PureBasic 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.

PureBasic

IncludeFile "CkFileAccess.pb"
IncludeFile "CkStringBuilder.pb"
IncludeFile "CkJsonObject.pb"
IncludeFile "CkHttpCurl.pb"

Procedure ChilkatExample()

    success.i = 0

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

    success = 0

    ;  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.
    curl.i = CkHttpCurl::ckCreate()
    If curl.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkHttpCurl::ckSetVar(curl,"access_token","BOX_ACCESS_TOKEN")

    state.i = CkJsonObject::ckCreate()
    If state.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    files.i = CkFileAccess::ckCreate()
    If files.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    statePath.s = "qa_data/box_events_state.json"
    If CkFileAccess::ckFileExists(files,statePath) = 1
        success = CkJsonObject::ckLoadFile(state,statePath)
        If success <> 1
            Debug CkJsonObject::ckLastErrorText(state)
            CkHttpCurl::ckDispose(curl)
            CkJsonObject::ckDispose(state)
            CkFileAccess::ckDispose(files)
            ProcedureReturn
        EndIf

        If CkJsonObject::ckHasMember(state,"position") <> 1
            Debug "Invalid checkpoint: position missing."
            CkHttpCurl::ckDispose(curl)
            CkJsonObject::ckDispose(state)
            CkFileAccess::ckDispose(files)
            ProcedureReturn
        EndIf

    Else
        ;  "now" starts a new subscription. It deliberately skips historical events.
        CkJsonObject::ckUpdateString(state,"position","now")
    EndIf

    CkHttpCurl::ckSetVar(curl,"position",CkJsonObject::ckStringOf(state,"position"))
    page.i = CkJsonObject::ckCreate()
    If page.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    seenPath.i = CkStringBuilder::ckCreate()
    If seenPath.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    eventId.s
    nextPosition.s
    batch.i = 0
    i.i
    count.i
    more.i = 1
    While (more = 1) AND (batch < 20)
        CkHttpCurl::ckClearTargetOutput(curl,"*")
        authorizedCommand1.i = CkStringBuilder::ckCreate()
        If authorizedCommand1.i = 0
            Debug "Failed to create object."
            ProcedureReturn
        EndIf

        CkStringBuilder::ckSetString(authorizedCommand1,"curl -X GET " + Chr(34) + "https://api.box.com/2.0/events?stream_type=all&stream_position={{position}}&limit=100" + Chr(34) + " -H " + Chr(34) + "Authorization: Bearer {{access_token}}" + Chr(34))
        headerReplacement1.i = CkStringBuilder::ckReplace(authorizedCommand1,"{{access_token}}",CkHttpCurl::ckGetVar(curl,"access_token"))
        success = CkHttpCurl::ckDoYourThing(curl,CkStringBuilder::ckGetAsString(authorizedCommand1))
        If (success <> 1) OR (CkHttpCurl::ckStatusCode(curl) <> 200)
            Debug "Box request failed. HTTP status: " + Str(CkHttpCurl::ckStatusCode(curl))
            Debug "Failure reason: " + Str(CkHttpCurl::ckFailReason(curl))
            Debug CkHttpCurl::ckResponseBodyStr(curl)
            CkHttpCurl::ckDispose(curl)
            CkJsonObject::ckDispose(state)
            CkFileAccess::ckDispose(files)
            CkJsonObject::ckDispose(page)
            CkStringBuilder::ckDispose(seenPath)
            CkStringBuilder::ckDispose(authorizedCommand1)
            ProcedureReturn
        EndIf

        success = CkHttpCurl::ckGetResponseJson(curl,page)
        If success <> 1
            Debug CkHttpCurl::ckLastErrorText(curl)
            CkHttpCurl::ckDispose(curl)
            CkJsonObject::ckDispose(state)
            CkFileAccess::ckDispose(files)
            CkJsonObject::ckDispose(page)
            CkStringBuilder::ckDispose(seenPath)
            CkStringBuilder::ckDispose(authorizedCommand1)
            ProcedureReturn
        EndIf

        count = CkJsonObject::ckSizeOfArray(page,"entries")
        i = 0
        While i < count
            CkJsonObject::setCkI(page, i)
            eventId = CkJsonObject::ckStringOf(page,"entries[i].event_id")
            If eventId = ""
                Debug "Event without an event_id; checkpoint not advanced."
                CkHttpCurl::ckDispose(curl)
                CkJsonObject::ckDispose(state)
                CkFileAccess::ckDispose(files)
                CkJsonObject::ckDispose(page)
                CkStringBuilder::ckDispose(seenPath)
                CkStringBuilder::ckDispose(authorizedCommand1)
                ProcedureReturn
            EndIf

            CkStringBuilder::ckClear(seenPath)
            CkStringBuilder::ckAppend(seenPath,"seen.")
            CkStringBuilder::ckAppend(seenPath,eventId)
            If CkJsonObject::ckHasMember(state,CkStringBuilder::ckGetAsString(seenPath)) = 0
                ;  Replace this logging with your idempotent business operation.
                ;  Record success only after that operation succeeds.
                Debug eventId + " " + CkJsonObject::ckStringOf(page,"entries[i].event_type") + " " + CkJsonObject::ckStringOf(page,"entries[i].source.id")
                CkJsonObject::ckUpdateBool(state,CkStringBuilder::ckGetAsString(seenPath),1)
            EndIf

            i = i + 1
        Wend
        nextPosition = CkJsonObject::ckStringOf(page,"next_stream_position")
        If nextPosition = ""
            Debug "Missing next_stream_position; checkpoint not advanced."
            CkHttpCurl::ckDispose(curl)
            CkJsonObject::ckDispose(state)
            CkFileAccess::ckDispose(files)
            CkJsonObject::ckDispose(page)
            CkStringBuilder::ckDispose(seenPath)
            CkStringBuilder::ckDispose(authorizedCommand1)
            ProcedureReturn
        EndIf

        more = (count > 0) AND (nextPosition <> CkHttpCurl::ckGetVar(curl,"position"))
        CkJsonObject::ckUpdateString(state,"position",nextPosition)
        success = CkJsonObject::ckWriteFile(state,statePath)
        If success <> 1
            Debug CkJsonObject::ckLastErrorText(state)
            CkHttpCurl::ckDispose(curl)
            CkJsonObject::ckDispose(state)
            CkFileAccess::ckDispose(files)
            CkJsonObject::ckDispose(page)
            CkStringBuilder::ckDispose(seenPath)
            CkStringBuilder::ckDispose(authorizedCommand1)
            ProcedureReturn
        EndIf

        CkHttpCurl::ckSetVar(curl,"position",nextPosition)
        batch = batch + 1
    Wend
    Debug "Checkpoint saved. Run again later to continue polling."


    CkHttpCurl::ckDispose(curl)
    CkJsonObject::ckDispose(state)
    CkFileAccess::ckDispose(files)
    CkJsonObject::ckDispose(page)
    CkStringBuilder::ckDispose(seenPath)
    CkStringBuilder::ckDispose(authorizedCommand1)


    ProcedureReturn
EndProcedure