pnoker
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- expand single-line Javadocs to multi-line blocks, rewrap Markdown prose, and reflow POM, YAML, and TypeScript formatting - formatting only: no Java code lines changed, no build-file semantics changed - verified: backend compile and check_documentation.py pass, pnpm check and pnpm lint:check pass, and the dc3 YAML files parse
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DC3 Common SQL
Overview
dc3-common-sql is the shared base for the database (JDBC) drivers of the IoT DC3 platform. It provides
AbstractJdbcDriverCustomService, a common driver-service base that handles JDBC connection management (via HikariCP)
and query execution, so each database driver only supplies its dialect/connection specifics.
Module Information
- Group ID: io.github.pnoker
- Artifact ID: dc3-common-sql
Key Components
| Component | Purpose |
|---|---|
AbstractJdbcDriverCustomService |
Base driver service for JDBC sources — pooled connections + queries |
Dependencies
dc3-common-driver— Driver SDK that the base service plugs intoHikariCP— JDBC connection pool
Connection Management
One HikariCP pool is cached per device (ConcurrentHashMap<Long, HikariDataSource>), created lazily on first access and
configured with a maximum of 5 connections and a minimum idle of 1. Pools are evicted when:
- the device is deleted or updated (device metadata event),
- the driver configuration is updated or the driver is deleted (driver metadata event — every pool is closed),
- a read/write fails at the connection level, so the next access rebuilds the pool from current configuration.
Driver Attributes
| Attribute | Default | Semantics |
|---|---|---|
| host | localhost |
Database host |
| port | dialect-specific | Database port |
| database | — | Database name (MySQL, PostgreSQL, SQL Server; Oracle uses SID/ServiceName instead) |
| username | root |
Login name |
| password | — | Login password |
| queryTimeout | 30 |
SQL statement timeout in seconds, applied via PreparedStatement.setQueryTimeout to every read and write |
Point Attributes
| Attribute | Semantics |
|---|---|
readQuery |
SQL SELECT executed on read; must not contain ? placeholders because reads bind no parameters |
writeQuery |
SQL UPDATE/INSERT/DELETE executed on write; must contain exactly one ? placeholder — the point value is bound via setString, preventing SQL injection |
validatePoint derives which queries are required from the point's read/write flag: read-only points require
readQuery, write-only points require writeQuery, and read-write points require both. A point with an unknown flag is
treated as read-only.
Build Instructions
mvn -s .mvn/settings.xml -pl dc3-common/dc3-common-sql -am package
Testing
Run the module tests from the repository root:
mvn -s .mvn/settings.xml -pl dc3-common/dc3-common-sql -am test
Related Modules
dc3-driver-mysql,dc3-driver-oracle,dc3-driver-postgresql,dc3-driver-sqlserver— JDBC drivers that extendAbstractJdbcDriverCustomService