Xojo Plugin Requires Chilkat v11.5.0+

Box: Poll User Events and Save a Checkpoint

See more Box Examples

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.

Xojo Plugin

Dim success As Boolean
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.
Dim curl As New Chilkat.HttpCurl
curl.SetVar "access_token","BOX_ACCESS_TOKEN"

Dim state As New Chilkat.JsonObject
Dim files As New Chilkat.FileAccess
Dim statePath As String
statePath = "qa_data/box_events_state.json"
If (files.FileExists(statePath) = True) Then
    success = state.LoadFile(statePath)
    If (success <> True) Then
        System.DebugLog(state.LastErrorText)
        Return
    End If

    If (state.HasMember("position") <> True) Then
        System.DebugLog("Invalid checkpoint: position missing.")
        Return
    End If

Else
    //  "now" starts a new subscription. It deliberately skips historical events.
    success = state.UpdateString("position","now")
End If

curl.SetVar "position",state.StringOf("position")
Dim page As New Chilkat.JsonObject
Dim seenPath As New Chilkat.StringBuilder
Dim eventId As String
Dim nextPosition As String
Dim batch As Int32
batch = 0
Dim i As Int32
Dim count As Int32
Dim more As Boolean
more = True
While (more = True) And (batch < 20)
    curl.ClearTargetOutput "*"
    Dim authorizedCommand1 As New Chilkat.StringBuilder
    success = 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}}""")
    Dim headerReplacement1 As Int32
    headerReplacement1 = authorizedCommand1.Replace("{{access_token}}",curl.GetVar("access_token"))
    success = curl.DoYourThing(authorizedCommand1.GetAsString())
    If ((success <> True) Or (curl.StatusCode <> 200)) Then
        System.DebugLog("Box request failed. HTTP status: " + Str(curl.StatusCode))
        System.DebugLog("Failure reason: " + Str(curl.FailReason))
        System.DebugLog(curl.ResponseBodyStr)
        Return
    End If

    success = curl.GetResponseJson(page)
    If (success <> True) Then
        System.DebugLog(curl.LastErrorText)
        Return
    End If

    count = page.SizeOfArray("entries")
    i = 0
    While i < count
        page.I = i
        eventId = page.StringOf("entries[i].event_id")
        If (eventId = "") Then
            System.DebugLog("Event without an event_id; checkpoint not advanced.")
            Return
        End If

        seenPath.Clear 
        success = seenPath.Append("seen.")
        success = seenPath.Append(eventId)
        If (state.HasMember(seenPath.GetAsString()) = False) Then
            //  Replace this logging with your idempotent business operation.
            //  Record success only after that operation succeeds.
            System.DebugLog(eventId + " " + page.StringOf("entries[i].event_type") + " " + page.StringOf("entries[i].source.id"))
            success = state.UpdateBool(seenPath.GetAsString(),True)
        End If

        i = i + 1
    Wend
    nextPosition = page.StringOf("next_stream_position")
    If (nextPosition = "") Then
        System.DebugLog("Missing next_stream_position; checkpoint not advanced.")
        Return
    End If

    more = (count > 0) And (nextPosition <> curl.GetVar("position"))
    success = state.UpdateString("position",nextPosition)
    success = state.WriteFile(statePath)
    If (success <> True) Then
        System.DebugLog(state.LastErrorText)
        Return
    End If

    curl.SetVar "position",nextPosition
    batch = batch + 1
Wend
System.DebugLog("Checkpoint saved. Run again later to continue polling.")