How do you give each data subscriber only the columns of their plan?

A data provider sells a daily feed in three plans. The basic plan has a few columns: date, product code, price and volume. The premium plan adds price history and regional breakdowns. The full plan adds supplier and customer identifiers.

The pipeline writes one file with every column. Building a separate file for each plan means three jobs to run and three to change whenever a column changes, so the full file goes to every subscriber and the contract says which columns each plan may use.

The contract is the only thing separating the plans. A basic subscriber has every column in the file, and nothing stops them using the premium ones. They may pass the file to a colleague at another company, or to a reseller who has never paid.

The file sits in a download folder, and you cannot see who opened it.

Revenue, first. Subscribers use premium data at a basic price, so there is little reason to upgrade. The identifiers in the full plan sit with companies that never bought them. You have a contract clause to point to, and no way to see a breach.

A separate file for each plan, built by hand or in the pipeline, means more jobs to run and fix. A password on a zip file travels with the file. A clause in the contract gives you a legal claim but no way to see misuse.

You register the feed once and write a policy for each plan: the columns that plan may have. Each run produces one protected file for each plan, and a subscriber receives only its plan’s file. A column the plan may not have is not in the file. It is not hidden by software on the subscriber’s machine.

Before a file is protected, the NakodaX library reads its column names and refuses if a column the plan may not have is present. Each run reports the columns that went in and out, with names and counts, never data.

Each subscriber has its own licence with an end date, and an optional limit on how many times a file can be opened. When a subscription ends, you end that licence and NakodaX stops releasing keys for it, within the hour even for a long running job. Other subscribers are not affected. NakodaX does not store the feed: it moves from your systems to the subscriber’s.

A subscriber who already opened a file keeps what they opened. Ending a licence stops the next key request and does not reach data already read. Subscribers need a licence key and the NakodaX library, or the reader in the console. NakodaX does not decide which columns belong to which plan: you write the policies.