Downloading blob content from a custom table

Question

In our hosted Apex application, the following code from the Application Express Developer's Guide works great for allowing a user to download blob content from one of our custom tables via a download button. However, the code doesn't work on the Oracle Cloud because the "owa_util" package is no longer available. The code is as follows:
CREATE OR REPLACE PROCEDURE download_my_file(p_file in number) AS
v_mime VARCHAR2(48);
v_length NUMBER;
v_file_name VARCHAR2(2000);
Lob_loc BLOB;
BEGIN
SELECT MIME_TYPE, BLOB_CONTENT, name,DBMS_LOB.GETLENGTH(blob_content)
INTO v_mime,lob_loc,v_file_name,v_length
FROM file_subjects
WHERE id = p_file;
-- set up HTTP header
-- use an NVL around the mime type and
-- if it is a null set it to application/octect
-- application/octect may launch a download window from windows
owa_util.mime_header( nvl(v_mime,'application/octet'), FALSE );
-- set the size so the browser knows how much to download
htp.p('Content-length: ' || v_length);
-- the filename will be used by the browser if the users does a save as
htp.p('Content-Disposition: attachment; filename="'||replace(replace(substr(v_file_name,instr(v_file_name,'/')+1),chr(10),null),chr(13),null)|| '"');
-- close the headers
owa_util.http_header_close;
-- download the BLOB
wpg_docload.download_file( Lob_loc );
end download_my_file;
Besides using web services, does anyone know of a way to do this? Is there a way to add access to the "owa_util" package in the cloud? I have also tried apex_util.get_blob_file_src but that is also unavailable in the Oracle Cloud.
Thanks,
Steve

Answer 1

Following Joel's advice:
The way I solved this was to split the code between two page processes and one application process. The download button first calls a page process to move the report data into a blob column and then calls another page process which is of "run application process" type. This calls the application level process where the download code, shown below, is called.
Notice the following changes to the code from the one posted earlier (also from Joel)
1) added sys.htp.init;
2) "sys." to all htp, owa and wpg_docload calls
3) added apex_application.stop_apex_engine; after the wpg_docload statement at the bottom of the script.
Now the download button launches a "save as" dialog box and the report content is downloaded to the client.
The code now looks like:
CREATE OR REPLACE PROCEDURE download_my_file(p_file in number) AS
v_mime VARCHAR2(48);
v_length NUMBER;
v_file_name VARCHAR2(2000);
Lob_loc BLOB;
BEGIN
SELECT MIME_TYPE, BLOB_CONTENT, name,DBMS_LOB.GETLENGTH(blob_content)
INTO v_mime,lob_loc,v_file_name,v_length
FROM oehr_file_subject
WHERE id = p_file;
-- set up HTTP header
-- use an NVL around the mime type and
-- if it is a null set it to application/octect
-- application/octect may launch a download window from windows
sys.htp.init;
sys.owa_util.mime_header( nvl(v_mime,'application/octet'), FALSE );
-- set the size so the browser knows how much to download
sys.htp.p('Content-length: ' || v_length);
-- the filename will be used by the browser if the users does a save as
sys. htp.p('Content-Disposition: attachment; filename="'||replace(replace(substr(v_file_name,instr(v_file_name,'/')+1),chr(10),null),chr(13),null)|| '"');
-- close the headers
sys.owa_util.http_header_close;
-- download the BLOB
sys.wpg_docload.download_file( Lob_loc );
apex_application.stop_apex_engine;
end download_my_file;
Thanks Joel for your help.
Steve