Skip Headers
Oracle® Outside In XML Export Developer's Guide
Release 8.4.1
Part Number E12888-05
Go to Documentation Home
Home		 Go to Table of Contents
Contents		 Go to Index
Index		 Go to Feedback page
Contact Us
Go to previous page
Previous		 Go to next page
Next
View PDF

4 Data Access Common Functions

The Data Access module is common to all Outside In technologies. It provides a way to open a generic handle to a source file. This handle can then be used in the functions described in this chapter.

This chapter includes the following sections:

4.1 Deprecated Functions

DAInit and DaThreadInit have both been deprecated. DAInitEx now replaces these two functions. All new implementations should use DAInitEX, although the other two functions will continue to be supported.

4.2 DAInitEx

This function tells the Data Access module to perform any necessary initialization it needs to prepare for document access. This function must be called before the first time the application uses the module to retrieve data from any document. This function supersedes the old DAInit and DAThreadInit functions.

Note:

DAInitEx should only be called once per application, at application startup time. Any number of documents can be opened for access between calls to DAInitEx and DADeInit. If DAInitEx succeeds, DADeInit must be called regardless of any other API calls.

If the ThreadOption parameter is set to something other than DATHREAD_INIT_NOTHREADS, then this function's preparation includes setting up mutex function pointers to prevent threads from clashing in critical sections of the technology's code. The developer must actually code the threads after this function has been called. DAInitEx should be called only once per process and should be called before the developer's application begins the thread.

Note:

Multiple threads are supported for all Windows platforms and the 32-bit versions of Linux x86 and Solaris SPARC. Failed initialization of the threading function will not impair other API calls. If threading isn't initialized or fails, stub functions are called instead of mutex functions.

Prototype

DAERR DAInitEx(VTSHORT ThreadOption, VTDWORD dwFlags);

Parameters

Return Values

4.3 DADeInit

This function tells the Data Access module that it will not be asked to read additional documents, so it should perform any cleanup tasks that may be necessary. This function should be called at application shutdown time, and only if the module was successfully initialized with a call to DAInitEx.

Prototype

DAERR DADeInit();

Return Values

4.4 DAOpenDocument

Opens a source file to make it accessible by one or more of the data access technologies. If DAOpenDocument succeeds, DACloseDocument must be called regardless of any other API calls.

For IO types other than IOTYPE_REDIRECT, the subdocument specification may be specified as part of the file's path. This is accomplished by appending a question mark delimiter to the path, followed by the subdocument specification. For example, to specify the third item within the file c:\docs\file.zip, specify the path c:\docs\file.zip?item.3 in the call to DAOpenDocument. DAOpenDocument always attempts to open the specification as a file first. In the unlikely event there is a file with the same name (including the question mark) as a file plus the subdocument specification, that file is opened instead of the archive item.

To take advantage of this feature when providing access to the input file using redirected IO, a subdocument specification must be provided via a response to an IOGetInfo message, IOGETINFO_SUBDOC_SPEC. To specify an item in an archive, first follow the standard redirected IO methods to provide a BASEIO pointer to the archive file itself. To specify an item within the archive, a redirected IO object must respond to the IOGETINFO_SUBDOC_SPEC message by copying to the supplied buffer the subdocument specification of the archive item to be opened. This message is received during the processing of DAOpenDocument.

Prototype

DAERR DAOpenDocument(
   VTLPHDOC   lphDoc,
   VTDWORD    dwSpecType,
   VTLPVOID   pSpec,
   VTDWORD    dwFlags);

Parameters

Return Values

4.4.1 IOSPECLINKEDOBJECT Structure

Structure used by DAOpenDocument.

Prototype

typedef struct IOSPECLINKEDOBJECTtag
   {
   VTDWORD    dwStructSize;
   VTSYSPARAM hDoc;
   VTDWORD    dwObjectId;  /* Object identifier. */
   VTDWORD    dwType;      /* Linked Object type */
                           /* (SO_LOCATORTYPE_*) */
   VTDWORD    dwParam1;    /* parameter for DoSpecial call */
   VTDWORD    dwParam2;    /* parameter for DoSpecial call */
   VTDWORD    dwReserved1; /* Reserved. */
   VTDWORD    dwReserved2; /* Reserved. */
} IOSPECLINKEDOBJECT,  * PIOSPECLINKEDOBJECT;

4.4.2 IOSPECARCHIVEOBJECT Structure

Structure used by DAOpenDocument.

Prototype

typedef struct IOSPECARCHIVEOBJECTtag
   {
   VTDWORD dwStructSize;
   VTDWORD hDoc;        /* Parent Doc hDoc */
   VTDWORD dwNodeId;    /* Node ID */
   VTDWORD dwStreamId; 
   VTDWORD dwReserved1; /* Must always be 0 */
   VTDWORD dwReserved2; /* Must always be 0 */
} IOSPECARCHIVEOBJECT,  * PIOSPECARCHIVEOBJECT;

4.5 DAOpenSubdocumentById

Allows an embedding to be opened using the integer value of the object_id attribute from the locator element.

