XMLParserItf Interface CATISAXEntityResolver

Usage: you can freely reimplement this interface.

interface CATISAXEntityResolver

Interface for resolving entities.

If a SAX application needs to implement customized handling for external entities, it must implement this interface and register an instance with the SAX parser using the parser method .

The parser will then allow the application to intercept any external entities (including the external DTD subset and external parameter entities, if any) before including them.

Many SAX applications will not need to implement this interface, but it will be especially useful for applications that build XML documents from databases or other specialised input sources, or for applications that use URI types other than URLs.

The following resolver would provide the application with a special character stream for the entity with the system identifier "http://www.myhost.com/today":

 #include "CATISAXEntityResolver.h"
 #include "CATISAXInputSource.h"
	
 class MyResolver : public CATBaseUnknown {
     public:
         HRESULT ResolveEntity (
             const CATUnicodeString & iPublicId, 
             const CATUnicodeString & iSystemId, 
             CATISAXInputSource *& oInputSource);
         ...
 };
 
 // Declaration of the class as a CNext implementation class.
 CATImplementClass( MyResolver, Implementation, CATBaseUnknown, CATnull );
 
 // Implement the CATISAXEntityResolver interface.
 #include "TIE_CATISAXEntityResolver.h"
 TIE_CATISAXEntityResolver( MyResolver );
 
 
 HRESULT MyResolver::ResolveEntity (
     const CATUnicodeString & iPublicId, 
     const CATUnicodeString & iSystemId, 
     CATISAXInputSource *& oInputSource) {
 
     HRESULT hr = E_FAIL;
     oInputSource = NULL;
     if (iSystemId == "http://www.myhost.com/today") {
         hr = CATISAXInputSourceFactory::CreateURLInputSource(iSystemId, oInputSource);
     }
     return hr;
 }

The application can also use this interface to redirect system identifiers to local URIs or to look up replacements in a catalog (possibly by using the public identifier).

The class implements the default behaviour for this interface, which is simply always to return NULL (to request that the parser use the default system identifier).

See also:

, ,

Method Index

o ResolveEntity(CATUnicodeString&,CATUnicodeString&,CATISAXInputSource_var&)

Allows the application to resolve external entities.

Methods

Allows the application to resolve external entities.

The will call this method before opening any external entity except the top-level document entity (including the external DTD subset, external entities referenced within the DTD, and external entities referenced within the document element): the application may request that the parser resolve the entity itself, that it use an alternative URI, or that it use an entirely different input source.

Application writers can use this method to redirect external system identifiers to secure and/or local URIs, to look up public identifiers in a catalogue, or to read an entity from a database or other input source (including, for example, a dialog box).

If the system identifier is a URL, the SAX parser must resolve it fully before reporting it to the application.

Parameters:

iPublicId

The public identifier of the external entity being referenced (can be an empty

if no public identifier was given).

iSystemId

The system identifier of the external entity being referenced.

oInputSource

An InputSource object describing the new input source, or NULL to request that the parser open a regular URI connection to the system identifier.

Errors Returned:

Error Class	Error Id	Description
	XMLParserERR_2000	The method can raise a CATSAXException
	XMLParserERR_2001	If an I/O error occurs, possibly the result of creating a new the method can raise this error.

See also:

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