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API Gateway pattern

The Graphql Application API gateway pattern

There are two API layers involved for the main NSHM web applications (Kororaa and Weka). 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. Try google or here for information about this style of services organisation.

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

For specific configurations please see:

Example: Kororaa TEST

The Kororaa application communicates with a single API gateway, which passes on calls to the relevant API microservice(s):

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["Microservice layer"]
        direction LR

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

Kororaa connects to API Gateway at nshm-api-test.gns.cri.nz/kororaa-app-api. The gateway path maps to the associated lambda function i.e nshm-kororaa-apigw-test-app. in turn, this lambda function runs a lightweight node express service that stitches and proxies to the required microservices.

For Kororaa the microservices are: