feat(tcp): TCPStreamer DataSources, in-process TCPStreamService, stream multiplexing and TCPStreamJoin

Add TCPStreamer/TCPStreamerClient (TCP transport behind the UDPSServerI/UDPSClientI
seam), an optional single in-process TCPStreamService serving many streams over
worker threads, multiplexed SUBSCRIBE (comma list, stream index in fragmentIdx),
and TCPStreamJoin, which merges several streams into one sample-and-hold stream
paced by a master. StreamHub takes a comma list of streams over one connection.
Includes GTests, E2E scenarios s58-s73 and docs.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Source/Applications/StreamHub/UDPSourceSession.cpp

@@ -51,6 +51,8 @@ UDPSourceSession::UDPSourceSession()
       ringTemporal_(1000000u),
       ringScalar_(100000u),
       initialised_(false),
+      client_(static_cast<MARTe::UDPSClientI *>(0)),
+      external_(false),
       numSignals_(0u),
       publishMode_(0u),
       configured_(false),
@@ -112,7 +114,10 @@ bool UDPSourceSession::Initialise(const char *id, const char *label,
                                    const char *addr, uint16 port,
                                    uint32 maxPts,
                                    const char *mcGroup,
-                                   uint16 dataPort) {
+                                   uint16 dataPort,
+                                   const char *transport,
+                                   const char *streamName,
+                                   MARTe::UDPSClientI *external) {
     (void) Stop();
 
     id_    = id;
@@ -121,25 +126,42 @@ bool UDPSourceSession::Initialise(const char *id, const char *label,
     port_  = port;
     mcGroup_  = (mcGroup != static_cast<const char *>(0)) ? mcGroup : "";
     dataPort_ = dataPort;
+    transport_  = ((transport != static_cast<const char *>(0)) && (strcmp(transport, "tcp") == 0)) ? "tcp" : "udp";
+    streamName_ = (streamName != static_cast<const char *>(0)) ? streamName : "";
     maxPoints_ = (maxPts > 0u) ? maxPts : 20000u;
 
     /* Build ConfigurationDatabase for UDPSClient */
     ConfigurationDatabase cfg;
     (void) cfg.Write("ServerAddr", addr);
     (void) cfg.Write("Port", static_cast<uint32>(port));
-    if ((mcGroup != static_cast<const char *>(0)) && (strlen(mcGroup) > 0u)) {
+    const bool useTcp = (transport_ == "tcp");
+    if (useTcp) {
+        if (streamName_.Size() > 0u) {
+            (void) cfg.Write("StreamName", streamName_.Buffer());
+        }
+    } else if ((mcGroup != static_cast<const char *>(0)) && (strlen(mcGroup) > 0u)) {
         (void) cfg.Write("MulticastGroup", mcGroup);
         if (dataPort > 0u) {
             (void) cfg.Write("DataPort", static_cast<uint32>(dataPort));
         }
     }
 
-    if (!client_.Initialise(cfg)) {
+    external_ = (external != static_cast<MARTe::UDPSClientI *>(0));
+    if (external_) {
+        client_ = external; /* already configured by its owner */
+    }
+    else {
+        client_ = useTcp ? static_cast<MARTe::UDPSClientI *>(&tcpClient_)
+                         : static_cast<MARTe::UDPSClientI *>(&udpClient_);
+    }
+    if (!external_ && !client_->Initialise(cfg)) {
         REPORT_ERROR_STATIC(MARTe::ErrorManagement::FatalError,
-                            "UDPSourceSession[%s]: Failed to initialise UDPSClient.", id);
+                            "UDPSourceSession[%s]: Failed to initialise %s client.",
+                            id, useTcp ? "TCPSClient" : "UDPSClient");
+        client_ = static_cast<MARTe::UDPSClientI *>(0);
         return false;
     }
-    client_.SetListener(this);
+    client_->SetListener(this);
 
     (void) metaMutex_.FastLock();
     numSignals_ = 0u;
@@ -165,12 +187,22 @@ bool UDPSourceSession::Start() {
     statByteCount_   = 0u;
     stateStr_ = "connecting";
     statsMutex_.FastUnLock();
-    return client_.Start();
+    return client_->Start();
+}
+
+void UDPSourceSession::DetachClient() {
+    if (!external_) { return; }
+    (void) Stop();
+    if (client_ != static_cast<MARTe::UDPSClientI *>(0)) {
+        client_->SetListener(static_cast<MARTe::UDPSClientListener *>(0));
+    }
+    client_   = static_cast<MARTe::UDPSClientI *>(0);
+    external_ = false;
 }
 
 bool UDPSourceSession::Stop() {
-    if (!initialised_) { return true; }
-    return client_.Stop();
+    if (!initialised_ || (client_ == static_cast<MARTe::UDPSClientI *>(0))) { return true; }
+    return client_->Stop();
 }
 
 /*---------------------------------------------------------------------------*/
@@ -200,7 +232,7 @@ void UDPSourceSession::OnUDPSConfig(const uint8 *payload, uint32 payloadSize) {
 
 void UDPSourceSession::OnUDPSData(const uint8 *payload, uint32 payloadSize) {
     /* Valid only for the duration of this callback. */
-    ParseDataPayload(payload, payloadSize, client_.GetLastDataGap());
+    ParseDataPayload(payload, payloadSize, client_->GetLastDataGap());
 }
 
 /*---------------------------------------------------------------------------*/
@@ -947,6 +979,10 @@ StreamString UDPSourceSession::GetMulticastGroup() const { return mcGroup_; }
 
 uint16 UDPSourceSession::GetDataPort() const { return dataPort_; }
 
+StreamString UDPSourceSession::GetTransport() const { return transport_; }
+
+StreamString UDPSourceSession::GetStreamName() const { return streamName_; }
+
 bool UDPSourceSession::IsConfigured() const {
     (void) metaMutex_.FastLock();
     bool c = configured_;