Prototype

DAERR DAOpenSubdocumentById(
   VTHDOC     hDoc,
   VTLPHDOC   lphDoc,
   VTDWORD    pSpec,
   VTDWORD    dwFlags);

Parameters

4.6 DACloseDocument

This function is called to close a file opened by the reader that has not encountered a fatal error.

Prototype

DAERR DACloseDocument(
   VTHDOC hDoc);

Parameters

Return Value

4.7 DARetrieveDocHandle

This function returns the document handle associated with any type of Data Access handle. This allows the developer to only keep the value of hItem, instead of both hItem and hDoc.

Prototype

DAERR DARetrieveDocHandle(
   VTHDOC     hItem,
   VTLPHDOC   phDoc);

Parameters

Return Value

4.8 DASetOption

This function is called to set the value of a data access option.

Prototype

DAERR DASetOption(
   VTHDOC      hDoc,
   VTDWORD     dwOptionId,
   VTLPVOID    pValue,
   VTDWORD     dwValueSize);

Parameters

Return Value

4.9 DAGetOption

This function is called to retrieve the value of a data access option. The results of a call to this option are only valid if DASetOption has already been called on the option.

Prototype

DAERR DAGetOption(
   VTHDOC    hItem,
   VTDWORD   dwOptionId,
   VTLPVOID  pValue,
   VTLPDWORD pSize);

Parameters

Return Value

4.10 DAGetFileId

This function allows the developer to retrieve the format of the file based on the technology's content-based file identification process. This can be used to make intelligent decisions about how to process the file and to give the user feedback about the format of the file they are working with.

Note: in cases where File ID returns a value of FI_UNKNOWN, then this function will apply the Fallback Format before returning a result.

Prototype

DAERR DAGetFileId(
   VTHDOC      hDoc,
   VTLPDWORD   pdwFileId);

Parameters

Return Value

4.11 DAGetFileIdEx

This function allows the developer to retrieve the format of the file based on the technology's content-based file identification process. This can be used to make intelligent decisions about how to process the file and to give the user feedback about the format of the file they are working with. This function has all the functionality of DAGetFileID and adds the ability to return the raw FI value; in other words, the value returned by normal FI, without applying the FallbackFI setting.

Prototype

DAERR DAGetFileIdEx(
   VTHDOC      hDoc,
   VTLPDWORD   pdwFileId,
   VTDWORD     dwFlags);

Parameters

Return Value

Values with RAWFI turned off

Input file type ExtendedFI FallbackID DAGetFileId DAGetFileIdEx

true binary

off

fallback value

fallback value

fallback value

true binary

on

fallback value

fallback value

fallback value

true text

off

fallback value

fallback value

fallback value

true text

on

fallback value

40XX

40XX

Values with RAWFI turned on

Input file type ExtendedFI FallbackID DAGetFileId DAGetFileIdEx

true binary

off

fallback value

fallback value

1999

true binary

on

fallback value

fallback value

1999

true text

off

fallback value

fallback value

1999

true text

on

fallback value

40XX

1999

4.12 DAGetErrorString

This function returns to the developer a string describing the input error code. If the error string returned does not fit the buffer provided, it is truncated.

VTVOID DAGetErrorString(
   DAERR      deError,
   VTLPVOID   pBuffer,
   VTDWORD    dwBufSize);

Parameters

Return Value

4.13 DAGetTreeCount

This function is called to retrieve the number of records in an archive file.

DAERR DAGetTreeCount(
      VTHDOC      hDoc,
      VTLPDWORD   lpRecordCount);

Parameters

Return Value

4.14 DAGetTreeRecord

This function is called to retrieve information about a record in an archive file.

DAERR DAGetTreeRecord(
      VTHDOC         hDoc,
      PSCCDATREENODE pTreeNode);

Parameters

Return Values

4.14.1 SCCDATREENODE Structure

This structure is passed by the OEM through the DAGetTreeRecord function. The structure is defined in sccda as follows:

typedef struct SCCDATREENODEtag{
   VTDWORD   dwSize;
   VTDWORD   dwNode;
   VTBYTE    szName[1024];
   VTDWORD   dwFileSize;
   VTDWORD   dwTime;
   VTDWORD   dwFlags;
   VTDWORD   dwCharSet;
   } SCCDATREENODE,  *PSCCDATREENODE;

Parameters

  • dwSize: Must be set by the OEM to sizeof(SCCDATREENODE).

  • dwNode: The number of the record to retrieve information about. The first node is node 0.

  • szName: A buffer to hold the name of the record.

  • dwFileSize: Returns the file size, in bytes, of the requested record.

  • dwTime: Returns the timestamp of the requested record, in MS-DOS time.

  • dwFlags: Returns additional information about the node. It can be a combination of the following:

    • SCCDA_TREENODEFLAG_FOLDER: Indicating that the selected node is a folder and not a file.

    • SCCDA_TREENODEFLAG_SELECTED: Indicating that the node is selected.

    • SCCDA_TREENODEFLAG_FOCUS: Indicating that the node has focus.

    • SCCDA_TREENODEFLAG_ENCRYPT: Indicating that the node is encrypted and can not be decrypted.

