org.mmbase.bridge
Interface Cloud

All Known Subinterfaces:
Transaction
All Known Implementing Classes:
BasicCloud, RemoteCloud_Impl, RemoteTransaction_Impl

public interface Cloud

A Cloud is a collection of Nodes (and relations that are also nodes). A Cloud is part of a CloudContexts.

Version:
$Id: Cloud.java,v 1.24 2002/02/05 12:57:06 michiel Exp $
Author:
Rob Vermeulen, Pierre van Rooden, Jaco de Groot

Method Summary
 Transaction createTransaction()
          Creates a transaction on this cloud.
 Transaction createTransaction(java.lang.String name)
          Creates a transaction on this cloud with a specified name.
 Transaction createTransaction(java.lang.String name, boolean overwrite)
          Creates a transaction on this cloud with a specified name.
 CloudContext getCloudContext()
          Returns the context to which this cloud belongs.
 java.lang.String getDescription()
          Returns the description of the cloud.
 NodeList getList(java.lang.String startNodes, java.lang.String nodePath, java.lang.String fields, java.lang.String constraints, java.lang.String orderby, java.lang.String directions, java.lang.String searchDir, boolean distinct)
          Returns a list of virtual nodes that are composed by fields of other nodes.
 java.lang.String getName()
          Returns the name of this cloud.
 Node getNode(int number)
          Returns the node with the specified number from this cloud.
 Node getNode(java.lang.String number)
          Returns the node with the specified number from this cloud.
 Node getNodeByAlias(java.lang.String alias)
          Returns the node with the specified alias from this cloud.
 NodeManager getNodeManager(java.lang.String name)
          Returns the specified node manager.
 NodeManagerList getNodeManagers()
          Returns all node managers available in this cloud.
 RelationManager getRelationManager(java.lang.String roleName)
          Returns the specified relation manager.
 RelationManager getRelationManager(java.lang.String sourceManagerName, java.lang.String destinationManagerName, java.lang.String roleName)
          Returns the specified relation manager.
 RelationManagerList getRelationManagers()
          Returns all relation managers available in this cloud.
 Transaction getTransaction(java.lang.String name)
          Returnes the transaction with the specified name.
 User getUser()
          Who is using this cloud.
 

Method Detail

getNode

public Node getNode(int number)
Returns the node with the specified number from this cloud. The returned node is a new instance of Node with a reference to this instance of Cloud.
Parameters:
number - the number of the requested node
Returns:
the requested node
Throws:
NotFoundException - if the specified node could not be found

getNode

public Node getNode(java.lang.String number)
Returns the node with the specified number from this cloud. The returned node is a new instance of Node with a reference to this instance of Cloud.
Parameters:
number - the number of the requested node
Returns:
the requested node
Throws:
NotFoundException - if the specified node could not be found

getNodeByAlias

public Node getNodeByAlias(java.lang.String alias)
Returns the node with the specified alias from this cloud. The returned node is a new instance of Node with a reference to this instance of Cloud.
Parameters:
alias - the alias of the requested node
Returns:
the requested node
Throws:
NotFoundException - if the specified node could not be found

getNodeManagers

public NodeManagerList getNodeManagers()
Returns all node managers available in this cloud.
Returns:
a NodeManagerList containing all node managers available in this cloud.

getNodeManager

public NodeManager getNodeManager(java.lang.String name)
Returns the specified node manager.
Parameters:
name - the name of the requested node manager
Returns:
the requested node manager
Throws:
NodeManagerNotFoundException - if the specified node manager could not be found

getRelationManager

public RelationManager getRelationManager(java.lang.String sourceManagerName,
                                          java.lang.String destinationManagerName,
                                          java.lang.String roleName)
Returns the specified relation manager.
Parameters:
sourceManagerName - name of the node manager of the source node
destinationManagerName - name of the node manager of the destination node
roleName - name of the role
Returns:
the requested relation manager
Throws:
RelationManagerNotFoundException - if the specified relation manager could not be found

getRelationManager

public RelationManager getRelationManager(java.lang.String roleName)
Returns the specified relation manager. This is a very generic Relation Manager, which does not contain type information (it does, however, validate new relations).
Parameters:
roleName - name of the role
Returns:
the requested relation manager
Throws:
RelationManagerNotFoundException - if the specified relation manager could not be found

getRelationManagers

public RelationManagerList getRelationManagers()
Returns all relation managers available in this cloud.
Returns:
a RelationManagerList containing all relation managers available in this cloud

getCloudContext

public CloudContext getCloudContext()
Returns the context to which this cloud belongs.
Returns:
a CloudContext to which this cloud belongs

createTransaction

public Transaction createTransaction()
Creates a transaction on this cloud. The returned Transaction will have a generic ID.
Returns:
a Transaction on this cloud

createTransaction

public Transaction createTransaction(java.lang.String name)
Creates a transaction on this cloud with a specified name.
Parameters:
name - an unique name to use for the transaction
Returns:
a Transaction on this cloud
Throws:
TransactionAllreadyExistsException - if a transaction with the specified name allready exists

