This functional structure is going to be built from the ground up, but there are other options that might work as well, or even better in other contexts. There are, for example, several Object Relational Mapper (ORM) packages/libraries available that would allow the definition of databases and structure to be defined in code and propagated out to a data store, some of which are integrated into full application frameworks. These include Django's models module, which is part of the overall Django web application framework, a common and popular option for developing web applications. Other variants include SQLAlchemy, providing an abstraction layer over SQL operations and an ORM to work with an object's data.

There are also specific driver libraries for several database options (SQL and NoSQL both), some of which may provide ORM functionality, but all of which provide at least the basic capability to connect to a data source and execute queries or perform operations against those data sources. It's quite possible to write code that simply executes SQL against an RDBMS such as MySQL or MariaDB, or executes functions that correspond to that SQL against a NoSQL engine like MongoDB or even cloud-resident data stores such as Amazon's DynamoDB. For simple applications, that may actually be a better approach, at least initially. It would keep the development time down, since the various abstraction layers that we've explored so far simply wouldn't be in the picture at all, and the code itself would have a certain type of simplicity, since all it would need to do is execute basic CRUD operations, and maybe not even all of those.

The data objects structure that is being developed for hms_sys will expose a lot of the underlying principles that go into the design of a data access framework, and that's part of the reason that the from-the-ground-up approach it entails was selected. Another reason is that, because it will live somewhere between a full-on ORM approach and the a low-level "execute a query against a connection" implementation strategy, it will show a lot of the relevant aspects of both of those approaches.