iModel.js Agents QA (Jump Start)

[roopksaini]

RECORDINGS

Captured Q&A from the iModel.js Jump Start event on July 15th 2020, “iModel.js Agents”.

In this session, Bill Goehrig introduced iModel.js agents, services that can leverage the power of change-sets to enhance the value of your digital twin. He demonstrated how to extract information from change summaries to fulfill common industry use-cases in groundbreaking ways.

Please don't reply to this discussion. If you have follow-up questions or comments please start a new discussion.

[roopksaini]

Q: Can one agent update more than one iModel?
A: An Agent normally shouldn't be used to update the current iModel as they are triggered by iModel updates. However, technically you can use the event of one iModel to update the contents of another iModel. Feel free to reach out if you have a use-case in mind and would like to discuss further.

Q: Does iModel.js integrate with ProjectWise? Are there any examples of this (or similar)? Is it possible to push changes back to ProjectWise via iModel.js?
A: We can setup bridges to synchronize data from files stored in ProjectWise into an iModel, but we do not synchronize data back into the source files.

Q: What is the importance of setting the applicationType? If this is not set, are there some adverse effects later down the line?
A: The application type is important because it determines the authentication type used. We follow the OAuth/OIDC standards and therefore use a client credentials workflow for agents. Here is some documentation on the Agent authentication: https://www.imodeljs.org/reference/backend-itwin-client/authentication/agentauthorizationclient/

Q: Can users host their own iTwin Server? Is there a list of steps for that? 
A: Users can host their own frontend services which talk to our backends. They can also host their own backend by pulling iModels from the iModel Hub. Finally, there is iTwin Stack which can run a limited set of functionality in your own cloud. We have some of this covered by our tutorials here: https://www.imodeljs.org/learning/tutorials/

We also have a blog post covering deploying a frontend: https://medium.com/imodeljs/ship-it-415cfc1c70fa

If you are interested in iTwin Stack please contact Bentley directly.

Q: Instead of having to reverse engineer these schemas, do any of the bridges provide documentation on their schemas?
A: There is some documentation for the schemas used by the bridges, however this excludes any of the dynamic schemas, which are not documented. Here's a link to the documentation: https://www.imodeljs.org/bis/domains/

If a schema you're interested in isn't represented there, or lacking in a description, please reach out to us as we're always trying to improve them.

Q: Can someone elaborate a bit on the differences between ECSQL vs. traditional SQL and ECSQL classes vs DB tables?
A: iModels include meta-data on how the tables, columns, foreign key columns, link tables, etc. are mapped to higher level constructs like classes, properties and relationships. So instead of querying tables, columns, foreign keys, link tables with SQL -- you would instead query classes, properties and relationships with ECSQL. iModel.js maps these ECSQL queries to SQL queries and executes them. It uses the information on how the classes are mapped to the tables to do this. ECSQL follows the very familiar SQL syntax. ECSQL is an implementation of SQL. The key difference between ECSQL and SQL is that ECSQL targets the logical schema, and not the underlying database’s persistence schema. Take a look at the docs - https://www.imodeljs.org/learning/ecsql/?term=ecsql

Q: For ECSQL can we do "IS IN (...)"?
A: Here is the documentation for the IS syntax, it is very flexible. IN is not supported but it is not needed. https://www.imodeljs.org/learning/ecsqltutorial/typefilter/

Q: Are there any examples that show the agent workflow? On GitHub by any chance?
A: The starting point that Bill mentioned for a new Agent is already available on GitHub https://github.com/imodeljs/agent-starter.

Also, the code that shows the finished result from Bill’s presentation is here: https://github.com/iModeljsJumpStart/jumpstart-agent

For other resources, the links should be available on https://imodeljsjumpstart.github.io/.

Q: It seems that iModel covers role-based security. Does it also cover fine grained access (e.g. Attribute level)?
A: No, the finest grain is per iModel (this is new or pending ... it used to be only per project)