Overview of the Holochain Development Kit
The Holochain Development Kit (HDK) provides the core libraries, APIs, and tools that developers need to build applications on the Holochain framework. Written in Rust, the HDK offers a comprehensive set of functions for managing entries, links, and other aspects of Holochain application development.
Core Components
HDK Core
- Primary development library for Holochain applications
- Rust-based API for interacting with Holochain runtime
- Core functions for managing application state
- Entry and link manipulation utilities
Holochain Development Interface (HDI)
- Interface definitions for Holochain applications
- Type definitions and trait implementations
- Validation callback interfaces
- Core data structures
Key Functionality
Entry Manipulation
- Creating, reading, updating, and deleting entries
- Entry type definitions
- Validation logic implementation
- Entry serialization and deserialization
Link Manipulation
- Creating and managing relationships between entries
- Link type definitions
- Link tag management
- Querying and traversing links
Source Chain Operations
- Accessing agent source chain data
- Querying historical actions
- Managing local state
- Chain validation
Zome Calls
- Inter-zome communication
- Remote zome calls
- Capability-based authorization
- Cross-DNA interactions
Development Workflow
- Define entry and link types using the HDI
- Implement CRUD operations using HDK functions
- Create validation callbacks for data integrity
- Implement query functions for data retrieval
- Build UI integration using the Holochain Client API
Best Practices
- Use strongly typed entry definitions
- Implement comprehensive validation rules
- Follow capability-based security patterns
- Design for eventual consistency
- Leverage HDK utility functions
Version Compatibility
- HDK versions correspond to Holochain runtime versions
- Breaking changes between major versions
- Backward compatibility considerations
- Migration strategies for upgrading