PowerBuilder 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.

PowerBuilder

integer li_rc
long li_Success
oleobject loo_Curl
oleobject loo_State
oleobject loo_Files
string ls_StatePath
oleobject loo_Page
oleobject loo_SeenPath
string ls_EventId
string ls_NextPosition
long li_Batch
long i
long li_Count
long li_More
oleobject loo_AuthorizedCommand1
long li_HeaderReplacement1

li_Success = 0

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

li_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.
loo_Curl = create oleobject
li_rc = loo_Curl.ConnectToNewObject("Chilkat.HttpCurl")
if li_rc < 0 then
    destroy loo_Curl
    MessageBox("Error","Connecting to COM object failed")
    return
end if
loo_Curl.SetVar("access_token","BOX_ACCESS_TOKEN")

loo_State = create oleobject
li_rc = loo_State.ConnectToNewObject("Chilkat.JsonObject")

loo_Files = create oleobject
li_rc = loo_Files.ConnectToNewObject("Chilkat.FileAccess")

ls_StatePath = "qa_data/box_events_state.json"
if loo_Files.FileExists(ls_StatePath) = 1 then
    li_Success = loo_State.LoadFile(ls_StatePath)
    if li_Success <> 1 then
        Write-Debug loo_State.LastErrorText
        destroy loo_Curl
        destroy loo_State
        destroy loo_Files
        return
    end if

    if loo_State.HasMember("position") <> 1 then
        Write-Debug "Invalid checkpoint: position missing."
        destroy loo_Curl
        destroy loo_State
        destroy loo_Files
        return
    end if

else
    //  "now" starts a new subscription. It deliberately skips historical events.
    loo_State.UpdateString("position","now")
end if

loo_Curl.SetVar("position",loo_State.StringOf("position"))
loo_Page = create oleobject
li_rc = loo_Page.ConnectToNewObject("Chilkat.JsonObject")

loo_SeenPath = create oleobject
li_rc = loo_SeenPath.ConnectToNewObject("Chilkat.StringBuilder")

li_Batch = 0

li_More = 1
do while (li_More = 1) AND (li_Batch < 20)
    loo_Curl.ClearTargetOutput("*")
    loo_AuthorizedCommand1 = create oleobject
    li_rc = loo_AuthorizedCommand1.ConnectToNewObject("Chilkat.StringBuilder")

    loo_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}}~"")
    li_HeaderReplacement1 = loo_AuthorizedCommand1.Replace("{{access_token}}",loo_Curl.GetVar("access_token"))
    li_Success = loo_Curl.DoYourThing(loo_AuthorizedCommand1.GetAsString())
    if (li_Success <> 1) OR (loo_Curl.StatusCode <> 200) then
        Write-Debug "Box request failed. HTTP status: " + string(loo_Curl.StatusCode)
        Write-Debug "Failure reason: " + string(loo_Curl.FailReason)
        Write-Debug loo_Curl.ResponseBodyStr
        destroy loo_Curl
        destroy loo_State
        destroy loo_Files
        destroy loo_Page
        destroy loo_SeenPath
        destroy loo_AuthorizedCommand1
        return
    end if

    li_Success = loo_Curl.GetResponseJson(loo_Page)
    if li_Success <> 1 then
        Write-Debug loo_Curl.LastErrorText
        destroy loo_Curl
        destroy loo_State
        destroy loo_Files
        destroy loo_Page
        destroy loo_SeenPath
        destroy loo_AuthorizedCommand1
        return
    end if

    li_Count = loo_Page.SizeOfArray("entries")
    i = 0
    do while i < li_Count
        loo_Page.I = i
        ls_EventId = loo_Page.StringOf("entries[i].event_id")
        if ls_EventId = "" then
            Write-Debug "Event without an event_id; checkpoint not advanced."
            destroy loo_Curl
            destroy loo_State
            destroy loo_Files
            destroy loo_Page
            destroy loo_SeenPath
            destroy loo_AuthorizedCommand1
            return
        end if

        loo_SeenPath.Clear()
        loo_SeenPath.Append("seen.")
        loo_SeenPath.Append(ls_EventId)
        if loo_State.HasMember(loo_SeenPath.GetAsString()) = 0 then
            //  Replace this logging with your idempotent business operation.
            //  Record success only after that operation succeeds.
            Write-Debug ls_EventId + " " + loo_Page.StringOf("entries[i].event_type") + " " + loo_Page.StringOf("entries[i].source.id")
            loo_State.UpdateBool(loo_SeenPath.GetAsString(),1)
        end if

        i = i + 1
    loop
    ls_NextPosition = loo_Page.StringOf("next_stream_position")
    if ls_NextPosition = "" then
        Write-Debug "Missing next_stream_position; checkpoint not advanced."
        destroy loo_Curl
        destroy loo_State
        destroy loo_Files
        destroy loo_Page
        destroy loo_SeenPath
        destroy loo_AuthorizedCommand1
        return
    end if

    li_More = (li_Count > 0) AND (ls_NextPosition <> loo_Curl.GetVar("position"))
    loo_State.UpdateString("position",ls_NextPosition)
    li_Success = loo_State.WriteFile(ls_StatePath)
    if li_Success <> 1 then
        Write-Debug loo_State.LastErrorText
        destroy loo_Curl
        destroy loo_State
        destroy loo_Files
        destroy loo_Page
        destroy loo_SeenPath
        destroy loo_AuthorizedCommand1
        return
    end if

    loo_Curl.SetVar("position",ls_NextPosition)
    li_Batch = li_Batch + 1
loop
Write-Debug "Checkpoint saved. Run again later to continue polling."


destroy loo_Curl
destroy loo_State
destroy loo_Files
destroy loo_Page
destroy loo_SeenPath
destroy loo_AuthorizedCommand1