org.topoweb.ila.server.spi
Class IlaImpl

java.lang.Object
  |
  +--org.topoweb.ila.server.spi.IlaImpl

All Implemented Interfaces:

Ila, LocalIla, NodeConstants, StateConstants

public class IlaImpl

extends java.lang.Object

implements LocalIla, StateConstants

Base local Ila implementation class. This is just a thin wrapper around a DataAccessor instance. The methods in this class throw the following more specific IlaExceptions:

• ResolutionException
  If this server is not the authority on the src ORI
• DataAccessorException
  If the underlying DataAccessor throws it.

Author:

Babak Farhang

See Also:

DataAccessor

Field Summary

Fields inherited from interface org.topoweb.ila.NodeConstants

BACK, FIRST_PAGE, FORE, LAST_PAGE, LINK_MASK, PAGE_MASK

Fields inherited from interface org.topoweb.ila.StateConstants

NF, NK, NV, OK

Constructor Summary

IlaImpl(DataAccessor db, ServiceProviderResolver resolver)
Creates a new instance with the given DataAccessor.

Method Summary

NodeSet	getKnown(org.topoweb.util.StringRange range, int pageOrder, int maxCount) Returns a list of nodes known by Ila in the given lexical range as a NodeSet.
LinkNode	getLinkNode(org.topoweb.net.Ori src, int linkType, org.topoweb.util.StringRange linkRange, int pageOrder, int maxCount) Returns a linked-node containing links with the specified type and in the specified lexical range.
NodeSet	getLinks(org.topoweb.net.Ori src, int linkType, org.topoweb.util.StringRange linkRange, int pageOrder, int maxCount) Returns the links of the specified type for the node with the given Ori as a NodeSet.
Node	getNode(org.topoweb.net.Ori ori) Returns the node for the specified Ori.
LinkNode	register(org.topoweb.net.Ori ori) This base implementation just returns a node in the NK state.

Methods inherited from class java.lang.Object

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

Constructor Detail

IlaImpl

public IlaImpl(DataAccessor db,
               ServiceProviderResolver resolver)

Creates a new instance with the given DataAccessor. The resolver is used to ensure that the instance is the authority server for any given src ORI.

Parameters:

db - the data accessor implementation class

resolver - the service resolver (used to do sanity checks on the arguments)

Method Detail

getNode

public Node getNode(org.topoweb.net.Ori ori)
             throws ResolutionException,
                    DataAccessorException,
                    IlaException

Description copied from interface: Ila

Returns the node for the specified Ori. The returned node encapsulates Ila's state of knowledge about the resource represented by the given ORI. That is, getNode(src, ..).getOri().equals(src) must evaluate to true.

Specified by:

getNode in interface Ila

Parameters:

ori - the ORI of the resource

Returns:

the node representing the resource as known by Ila. Never null.

Throws:

ResolutionException - if this server is not the authority on the ori

DataAccessorException - if the underlying data accessor throws it

IlaException - if an error occurs

getLinks

public NodeSet getLinks(org.topoweb.net.Ori src,
                        int linkType,
                        org.topoweb.util.StringRange linkRange,
                        int pageOrder,
                        int maxCount)
                 throws ResolutionException,
                        DataAccessorException,
                        IlaException

Description copied from interface: Ila

Returns the links of the specified type for the node with the given Ori as a NodeSet.

The type of links returned, forelinks or backlinks, is determined by bitwise ORing the linkType parameter with NodeConstants mask.

The lexical range of the links to be returned is determined by the linkRange parameter.

Some nodes can have very many links, and it may be infeasible for an Ila server to return all the links that match a given request. In such an event the returned links will either start from the linkRange's lower bound if (pageOrder & PAGE_MASK ) == FIRST_PAGE, or end at its upper bound, otherwise. The user can detect whether the returned links were truncated by examining the returned NodeSet.

Note

The state information of the returned links is seldom authoritative. In fact, if the links are of the forward type (FORE) and they were just added, then it is likely they will be returned in the NK state. For any given linked node, authoritative state information is retrieved using the getNode method.

Specified by:

getLinks in interface Ila

Parameters:

src - the Ori of the return linked-node

linkType - specifies whether the returned node set contains forelinks or backlinks

linkRange - the lexical range of the links returned

pageOrder - specifies whether if truncated, the links should begin from the first page or end on the last page of the link result set

maxCount - the maximum number of links that may be returned; a value <= 0 indicates an unlimited number

Returns:

a node set encapsulating the Ila server's response

Throws:

ResolutionException - if this server is not the authority on the src ORI

DataAccessorException - if the underlying data accessor throws it

IlaException - if an error occurs

See Also:

NodeConstants, NodeConstants.FIRST_PAGE, NodeConstants.LAST_PAGE

getLinkNode

public LinkNode getLinkNode(org.topoweb.net.Ori src,
                            int linkType,
                            org.topoweb.util.StringRange linkRange,
                            int pageOrder,
                            int maxCount)
                     throws ResolutionException,
                            DataAccessorException,
                            IlaException

Description copied from interface: Ila

Returns a linked-node containing links with the specified type and in the specified lexical range. The returned node represents Ila's state of knowledge about the resource represented by the given ORI src. That is, the expression getLinkNode(src, ..).getOri().equals(src) must evaluate to true.

This method is equivalent to invoking getNode followed by getLinks. That is, for example,

new LinkNode(src, getNode(src).getState(), null, getLinks(src, BACK, StringRange.ALL, FIRST_PAGE, 0) ); Example usage:

      Ila ila = .. ;
      LinkNode node
      = ila.getLinkNode(
      srcOri, NodeConstants.BACK, StringRange.ALL, FIRST_PAGE, 100);
      ..
 

The goal here is not a convenience method. Rather, we expect if implemented over the wire, the returned LinkNode will be marshalled in one pass, not two.

Specified by:

getLinkNode in interface Ila

Parameters:

src - the ORI of the return linked-node

linkType - specifies whether the returned linked-node contains forelinks or backlinks

linkRange - the lexical range of the links returned

pageOrder - specifies whether if truncated, the links should begin from the first page or end

maxCount - the maximum number of links that may be returned; a value <= 0 indicates an unlimited number

Returns:

a linked-node encapsulating the Ila server's response

Throws:

ResolutionException - if this server is not the authority on the src ORI

DataAccessorException - if the underlying data accessor throws it

IlaException - if an error occurs

See Also:

NodeConstants, NodeConstants.FIRST_PAGE, NodeConstants.LAST_PAGE

getKnown

public NodeSet getKnown(org.topoweb.util.StringRange range,
                        int pageOrder,
                        int maxCount)
                 throws DataAccessorException

Description copied from interface: Ila

Returns a list of nodes known by Ila in the given lexical range as a NodeSet.

Specified by:

getKnown in interface Ila

Parameters:

range - the lexical range of the ORIs of the nodes to be returned

pageOrder - the page order

maxCount - the maximum number of links that may be returned; a value <= 0 indicates an unlimited number

Returns:

a perhaps truncated list of nodes

Throws:

DataAccessorException - if the underlying data accessor throws it

See Also:

NodeConstants.FIRST_PAGE, NodeConstants.LAST_PAGE

register

public LinkNode register(org.topoweb.net.Ori ori)
                  throws ResolutionException,
                         IlaException

This base implementation just returns a node in the NK state. It does not even log the invocation.

Specified by:

register in interface Ila

Parameters:

ori - the ORI of the resource

Returns:

a link-node containing the forward links of the resource

Throws:

ResolutionException - if this server is not the authority on the ori

IlaException - if an error occurs