// Copyright (c) 2006-2009 Nokia Corporation and/or its subsidiary(-ies).
// All rights reserved.
// This component and the accompanying materials are made available
// under the terms of the License "Eclipse Public License v1.0"
// which accompanies this distribution, and is available
// at the URL "http://www.eclipse.org/legal/epl-v10.html".
//
// Initial Contributors:
// Nokia Corporation - initial contribution.
//
// Contributors:
//
// Description:
// NOTE: For the purpose of clarity we have ommitted full error checking in the 
// <hr>
// The Supplier API allows agents to publicise the MIME types they are 
// interested in. When those files arrive on the device, message handling
// applications can check these MIME types and import the file 
// into CAF. The agent transforms the file into a different format
// for use within the device. 
// In most cases this won't be necessary, since the files will arrive in the 
// same format that they will be used in. However, some agents require the device 
// to protect (encrypt) the content at the moment it arrives; the Supplier 
// API fulfills that role.
// The classes used in the supply operation are:
// <code>ContentAccess::CSupplier</code> and instances of <code>ContentAccess::CImportFile</code>.
// <hr>
// The <code>ContentAccess::CSupplier</code> is designed to allow several unrelated files to be imported 
// into CAF. It uses its <code>ContentAccess::CAgentResolver</code> member to determine 
// which CA agent should be used to import each file. The <code>CAgentResolver</code> builds 
// a list of all agents when it is created and updates the list if new agents
// are installed.
// A typical import session will start with the creation of a <code>CSupplier</code>, e.g.,
// //Create Supplier
// CSupplier *mySupplier = CSupplier::NewL();
// Most applications will have a preference for the directory where output files
// are to be stored. Usually the first thing to do with the new <code>CSupplier</code> instance 
// is to set the output path. 
// //Set output path for DRM protected content
// _LIT(KPath,"C:\myOutputFiles");
// mySupplier->SetOutputDirectoryL(KPath());
// It is not necessary to set the output path if the application
// provides output file handles to the agent.
// <hr>
// <b> Check that the MIME type is supported </b>
// Before importing a file into the content access framework, an application
// should check that the MIME type of the file is supported. Each agent publishes a 
// list of the MIME types it supports. The list is configured in the agent's 
// resource file and can be checked using <code>ContentAccess::CSupplier::IsImportSupported()</code>
// if(!mySupplier->IsImportSupported(myMimeType))
// return;
// <b> Create a CMetaDataList object </b>
// The <code>CMetaDataList</code> object is used to store any information associated with the import file that
// may be useful for the agent. These values will be passed to the agent.
// For example OMA DRM 1.0 files sometimes arrive with the HTTP header 
// <code>X-Oma-Drm-Separate-Delivery</code>. This informs the agent how long before rights are expected 
// for the content. If the rights were expected in 12 seconds it would be something like 
// the following:
// // Create meta-data array
// CMetaDataArray *metaDataArray = new (ELeave) CMetaDataArray();
// CleanupStack::PushL(metaDataArray);
// // Add any useful information we can think of....
// metaDataArray->AddL(_L("Content Type"), _L("application/vnd.oma.drm.dm"));
// metaDataArray->AddL(_L("X-Oma-Drm-Separate-Delivery"), _L("12"));
// The file is 'written' to CAF using a <code>ContentAccess::CImportFile</code> object. 
// <code>ContentAccess::CSupplier::ImportFile()</code> creates an <code>CImportFile</code> object for importing a file. 
// The parameters supplied indicate whether the agent will create the output files or whether
// the application using CAF will generate output files for the agent on demand.
// // Create the import object, passing in the metaDataArray created earlier
// // The application will supply the output files
// CImportFile *import = mySupplier->ImportFileL(sourceMimeType, *metaDataArray);
// The application should now transfer the file to CAF using the <code>CImportFile</code> object. 
// Only one file can be transferred by each instance although several output files
// may be produced. Applications should create new <code>CImportFile</code> objects in order to import more files.
// <b> Agents Generating the Output files </b>
// If the application wants the agent to generate the output files, it should supply a suggested
// file name in the call to <code>CSupplier::ImportFile()</code>. Even if this parameter is a zero length
// descriptor, it still indicates that the agent is responsible for generating output files.
// Agents will create the output files in a directory nominated by the application when it called
// <code>CSupplier::SetOutputDirectoryL()</code> or they may decide to store the output files in their private 
// directory.
// Applications should check at the end of the import to find out how many output files were created
// and where they are stored.
