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ETL script, multiple input models [message #1835093]

Tue, 24 November 2020 16:34

Maximilian Schiedermeier

Messages: 3
Registered: November 2020

Junior Member

Hi,

I can not figure out how to pick up multiple input models in an ETL script.

More precisely:
I want to toss in two input models and transform them into a single output model. The Book says:
Quote:

... ETL can be used to transform an arbitrary number of input models into an arbitrary number of output models ...

However looking at the abstract syntax of ETL scripts, it seems that only a single input model is allowed:

(@abstract)?
(@lazy)?
(@primary)?
rule <name>
    transform <sourceParameterName>:<sourceParameterType>
    to <targetParameterName>:<targetParameterType>
        (,<targetParameterName>:<targetParameterType>)*
    (extends <ruleName> (, <ruleName>*)? {
    (guard (:expression)|({statementBlock}))?
    statement+
}

Specifically, unlike for output model, the line:

transform <sourceParameterName>:<sourceParameterType>

does not allow a comma-separated pickup of multiple input models.

Any help is greatly appreciated!

Thanks in advance,
Maximilian

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Re: ETL script, multiple input models [message #1835094 is a reply to message #1835093]

Tue, 24 November 2020 16:38

Dimitris Kolovos

Messages: 2165
Registered: July 2009
Location: York, UK

Senior Member

Hi Maximilian,

ETL rules cannot have multiple source parameters. However, you can have rules in the same transformation that consume elements from different models.

If you need rules with multiple inputs (whether from the same or from different models), you can use EPL [1] first and then pass the matched patterns to ETL.

Thanks,
Dimitris

[1] https://www.eclipse.org/epsilon/doc/epl/#interoperability-with-other-model-management-tasks

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