Box: Poll User Events and Save a Checkpoint

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Poll the authenticated user event stream in bounded batches. The local JSON checkpoint keeps processed event IDs and the next stream position. This single-process demonstration logs events; a production worker should commit its business action, deduplication record, and cursor transactionally and prune old IDs.

See the Box API guide for setup and the complete workflow.

var success = false;

//  Requires Chilkat 11.5.0 or later and a previously unlocked Chilkat bundle.
//  See Global Unlock Sample.
//  Guide: Box API Guide.

success = false;

//  Supply an unexpired token obtained with one of the Box authentication examples.
//  A token represents a particular user or service account. IDs must be accessible to it.
var curl = new CkHttpCurl();
curl.SetVar("access_token","BOX_ACCESS_TOKEN");

var state = new CkJsonObject();
var files = new CkFileAccess();
var statePath = "qa_data/box_events_state.json";
if (files.FileExists(statePath) == true) {
    success = state.LoadFile(statePath);
    if (success !== true) {
        console.log(state.LastErrorText);
        return;
    }

    if (state.HasMember("position") !== true) {
        console.log("Invalid checkpoint: position missing.");
        return;
    }

}
else {
    //  "now" starts a new subscription. It deliberately skips historical events.
    state.UpdateString("position","now");
}

curl.SetVar("position",state.StringOf("position"));
var page = new CkJsonObject();
var seenPath = new CkStringBuilder();
var eventId;
var nextPosition;
var batch = 0;
var i;
var count;
var more = true;
while ((more == true) && (batch < 20)) {
    curl.ClearTargetOutput("*");
    var authorizedCommand1 = new CkStringBuilder();
    authorizedCommand1.SetString("curl -X GET \"https://api.box.com/2.0/events?stream_type=all&stream_position={{position}}&limit=100\" -H \"Authorization: Bearer {{access_token}}\"");
    var headerReplacement1 = authorizedCommand1.Replace("{{access_token}}",curl.GetVar("access_token"));
    success = curl.DoYourThing(authorizedCommand1.GetAsString());
    if ((success !== true) || (curl.StatusCode !== 200)) {
        console.log("Box request failed. HTTP status: " + curl.StatusCode);
        console.log("Failure reason: " + curl.FailReason);
        console.log(curl.ResponseBodyStr);
        return;
    }

    success = curl.GetResponseJson(page);
    if (success !== true) {
        console.log(curl.LastErrorText);
        return;
    }

    count = page.SizeOfArray("entries");
    i = 0;
    while (i < count) {
        page.I = i;
        eventId = page.StringOf("entries[i].event_id");
        if (eventId == "") {
            console.log("Event without an event_id; checkpoint not advanced.");
            return;
        }

        seenPath.Clear();
        seenPath.Append("seen.");
        seenPath.Append(eventId);
        if (state.HasMember(seenPath.GetAsString()) == false) {
            //  Replace this logging with your idempotent business operation.
            //  Record success only after that operation succeeds.
            console.log(eventId + " " + page.StringOf("entries[i].event_type") + " " + page.StringOf("entries[i].source.id"));
            state.UpdateBool(seenPath.GetAsString(),true);
        }

        i = i+1;
    }

    nextPosition = page.StringOf("next_stream_position");
    if (nextPosition == "") {
        console.log("Missing next_stream_position; checkpoint not advanced.");
        return;
    }

    more = (count > 0) && (nextPosition !== curl.GetVar("position"));
    state.UpdateString("position",nextPosition);
    success = state.WriteFile(statePath);
    if (success !== true) {
        console.log(state.LastErrorText);
        return;
    }

    curl.SetVar("position",nextPosition);
    batch = batch+1;
}

console.log("Checkpoint saved. Run again later to continue polling.");