    • SCCDA_TREENODEFLAG_ARCKNOWNENCRYPT: indicating that the node is encrypted with an unknown encryption and can not be decrypted.

    • SCCDA_TREENODEFLAG_BUFFEROVERFLOW: the name of the node was too long for the szName field.

    Note:

    DAOBJECTFLAG_ARCKNOWNENCRYPT indicates that the object is protected by a known encryption. It can be accessed after the correct credentials (password and/or Lotus Notes id file) are provided through the File Access Callback. See DASetFileAccessCallback.

  • dwCharSet: Returns the SO_* (charsets.h) character set of the characters in szName. The output character set is either the default native environment character set or Unicode if the SCCOPT_SYSTEMFLAGS option is set to SCCVW_SYSTEM_UNICODE.

4.15 DAOpenTreeRecord

This function is called to open a record within an archive file and make it accessible by one or more of the data access technologies.

Search Export Only: Search Export's default behavior is to automatically open and process the contents of an archive. Use DAOpenTreeRecord and SCCOPT_XML_SEARCHML_FLAGS to change the default behavior if discrete processing of each document in an archive is desired.

DAERR DAOpenTreeRecord(
      VTHDOC      hDoc,
      VTLPHDOC    lphDoc,
      VTDWORD     dwRecord);

lphDoc is not a file handle.

Parameters

Return Value

4.16 DASaveTreeRecord

This function is called to extract a record in an archive file to disk.

DAERR DASaveTreeRecord(
      VTHDOC      hDoc,
      VTDWORD     dwRecord,
      VTDWORD     dwSpecType,
      VTLPVOID    pSpec,
      VTDWORD     dwFlags);

Parameters

Return Values

Currently, only extracting a single file is supported. There is a known limitation where files in a Microsoft Binder file cannot be extracted.

4.17 DACloseTreeRecord

This function is called to close an open record file handle.

Search Export Only: Search Export's default behavior is to automatically open and process the contents of an archive. Use DACloseTreeRecord and SCCOPT_XML_SEARCHML_FLAGS to change the default behavior if discrete processing of each document in an archive is desired.

DAERR DACloseTreeRecord(
      VTHDOC      hDoc);

Parameters

Return Value

4.18 DASetStatCallback

This function sets up a callback that the technology periodically calls to verify the file is still being processed. The customer can use this with a monitoring process to help identify files that may be hung. Because this function is called more frequently than other callbacks, it is implemented as a separate function.

Use of the Status Callback Function

An application's status callback function will be called periodically by Outside In to provide a status message. Currently, the only status message defined is OIT_STATUS_WORKING, which provides a "sign of life" that can be used during unusually long processing operations to verify that Outside In has not stopped working. If the application decides that it would not like to continue processing the current document, it may use the return value from this function to tell Outside In to abort.

The status callback function has two return values defined:

The following is an example of a minimal status callback function.

VTDWORD MyStatusCallback( VTHANDLE hUnique, VTDWORD dwID, VTSYSVAL
pCallbackData, VTSYSVAL pAppData)
{
    if(dwID == OIT_STATUS_WORKING)
    {
        if( checkNeedToAbort( pAppData ) )
            return (OIT_STATUS_ABORT);
    }
  
    return (OIT_STATUS_CONTINUE);
}

Prototype

DAERR DASetStatCallback(DASTATCALLBACKFN pCallback, 
   VTHANDLE hUnique, 
   VTLPVOID pAppData)

Parameters

The callback function should be of type DASTATCALLBACKFN. This function has the following signature:

(VTHANDLE hUnique, VTDWORD dwID, VTSYSVAL pCallbackData, VTSYSVAL pAppData)

Return Values

4.19 DASetFileAccessCallback

This function sets up a callback that the technology will call into to request information required to open an input file. This information may be the password of the file or a support file location.

Use of the File Access Callback

When the technology encounters a file that requires additional information to access its contents, the application's callback function will be called for this information. Currently, only two different forms of information will be requested: the password of a document, or the file used by Lotus Notes to authenticate the user information.

The status callback function has two return values defined:

This function will be repeatedly called if the information provided is not valid (such as the wrong password). It is the responsibility of the application to provide the correct information or return SCCERR_CANCEL.

Prototype

DAERR DASetFileAccessCallback (DAFILEACCESSCALLBACKFN pCallback);
   VTHANDLE hUnique, 
   VTLPVOID pAppData)

Parameters

Return Values

The callback function should be of type DAFILEACCESSCALLBACKFN. This function has the following signature:

typedef VTDWORD (* DAFILEACCESSCALLBACKFN)(VTDWORD dwID, VTSYSVAL pRequestData, VTSYSVAL pReturnData, VTDWORD dwReturnDataSize);

Note:

Not all formats that use passwords are supported. Only Microsoft Office binary (97-2003), Microsoft Office 2007, Lotus NSF, PDF (with RC4 encryption), Zip (with AES 128 & 256 bit, ZipCrypto) are currently supported.

Go to previous page
Previous		 Go to next page
Next
Go to Documentation Home
Home		 Go to Table of Contents
Contents		 Go to Index
Index		 Go to Feedback page
Contact Us