ROAPI automatically spins up read-only APIs for static datasets without requiring you to write a single line of code. It builds on top of Apache Arrow and Datafusion. The core of its design can be boiled down to the following:

• Query frontends to translate SQL, GraphQL and REST API queries into Datafusion plans.
• Datafusion for query plan execution.
• Data layer to load datasets from a variety of sources and formats with automatic schema inference.
• Response encoding layer to serialize intermediate Arrow record batch into various formats requested by client.

See below for a high level diagram:

cargo install --git https://github.com/roapi/roapi --branch main --bin roapi-http

Pre-built docker images are also available at ghcr.io/roapi/roapi-http.

Spin up APIs for test_data/uk_cities_with_headers.csv and test_data/spacex-launches.json:

roapi-http \
    --table 'uk_cities:test_data/uk_cities_with_headers.csv' \
    --table 'spacex_launches:test_data/spacex-launches.json'

Or using docker:

docker run -t --rm -p 8080:8080 ghcr.io/roapi/roapi-http:latest --addr 0.0.0.0:8080 \
    --table 'uk_cities:test_data/uk_cities_with_headers.csv' \
    --table 'spacex_launches:test_data/spacex-launches.json'

Query tables using SQL, GraphQL or REST:

curl -X POST -d "SELECT city, lat, lng FROM uk_cities LIMIT 2" localhost:8080/api/sql
curl -X POST -d "query { uk_cities(limit: 2) {city, lat, lng} }" localhost:8080/api/graphql
curl "localhost:8080/api/tables/uk_cities?columns=city,lat,lng&limit=2"

Get inferred schema for all tables:

curl 'localhost:8080/api/schema'

You can also configure multiple table sources using YAML config, which supports more advanced format specific table options:

addr: 0.0.0.0:8084
tables:
  - name: "blogs"
    uri: "test_data/blogs.parquet"

  - name: "ubuntu_ami"
    uri: "test_data/ubuntu-ami.json"
    option:
      format: "json"
      pointer: "/aaData"
      array_encoded: true
    schema:
      columns:
        - name: "zone"
          data_type: "Utf8"
        - name: "name"
          data_type: "Utf8"
        - name: "version"
          data_type: "Utf8"
        - name: "arch"
          data_type: "Utf8"
        - name: "instance_type"
          data_type: "Utf8"
        - name: "release"
          data_type: "Utf8"
        - name: "ami_id"
          data_type: "Utf8"
        - name: "aki_id"
          data_type: "Utf8"

  - name: "spacex_launches"
    uri: "https://api.spacexdata.com/v4/launches"
    option:
      format: "json"

  - name: "github_jobs"
    uri: "https://jobs.github.com/positions.json"

To run serve tables using config file:

roapi-http -c ./roapi.yml

See config documentation for more options including using Google spreadsheet as a table source.

By default, ROAPI encodes responses in JSON format, but you can request different encodings by specifying the ACCEPT header:

curl -X POST \
    -H 'ACCEPT: application/vnd.apache.arrow.stream' \
    -d "SELECT launch_library_id FROM spacex_launches WHERE launch_library_id IS NOT NULL" \
    localhost:8080/api/sql

You can query tables through REST API by sending GET requests to /api/tables/{table_name}. Query operators are specified as query params.

REST query frontend currently supports the following query operators:

• columns
• sort
• limit
• filter

To sort column col1 in ascending order and col2 in descending order, set query param to: sort=col1,-col2.

To find all rows with col1 equal to string 'foo', set query param to: filter[col1]='foo'. You can also do basic comparisons with filters, for example predicate 0 <= col2 < 5 can be expressed as filter[col2]gte=0&filter[col2]lt=5.

To query tables using GraphQL, send the query through POST request to /api/graphql endpoint.

GraphQL query frontend supports the same set of operators supported by REST query frontend. Here how is you can apply various operators in a query:

{
    table_name(
        filter: {
            col1: false
            col2: { gteq: 4, lt: 1000 }
        }
        sort: [
            { field: "col2", order: "desc" }
            { field: "col3" }
        ]
        limit: 100
    ) {
        col1
        col2
        col3
    }
}

To query tables using a subset of standard SQL, send the query through POST request to /api/sql endpoint. This is the only query interface that supports table joins.

Query layer:

• REST API GET
• GraphQL
• SQL
• join between tables
• support filter on nested struct fields
• index
• protocol
  • gRPC
  • MySQL
  • Postgres

Response serialization:

• JSON application/json
• Arrow application/vnd.apache.arrow.stream
• msgpack

Data layer:

• filesystem
• HTTP/HTTPS
• S3
• GCS
• ABS
• Google spreadsheet
• MySQL
• Postgres
• Airtable
• Data format
  • CSV
  • JSON
  • parquet
  • xls, xlsx, xlsm, ods: https://github.com/tafia/calamine

Misc:

• auto gen OpenAPI doc for rest layer
• query input type conversion based on table schema
• stream arrow encoding response
• authentication layer

The core of ROAPI, including query frontends and data layer, lives in the self-contained columnq crate. It takes queries and outputs Arrow record batches. Data sources will also be loaded and stored in memory as Arrow record batches.

The roapi-http crate wraps columnq with a HTTP based API layer. It serializes Arrow record batches produced by columnq into different formats based on client request.

Building ROAPI with simd optimization requires nightly rust toolchain.

docker build --build-arg RELEASE=main --rm -t ghcr.io/roapi/roapi-http:latest .

You can set RELEASE variable to any git reference to build for a specific version.