Data Access Logic

In the previous chapter, we introduced data processing logic: the layer that turns raw data into decision-ready information. To do that work, data processing logic often needs to retrieve and store data.

This chapter introduces the layer responsible for that job: data access logic.

Data access logic is where a system performs CRUD operations in a specific data store.

What Data Access Logic Does

Data access logic is responsible for creating, reading, updating, and deleting data. It knows how to talk to a particular data store and how to perform operations safely and consistently.

Depending on the architecture, data access logic may be implemented in different ways, for example:

• A set of database queries (SQL) or stored procedures
• A repository or data access object (DAO)
• A client for a RESTful CRUD service
• An adapter for a message-based API

The form may differ, but the responsibility remains the same: perform data operations and return results.

Relationship to Data Processing Logic

Data processing logic manages the overall preparation of information. When it needs data, it calls data access logic to retrieve it.

A simple way to remember the difference:

• Data access logic fetches and saves data.
• Data processing logic merges, transforms, and prepares it.

This separation keeps responsibilities clean. Data processing logic does not need to know whether data comes from SQL Server, a REST API, or a file. Data access logic hides those details.

Business Rules in Data Access

Data access logic may still include rules, but they are rules about data access itself:

• What can be created or changed
• Validation and constraints at the data boundary
• Security rules (who can read or update data)
• Concurrency rules (how conflicts are handled)

These rules protect the integrity of the data store and ensure that data operations remain consistent.

Definition

With this context, we can define data access logic as follows:

Data access logic manages CRUD operations according to business rules in a specific type of data store.

In the next chapter, we will introduce a layer that connects business process states to the data that is available in those states: state logic.

Table of Content Introduction into Business Process Previous: Data Processing Logic Next: State Logic