org.cloudgraph.hbase.graph

Class GraphAssembler

java.lang.Object

org.cloudgraph.hbase.graph.DefaultAssembler

org.cloudgraph.hbase.graph.DistributedAssembler

org.cloudgraph.hbase.graph.GraphAssembler

All Implemented Interfaces:

HBaseGraphAssembler, org.plasma.sdo.access.DataGraphAssembler

public class GraphAssembler
extends DistributedAssembler

Constructs a data graph starting with a given root SDO type based on a map of selected SDO properties, where properties are mapped by selected types required in the result graph.

The assembly is triggered by calling the GraphAssembler#assemble(Result resultRow) method which recursively reads HBase keys and values re-constituting the data graph. The assembly traversal is driven by HBase column values representing the original edges or containment structure of the graph.

Since every column key in HBase must be unique, and a data graph may contain any number of nodes, a column key factory is used both to persist as well as re-constitute a graph. A minimal amount of "state" information is therefore stored with each graph which maps user readable sequence numbers (which are used in column keys) to UUID values. The nodes of the resulting data graph are re-created with the original UUID values.

Since:

0.5.1

Author:

Scott Cinnamond

See Also:

StatefullColumnKeyFactory

Field Summary

Fields inherited from class org.cloudgraph.hbase.graph.DistributedAssembler

distributedReader

Fields inherited from class org.cloudgraph.hbase.graph.DefaultAssembler

charset, graph, keyFactories, root, rootTableReader, rootType, selection, snapshotDate

Constructor Summary

Constructors

Constructor and Description
GraphAssembler(org.plasma.sdo.PlasmaType rootType, org.plasma.query.collector.Selection selection, DistributedReader distributedReader, Timestamp snapshotDate) Constructor.

Method Summary

Modifier and Type	Method and Description
protected void	assemble(org.plasma.sdo.PlasmaDataObject target, long targetSequence, EdgeReader sourceCollection, org.plasma.sdo.PlasmaDataObject source, org.plasma.sdo.PlasmaProperty sourceProperty, RowReader rowReader, int level) Populates the given data object target, recursively fetching data for and linking related data objects which make up the resulting directed graph.
protected void	assembleEdges(org.plasma.sdo.PlasmaDataObject source, long sourceSequence, org.plasma.sdo.PlasmaProperty sourceProp, EdgeReader collection, RowReader rowReader, TableReader childTableReader, RowReader childRowReader, int level)
protected void	assembleExternalEdges(org.plasma.sdo.PlasmaDataObject source, long sourceSequence, org.plasma.sdo.PlasmaProperty sourceProp, EdgeReader collection, RowReader rowReader, TableReader childTableReader, int level) Assembles a given set of edges where the target is a different row, within this table or another.

Methods inherited from class org.cloudgraph.hbase.graph.DistributedAssembler

assemble, assembleEdge, assembleExternalEdge, clear

Methods inherited from class org.cloudgraph.hbase.graph.DefaultAssembler

assembleData, assembleUUID, createChild, createChild, createChild, createRoot, fetchGraph, fetchRootType, fetchRootUUID, fetchType, fetchUUID, findMetaDataColumnValue, findMetaDataColumnValue, findRootType, findRootUUID, getDataColumnValue, getDataColumnValue, getDataGraph, getKeyFactory, getMetaDataColumnValue, getMetaDataColumnValue, getProperties, getProperties, link

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.plasma.sdo.access.DataGraphAssembler

getDataGraph

Constructor Detail

GraphAssembler

public GraphAssembler(org.plasma.sdo.PlasmaType rootType,
                      org.plasma.query.collector.Selection selection,
                      DistributedReader distributedReader,
                      Timestamp snapshotDate)

Constructor.

Parameters:

rootType - the SDO root type for the result data graph

selection - selected SDO properties. Properties are mapped by selected types required in the result graph.

snapshotDate - the query snapshot date which is populated into every data object in the result data graph.

Method Detail

assemble

protected void assemble(org.plasma.sdo.PlasmaDataObject target,
                        long targetSequence,
                        EdgeReader sourceCollection,
                        org.plasma.sdo.PlasmaDataObject source,
                        org.plasma.sdo.PlasmaProperty sourceProperty,
                        RowReader rowReader,
                        int level)
                 throws IOException

Description copied from class: DistributedAssembler

Populates the given data object target, recursively fetching data for and linking related data objects which make up the resulting directed graph.

Specified by:

assemble in class DistributedAssembler

targetSequence - the current data object sequence

source - the source or parent data object

sourceProperty - the source (reference) property

rowReader - the current row reader

level - the current graph level

Throws:

IOException - if a remote or network exception occurs.

assembleEdges

protected void assembleEdges(org.plasma.sdo.PlasmaDataObject source,
                             long sourceSequence,
                             org.plasma.sdo.PlasmaProperty sourceProp,
                             EdgeReader collection,
                             RowReader rowReader,
                             TableReader childTableReader,
                             RowReader childRowReader,
                             int level)
                      throws IOException

Throws:

IOException

assembleExternalEdges

protected void assembleExternalEdges(org.plasma.sdo.PlasmaDataObject source,
                                     long sourceSequence,
                                     org.plasma.sdo.PlasmaProperty sourceProp,
                                     EdgeReader collection,
                                     RowReader rowReader,
                                     TableReader childTableReader,
                                     int level)
                              throws IOException

Assembles a given set of edges where the target is a different row, within this table or another. Since we are assembling a graph, each edge requires a new row reader. Each edge is a new root in the target table so need a new row reader for each.

Parameters:

source - the object source to which we link edges

sourceProp - the edge property

edges - the edges

rowReader - the row reader

childTableReader - the table reader for the child objects

level - the assembly level

Throws:

IOException