org.activemath.abstractcontent
Class MultiMBase

java.lang.Object
  org.activemath.abstractcontent.MultiMBase

All Implemented Interfaces:

MBaseRef

public class MultiMBase
extends Object
implements MBaseRef

A class to provide access to several MBaseRefs through one single interface. It's implementing MBaseRef itself, therefore it's cascadable. Its functions include content aggregation (provide collections (content blocks) of several MBases that not necessarily contain the same collections) and a bit of load balancing. It implements only the new style MBaseRef interface, which was mainly created to make this class possible.

Version:

0.1 CVS $Revision: 1.14 $ updated at $Date: 2007/04/16 22:28:13 $ by $Author: paul $

Nested Class Summary

Nested classes/interfaces inherited from interface org.activemath.abstractcontent.MBaseRef

MBaseRef.Dependency, MBaseRef.Relation

Field Summary

protected Hashtable	connectedMBaseHash Hashtable of supported collections / connected databases.
protected Set	providedCollections a set of Strings with provided collections
protected Set	usedMBaseRefs a set of the MBaseRefs inside this

Constructor Summary

MultiMBase(Collection connections)
constructs a new MultiMBase

Method Summary

protected void	assertCollectionCompatibility(Collection collections) makes sure the given collections Collection only contains the collection this MBase provides
void	assertItsUp() Asserts that the database connection is up and running.
String	getAttribute(MBaseID id, String attName) Returns the attribute value of the attribute of given name of the element with given ID.
MBaseID	getCanonicalID(MBaseID source) Returns a fully-qualified unique ID that enables collections of IDs to behave properly.
OJElement	getChildren(MBaseID id, String xPathReducedExpression) Returns the content of the named descendant of the element of given ID.
Collection	getCollectionsProvided() returns a Collection (object) with the collections (content blocks) provided by this MBaseRef
Map	getCommonName(MBaseID id) Returns the names of this element which is fetched either from the <metadata><dc:Title> descendant or from the <commonname> elements.
OJElement	getCompleteDCMetadata(MBaseID id) Returns a metadata element with only Dublin-Core children including inherited ones from their parents.
Iterator	getDefinitions(MBaseID id, Collection collections) For a symbol, this method returns the IDs of all definitions.
Iterator	getDependencies(MBaseID mBaseID) Gets an Iterator of MBaseRef.Dependency dependencies with all dependencies registered for that element.
OJElement	getFormalContent(MBaseID id) From any ID this method returns the row of FMP elements' contents.
MBaseID[]	getForWhat(MBaseID id) Returns the ID contained in the attribute for
Iterator	getIncomingRelations(MBaseID id, Collection collections) Returns an iterator of MBaseRef.Relations objects describing the relations that point to this item.
Iterator	getItemsModifiedSince(Date date)
Date	getLastModified(Collection ids) Returns the latest modification dates of the elements whose IDs are given.
protected MBaseRef	getMBase(MBaseID forContent) finds an appropriate MBase to query and returns the result.
protected MBaseRef	getMBase(String forCollection) finds an appropriate MBase to query and returns the result.
OJElement	getMetadata(MBaseID id) Returns the contents of the <metdata> child of this element.
Iterator	getOutgoingRelations(MBaseID id) Returns an iterator of MBaseRef.Relations objects describing the relations that point from this item.
Iterator	getProofs(MBaseID assertionID, Collection collections) For an assertion, this method returns the IDs of all of its proofs.
Iterator	getRelated(MBaseID id, Collection collections) Same as getDependencies(org.activemath.abstractcontent.MBaseID) but returns the converse: all dependencies whose Dependency#idOn is the given ID.
OJDocument	getStructuredListOfConcepts(Collection collections) This expensive operation walks the complete XML structure stored in the server and creates a theory element for each theory then a concept element for each of the concepts (symbol, definition, assertion, proof, methods).
Map	getTagFreeCommonName(MBaseID id) Returns the titles without any tags, just extracting the text or partially rendering it.
List	getTextualContent(MBaseID id) From any ID this method returns the row of CMP elements' contents.
MBaseID	getTheory(MBaseID id) Returns the ID of the closest parent (including the element itself) that either has a theory attribute or is a theory element or null if there is no such parent.
String	getTypeString(MBaseID id) Returns the name of the element whose ID is given.
Iterator	listItems(Collection collections, String type) Lists all the items being children of the element of the indicated ID.
Iterator	listItems(MBaseID id) Lists all the items being children of the element of the indicated ID.
Iterator	listTheories(Collection collections) Lists all the IDs of the theory elements contained in the indicated collections .
protected void	registerConnections(Collection connections) registers the given connections of MBaseRefs to the connectedMBaseHash hashtable.
Iterator	searchText(String textToSearch, Collection collections) Searches the union of all text elements, but not the attributes, for the given substring in a case-sensistive manner.

