIndex(String key, Field field)
void	removeFromIndex(String key, Field field)
int	size() Determine the number of objects in this table.

Methods inherited from class java.lang.Object

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

Field Detail

maxNodesFromQuery

protected int maxNodesFromQuery

Maximum number of nodes to return on a query (-1 means no limit, and is also the default)

builder

protected final MMObjectBuilder builder

Javadoc:

Constructor Detail

StorageConnector

public StorageConnector(MMObjectBuilder builder)

Javadoc:

Method Detail

size

public int size()

Determine the number of objects in this table.

Returns:

The number of entries in the table.

created

public boolean created()

Check whether the table is accessible. In general, this means the table does not exist. Please note that this routine may also return false if the table is inaccessible due to insufficient rights.

Returns:

true if the table is accessible, false otherwise.

getIndices

public Map<String,Index> getIndices()

addIndex

public void addIndex(Index index)

addIndices

public void addIndices(List<Index> indexList)

getIndex

public Index getIndex(String key)

createIndex

public Index createIndex(String key)

addToIndex

public void addToIndex(String key,
                       Field field)

removeFromIndex

public void removeFromIndex(String key,
                            Field field)

isInIndex

public boolean isInIndex(String key,
                         Field field)

getNode

public MMObjectNode getNode(int number,
                            boolean useCache)
                     throws StorageException

Retrieves a node based on it's number (a unique key).

Parameters:

number - The number of the node to search for

useCache - If false, a fresh copy is returned.

Returns:

null if the node does not exist, the key is invalid,or a MMObjectNode containing the contents of the requested node.

Throws:

StorageException

To Do:

when something goes wrong, the method currently catches the exception and returns null. It should actually throw a NotFoundException instead.

getBuilderForNode

public MMObjectBuilder getBuilderForNode(int number)

getNodeType

public int getNodeType(int number)
                throws StorageException

Retrieves an object's type. If necessary, the type is added to the cache.

Parameters:

number - The number of the node to search for

Returns:

an int value which is the object type (otype) of the node.

Throws:

StorageException

To Do:

when something goes wrong, the method currently catches the exception and returns -1. It should actually throw a NotFoundException instead.

getNodes

public List<MMObjectNode> getNodes(Collection<MMObjectNode> virtuals)
                            throws SearchQueryException

Convert virtual nodes to real nodes based on their otype Normally a multirelations-search will return virtual nodes. These nodes will only contain values which where specified in the field-vector. This method will make real nodes of those virtual nodes.

Parameters:

virtuals - containing virtual nodes

Returns:

List containing real nodes, directly from this Builders

Throws:

SearchQueryException

addSubResult

protected void addSubResult(NodeSearchQuery query,
                            List<Integer> subResult,
                            List<MMObjectNode> result)
                     throws SearchQueryException

Parameters:

query - Query with nodestep with added nodes.

subResult - List of Integer

result - List to which the real nodes must be added.

Throws:

SearchQueryException

Since:

MMBase-1.8.2

assertSizes

protected boolean assertSizes(Collection<MMObjectNode> virtuals,
                              Collection<MMObjectNode> result)

Since:

MMBase-1.8.2

count

public int count(SearchQuery query)
          throws SearchQueryException

Counts number of nodes matching a specified constraint. The constraint is specified by a query that selects nodes of a specified type, which must be the nodetype corresponding to this builder.

Parameters:

query - The query.

Returns:

The number of nodes.

Throws:

IllegalArgumentException - when an invalid argument is supplied.

SearchQueryException - when failing to retrieve the data.

getCache

protected QueryResultCache getCache(SearchQuery query)

Returns the Cache which should be used for the result of a certain query. The current implementation only makes the distinction between queries for the 'related nodes caches' and for the 'node list caches'. Multilevel queries are not done here, so are at the moment not anticipated. It returns a Map rather then a Cache. The idea behind this is that if in the future a query-result can be in more than one cache, a kind of 'chained map' can be returned, to reflect that.

To Do:

Perhaps other usefull parameters like query-duration and query-result could be added (in that case searching a result should certainly returns such a chained map, because then of course you don't have those).

getNodes

public List<MMObjectNode> getNodes(SearchQuery query)
                            throws SearchQueryException

Returns nodes matching a specified constraint. The constraint is specified by a query that selects nodes of a specified type, which must be the nodetype corresponding to this builder.

Parameters:

query - The query.

Returns:

The nodes.

Throws:

IllegalArgumentException - When the nodetype specified by the query is not the nodetype corresponding to this builder.

SearchQueryException

getNodes

public List<MMObjectNode> getNodes(SearchQuery query,
                                   boolean useCache)
                            throws SearchQueryException

Returns nodes matching a specified constraint. The constraint is specified by a query that selects nodes of a specified type, which must be the nodetype corresponding to this builder.

Parameters:

query - The query.

useCache - if true, the querycache is used

Returns:

The nodes.

Throws:

IllegalArgumentException - When the nodetype specified by the query is not the nodetype corresponding to this builder.

SearchQueryException

getNodes

public List<MMObjectNode> getNodes()
                            throws SearchQueryException

Returns all the nodes from the associated builder.

Returns:

The nodes.

Throws:

SearchQueryException

getSearchQuery

public NodeSearchQuery getSearchQuery(String where)

Creates search query that retrieves nodes matching a specified constraint.

Parameters:

where - The constraint, can be a SQL where-clause, a MMNODE expression, an altavista-formatted expression, empty or null.

Returns:

The query.

Since:

MMBase-1.7