LRECL for sending images from mainframes.

vasanthz · Posted: Fri Nov 13, 2009 6:46 pm

Hi,

An image e.g. company_logo.gif was transferred from desktop to mainframes in binary format into a FB file of LRECL 300.

The PS file has some fuzzy data of the image as shown,

Robert Sample · Posted: Fri Nov 13, 2009 7:21 pm

I don't remember ever getting an image to transfer through SMTP. I don't know if that's due to SMTP issues or my lack of knowledge, though.

The LRECL should not affect the transfer if it is done correctly. However, CONTENT-TYPE: TEXT/RICH TEXT is absolutely not going to work. Images are binary files and have to be transferred as such. Transferring as a text file, the records will be terminated with 0D0A (carriage return / line feed) characters or 0A (line feed) characters, depending on what kind of system you are transferring to, and adding these characters into the middle of the image will definitely mess up your image. I've done some testing with CONTENT-TYPE: IMAGE/GIF but I haven't (yet) figured out the right combination of options to get the image to transfer and be readable.

vasanthz · Posted: Fri Nov 13, 2009 7:35 pm

Hi Robert,

Thanks for your time & inputs. But surprisingly I have got the image transferred sometime back with CONTENT-TYPE: TEXT/RICH TEXT (a gif image) but its not working now though

. I think "CONTENT-TYPE: TEXT/RICH TEXT" does not apply to attachments, so it should not affect the image contents (I may be wrong).

It worked sometime back with some other images file, but I did not pay attention at that time & now I don't have any backups of the stuff. Arrrgggh..!!

Should I try meddling with LRECL more? or is it the "CONTENT-TYPE:" ?

Please let me know your thoughts.

And one more detail is that, I use IND$FILE FTP method with binary mode.

Thanks,

superk · Posted: Fri Nov 13, 2009 7:39 pm

Just my thoughts, but I would think that any file that's an image (i.e. binary) would HAVE to be allocated as V or VB to assure that there are no extra characters (most likely blanks) filling up the last record.

vasanthz · Posted: Fri Nov 13, 2009 7:42 pm

Hi,

I will give it a try Superk.

Thanks.

vasanthz · Posted: Fri Nov 13, 2009 7:49 pm

Hi,

I guess there is some problem with FTP. I transferred the image to PS VB 300 from desktop to Mainframe.
And transferred back from MF to PCu sing same FTP, When we open the image in PC the image is messed up.
So the transfer maybe a prob.

Thanks,

Robert Sample · Posted: Fri Nov 13, 2009 8:01 pm

I have used FTP in binary mode to transfer .GIF files from a PC to the mainframe; those files can be displayed in a web browser by pointing to them. However, they are Unix System Services files NOT z/OS files.

My reading of the SMTP RFC standards is that any non-text data being transferred as email must be in MIME format. The CONTENT-TYPE identifies the data type for MIME and IMAGE/JPG, audio/mp3, and video/mp4 are all various types that are supported. I do not believe LRECL matters if the MIME headers are not right. But I haven't been able to spend the time to get the MIME headers right for images from z/OS (as yet).

vasanthz · Posted: Fri Nov 13, 2009 8:57 pm

Hi,

Thanks again for your time & thoughts.
The problem seems to be in the initial FTP & the LRECL I guess.
I have done some testing with the different LRECLs by transferring image from PC TO MF & immediately back from MF to PC.
Although I am not getting anywhere with this testing, I understood that this task is not easy.

LRECL of 80 FB gave incorrupt data error.
LRECL of 1000 FB gave a distorted image.
LRECL of 10000 FB gave half clear & half distorted image.(the data in PS file spanned over 2 lines, maybe thats the reason half of the image was clear)
LRECL of 20000 FB gave the clear and exact image.(the data in PS file spanned over one line, the image was perfect)

Attached are the pics.

Thanks,

vasanthz · Posted: Fri Nov 13, 2009 10:02 pm

MBabu · Posted: Sat Nov 14, 2009 2:08 am

Don't you need to convert it to a base64 encoding? I've never done it either, so I'm just guessing.

Robert Sample · Posted: Sat Nov 14, 2009 2:09 am

Looking through the PlanetMVS web site material on SMTP from z/OS (MVS), it appears that the binary must be in base64 encoding to go. I may get a chance to try this over the weekend.

vasanthz · Posted: Sat Nov 14, 2009 2:16 am

Marso · Posted: Sat Nov 14, 2009 4:29 am

BASE64 is an encoding method that allows you to transform a binary file into text and back.
This allows two things (basically):
- the file can be processed by XML engines.
- the file can be translated from ASCII to EBCDIC and back.

There are encoders-decoders for most programming languages (i even found in COBOL).

Ajay Baghel · Posted: Mon Nov 23, 2009 2:10 pm

Vasanth,

Just wondering about LRECL considerations as you mentioned in your post, in DB2 also, we use BLOB datatype for storing non-traditional stuff like images/pictures/audio/video etc where the data is between 32K and less than 2GB in size.
And you are getting it right when you nearly reach 32 K as lrecl.

I may be wrong also in this understanding.

-Ajay

vasanthz · Posted: Tue Nov 24, 2009 3:08 am

Hi Ajay,