createTransaction

public Transaction createTransaction(java.lang.String name,
                                     boolean overwrite)
Creates a transaction on this cloud with a specified name.
Parameters:
name - an unique name to use for the transaction
overwrite - if true, cancels and the replaces any existing transaction of this name for the current user
Returns:
a Transaction on this cloud
Throws:
TransactionAllreadyExistsException - if a transaction with the specified name allready exists and overwrite is false

getTransaction

public Transaction getTransaction(java.lang.String name)
Returnes the transaction with the specified name. If no active transaction exists, a new transaction is craeted.
Parameters:
name - the name of the requested transaction
Returns:
the requested transaction

getName

public java.lang.String getName()
Returns the name of this cloud.
Returns:
the name of this cloud

getDescription

public java.lang.String getDescription()
Returns the description of the cloud.
Returns:
the description of this cloud

getUser

public User getUser()
Who is using this cloud.
Returns:
the User object describing who is using this cloud now.

getList

public NodeList getList(java.lang.String startNodes,
                        java.lang.String nodePath,
                        java.lang.String fields,
                        java.lang.String constraints,
                        java.lang.String orderby,
                        java.lang.String directions,
                        java.lang.String searchDir,
                        boolean distinct)
Returns a list of virtual nodes that are composed by fields of other nodes. Starting at one or more specified nodes traversals are made according to a specified path. One traversal makes up one virtual node. All possible traversals that can be made starting at one or more nodes of the same type and following a specified path are stored in the returned list. Suppose we have defined the following:
 - A node manager recordcompany containing a field name.
 - A node manager artist containing a field name.
 - A node manager url containing a field description and url.
 - A relation type related between recordcompany and artist.
 - A relation type related between artist and url.
 - A relation type homepagerel between artist and url.
 
If node 100 has a node manager called recordcompany we can do the following to get a list of the record company's artists and all urls belonging to these artist (including nodes found through the related relation and the homepagerel relation):
 getList("100", "recordcompany,artist,url",
         "artist.name,description,url", null, null, null, null, true);
 
This call returns a list of virtual nodes with the fields artist.name, description and url for every valid traversal.

If we only want to list homepage urls of the artists we do:

 getList("100", "recordcompany,artist,url",
         "artist.name,description,homepagerel,url", null, null, null,
         null, true);
 

If we want to list all url's except the the homepage urls we do:

 getList("100", "recordcompany,artist,url",
         "artist.name,description,related,url", null, null, null, null, true);
 

If node 200 also has a node manager with name recordcompany we can get the info from their artist together with the info of the artist from the first company by also putting number 200 in the first parameter:

 getList("100,200", "recordcompany,artist,url",
         "artist.name,description,related,url", null, null, null, null, true);
 
For more information about the constraints parameter consult NodeManager.getList(String constraints, String orderby, String directions).
Parameters:
startNodes - A comma separated list of node numbers that should be used as a starting point for all traversals or null if all nodes of the first node manager in nodePath should be used.
nodePath - A comma seperated list of node manager names which specifies the path that should be followed. It is possible to explicitly specify a relation manager that should be used to go from one node to an other. If no relation manager is specified between two nodes, all possible relation managers that can be used to go to the next specified node in the path are followed.
fields - A comma separated list of field names that will make up the returned virtual nodes. A fieldname can be prefixed with the original node manager name of the field and a dot in cases where more than one node manager in the path has a field with the same name.
constraints - Contraints to prevent nodes from being included in the resulting list which would normally by included or null if no contraints should be applied.
orderby - A comma separated list of field names on which the returned list should be sorted or null if the order of the returned virtual nodes doesn't matter.
directions - A comma separated list of values indicating wether to sort up (ascending) or down (descending) on the corresponding field in the orderby parameter or null if sorting on all fields should be up. The value DOWN (case insensitive) indicates that sorting on the corresponding field should be down, all other values (including the empty value) indicate that sorting on the corresponding field should be up. If the number of values found in this parameter are less than the number of fields in the orderby parameter, all fields that don't have a corresponding direction value are sorted according to the last specified direction value.
searchDir - Determines how directionality affects the search. This is a string with the following possible values:
"both", which is the default, searches for all valid relations through a path, checking full directionality of relations where appropriate. "destination" searches for only those relations in a path where valid relations exist from source to destination, in the order of the nodemanagers given in the nodePath. "source" searches for only those relations in a path where valid relations exist from destination to source, in the order of the nodemanagers given in the nodePath. "all" searches all existing relations, and does not check on directionality. A value of null or any other values than those listed above are ignored. In that case, search is treated as if the default ("both") was specified.
distinct - true if nodes who allready exist in the list should not be added to the list. false if all nodes should be added to the list even if a node with exactly the same field values is allready present.
Returns:
a list of virtual nodes


MMBase 2002