# Tycho Common
This tycho-common crate defines all core models used across the various Tycho services. This crate encapsulates the core
models only, separate from the database storage models, which are located in the [tycho-storage](../tycho-storage/)
crate.
The core models in this crate are grouped based on their use case:
- Internal Models: These models represent the underlying structures used by Tycho's internal services.
- Message Models: These Data Transfer Objects (DTOs) facilitate communication between the server and clients.
## Internal Models
The internal models are located in the [models](./src/models/) module. These structs capture the detailed, low-level
data structures that underpin the internal logic of Tycho services. They are designed to be highly granular to support
the complex operations within Tycho.
## Message Models
The message models, also known as DTOs, are found in [dto.rs](./src/dto.rs). These structs serve to serialise and
deserialise messages between server and client. Unlike internal models, DTOs are intentionally kept simple, focusing
solely on data representation without embedding business logic.
### Encoding Standards
Most fields within the message models are encoded using hex bytes. Some useful tools for serialising and deserialising
structs containing hex bytes are provided in [serde_primitives](./src/serde_primitives.rs).
Note: while encoding specifics may vary depending on the protocol, integers are generally encoded in big-endian format.