Swift Requires Chilkat v11.5.0+

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.

Swift

func chilkatTest() {
    var success: Bool = 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.
    let curl = CkoHttpCurl()!
    curl.setVar(varName: "access_token", varValue: "BOX_ACCESS_TOKEN")

    let state = CkoJsonObject()!
    let files = CkoFileAccess()!
    var statePath: String? = "qa_data/box_events_state.json"
    if files.fileExists(path: statePath) == true {
        success = state.loadFile(path: statePath)
        if success != true {
            print("\(state.lastErrorText!)")
            return
        }

        if state.hasMember(jsonPath: "position") != true {
            print("Invalid checkpoint: position missing.")
            return
        }

    }
    else {
        //  "now" starts a new subscription. It deliberately skips historical events.
        state.updateString(jsonPath: "position", value: "now")
    }

    curl.setVar(varName: "position", varValue: state.string(of: "position"))
    let page = CkoJsonObject()!
    let seenPath = CkoStringBuilder()!
    var eventId: String?
    var nextPosition: String?
    var batch: Int = 0
    var i: Int
    var count: Int
    var more: Bool = true
    while (more == true) && (batch < 20) {
        curl.clearTargetOutput(varName: "*")
        let authorizedCommand1 = CkoStringBuilder()!
        authorizedCommand1.setString(value: "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: Int = authorizedCommand1.replace(value: "{{access_token}}", replacement: curl.getVar(varName: "access_token")).intValue
        success = curl.doYourThing(targetCurl: authorizedCommand1.getAsString())
        if (success != true) || (curl.statusCode.intValue != 200) {
            print("Box request failed. HTTP status: \(curl.statusCode.intValue)")
            print("Failure reason: \(curl.failReason.intValue)")
            print("\(curl.responseBodyStr!)")
            return
        }

        success = curl.getResponseJson(json: page)
        if success != true {
            print("\(curl.lastErrorText!)")
            return
        }

        count = page.size(ofArray: "entries").intValue
        i = 0
        while i < count {
            page.i = i
            eventId = page.string(of: "entries[i].event_id")
            if eventId == "" {
                print("Event without an event_id; checkpoint not advanced.")
                return
            }

            seenPath.clear()
            seenPath.append(value: "seen.")
            seenPath.append(value: eventId)
            if state.hasMember(jsonPath: seenPath.getAsString()) == false {
                //  Replace this logging with your idempotent business operation.
                //  Record success only after that operation succeeds.
                print("\(eventId!) \(page.string(of: "entries[i].event_type")!) \(page.string(of: "entries[i].source.id")!)")
                state.updateBool(jsonPath: seenPath.getAsString(), value: true)
            }

            i = i + 1
        }

        nextPosition = page.string(of: "next_stream_position")
        if nextPosition == "" {
            print("Missing next_stream_position; checkpoint not advanced.")
            return
        }

        more = (count > 0) && (nextPosition != curl.getVar(varName: "position"))
        state.updateString(jsonPath: "position", value: nextPosition)
        success = state.writeFile(path: statePath)
        if success != true {
            print("\(state.lastErrorText!)")
            return
        }

        curl.setVar(varName: "position", varValue: nextPosition)
        batch = batch + 1
    }

    print("Checkpoint saved. Run again later to continue polling.")

}