featurehub-eventsource-sdk/lib/featurehub_eventsource.js

FeatureHub SDK. Supports near real-time feature flag updates via eventsource (SSE) or on-demand updates via REST requests.

import { fhLog, SSEResultState } from 'featurehub-repository';
import EventSource from 'eventsource';
export class FeatureHubEventSourceClient {
    constructor(config, repository) {
        this._config = config;
        this._repository = repository;
    }
    init() {
        const options = {};
        if (this._header) {
            options.headers = {
                'x-featurehub': this._header
            };
        }
        fhLog.log('listening at ', this._config.url());
        this.eventSource = new EventSource(this._config.url(), options);
        [SSEResultState.Features, SSEResultState.Feature, SSEResultState.DeleteFeature,
            SSEResultState.Bye, SSEResultState.Failure, SSEResultState.Ack].forEach((name) => {
            const fName = name.toString();
            this.eventSource.addEventListener(fName, e => {
                try {
                    fhLog.log("received ", fName, JSON.stringify(e));
                    this._repository.notify(name, JSON.parse(e.data));
                }
                catch (e) {
                    fhLog.error(JSON.stringify(e));
                }
            });
        });
        this.eventSource.onerror = (e) => {
            fhLog.error("got error", e);
            this._repository.notify(SSEResultState.Failure, null);
        };
    }
    close() {
        if (this.eventSource != null) {
            const es = this.eventSource;
            this.eventSource = undefined;
            es.close();
        }
    }
    clientEvaluated() {
        return this._config.clientEvaluated();
    }
    contextChange(header) {
        this._header = header;
        if (this.eventSource !== undefined) {
            this.close();
        }
        this.init();
        return Promise.resolve(undefined);
    }
    poll() {
        if (this.eventSource == undefined) {
            this.init();
        }
        return new Promise((resolve) => resolve());
    }
    requiresReplacementOnHeaderChange() {
        return true;
    }
}
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