Methods inherited from class java.lang.Object

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

Field Detail

connectedMBaseHash

protected Hashtable connectedMBaseHash

Hashtable of supported collections / connected databases. The key is the String naming the collection, the value is a Vector containing the MBaseRefs that provide this collection

providedCollections

protected Set providedCollections

a set of Strings with provided collections

usedMBaseRefs

protected Set usedMBaseRefs

a set of the MBaseRefs inside this

Constructor Detail

MultiMBase

public MultiMBase(Collection connections)
           throws MBaseException

constructs a new MultiMBase

Parameters:

connections - a Collection with all the connections this MultiMBase shall provide. Load balancing and content collection dependencies are automatically set up. If you want to weighten load balancing access, you may pass the same connection multiple times; yet this is to the cost of setup time and only usable if the connection weights are small entire numbers (e.G. one could pass a collection 100 times and another 103 times to show a 1.5% preference for the later, but this would imply far longer setup time and more space requirements)

Throws:

MBaseException - If antyhing goes wrong

Method Detail

getChildren

public OJElement getChildren(MBaseID id,
                             String xPathReducedExpression)
                      throws MBaseException

Returns the content of the named descendant of the element of given ID. The descendant are found using the xPathReducedExpression parameter which aims at imitating an XPath expression except it only accepts the ., / and named elements.

This walks the tree of descendants, taking children everytime a /elementName is found in the xPathReducedExpression and returns the content of the end child.

Such a method might be a warmer future for all requests, including getDependencies, getMetaData and getCommonName.

Specified by:

getChildren in interface MBaseRef

Parameters:

id - the MBaseID to get the children of

xPathReducedExpression - as described above

Returns:

the OJElement thus crafted

Throws:

MBaseException - if something fails

getAttribute

public String getAttribute(MBaseID id,
                           String attName)
                    throws MBaseException

Description copied from interface: MBaseRef

Returns the attribute value of the attribute of given name of the element with given ID. throws MBaseException if something fails

Specified by:

getAttribute in interface MBaseRef

Parameters:

id - the id of the XML element that is to be looked for

attName - the name of the attribute to be looked for in this element

Returns:

the attribute value

Throws:

MBaseException - if anything goes wrong

getDependencies

public Iterator getDependencies(MBaseID mBaseID)
                         throws MBaseException

Gets an Iterator of MBaseRef.Dependency dependencies with all dependencies registered for that element. Dependencies are of many types as described in the MBaseRef,Dependency class.

Note that the server implementation is not required to return all these types only the content of the <depends-on> elements are required to be returned.

Specified by:

getDependencies in interface MBaseRef

Parameters:

mBaseID - which's dependencies are to be returned

Returns:

Iterator of MBaseIDs that are dependent

Throws:

MBaseException - if something's wrong, i.e. if a collection was queried that is not provided

getRelated

public Iterator getRelated(MBaseID id,
                           Collection collections)
                    throws MBaseException

Same as getDependencies(org.activemath.abstractcontent.MBaseID) but returns the converse: all dependencies whose Dependency#idOn is the given ID.

