API Overview
Overview
The Liquibase API consists of pluggable interfaces and the driving logic that surrounds them.
Even the main Liquibase code itself is layered between the API-level code which works purely with interfaces, and the implementation-level code which is written and auto-discovered exactly like external extensions are.
Tip
The complete Javadocs for Liquibase are available at https://javadoc.liquibase.com.
Environmental Setup
The following classes are used to connect the generic Liquibase logic to the environment it is running in. They tend to be called from integrations before executing commands.
| Package | Interface | Notes |
|---|---|---|
| liquibase | Scope | Alternative to global variables |
| ScopeManager | Controls Scope creation | |
| liquibase.configuration | LiquibaseConfiguration | Access configuration values |
| ConfigurationDefinition | Defines new configuration options | |
| ConfigurationValueProvider | Defines new configuration stores | |
| ConfiguredValueModifer | Modifies configuration values before returning them to code | |
| liquibase.logging | LogFactory | Facade for working with the Logger |
| Logger | Wraps underlying logging systems in a common API | |
| liquibase.resource | ResourceAccessor | Defines resource accessors |
| PathHandler | Defines path handlers | |
| Resource | Objects returned from resources accessors | |
| liquibase.servicelocator | ServiceLocator | Controls pluggable service infrastructure |
| liquibase.ui | UIService | Wraps the underlying user interaction in a common API |
Command Facade
The following classes are the main entry points for calling overall Liquibase commands.
| Package | Interface | Notes |
|---|---|---|
| liquibase | Liquibase | Legacy facade for calling commands |
| liquibase.command | CommandScope | Facade for calling commands from an integration |
Business Logic and Data Models
The following classes contain or coordinate business logic or hold data for transfer between components.
| Package | Interface | Notes |
|---|---|---|
| liquibase.command | CommandStep | Defines a step within a command pipeline |
| liquibase.diff | DiffGeneratorFactory | Facade for creating diffs between existing databases |
| DiffResult | Holds differences from a database comparison | |
| DatabaseObjectComparator | Determines whether objects from different databases are the same object or different |
Extensible Capabilities
The following classes define functionality available within Liquibase. They tend to be called
from business logic, especially CommandStep implementations.
Liquibase ships with standard implementations of these interfaces, but they can be extended or replaced by external extensions.
| Package | Interface | Notes |
|---|---|---|
| liquibase.change | Change | Defines change types available to changelog files |
| liquibase.changelog | DatabaseChangeLog | Format-independent changelog file object |
| ChangeLogHistoryService | Tracks what changesets have been run against a database | |
| liquibase.database | Database | Defines a database dialect |
| DatabaseConnection | Wraps the underlying connection to a database | |
| liquibase.datatype | DataTypeFactory | Translates generic to database-specific data types and vice versa |
| DatabaseDataType | Defines mappings for DataTypeFactory | |
| LiquibaseDataType | Defines generic data types | |
| liquibase.executor | ExecutorService | Facade for executing statements |
| Executor | Defines a new RunWith Executor | |
| liquibase.lockservice | LockServiceFactory | Facade for finding the LockService |
| LockService | Manages the Liquibase Lock | |
| liquibase.parser | ChangeLogParser | Defines changelog file formats |
| Parser | Parses a stored snapshot file | |
| liquibase.precondition | Precondition | Defines preconditions |
| liquibase.serializer | ChangeLogSerializer | Allows changelog file formats to be used in diffChangelog and generateChangelog operations |
| Serializer | Stores a snapshot of a database | |
| liquibase.snapshot | GeneratorFactory | Facade for snapshotting a database |
| SnapshotGenerator | Defines how to snapshot a particular object type | |
| liquibase.sql | Sql | Interface for holding SQL to execute |
| UnparsedSql | Holds SQL to execute | |
| liquibase.sqlgenerator | SqlGeneratorFactory | Facade for converting SqlStatements database-specific SQL |
| SqlGenerator | Defines how to convert a cross-database SqlStatement to database-specific SQL | |
| liquibase.statement | SqlStatement | Defines database-independent operations that can be performed |
| liquibase.structure | DatabaseObject | Base interface for all types of objects which can be snapshotted |
Next Steps
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