fr.gael.drb
Interface DrbFactoryImpl

All Known Subinterfaces:

DrbUpdateImpl

All Known Implementing Classes:

FileFactory, FtpFactory, GZipFactory, JarFactory, SdfFactory, TarFactory, XmlFactory, ZipFactory

public interface DrbFactoryImpl

Common interface for Node factory implementations. All the classes implementing this interface can be used by the DrbFactory class. As a summary, the "Data Request Broker" (DRB) implementations are packages that break down a specific data resource (e.g. an XML document, an HTML file, a Zip archive, a database, etc.) into a tree of DrbNode instances.

As an example, an implementation may handle file systems, breaking down the hard disk devices into directories and regular files. Another one may provide nodes corresponding to the tables and records of a database.

The factory implementations are supposed to be used by the DrbFactory class and not outside. It may however be useful to create DrbNodes directly from a specific implementation disregarding the DrbFactory abstract level. It is therefore recommended to be careful in such situation.

Here are some examples of direct use of this interface to open DrbNodes from a path, maybe with an existing context. The following examples are not supposed to work with existing implementations but intends to provides an overview of the DrbFactoryImpl interface. Report to the implementations specific documentations for an accurate description of their use:

Method Summary

String	getIdentifier() The scheme identifier of the implementation.
String	getName() The name of the implementation.
DrbNode	open(DrbNode base_node) Opens the node from an existing node.
DrbNode	open(URL uri) Opens the node matching a given path.
DrbNode	open(URL uri, DrbNode base_node) Opens the node matching a given URI from an existing node.

Method Detail

getIdentifier

String getIdentifier()

The scheme identifier of the implementation. This string is short name identifying univocally the implementation regarding the others. Basically the identifier shall be composed of lowercase characters and shall nearly be composed of alpabetical characters. The returned identifier shall never be null.

Returns:

The identifier of the implementation.

getName

String getName()

The name of the implementation. This name is the full explicit name of the implementation. Because other operations are supposed to provide configuration management information, it is not necessary to embed any version or release numbers in the name string. The returned name shall never be null.

Returns:

The name of the implementation.

open

DrbNode open(URL uri)

Opens the node matching a given path. This operation creates and returns a DrbNode corresponding to the given "Uniform Resource Identifier" (URI). Because URL class provided by java.net package supports the URI specifications, it has been used has URI parameter. The implementation is supposed to be able to handle the URI with a default or absolute context.

open

DrbNode open(DrbNode base_node)

Opens the node from an existing node. This operation creates and returns a DrbNode using an existing node as base or context. The input DrbNode has to be used as base of the creation. If the implementation is not able to handle any input node, it shall always return null. The reference to the input shall not be null.

Parameters:

base_node - The input node to be used as context or base. This parameter shall not be null.

Returns:

A root node or null if an error occured or if the implementation does not supports the input node.

open

DrbNode open(URL uri,
             DrbNode base_node)

Opens the node matching a given URI from an existing node. This operation creates and returns a DrbNode corresponding to the given "Uniform Resource Identifier" (URI) using an existing node as base or context. Because URL class provided by java.net package supports the URI specifications, it has been used has URI parameter. The input DrbNode has to be used as base of the creation. If the implementation is not able to handle any input node, it shall always return null even if it is able to use the passed URI standalone. If the reference to the URI is null the operation works as the open(DrbNode baseNode). Similary, if the URI reference is null, the operation works as the open(URL uri).