276 WPG_DOCLOAD

The WPG_DOCLOAD package provides an interface to download files, BLOBs and BFILEs.

The chapter contains the following topics:

276.1 WPG_DOCLOAD Constants

WPG_DOCLOAD defines several constants to use when specifying parameter values.

The WPG_DOCLOAD constants are listed below:

  • NAME_COL_LEN

  • MIMET_COL_LEN

  • MAX_DOCTABLE_NAME_LEN

NAME_COL_LEN

The NAME column in your document table must be the same as the value of name_col_len.

name_col_len CONSTANT pls_integer := 64;

MIMET_COL_LEN

The MIME_TYPE column in your document table must be the same as the value of mimet_col_len.

mimet_col_len CONSTANT pls_integer := 48;

MAX_DOCTABLE_NAME_LEN

The name length of your document table must be less than max_doctable_name_len.

max_doctable_name_len CONSTANT pls_integer := 256;

276.2 Summary of WPG_DOCLOAD Subprograms

The WPG_DOCLOAD package uses one subprogram, the DOWNLOAD_FILE procedure.

Table 276-1 WPG_DOCLOAD Package Subprograms

Subprogram Description

DOWNLOAD_FILE Procedures

Downloads files, BLOBS and BFILES

276.2.1 DOWNLOAD_FILE Procedures

There are three versions of this download file procedure.

  • The first version downloads files and is invoked from within a document download procedure to signal the PL/SQL Gateway that p_filename is to be downloaded from the document table to the client's browser.

  • The second version can be called from within any procedure to signal the PL/SQL Gateway that p_blob is to be downloaded to the client's browser.

  • The third version can be called from within any procedure to signal the PL/SQL Gateway that p_bfile is to be downloaded to the client's browser.

Syntax

WPG_DOCLOAD.DOWNLOAD_FILE(
   p_filename      IN             VARCHAR2, 
   p_bcaching      IN             BOOLEAN DEFAULT TRUE);

WPG_DOCLOAD.DOWNLOAD_FILE(
   p_blob          IN OUT NOCOPY  BLOB);

WPG_DOCLOAD.DOWNLOAD_FILE(
   p_bfile         IN OUT         BFILE);

Parameters

Table 276-2 DOWNLOAD_FILE Procedure Parameters

Parameter Description

p_filename

The file to download from the document table.

p_blob

The BLOB to download.

p_bfile

The BFILE to download (see Usage Notes).

p_bcaching

Whether browser caching is enabled (see Usage Notes).

Usage Notes

  • Normally, a document will be downloaded to the browser unless the browser sends an 'If-Modified-Since' header to the gateway indicating that it has the requested document in its cache. In that case, the gateway will determine if the browser's cached copy is up to date, and if it is, it will send an HTTP 304 status message to the browser indicating that the browser should display the cached copy. However, because a document URL and a document do not necessarily have a one-to-one relationship in the PL/SQL Web Gateway, in some cases it may be undesirable to have the cached copy of a document displayed. In those cases, the p_bcaching parameter should be set to FALSE to indicate to the gateway to ignore the 'If-Modified-Since' header, and download the document.

  • p_bfile and p_blob are declared as IN OUT because the locator is initially opened to check for file accessibility and existence. The open operation can only be performed if the locator is writable and readable.