This article provides a brief overview of technology in MicroStation CONNECT …
The information presented here is an informal guide to Item Types. Its intended audience includes MicroStation administrators and MicroStation developers.
Item Types is the term used in user documentation.
The MicroStationAPI and DgnPlatformNet APIs uses terms such as
VBA support for Item Types arrived with MicroStation CONNECT Update 10. See the following class descriptions in VBA help …
This article about AreaAnnotator CONNECT Edition™ shows how Item Types help obtain reports about area features in a DGN model.
There's a useful table in MicroStation CONNECT help that compares various annotation technologies, including Item Types and Text Fields. To find this table in MicroStation help, search for Comparing Text Field, Label, Note, Table, Report, Item, Item Type, and Item Sets.
MicroStation CONNECT help is available on line. Here's that comparison table in MicroStation Help.
To dispel confusion, Item Sets are an earlier and different technology. They are unrelated to Item Types other than having a similar name.
Item Types, new to MicroStation CONNECT, are meta data that define data types. In other words, a schema. An Item Type has a name and a number of properties. Each property has a name and a data type (e.g. Text, Integer, Number). Item Types are not graphic elements; rather, they represent a MicroStation capability for storing structured alpha-numeric data on an object. Item data can be attached to an element, DGN model or DGN file. Bentley Systems terminology for data stored in Item Types includes 'business data' and 'EC Schema data'.
Item Types provide a simplified way for users and applications to create, manage, and use EC data within DgnFiles.
An Item Type is an ECClass which supports a subset of the features available to ECClasses. In comparison to full-fledged ECClasses, Item Types:
Item Types are stored an Item Type Library, which is a similarly restricted ECSchema. In comparison to full-fledged ECSchemas, Item Type Libraries:
An Item Type Library is a resource, stored in a DGN file. Typically they are managed by defining the Item Type and its properties in a DGNLib, which is made available to all users who need to use that Item Type. A management dialog is provided by MicroStation for the end user …
Item Types are metadata. They become useful when they are "attached" to a host to produce an Item. An Item is an ECInstance of an Item Type ECClass.
From MicroStation CONNECT Update 10 Item Types are supported by MicroStation VBA.
MicroStation CONNECT Update 10 introduces the Picklist. A Picklist is a user-defined list of possible values for an Item property.
For example, suppose you want to annotate door cells with your Item Type. One property of your Item Type is door-type. You would like to restrict the value of the door-type property to internal door, internal fire door, external door and fire escape door. A Picklist enables you to constrain what the user can assign to your Item's door-type property.
MicroStation CONNECT Update 7 introduced the Edit Item Dialog..
MicroStation CONNECT introduced Reports. Reports is an analytic tool. It extracts alphanumeric data (business data) from your DGN file, model, elements or elsewhere. When Item Types are in use, Reports can extract Item instance data attached to your DGN model or elements.
Visit the reports page for more information, and to see an example of Reports in action.
I am indebted to Bentley Systems staff member Paul Connelly and to Be Communities MVP Jan Slegr. Both have contributed both factual information about Item Types and EC Schemas as well as their interpretation of how they can be used. They contribute enthusiastically to the MicroStation Programming Forum.
EC Schemas were introduced with MicroStation V8i and are continued in MicroStation CONNECT. EC Schemas are meta data that define data types, analogous to a relational database schema. EC Schemas are not graphic elements; rather, they represent a MicroStation capability for storing structured alpha-numeric data. Bentley Systems terminology for data stored in Item Types include 'business data' and 'EC Schema data'.
ECX command lets you
export a schema, or other information.
Q To define an Item Type Library implicitly defines an EC Schema?
Q Is the schema that it defines a first-class schema, equivalent to a schema defined any other way?
Yes, to workflows which operate on EC Schemas, Item Type Libraries look like any other EC Schema. e.g., Reporting, Explorer, etc.
Q That is, do we lose any capability by creating an Item Type Library?
You lose some capabilities and gain others.
An Item Type Library supports a subset of the features supported by hand-rolled EC Schemas, for two reasons:
At the time of writing with respect to MicroStation CONNECT Update 6, some EC features are not supported by Item Types …
Some capabilities are only available for Item Types …
Neither of the above is a comprehensive list.
Q To define an Item Type Library implicitly defines an EC Schema?
It can be discovered easily:
- Create a new empty file.
ecx schema listkey-in to list all schemas stored in the file.
- Create your Item Type definition and save it to the file.
- Use the key-in again to check how the number of stored schemas changed.
- You will see some standard (supplement) schemas area added and also
DgnCustomItemTypes_<name>.01.00schema is created.
For further research you can export the schema and open it in Bentley Class Editor.
There a number of MicroStation key-in commands that enable export of an ECSchema or a sub-set of a schema …
ECX SCHEMA EXPORT schema-name ECX SCHEMA IMPORT schema-name ! Use with caution ! ECX SCHEMA LIST ECX SCHEMA UPDATE ECX ITEMS COUNT ECX ITEMS DUMP
Those ECX commands have some options …
TEMPfolder with a unique name derived from the Active Design File Name.
About the time that MicroStation CONNECT Update 5 was released, Bentley Systems announced the first CONNECT ECSchema Editor 1.0. The title editor belies the fact that is a read-only viewing tool. Perhaps later versions will enable editing.
None the less, it provides a useful way to view the structure of a schema. Moreover, its help documentation provides a valuable insight into the raison d'être of ECSchemas and their use in products from Bentley Systems.
Bentley Systems developer Paul Connelly commented about Class Editor V8 …
Don't edit an Item Type Library schema in Class Editor V8!
Veteran independent MicroStation developer Jan Slegr commented …
I am not sure if there is "Bentley Class Editor CONNECT Edition" available. Checking my computer with CONNECT Edition SDK installed I can found Class Editor 8.1, which I guess was installed together with Navigator or V8i SDK (not sure ;-)
It would be nice if Class Editor will be enhanced. If I need to create some schema (which is not very often), I am quite happy with the current version, but:
- From time to time it crashes or starts work in a strange way. Restart the app is quick but annoying.
- Very limited documentation about e.g. available Property Attributes ro more advanced concepts like relationship classes etc. This is not primarily Editor issue, but it limits its usage.
Jan further added My personal list …
- Based on stable powerfull EC Framework technology. Maybe it's an "internal thing", but EC data is common and used by many Bentley products and it's stored as XAttributes, so it's fully supported and compatible with DGN V8, i-model and Bentley world in general. Not as tags, that were implemented "on top of DGN V7" with many limitations
- Fully compatible with i-Model, so nothing is lost when exported e.g. to Navigator and used on Android or iPad (including ability to search
- Can be attached not to elements only, but also to design while, to particular model and also to references and attached rasters
- Easy to search in Explorer for Item Types including standard table display format (including ability to export the results to CSV or Excel)
- Possibility to create (and store) complex queries
- Item Types can be used as an input to other tools (reports, charts etc)
- Standard storage format allows to access data easily by other applications
We don't discuss Item Sets here in any detail. We mention them because of the similarity in their name to Item Types. Item Sets were introduced with MicroStation V8i. Item Sets are unrelated to Item Types.