Specified by:

getRelated in interface MBaseRef

Parameters:

id - which's relations are to be returned

collections - java.util.Collection of (content) collections as Strings to search in

Returns:

Iterator of MBaseIDs that are dependent

Throws:

MBaseException - if something's wrong.

getDefinitions

public Iterator getDefinitions(MBaseID id,
                               Collection collections)
                        throws MBaseException

Description copied from interface: MBaseRef

For a symbol, this method returns the IDs of all definitions.

Specified by:

getDefinitions in interface MBaseRef

Parameters:

id - id the id of the symbol whose definitions are looked at

collections - collections the name of the collections to be searched

Returns:

null for non-symbol elements or if no definition is found.

Throws:

MBaseException - if something's wrong.

getProofs

public Iterator getProofs(MBaseID assertionID,
                          Collection collections)
                   throws MBaseException

Description copied from interface: MBaseRef

For an assertion, this method returns the IDs of all of its proofs.

Specified by:

getProofs in interface MBaseRef

Parameters:

assertionID - MBaseID denoting the assertion whose proofs are to be searched

collections - Collection of (content) collections to search in

Returns:

an Iterator with the proofs, that is empty for non-assertion elements or if no proof is found.

Throws:

MBaseException - if something's wrong.

getTextualContent

public List getTextualContent(MBaseID id)
                       throws MBaseException

From any ID this method returns the row of CMP elements' contents. The server is supposed to "resolve" the occurrences of <OMS> who are "referenced" by means of the xref attribute.

Specified by:

getTextualContent in interface MBaseRef

Parameters:

id - The ID of the item whose CMPs are to be returned

Returns:

A list of OJElements being the CMP nodes

Throws:

MBaseException - if something fails

getFormalContent

public OJElement getFormalContent(MBaseID id)
                           throws MBaseException

From any ID this method returns the row of FMP elements' contents. The server is supposed to "resolve" the occurrences of <OMS> who are "referenced" by means of the xref attribute.

Specified by:

getFormalContent in interface MBaseRef

Parameters:

id - The ID whose FMP child is to be fetched

Returns:

a the OJElement representing the <FMP> or null if there is no <FMP> content behind the ID

Throws:

MBaseException - if something fails

getMetadata

public OJElement getMetadata(MBaseID id)
                      throws MBaseException

Returns the contents of the <metdata> child of this element.

Specified by:

getMetadata in interface MBaseRef

Parameters:

id - The ID of the item whose metadata element is to be fetched.

Returns:

The metadata OJElement

Throws:

MBaseException - if something fails

getCompleteDCMetadata

public OJElement getCompleteDCMetadata(MBaseID id)
                                throws MBaseException

Description copied from interface: MBaseRef

Returns a metadata element with only Dublin-Core children including inherited ones from their parents. The inheritance is described in OMDoc 1.1 specifications (i.e. added values with children taking precedence when a triple (language, element-name, role) also exists.

This allows most of the copyright informations to be stored in the metadata element of the OMDoc while additions can override or enrich these values.

Specified by:

getCompleteDCMetadata in interface MBaseRef

Parameters:

id - the ID of the item whose metadata is to be fetched

Returns:

the completed OJElement metadata node

Throws:

MBaseException - If anything happens

getTheory

public MBaseID getTheory(MBaseID id)
                  throws MBaseException

Returns the ID of the closest parent (including the element itself) that either has a theory attribute or is a theory element or null if there is no such parent.

Specified by:

getTheory in interface MBaseRef

Parameters:

id - The item whose theory is to be found

Returns:

The MBaseID of the related theory element

Throws:

MBaseException - if something's wrong.

getCommonName

public Map getCommonName(MBaseID id)
                  throws MBaseException

Returns the names of this element which is fetched either from the <metadata><dc:Title> descendant or from the <commonname> elements.

The table returned has, as keys, the language and as values the text of this common-name.

Specified by:

getCommonName in interface MBaseRef

Parameters:

id - The ID of the item whose titles are to be looked at.

