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Mon, 04 September 2006 09:16

Eclipse User

hi,

I've got a bit confused with how BIRT can talk to the ODA dataSources,
and was hoping someone could help.

I understand that the datasource is abstracted behind the dataSource
extension point, and that the query syntax can be specific to the
datasource.

I don't see how having a customisable query syntax can help when the
consumer of the datasource needs to get data though, i.e. surely the
datasource consumer needs to query via a particular query language?

put another way, to what extent (if at all..) does custom query syntax
defeat abstraction of the datasource?

thanks,
Andrew

Re: ODA BIRT interaction [message #21196 is a reply to message #21163]

Tue, 05 September 2006 19:19

Eclipse User

Andrew,

An ODA consumer like BIRT, treats an ODA data set query text as data source
specific, and does not manipulate it directly. A data set's custom query
text, along with any input parameter values, are passed back to the ODA
driver for processing. Thus it is able to stay above the abstraction
layer.

To give this a bit more context...
At design-time, a custom ODA designer would define a data set design, which
is communicated to an ODA host designer, e.g. BIRT report designer, via the
the oda.design API. This API is based on EMF model, and includes the
custom query text, result set and parameter definitions. A consumer can
then bind with the result set columns and parameters defined in the data
set design. At runtime, the data retrieved by the query text is expected
to be in sync with the metadata defined in the data set design. Some
insignificant delta may be tolerated, depending on how sophisticated an ODA
consumer is. But in general, if significant difference is found between
data returned at runtime, vs. the definition specified at design-time, a
runtime error may occur.

Hope this addresses your question.

Linda

andrew wrote:

> hi,
>
> I've got a bit confused with how BIRT can talk to the ODA dataSources,
> and was hoping someone could help.
>
> I understand that the datasource is abstracted behind the dataSource
> extension point, and that the query syntax can be specific to the
> datasource.
>
> I don't see how having a customisable query syntax can help when the
> consumer of the datasource needs to get data though, i.e. surely the
> datasource consumer needs to query via a particular query language?
>
> put another way, to what extent (if at all..) does custom query syntax
> defeat abstraction of the datasource?
>
> thanks,
> Andrew

Re: ODA BIRT interaction [message #21228 is a reply to message #21196]

Wed, 06 September 2006 06:16

Eclipse User

thanks Linda :)

I think I need to spend some more time with the docs, but its very helpful
to know that I've not yet understood how querying works..

Re: ODA BIRT interaction [message #582119 is a reply to message #21163]

Tue, 05 September 2006 19:19

Eclipse User