[V8i/CE] Text properties of Item Types are read only in v8i

The concept of Item Types was introduced into MicroStation CONNECT Edition as a replacement to Tag Sets. You may be able to view this information in V8i but would not be able to make any modifications as it is not backwards compatible.

https://communities.bentley.com/products/microstation/f/microstation-forum/147140/connect-edition---backwards-compatibility-with-select-series/447738#447738

https://communities.bentley.com/products/microstation/w/microstation__wiki/23674/microstation-connect-edition-frequently-asked-questions

I know Item Types came with CE thats why I wanted to see if they where readable in V8i which they obviously are. I've attached a test file.

I can also edit all properties except for the text properties.

If I understand you right any backward compability of Item Types in V8i is more of a strike of luck that design intention?

/Krister

2746.Test.dgn

I know Item Types came with CE thats why I wanted to see if they where readable in V8i which they obviously are. I've attached a test file.

I can also edit all properties except for the text properties.

If I understand you right any backward compability of Item Types in V8i is more of a strike of luck that design intention?

/Krister

2746.Test.dgn

Krister Surell said:

If I understand you right any backward compability of Item Types in V8i is more of a strike of luck that design intention?

Not quite, but an explanation of this issue requires a good knowledge of EC Framework (which is a part of dev documentation) and also technical details how this technology has been implemented in different MicroStation versions, which is Bentley internal topic and we can guess only ;-)

When I simplify it (but still lenghty explanation remains ;-), the backward compatibility itself is not a strike of luck, but natural consequence of used technology. EC Framework has been developed and used by Bentley in different products for (my assumption) at least 15 years. In MicroStation it has become visible in V8i and I guess the first user tool based on EC Framework was SHP format support (where SHP attributes are converted on the fly to EC data).

Item Types are also based on EC Framework, technically "a special Item Types schema" is created at background. Because EC in V8i and EC in CE are "nearly the same" (and nearly is crucial here), V8i is able to read the data, because EC schemas defining data structure are compatible.

But "a definition chain" is more complicated; it's EC schema > EC class (that can be modified further by custom attributes) > EC property (again can be modified by custom attributes). And some definitions, especially pre-defined custom attributes supported by MicroStation, have been enhanced (so Attribute schema changed from 1.2 in V8i to 1.13 in CE), and implementations of EC engine and EC GUI have been improved (especially element properties dialog).

It's a good demonstration of EC power and main features: Because data are described using EC schemas (metadata language), even older version is able to read them. But because details have changed and it's not possible to change what is hardcoded in V8i, the readibility is ensured, but some properties cannot be edited, because MicroStation V8i does not know how.

BTW As a matter of interest, whereas EC in "classic" products like MicroStation evolves slowly and basic compatibility is ensured (because ECObjects2 are used internally),  iModelJS initiaitve and libraries broke the compatibility, because some extra conceptual changes were required to implement into EC schemas and related APIs (ECObjects3) to be able to support digital twins concept and other new features. See this page for more details.

HTH Jan

I've got a basic knowledge about the EC Framework and the relationship to Item Type through developing FDO Reader (thank's Jan for helping me out with many issues!).  For the V8i version I use the EC api and for the CONNECT version the Item Types.

I was just hoping that the basic property types would be backward compatible and most of the obviously are (integers, doubles, point). "Just" add strings to that and you would be able to use Items Types in V8i to a larger extent.

Well, if Bentley get their way my customers will all using CE soon and this will not be an issue!

/Krister

Krister Surell said:

I was just hoping that the basic property types would be backward compatible

I agree such assumption makes sense. Why it does not work this way is probably hidden somewhere in internal implementation, maybe when EC schema will be created not as Item Types but using another tools (Bentley Class Editor or  API) as "normal simple custom EC schema", the compatibility will be better.

But it requires time to test it.

Regards,

  Jan