Implemented client datasource

Source/Applications/StreamHub/HistoryWriter.cpp

@@ -5,6 +5,7 @@
 
 #include "HistoryWriter.h"
 #include "AdvancedErrorManagement.h"
+#include "UDPSProtocol.h"
 
 #include <stdio.h>
 #include <string.h>
@@ -129,8 +130,8 @@ void HistoryWriter::OnSourceConfigured(uint32 sessionIdx, const char *sourceId,
         MARTe::UDPSSignalDescriptor desc;
         if (!sess.GetSignalDescriptor(s, desc)) { continue; }
 
-        /* Skip time-only signals (type uint64, typically TimeArray) */
-        if (desc.typeCode == 13u) { continue; } /* uint64 = 13 in UDPS */
+        /* Skip time-reference signals (uint64 type, typically TimeArray) */
+        if (desc.typeCode == MARTe::UDPS_TYPECODE_UINT64) { continue; }
 
         float64 estRate = static_cast<float64>(desc.samplingRate);
         if (estRate <= 0.0) { estRate = 1000.0; } /* fallback */
@@ -490,8 +491,9 @@ void HistoryWriter::AppendInfoJSON(char *&buf, uint32 &off, uint32 &cap) const {
         for (uint32 s = 0u; s < kHistMaxSignals; s++) {
             if (!fileActive_[i][s]) { continue; }
             const SignalFile &sf = files_[i][s];
-            if (sf.count == 0u) { continue; }
-
+            /* Report even when count==0 — the file exists but hasn't received
+             * data yet (or was just created).  Clients need the entry to enable
+             * history UI; t0/t1 == 0 signals "still priming". */
             HistJsonAppendf(buf, off, cap,
                 "%s\"%s:%s\":{\"t0\":%.17g,\"t1\":%.17g,\"count\":%u,\"capacity\":%u}",
                 (first ? "" : ","),