Please note that this documentation is provided as-is and may change at any time. Likewise, no guarantees are given that this documentation is fully up to date. No support can be provided for users of this documentation, but issues may still be raised at https://github.com/neo4j-drivers/neo4j-drivers.github.io/issues
Overview of Driver Technology
The sections below contain links to current, historic, and proposed future specifications.
PackStream
PackStream is a binary presentation format for the exchange of richly-typed data. It provides a syntax layer for the Bolt messaging protocol.
- Version 1, corresponds to the first releases of the PackStream specification.
Bolt
Bolt is an application protocol for the execution of database queries via a database query language, such as Cypher. It is generally carried over a regular TCP or WebSocket connection.
Bolt inherits its core type system from PackStream, over which its messages are generally carried. Each version of Bolt provides a number of type system extensions, via the PackStream type extension mechanism.
Bolt Protocol Handshake Specification
All Bolt connections begin with a handshake to negotiate which version of the messaging protocol to use. Following a successful negotiation, the agreed messaging protocol then takes ownership of the connection for the remainder of its lifetime. The handshake itself is not versioned.
- Version 1, corresponds to the first releases of the handshake specification.
- Version 4.0, incorporates an updated handshake specification. Now supports major and minor versions.
- Version 4.3, incorporates an updated handshake specification. Now supports ranges of minor versions.
Bolt Protocol Handshake Specification
Bolt Protocol Message Specification
- Version 1, corresponds to the first releases of the message specification. Uses PackStream Version 1.
- Version 2, incorporates no changes to the message specification.
- Version 3, incorporates an updated message specification.
- Version 4.0, incorporates an updated message specification.
- Version 4.1, incorporates an updated message specification.
- Version 4.2, incorporates no changes to the message specification.
- Version 4.3, incorporates an updated message specification.
- Version 4.4, incorporates an updated message specification.
Bolt Protocol Server State Specification
For the server, each connection using the Bolt Protocol will occupy one of several states throughout its lifetime.
This state is used to determine what actions may be undertaken by the client. Each server state specification corresponds to a message specification with the same version.
- Version 1, first version that defines the server states.
- Version 2, incorporates no changes to the server state specification.
- Version 3, incorporates major changes to the server state specification.
- Version 4.0, incorporates some changes to the server state specification.
- Version 4.1, incorporates no changes to the server state specification.
- Version 4.2, incorporates no changes to the server state specification.
- Version 4.3, incorporates no changes to the server state specification.
- Version 4.4, incorporates no changes to the server state specification.
Bolt Protocol and Neo4j Compatibility
| Neo4j Version | Bolt 1 |
Bolt 2 |
Bolt 3 |
Bolt 4.0 |
Bolt 4.1 |
Bolt 4.2 |
Bolt 4.3 |
Bolt 4.4 |
|---|---|---|---|---|---|---|---|---|
3.0 |
x |
|||||||
3.1 |
x |
|||||||
3.2 |
x |
|||||||
3.3 |
x |
|||||||
3.4 |
(x) |
x |
||||||
3.5 |
(x) |
x |
||||||
4.0 |
(x) |
x |
||||||
4.1 |
(x) |
(x) |
x |
|||||
4.2 |
(x) |
(x) |
(x) |
x |
||||
4.3 |
(x) |
(x) |
(x) |
(x) |
x |
|||
4.4 |
(x) |
(x) |
(x) |
(x) |
(x) |
x |
The (x) denotes that support could be removed in next version of Neo4j.
Neo4j Driver API
Neo4j Drivers export a uniform API.
This allows driver concepts and naming to be shared across ecosystems, making transition between languages and multi-language support easier and more consistent.