diff --git a/concoredocker.hpp b/concoredocker.hpp
index bcd2bcb..b4fa69b 100644
--- a/concoredocker.hpp
+++ b/concoredocker.hpp
@@ -13,6 +13,7 @@
 #include <stdexcept>
 #include <regex>
 #include <algorithm>
+#include <map>
 
 #include "concore_base.hpp"
 
@@ -28,6 +29,9 @@ class Concore {
     double simtime = 0;
     double maxtime = 100;
     std::unordered_map<std::string, std::string> params;
+#ifdef CONCORE_USE_ZMQ
+    std::map<std::string, concore_base::ZeroMQPort*> zmq_ports;
+#endif
 
     std::string stripstr(const std::string& str) {
         return concore_base::stripstr(str);
@@ -53,6 +57,14 @@ class Concore {
         load_params();
     }
 
+    ~Concore() {
+#ifdef CONCORE_USE_ZMQ
+        for (auto& kv : zmq_ports)
+            delete kv.second;
+        zmq_ports.clear();
+#endif
+    }
+
     Concore(const Concore&) = delete;
     Concore& operator=(const Concore&) = delete;
 
@@ -63,13 +75,23 @@ class Concore {
           inpath(std::move(other.inpath)), outpath(std::move(other.outpath)),
           simtime(other.simtime), maxtime(other.maxtime),
           params(std::move(other.params))
-    {}
+    {
+#ifdef CONCORE_USE_ZMQ
+        zmq_ports = std::move(other.zmq_ports);
+#endif
+    }
 
     Concore& operator=(Concore&& other) noexcept
     {
         if (this == &other)
             return *this;
 
+#ifdef CONCORE_USE_ZMQ
+        for (auto& kv : zmq_ports)
+            delete kv.second;
+        zmq_ports = std::move(other.zmq_ports);
+#endif
+
         iport = std::move(other.iport);
         oport = std::move(other.oport);
         s = std::move(other.s);
@@ -118,7 +140,7 @@ class Concore {
         return false;
     }
 
-    std::vector<std::string> read(int port, const std::string& name, const std::string& initstr) {
+    std::vector<double> read(int port, const std::string& name, const std::string& initstr) {
         std::this_thread::sleep_for(std::chrono::seconds(delay));
         std::string file_path = inpath + "/" + std::to_string(port) + "/" + name;
         std::ifstream infile(file_path);
@@ -126,10 +148,10 @@ class Concore {
 
         if (!infile) {
             std::cerr << "File " << file_path << " not found, using default value.\n";
-            return {initstr};
+            return concore_base::parselist_double(initstr);
         }
         std::getline(infile, ins);
-        
+
         int attempts = 0, max_retries = 5;
         while (ins.empty() && attempts < max_retries) {
             std::this_thread::sleep_for(std::chrono::seconds(delay));
@@ -142,22 +164,21 @@ class Concore {
 
         if (ins.empty()) {
             std::cerr << "Max retries reached for " << file_path << ", using default value.\n";
-            return {initstr};
+            return concore_base::parselist_double(initstr);
         }
-        
+
         s += ins;
-        try {
-            std::vector<std::string> inval = parselist(ins);
-            if (!inval.empty()) {
-                double file_simtime = std::stod(inval[0]);
-                simtime = std::max(simtime, file_simtime);
-                return std::vector<std::string>(inval.begin() + 1, inval.end());
-            }
-        } catch (...) {}
-        return {ins};
+        std::vector<double> inval = concore_base::parselist_double(ins);
+        if (inval.empty())
+            inval = concore_base::parselist_double(initstr);
+        if (inval.empty())
+            return inval;
+        simtime = simtime > inval[0] ? simtime : inval[0];
+        inval.erase(inval.begin());
+        return inval;
     }
 
-    void write(int port, const std::string& name, const std::vector<std::string>& val, int delta = 0) {
+    void write(int port, const std::string& name, const std::vector<double>& val, int delta = 0) {
         std::string file_path = outpath + "/" + std::to_string(port) + "/" + name;
         std::ofstream outfile(file_path);
         if (!outfile) {
@@ -174,15 +195,60 @@ class Concore {
         }
     }
 
-    std::vector<std::string> initval(const std::string& simtime_val) {
-        try {
-            std::vector<std::string> val = parselist(simtime_val);
-            if (!val.empty()) {
-                simtime = std::stod(val[0]);
-                return std::vector<std::string>(val.begin() + 1, val.end());
-            }
-        } catch (...) {}
-        return {};
+#ifdef CONCORE_USE_ZMQ
+    void init_zmq_port(const std::string& port_name, const std::string& port_type,
+                       const std::string& address, const std::string& socket_type_str) {
+        if (zmq_ports.count(port_name)) return;
+        int sock_type = concore_base::zmq_socket_type_from_string(socket_type_str);
+        if (sock_type == -1) {
+            std::cerr << "init_zmq_port: unknown socket type '" << socket_type_str << "'\n";
+            return;
+        }
+        zmq_ports[port_name] = new concore_base::ZeroMQPort(port_type, address, sock_type);
+    }
+
+    std::vector<double> read_ZMQ(const std::string& port_name, const std::string& name, const std::string& initstr) {
+        auto it = zmq_ports.find(port_name);
+        if (it == zmq_ports.end()) {
+            std::cerr << "read_ZMQ: port '" << port_name << "' not initialized\n";
+            return concore_base::parselist_double(initstr);
+        }
+        std::vector<double> inval = it->second->recv_with_retry();
+        if (inval.empty())
+            inval = concore_base::parselist_double(initstr);
+        if (inval.empty()) return inval;
+        simtime = simtime > inval[0] ? simtime : inval[0];
+        s += port_name;
+        inval.erase(inval.begin());
+        return inval;
+    }
+
+    void write_ZMQ(const std::string& port_name, const std::string& name, std::vector<double> val, int delta = 0) {
+        auto it = zmq_ports.find(port_name);
+        if (it == zmq_ports.end()) {
+            std::cerr << "write_ZMQ: port '" << port_name << "' not initialized\n";
+            return;
+        }
+        val.insert(val.begin(), simtime + delta);
+        it->second->send_with_retry(val);
+        // simtime must not be mutated here.
+    }
+
+    std::vector<double> read(const std::string& port_name, const std::string& name, const std::string& initstr) {
+        return read_ZMQ(port_name, name, initstr);
+    }
+
+    void write(const std::string& port_name, const std::string& name, std::vector<double> val, int delta = 0) {
+        return write_ZMQ(port_name, name, val, delta);
+    }
+#endif // CONCORE_USE_ZMQ
+
+    std::vector<double> initval(const std::string& simtime_val) {
+        std::vector<double> val = concore_base::parselist_double(simtime_val);
+        if (val.empty()) return val;
+        simtime = val[0];
+        val.erase(val.begin());
+        return val;
     }
 };