Getting Started Status

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Basic:	Intro/Trade	Quote	Category	Status	Symbol	Options
Detailed:	Trade	Quote

Introduction to Statuses

Status messages indicate general information about the tape has changed. pNxCoreSys contains details of the status message. pNxCoreSys is also populated for non-status messages as well. For this example we will be printing a timestamp every minute and printing the API version on initialization. Both NxCORESTATUS_WAITFORCOREACCESS and NxCORESTATUS_ERROR will not occur for demo.XU.nx2, but they are generally good checks to have while processing.

Code

using System;
using NxCoreAPI;

class StatusSample {
    static unsafe int OnNxCoreCallback(NxCoreSystem* pNxCoreSys, NxCoreMessage* pNxCoreMsg) {
        if (pNxCoreMsg->MessageType == NxCore.NxMSG_STATUS) {
            if (pNxCoreSys->ClockUpdateInterval >= NxCore.NxCLOCK_MINUTE)
            {
                int year = pNxCoreSys->nxDate.Year;
                int month = pNxCoreSys->nxDate.Month;
                int day = pNxCoreSys->nxDate.Day;
                int hour = pNxCoreSys->nxTime.Hour;
                int minute = pNxCoreSys->nxTime.Minute;
                Console.WriteLine("{0:d2}/{1:d2}/{2:d} {3:d2}:{4:d2}", month, day, year, hour, minute);
            }

            if (pNxCoreSys->Status == NxCore.NxCORESTATUS_WAITFORCOREACCESS)
                Console.WriteLine("Waiting on NxCore Access");

            if (pNxCoreSys->Status == NxCore.NxCORESTATUS_ERROR)
                Console.WriteLine("tape error:{0:d}", pNxCoreSys->StatusData);

            if (pNxCoreSys->Status == NxCore.NxCORESTATUS_INITIALIZING) {
                int major = NxCore.GetMajorVersion(pNxCoreSys->DLLVersion);
                int minor = NxCore.GetMinorVersion(pNxCoreSys->DLLVersion);
                int build = NxCore.GetBuildVersion(pNxCoreSys->DLLVersion);
                Console.WriteLine("Initialized with decoder version {0:d}.{1:d}.{2:d}", major, minor, build);
            }
        }
        return (int)NxCore.NxCALLBACKRETURN_CONTINUE;
    }

    static unsafe void Main(string[] args) {
        if (args.Length < 1)
            return;
        int returnValue = NxCore.ProcessTape(args[0], null, 0, 0, StatusSample.OnNxCoreCallback);
        NxCore.processReturnValue(returnValue);
    }
}

Callback Function

Since we only want to process status messages we check that MessageType equals NxMSG_STATUS.

static unsafe int OnNxCoreCallback(NxCoreSystem* pNxCoreSys, NxCoreMessage* pNxCoreMsg) {
    if (pNxCoreMsg->MessageType == NxCore.NxMSG_STATUS) {
        ...
    }
    return (int)NxCore.NxCALLBACKRETURN_CONTINUE;
}

On Interval

During status messages ClockUpdateInterval indicates if the timestamp has changed and whether it is a new hour, minute, or second. In this example we want to do something every minute, so we will check if ClockUpdateInterval is greater or equal to NxCLOCK_MINUTE, which is equivalent to 3. Checking greater than ensures we also perform the action on a new hour, since NxCLOCK_HOUR is equivalent to 4.
The fields nxDate and nxTime reflect the date and time of the server processing the data.

if (pNxCoreSys->ClockUpdateInterval >= NxCore.NxCLOCK_MINUTE)
{
    int year = pNxCoreSys->nxDate.Year;
    int month = pNxCoreSys->nxDate.Month;
    int day = pNxCoreSys->nxDate.Day;
    int hour = pNxCoreSys->nxTime.Hour;
    int minute = pNxCoreSys->nxTime.Minute;
    ...
}

Incomplete File

The Status field of NxCore message is the current state of the tape. Most of the time Status will be NxCORESTATUS_RUNNING. If the API is unable process the next message after a period of time, either because the file is incomplete or real-time stream is paused, Status will be set to NxCORESTATUS_WAITFORCOREACCESS.

if (pNxCoreSys->Status == NxCore.NxCORESTATUS_WAITFORCOREACCESS)
    Console.WriteLine("Waiting on NxCore Access");

Errors

If there is a problem while processing the tape, Status is set to NxCORESTATUS_ERROR. StatusData contains details of the Status. In this case it corresponds to the Error Codes Table.

if (pNxCoreSys->Status == NxCore.NxCORESTATUS_ERROR)
    Console.WriteLine("tape error:{0:d}", pNxCoreSys->StatusData);

Initialization

The first Status when beginning at the start of the file is NxCORESTATUS_INITIALIZING. If loading midday using states then the first status will instead be NxCORESTATUS_LOADED_STATE.
During the first message we will print the version of the API being used to process the tape. GetMajorVersion, GetMinorVersion, and GetBuildVersion can be used to get a more readable version from the int DLLVersion.

if (pNxCoreSys->Status == NxCore.NxCORESTATUS_INITIALIZING) {
    int major = NxCore.GetMajorVersion(pNxCoreSys->DLLVersion);
    int minor = NxCore.GetMinorVersion(pNxCoreSys->DLLVersion);
    int build = NxCore.GetBuildVersion(pNxCoreSys->DLLVersion);
    Console.WriteLine("Initialized with decoder version {0:d}.{1:d}.{2:d}",
        major, minor, build);
}

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