API Specifications for MinKNOW

Overview

MinKNOW is software from Oxford Nanopore Technologies plc to control its single-modecule (eg: DNA or RNA) sequencing devices. It comes embedded in GridION, PromethION and MinION Mk1C devices, and can also be installed on user PCs to run devices such as the MinION Mk1B/Mk1D and the P2 Solo. MinKNOW drives the sequencing hardware, analyses the data and provides the user with the results (which can be the raw data samples from the hardware, a DNA or RNA sequence, or the answer to a biological question).

The files and code in this repository provide a way of automating interactions with MinKNOW, including gathering information about running or finished experiments, starting and stopping those experiments, and even exerting more fine-grained control. Anything that can be done via MinKNOW's user interface (and more) can be done using the APIs in this project.

This project is targetted at LIMS developers or developers of other tools that have a need to integrate with MinKNOW. Some familiarity with Python is expected (although the APIs can be used from other languages), as the examples are written in Python. If you are not familiar with gRPC, it is worth reading through some of the gRPC documentation to get a feel for it.

Getting Started

Dependencies

The first thing you will need is an installation of MinKNOW to communicate with. This can be obtained from the Oxford Nanopore Community download pages if you want a local installation, although the installation on a GridION, PromethION, etc will also work.

Note that you will need a compatible version of MinKNOW for the version of minknow_api you are using - see the FAQs below.

Python

For the Python module and examples, you will also need Python 3.7 or later. The Python module depends on a few other packages, such as grpcio and numpy, but these should be handled as part of package installation.

See python/README.md for more information about the Python module.

Other Languages

MinKNOW's API is based on gRPC and can be used from any language supported by gRPC. This includes Go, Java, Ruby, JavaScript (although see the note below about JavaScript) and many more. The gRPC documentation describes how to generate client libraries from the API descriptions in this repository, and how to use those libraries. The .proto files themselves contain documentation about what the various RPCs do, and a more general overview is given below.

The Manager interface is available on port 9502 - see the FAQs for more details. From there, APIs are available to get the ports that other services operate on (including the services for each flow cell position).

JavaScript

How to use gRPC from JavaScript depends on whether you're using it from Node (in which case it works much like any other language - see above) or from a web browser environment. For web browsers (including Electron), you need to use the Web variant, which may also involve connecting to a different port.

Secure connections still start at 9502 for the Manager service. When using the Manager APIs to get ports for other services, you should use fields with grpc_web in the name, like secure_grpc_web.

Authentication

See AUTH.md for information on authenticating with the MinKNOW API.

API Highlights

The files in proto/minknow_api describe MinKNOW's APIs. Each file describes a single service, which covers a specific area of MinKNOW's functionality.

There are two global services, the manager service and basecaller service. There is only one instance of each of these services: see below for how to connect to them. All other services are provided by each flow cell position independently. For example, if you are using a GridION X5, which has 5 flow cell positions, there will be 5 ports (or sets of ports - secure, gRPC Web, etc), each of which will provide all the other services.

manager.proto

manager.proto is the entry point of MinKNOW's APIs. It is always available on a specific port 9502.

The most important method is flow_cell_positions, which provides information about how to connect to the services for each flow cell position. From there you can access all the flow cell position-specific services.

Other methods on the manager service provide general information about the MinKNOW installation and its high-level state, as well as port information for the basecaller service service, which can be used to basecall data from previous experiments.

instance.proto

instance.proto provides general information about the flow cell position. Of particular interest is the get_output_directories method, which indicates where data files will be written to. set_output_directories can be used to change this.

stream_instance_activity may also be useful, as it provides a continuously-updated summary of the state of the position.

This can be accessed via the ports reported by flow_cell_positions on the manager service.

protocol.proto

protocol.proto allows starting and stopping experiment protocols, as well as providing information about the current and previous protocol runs. Note that information about protocol runs from before the last restart is not available via this API.