Returns:

A Map of titles (keys String language}, values the String titles

Throws:

MBaseException - if something's wrong.

getTypeString

public String getTypeString(MBaseID id)
                     throws MBaseException

Returns the name of the element whose ID is given.

Specified by:

getTypeString in interface MBaseRef

Parameters:

id - The ID of the element

Returns:

The (XML) element-name of this node

Throws:

MBaseException - if something's wrong.

getForWhat

public MBaseID[] getForWhat(MBaseID id)
                     throws MBaseException

Returns the ID contained in the attribute for

Specified by:

getForWhat in interface MBaseRef

Parameters:

id - The ID of the item whose for attribute is to be looked at.

Returns:

The list of pointers interpreted from the pointer values in the for attribute of the element

Throws:

MBaseException - if something's wrong.

getStructuredListOfConcepts

public OJDocument getStructuredListOfConcepts(Collection collections)
                                       throws MBaseException

This expensive operation walks the complete XML structure stored in the server and creates a theory element for each theory then a concept element for each of the concepts (symbol, definition, assertion, proof, methods). This amalgamates

Specified by:

getStructuredListOfConcepts in interface MBaseRef

Parameters:

collections - strings with the name of the collection to search in

Returns:

an XML document structured by theory/element, or null, if there are no contents found

Throws:

MBaseException - if something fails

getCollectionsProvided

public Collection getCollectionsProvided()

returns a Collection (object) with the collections (content blocks) provided by this MBaseRef

Specified by:

getCollectionsProvided in interface MBaseRef

Returns:

Collection of Strings with the names of the provided collections

getCanonicalID

public MBaseID getCanonicalID(MBaseID source)
                       throws MBaseException

Description copied from interface: MBaseRef

Returns a fully-qualified unique ID that enables collections of IDs to behave properly. MBase engines may allow heuristics to interpret IDs, among others, to identify an item with an ID not containing a theory although the item is in a theory.

MBase engines should be consistent and never return more than one ID for a given item.

Specified by:

getCanonicalID in interface MBaseRef

Parameters:

source - the id that may be missing a theory or collection.

Returns:

a fully-qualified absolute ID pointing to the same element, or null if no such element was found.

Throws:

MBaseException - If anything goes wrong

searchText

public Iterator searchText(String textToSearch,
                           Collection collections)
                    throws MBaseException

Searches the union of all text elements, but not the attributes, for the given substring in a case-sensistive manner. This operation is expected to be rather expensive (at least o(number of all elements in all connected databases))

Specified by:

searchText in interface MBaseRef

Parameters:

textToSearch - String containing the text to be searched

collections - Collection of collections (as Strings) to search in

Returns:

an Iterator of MBaseIDs that contain the string

Throws:

MBaseException - if something's wrong.

listItems

public Iterator listItems(MBaseID id)
                   throws MBaseException

Description copied from interface: MBaseRef

Lists all the items being children of the element of the indicated ID. Implementations are required to support this operation on omgroup and theory elements only.

Specified by:

listItems in interface MBaseRef

Parameters:

id - the ID of the omgroup, theory or other element

Returns:

An iterator of MBaseID objects

Throws:

MBaseException - If anything goes wrong

listTheories

public Iterator listTheories(Collection collections)
                      throws MBaseException

Description copied from interface: MBaseRef

Lists all the IDs of the theory elements contained in the indicated collections .

Specified by:

listTheories in interface MBaseRef

Parameters:

collections - the set of collection-names to be walked through for theories.

Returns:

an iterator over the list of IDs that are children

Throws:

MBaseException - If anything goes wrong

listItems

public Iterator listItems(Collection collections,
                          String type)
                   throws MBaseException

Description copied from interface: MBaseRef

Lists all the items being children of the element of the indicated ID. Implementations are required to support this operation on omgroup and theory elements only.

