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Parsing question

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schroederms

Posted: Fri Nov 18, 2011 1:25 pm Post subject: Parsing question

Disciple

Joined: 21 Jul 2003
Posts: 169
Location: IA

Looking thru the example on version 7 of the toolkit I came across a sample for large messages (currently we have one message taking 6 hours to gnerate 380,000 + messages)

I see in the sample code they have this:
DECLARE ROOT_LEVEL CONSTANT CHARACTER 'SaleEnvelope';
DECLARE HEADER CONSTANT CHARACTER 'Header';
DECLARE REPEATING_ELEMENT_COUNT CONSTANT CHARACTER 'SaleListCount';
DECLARE REPEATING_ELEMENT CONSTANT CHARACTER 'SaleList';

IF FIELDNAME( InputBody.{ROOT_LEVEL}.{HEADER}.*[>]) = REPEATING_ELEMENT_COUNT THEN

Is this type of coding not using the parser since CONSTANTS are being used, or what is the advantage?

Thanks.

kimbert

Posted: Fri Nov 18, 2011 2:48 pm Post subject:

Jedi Council

Joined: 29 Jul 2003
Posts: 5542
Location: Southampton

Let's get a couple of things straight:
- ESQL changes message trees.
- A parser creates message trees from messages, or creates messages from message trees.

Maybe you are getting confused about on-demand parsing. ESQL can sometimes cause the parser to do some parsing. This happens when Parse Timing is set to 'On Demand' AND the message flow ( ESQL in this case ) tries to access a field that has not yet been parsed.

Now to answer your question. This line:

Code:

DECLARE ROOT_LEVEL CONSTANT CHARACTER 'SaleEnvelope';

...is just declaring a constant string value for ESQL to use. This line:

Code:

IF FIELDNAME( InputBody.{ROOT_LEVEL}.{HEADER}.*[>]) = REPEATING_ELEMENT_COUNT THEN

...is getting the name of a field in the message tree, and comparing that name to a constant string value. The field in question is the last child of InputBody.SaleEnvelope.Header.

I'm not sure why the author decided to declare/use those string constants, rather than writing the path references in the standard way. Maybe the other ESQL needs them. Whatever the reason, I can assure you that the parser still needs to create the message tree so that the ESQL can operate on it.

schroederms

Posted: Fri Nov 18, 2011 2:55 pm Post subject:

Disciple

Joined: 21 Jul 2003
Posts: 169
Location: IA

Thanks for clearing that up.

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