See the start_protocol example for an example of how to use this service to start a protocol.

acquisition.proto

The main work of a protocol is acquiring data, and this is managed in acquisition.proto. While most of the methods in acquisition.proto will not be useful to most external tools, get_acquisition_info is helpful for access detailed information about what was done by a protocol run reported by protocol.proto.

device.proto

device.proto provides more detailed information about the hardware of the flow cell position and the inserted flow cell. get_device_info provides some constant information about the position, while get_flow_cell_info provides information about the flow cell (a streaming version that provides updates about changes to the flow cell, such as it being removed, is also available). It is also possible to override the flow cell identifier and product code via this service (although this is not generally recommended).

statistics.proto

statistics.proto provides statistics about current and previous protocol runs, including duty time and temperature information. This is useful for generating reports or tables of data describing how well an experiment has performed.

Help

Licence and Copyright

© 2023 Oxford Nanopore Technologies PLC.

API Specifications for MinKNOW is distributed under the Terms and Conditions of the Nanopore Community.

FAQs

What MinKNOW versions will this work with?

MinKNOW's API changes over time, to support new features and occasionally for other reasons, such as improving security. The important version is that of MinKNOW Core - this version looks like 3.6.5 or 4.0.1 - rather than the date-based version of the entire MinKNOW release (which looks more like 19.12.5).

Every minor release of MinKNOW Core (the 4.0 in 4.0.1) has a fixed API, which is described by the corresponding minor releases of minknow_api. So you should use the latest 4.0.x release of minknow_api to talk to MinKNOW Core 4.0.1.

Note that while minknow_api does not strictly use semantic versioning, we aim to keep backwards-incompatible changes to a minimum, and to deprecate anything we are planning to remove for at least one minor version before we actually remove it. We also aim to only make incompatible changes that are likely to have an impact on third-party systems when we bump the major version.

What port should I connect to?

Since MinKNOW Core 5.6, there are two "entry" ports, providing manager service:

• 9501 can only be used with a gRPC secure channel. If you want to use client certificate authentication, you need to use this port.
• 9502 is for gRPC-Web connections, but can also be used with a gRPC secure channel. However, it cannot be used with client certificate authentication.

Versions prior to 5.6 only provided the 9502 port.

Ports reported by manager RPCs follow a similar pattern: there are two fields. For example, the basecaller_api RPC returns a response with two fields:

• secure is a port that can be connected to with a gRPC secure channel, and supports client certificates
• secure_grpc_web is a port that can be connected to with a gRPC-Web secure channel (but does not support client certificates)

How do I set up a gRPC secure channel?

MinKNOW provides TLS transport security for its APIs, but uses a self-signed certificate. This means that the client library you use has to trust this certificate.

If you are using the minknow_api Python package, this is all handled for you. If you are using the gRPC client libraries directly (for example, if you are connecting from a language other than Python), you will need to tell the library about MinKNOW's TLS certificates.

Within the MinKNOW installation, you can find the CA certificate at conf/rpc-certs/ca.crt. This can be passed to most gRPC client libraries as part of creating a secure/SSL channel.

Note that this certificate is only valid for the "localhost" name - connecting to 127.0.0.1 directly will not work, nor will connecting across the network. You can work around this by setting the grpc.ssl_target_name_override channel option to localhost.

Glossary

Acquisition

An acquisition period or acquisition run is a period in which data was being actively read from the flow cell. A typical protocol will have two acquisition periods - a short one with minimal analysis to calibrate the flow cell followed by a much longer one to actually gather sequence data.

Device

When the APIs refer to a device, this is the same as a flow cell position. Newer APIs use the more descriptive flow cell position, but there are plenty of older APIs that use device instead.

Experiment

In the user interface, an experiment name is another name for a protocol group ID (see Protocol). Note that what a user considers an "experiment" may not map onto a consistent concept in MinKNOW, and the APIs generally avoid this term in favour of a more precise term like "protocol run" or "protocol group".

Flow Cell

The flow cell is a consumable that plugs into the sequencing unit and contains the chemistry required to sequence the sample. Often, but not always, contains some core electronics.

The flow cell position is the location that a flow cell can be plugged in to. It is synonymous with device in the APIs.

Protocol

A protocol is a description of how to perform an experiment. This takes the form of some configuration and a Python script. A protocol run is a specific execution of that protocol.

A protocol group is a set of protocol runs given the same name (referred to as a "protocol group ID" in the API, and an "experiment name" in the user interface).