Skip to main content
Bag of words connects to an on-premises Power BI Report Server (PBIRS) over its REST API at /Reports/api/v2.0/ using NTLM authentication. It discovers Power BI (.pbix) reports, paginated (RDL) reports, shared datasets, KPIs, and the upstream data-source lineage behind them, and lets the agent query the ones that are queryable.
The Power BI Report Server connector is part of the Enterprise Edition.

​
How it works

Bag of words signs in with a Windows account, then enumerates the report server catalog and builds one schema entry per asset. Entries are prefixed by kind so the agent knows what it is looking at:

​
PBIX semantic models are a cached snapshot

Power BI Report Server has no executeQueries endpoint like the cloud service, so DAX cannot be run against an embedded .pbix model. Instead, Bag of words downloads the .pbix, extracts its Vertipaq tables to Parquet, and queries them with DuckDB. All tables from the same report are registered in one DuckDB session, so the agent can join them with plain SQL using the internal table names shown in the schema.
The data you query is a snapshot of the last PBIX refresh, not live upstream data. When the answer must be current, connect the report’s upstream source (SQL Server, a file share, and so on) as its own data source instead — the pbix:<Report> entry lists that source in its metadata.
The Parquet cache is keyed by report ID and last-modified date, so editing and re-publishing a report invalidates it automatically. Caches are also warmed on a schedule so the first question about a large report does not stall. Auto-generated internal date tables (LocalDateTable_*, DateTableTemplate_*) are filtered out. Reports larger than 200 MB, and individual model tables above 5 million rows, are skipped rather than materialized. DAX measures are captured as metadata but cannot be executed — they are expressions, not data. The agent rewrites them as SQL over the extracted columns when you ask for a measure-like aggregate.

​
Before you start

  • The report server’s web portal URL, reachable from Bag of words over HTTP(S).
  • A Windows account that can sign in to the report server and browse the folders you want to expose. It may be a domain account (DOMAIN\user) or a local machine account.
  • If the server uses a certificate issued by an internal CA, the CA bundle file must be readable on the Bag of words host.

​
Connect in Bag of words

Go to Settings → Data Sources → Add data source → Power BI Report Server. See Connecting a data source for the general flow. Test Connection authenticates, reads /System, and counts the catalog. A successful test reports the product name and version along with how many Power BI reports, paginated reports, shared datasets, and KPIs were found.

​
Authentication modes

  • username — the Windows username. It may already include a domain prefix (DOMAIN\user) or be a local machine user.
  • password — the Windows password.
  • domain — optional Windows domain (AD domain or workgroup/machine name). If you leave it blank and the username has no domain prefix, NTLM authenticates against the local machine.
Because the mode is available at both scopes, you can either configure one shared service account for the whole workspace (system) or require each user to supply their own Windows credentials (user), so the report server applies that person’s own permissions. Per-user credentials on a connector like this require Enterprise — see Authentication.

​
Troubleshooting

The server answered but rejected the credentials. Check the username, password, and especially the domain: a local machine account needs the machine name as the domain (or a MACHINE\user username), while an AD account needs the AD domain.
The /System endpoint was not reachable. Verify server_url (both http://host and http://host/Reports are accepted), that the host is routable from Bag of words, and — for HTTPS with an internal CA — that ca_bundle_path points at a valid bundle.
Set ca_bundle_path to the CA bundle file rather than disabling verify_ssl. Turning verification off should be reserved for throwaway test servers.
Some reports have nothing to materialize: the report exceeds the 200 MB limit, every model table is above the 5 million row cap, or the file has no embedded semantic model (for example a thin report over a shared dataset). The pbix:<Report> entry still carries the upstream data sources — connect one of those directly to query live data.
Expected: PBIX queries run against the Parquet snapshot taken from the last published/refreshed .pbix. Republishing or refreshing the report changes its modified date, which invalidates the cache on the next query.
/Datasets only lists standalone shared datasets. Models embedded inside a .pbix never appear there — they are discovered from the report itself as pbix:<Report>/<Table> entries.
For the cloud service, see Power BI.