MQSeries.net :: View topic - Issue while escaping special character in DFDL parser

MQSeries.net

Tech Exchange

Education

Certifications

Library

Info Center

SupportPacs

FAQÂ Â

Usergroups

RSS Feed - WebSphere MQ Support

RSS Feed - Message Broker Support

MQSeries.net Forum Index » WebSphere Message Broker (ACE) Support » Issue while escaping special character in DFDL parser

Issue while escaping special character in DFDL parser

« View previous topic :: View next topic »

Author

Message

rahulk01

Posted: Fri Sep 18, 2020 4:19 am Post subject: Issue while escaping special character in DFDL parser

Apprentice

Joined: 26 Dec 2019
Posts: 35

Hi,

I have a requirement where I am trying to set % in a text field, something like below:
SET rBelopRecord.RESERVASJONNR = 'O' || '%';

But after being validated by the DFDL parser in the output message, it appears as "O%.
How do I make this " go away from the output message being generated.

rahulk01

Posted: Fri Sep 18, 2020 4:33 am Post subject:

Apprentice

Joined: 26 Dec 2019
Posts: 35

So far I have tried escaping % in the following manner:
'%%'
'"%'
'"%"'
but nothing seems to work, everytime it just adds " before the entire text

rahulk01

Posted: Fri Sep 18, 2020 5:38 am Post subject:

Apprentice

Joined: 26 Dec 2019
Posts: 35

providing more information:

the escape scheme in my DFDL definition is as below:
<dfdl:defineEscapeScheme name="RecordEscapeScheme">
<dfdl:escapeScheme escapeKind="escapeBlock" escapeBlockStart='"' escapeBlockEnd='"' escapeCharacter='"'
escapeEscapeCharacter='"' extraEscapedCharacters='%#x0D; %#x0A;' generateEscapeBlock="whenNeeded"></dfdl:escapeScheme>
</dfdl:defineEscapeScheme>

I even tried setting the escapeKind to escapeCharacter and used the esql statement:
SET rBelopRecord.IDENTIFIER9 = 'O' || '"%'; and in another occasion as
SET rBelopRecord.IDENTIFIER9 = 'O' || '""%';

but none worked

timber

Posted: Fri Sep 18, 2020 2:04 pm Post subject:

Grand Master

Joined: 25 Aug 2015
Posts: 1292

Thanks for the clear problem description - we appreciate it when people tell us what they have already tried. It saves our time as well as yours.

I can definitely help you with this, but first I will need the following information:
- what type of data format are you trying to write? ( you have only quoted the escape scheme, so I know nothing at all about the rest of the DFDL schema)
- You said that the output appears as "O%. Surely you mean "O%" because escapeKind is set to 'escapeBlock' which will start and end the entire field value with the escape character.
- Do you have any need for escaping at all? If so, what are the requirements for escaping of delimiters?

rahulk01

Posted: Sun Sep 20, 2020 9:43 pm Post subject:

Apprentice

Joined: 26 Dec 2019
Posts: 35

timber wrote:

I see your point here. The escape schemes were set be default when I created the DFDL parser, so I did not touch them.
I have created a DFDL parser to send feed to a mainframe application (whose copybook we never got). This application uses % and * as their field separators, so I needed my DFDL parser to understand % and * as just literals, so escaping their special meaning was required.
I tried removing the entire escapeScheme and that has solved my problem.
You are correct, I do not need escaping at all, so have removed them.

timber

Posted: Mon Sep 21, 2020 3:18 am Post subject:

Grand Master

Joined: 25 Aug 2015
Posts: 1292

Quote:

This application uses % and * as their field separators

Are these fields variable-length? If so, please pick one of the following options:
a) the characters % and * can never, ever appear in the value of any of these fields.
b) there is a chance that % and * might appear in at least one of these fields, sometimes.

rahulk01

Posted: Mon Sep 21, 2020 3:23 am Post subject:

Apprentice

Joined: 26 Dec 2019
Posts: 35

timber wrote:

Quote:

This application uses % and * as their field separators

Option b is valid in this scenario.

timber

Posted: Mon Sep 21, 2020 5:34 am Post subject:

Grand Master

Joined: 25 Aug 2015
Posts: 1292

If the delimiters can appear within the data then you definitely do require an escape scheme. Your current solution is not safe. It only appears to work correctly because your are not testing with data values that include % and *.

You cannot just invent an escape scheme, though. You will need to speak to the team that owns the mainframe application. The mainframe app will probably be expecting a particular escape character to be used. When they have answered that question, you can set up a custom escape scheme as described here:

https://www.ibm.com/support/knowledgecenter/en/SSMKHH_9.0.0/com.ibm.etools.mft.doc/df00110_.htm

Probably, you will need to set escapeKind='escapeCharacter', not 'escapeBlock'

rahulk01

Posted: Mon Sep 21, 2020 5:50 am Post subject:

Apprentice

Joined: 26 Dec 2019
Posts: 35

timber wrote:

Well what has been done so far is, the delimiter is defined at each element level in the DFDL. % is not going to come as a part of the data (confirmed). * can be a part of the data, but thankfully only in those elements whose delimiter is not * (but rather %).
So I guess, removing the escape scheme should be a safe option.

timber

Posted: Mon Sep 21, 2020 7:03 am Post subject:

Grand Master

Joined: 25 Aug 2015
Posts: 1292

Quote:

So I guess, removing the escape scheme should be a safe option

Thanks for clarifying - I agree with that.

Display posts from previous:

Page 1 of 1

MQSeries.net Forum Index » WebSphere Message Broker (ACE) Support » Issue while escaping special character in DFDL parser

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

Protected by Anti-Spam ACP