// <b> Application generating the Output files</b>
// If no suggested file name is passed to the agent, the application will provide output files for
// the agent to use. This mechanism allows applications to open files in their own private directory and 
// ask the CAF agent to store the output in those files. 
// The way it works is the same as an any other import operation, the difference is that the call 
// to <code>CImportFile::WriteData()</code> or <code>CImportFile::WriteComplete()</code> may return an error code of 
// <code>KErrCANewFileHandleRequired</code>. 
// This error code indicates that the agent needs a new output file handle in order to continue. The 
// application should open a new output file with write access and call <code>CImportFile::ContinueWithNewOutputFile()</code> 
// to supply the new handle to the agent. It is possible that further handles may be needed, if so 
// <code>CImportFile::ContinueWithNewOutputFile()</code> will return <code>KErrCANewFileHandleRequired</code> and the application should 
// repeat the procedure with another file.
// The agent must cache its state before returning <code>KErrCANewFileHandleRequired</code>. The application MUST NOT resend
// the same <code>WriteData()</code> or <code>WriteComplete()</code> command.
// At the end of the import operation the output files will still be listed regardless of whether
// they were supplied by the application or the agent.
// <hr>
// <code>ContentAccess::CImportFile</code> is the class used to write the file data to CAF. 
// It is created by <code>ContentAccess::CSupplier</code> and can only be used to import a single file.
// An application should call <code>WriteData()</code> to transfer a field in 'chunks' to the Content 
// Access Framework. Usually this would be something like the following:
// TFileName fileName;
// TBuf8<128> data;
// TInt err = KErrNone;
// // start importing content
// while( (source still has data) && (err==KErrNone) )
// source.read(data);
// err = import->WriteData(data);
// // need to supply new file to import to ?
// while (err == KErrCANewFileHandleRequired)		
// // supply new file in order to continue writing
// RFile newFile;
// import->GetSuggestedOutputFileName(fileName);
// newFile.Open(fileName, EFileWrite);
// err = import->ContinueWithNewOutputFile(newFile, fileName);
// newFile.Close();
// <hr>
// When all the data is written, the application should call <code>ContentAccess::CImportFile::WriteComplete()</code>, this will 
// let the agent know that all the data has been transferred and allow it to perform any final processing.
// err = import->WriteComplete();
// // When application supplies file handles it must always check to see if 
// // the agent needs a new file handle
// while(err == KErrCANewFileHandleRequired)
// RFile newFile;
// import->GetSuggestedOutputFileName(fileName);
// newFile.Open(fileName, EFileWrite);
// err = import->ContinueWithNewOutputFile(newFile, filename);
// // It is possible that the agent needs yet another file handle
// newFile.Close();   // agent makes a copy so we don't need to keep our file handle
// At this stage all the agent's work is done, the <code>CImportFile</code> object can be deleted.
// <hr>
// When the import is finished the application may wish to check if any output files have 
// been produced. The list of output files is accessed using <code>ContentAccess::CImportFile::OutputFileL()</code>.
// // loop over all the output files produced
// for(TInt i =0; i < import->OutputFileCountL(); i++)
// // Can now retrieve filename, type of file (receipt or content) and 
// // MIME type for the file produced
// TPtr filename =	import->OutputFileL(i).FileName();
// TOutputType type = import->OutputFileL(i).OutputType();
// TPtr8 mimetype = import->OutputFileL(i).MimeType();
// The output files can be either content files or receipts for DRM rights. It is possible that no output
// files will be generated and the file will be "absorbed" into the agent.
// Also, it is important to remember that the MIME type and most likely the file extension of the output files are 
// almost certainly different to the MIME type and file extension of the imported file.
// <hr>
// 
//

/**
 @page CSupplierAPI Importing files into the Content Access Framework
 - @ref SupplierAPI
 - @ref ImportSession
 - @ref ImportCAF
 - @ref Importfile
 - @ref ImportComplete 
 - @ref ImportOutput
 code examples given below. For examples with error checking see @ref ExampleSupplier2.
 @section SupplierAPI Supplier API
 @section ImportSession Starting a new import session
 @code
 @endcode
 @code
 @endcode
 @section ImportCAF Preparing to import the file
 @code
 @endcode
 @code
 @endcode
 @section ImportFile Creating the CImportFile object
 @code
 @endcode
 @section Importfile Transferring the file to the Content Access Agent
 @code
 @endcode
 @section ImportComplete Completing the Import
 @code 
 @endcode
 @section ImportOutput Output files produced
 @code
 @endcode
*/