> For the complete documentation index, see [llms.txt](https://developer.barchart.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.barchart.com/architecture/core-protocols.md).

# Core Protocols

At the foundation is the **Openfeed wire protocol**, which is built on **Google Protocol Buffers (protobuf)**. Protocol Buffers are a language-neutral data serialization format designed for efficient communication between systems written in different programming languages.

Message structures are defined using the **Protocol Buffer language**, which describes the fields and format of each message type.

These definitions are stored in **`.proto` files**, which can be compiled using the Protocol Buffer compiler to generate code in a wide range of programming languages. This generated code handles the encoding and decoding of messages automatically.

This allows applications written in different languages to easily parse and produce Openfeed messages.

#### Data Transmission Workflow

Openfeed leverages the protobuf architecture to efficiently transmit market data:

**Encode → Compact → Transmit → Decode**

This approach minimizes bandwidth usage while maintaining high-performance real-time data delivery.

This architecture allows Openfeed to deliver high-performance, cross-platform market data with minimal bandwidth and processing overhead.

1. *openfeed.proto -* This protocol group defines the streaming market data messages.
2. instrument.proto - This protocol defines the instrument definition messages.
3. *api.proto -* This protocol defines the client <-> server API.


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