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API Gateway pattern

The Graphql Application API gateway pattern

There are two API layers involved for the main NSHM web application (Kororaa) . The pattern is commonly known as a microservice architecture, where the lower layer consists of domain-specific services that are then composed into collections by an API gateway. THe Kororaa application is required to communicate with a single API gateway, which in turn passes on call to the relevant API microservice(s). Try google or here for information about this style of services organisation.

graph TD
    classDef nshm stroke:lightgreen, stroke-width:3px
    classDef AWS stroke:orange, stroke-width:3px
    classDef SVC stroke:powderblue, stroke-width:3px
    classDef note stroke:black, stroke-width:1px

    K["Kororaa web app
    nshm-test.gns.cri.nz"]:::nshm
    NB["https://nshm-api-test.gns.cri.nz/kororaa-app-api/graphql"]:::note 
    subgraph GW["API Gateway layer"]
        A["API Gateway:
        test-nshm-kororaa-apigw (4ra58fifn3)"]:::AWS
        F["lambda:
        nshm-kororaa-apigw-test-app"]:::nshm
    end

    subgraph SUP["graphql microservices layer"]
        direction LR

        K-API[kororaa-graphql-api]:::nshm
        S-API[solvis-graphql-api]:::nshm
        T-API[nshm-toshi-api]:::nshm               
    end
    K -.-|graphql query| NB -.-> A -->|path: kororaa-app-api/graphql| F 
    F --> S-API
    F --> K-API
    F --> T-API

The NSHM service APIs are all using graphql standard. This means that the API gateway can also provide schema stitching to improve flexibilty and efficiencies that benefit the client application.

In the Kororaa APP API Gateway example shown above we have a web application client which communicates with a single API Gateway endpoint via the DNS hostname/path nshm-test.gns.cri.nz/kororaa-app-api. This API gateway simply directs request by path to the associated lambda function i.e nshm-kororaa-apigw-test-app. This lambda function runs a lightweight node express application that stitches and proxies to the required microservices.

Also shown as examples in the diagram above we have:

  • Kororaa application API Gateway which is the stitching app gateway for Koroaa.

  • kororaa-graphql-api is an API microservice that deals with kororaa app specific functions e.g help text, science publications, model release history.

  • solvis-graphql-api is an API microservice that deals with solvis functions.

  • nshm-toshi-api is an API microservice for tracking experimental processes and artefacts (inputs and outputs).

For more specific configurations please see API gateway deployments.