File Upload / Download - Advice Required

Question

Hi all,
This is really just a general question, looking for advice.
I have downloaded and successfully used the File Upload PJC for Forms 6i - thanks Oracle.
We are looking to use this to download and upload files from or to the client machine, and I am (relatively) confident of reversing the Java components to allow this to happen.
However, we are actually looking to transfer the files from the client machine, to the 9iAS Tier and then to the UNIX (AIX) tier where the database (8.1.7.4) resides - and vice versa.
I have considered a couple of different approaches :
1. Run the Java Server component in the Database JVM to enable the writing/reading of files on the UNIX filesystem.
2. Use TEXT_IO on the 9iAS tier, and UTL_FILE on the Database Tier, to move files between the two tiers.
3. Write the files to / from the Database, and then from/to there into the UNIX filesystem.
Does anyone have any expereince of attempting to implement a similar solution, or information on Oracle documentation explaining any of the above.
Plus, I'm sure I must be missing a trick !
Any other ideas ??
Regards
Marc Ludwig

Answer 1

We have build a similar solution,
for the download:
we use the pl/sql gateway to send the file to the client with the following function:
wpg_docload.download_File(lob_loc);
you could build a pl/sql procedure that accepts an id and selects the blob locater and
triggers this function. the procedure can be called by setting the configuration in your DAD correctly.
that way its easier then rebuilding the whole fileupload utility.
in the webforms you can have a code that opens a new window with an url you give.
the url will point to the pl/sql function and you can pass the id of the record you want to get the blob from.
for the upload to your database:
well, we chose to loose the zip functionality and modify the pl/sql library that comes with it.
instead of using the uploadserver class, you could build a pl/sql function in the database that
accepts the varchar32 strings (which are base64encoded chunks of your file) and appends them to a blob.
the function that could do that would look like:
PROCEDURE APPEND_DATA(P_ID IN NUMBER, P_DATA IN VARCHAR2) IS
bin_data blob;
append_data blob;
raw_data raw(16384);
BEGIN
dbms_lob.CREATETEMPORARY(append_data,true);
dbms_lob.OPEN(append_data,DBMS_LOB.LOB_READWRITE);
select binary_data into bin_data from ibs_physical_doc where id=P_ID for update;
raw_data:= utl_encode.BASE64_DECODE(utl_raw.CAST_TO_RAW(p_data));
dbms_lob.write(append_data, utl_raw.LENGTH(raw_data),1,raw_data);
dbms_lob.APPEND(bin_data,append_data);
dbms_lob.CLOSE(append_data);
COMMIT;
END;
you can increase the chunksize a bit more.
you still have a problem btw that you probably cant upload more then 4-8 mb before you get an out of memory error on the client.
you could solve that by rewriting the client java file to send the file piece by piece on request by the server instead of all the pieces after eachother, and first read a piece of the file and then encode that piece and then send it instead of reading the whole file, encoding it and sending the chunks.
Another option is to use the standard upload possibilties with web pl/sql, and open a new browser window to that window from forms. A drawback of that is that it is not integrated in the web forms program and that you cant see when the upload is finished (no callback). and that you are bound to the default table layout.
one final thing, if you are going to use this, you might want to take a look at using JInitiator 1.3.1.9 if you arent using it already this automaticly sets the signature in the clients database if he accepts it. there is a bug in it, look for it somewhere in this forum. if you are using the sample that comes with forms 6i you will have to replace the fileuploadprogressbar with the one that comes with the forms 9i sample and recompile everything and i think you will have to use JDK1.3.1_03 for that. that means that you will have to modify the make batch file. the command for compiling is different, the classpath is an option when you call javac, also you will have to sign it with jarsigner.exe (in the jdk) instead of the one in the example.
Hope this info is helpfull, if you like to have more specific code, mail me at [email protected]