Specified by:

listItems in interface MBaseRef

Parameters:

collections - the possible collections where to search for the items of this type

type - the element name wished to be returne

Returns:

An iterator of MBaseID objects to the given elements

Throws:

MBaseException - If anything goes wrong

assertItsUp

public void assertItsUp()
                 throws MBaseException

Asserts that the database connection is up and running. Here: assert that ALL the database connections are up and running.

Specified by:

assertItsUp in interface MBaseRef

Throws:

MBaseException - if something's wrong.

getLastModified

public Date getLastModified(Collection ids)
                     throws MBaseException

Description copied from interface: MBaseRef

Returns the latest modification dates of the elements whose IDs are given.

Specified by:

getLastModified in interface MBaseRef

Parameters:

ids - a list of MBaseIDs of items, theories, or Strings of collection name

Returns:

the latest modification date or, if unknown, the current date.

Throws:

MBaseException

getItemsModifiedSince

public Iterator getItemsModifiedSince(Date date)
                               throws MBaseException

Specified by:

getItemsModifiedSince in interface MBaseRef

Throws:

MBaseException

getTagFreeCommonName

public Map getTagFreeCommonName(MBaseID id)
                         throws MBaseException

Description copied from interface: MBaseRef

Returns the titles without any tags, just extracting the text or partially rendering it. Useful for string-only processors.

Specified by:

getTagFreeCommonName in interface MBaseRef

Parameters:

id - the item id.

Returns:

the map, associating a language string to a title-string.

Throws:

MBaseException

getIncomingRelations

public Iterator getIncomingRelations(MBaseID id,
                                     Collection collections)
                              throws MBaseException

Description copied from interface: MBaseRef

Returns an iterator of MBaseRef.Relations objects describing the relations that point to this item. If the item is a theory, the relations are the imports statements.

Specified by:

getIncomingRelations in interface MBaseRef

Parameters:

id - the id from which to see the relations

collections - from where should these relations be incoming

Returns:

an iterator of MBaseRef.Relations objects

Throws:

MBaseException - if anything

getOutgoingRelations

public Iterator getOutgoingRelations(MBaseID id)
                              throws MBaseException

Description copied from interface: MBaseRef

Returns an iterator of MBaseRef.Relations objects describing the relations that point from this item. If the item is a theory, the relations are the imports statements.

Specified by:

getOutgoingRelations in interface MBaseRef

Parameters:

id - the id from which to see the relations

Returns:

an iterator of MBaseRef.Relations objects

Throws:

MBaseException - if anything

getMBase

protected MBaseRef getMBase(MBaseID forContent)
                     throws MBaseCollectionNotProvidedException

finds an appropriate MBase to query and returns the result. The MBase is only compared using the collection part of the given ID. If the content's collection is provided by different connections, one of them is chosen at random.

Parameters:

forContent - MBaseID with the requested content

Returns:

MBaseRef that can serve this request

Throws:

MBaseCollectionNotProvidedException - if the collection part of the MBaseID is not amongst the providedCollections

getMBase

protected MBaseRef getMBase(String forCollection)
                     throws MBaseCollectionNotProvidedException

finds an appropriate MBase to query and returns the result. The MBase is only compared using the collection part of the given ID. If the content's collection is provided by different connections, one of them is chosen at random.

Parameters:

forCollection - String identifying the collection to focus on

Returns:

MBaseRef that can serve this request

Throws:

MBaseCollectionNotProvidedException - if the collection part of the MBaseID is not amongst the providedCollections

registerConnections

protected void registerConnections(Collection connections)
                            throws MBaseException

registers the given connections of MBaseRefs to the connectedMBaseHash hashtable.

Parameters:

connections - Collection with connections to register

Throws:

MBaseException - If some connection fails

assertCollectionCompatibility

protected void assertCollectionCompatibility(Collection collections)
                                      throws MBaseCollectionNotProvidedException

makes sure the given collections Collection only contains the collection this MBase provides

Parameters:

collections - Collection given

Throws:

MBaseCollectionNotProvidedException - if an unprovided collection is requested