diff --git a/Dockerfile.java b/Dockerfile.java
index a3eb3ad..b78f1e6 100644
--- a/Dockerfile.java
+++ b/Dockerfile.java
@@ -1,17 +1,14 @@
 #build stage
-FROM maven:3.9-eclipse-temurin-17-alpine AS builder
+FROM eclipse-temurin:17-jdk-alpine AS builder
 WORKDIR /build
-COPY pom.xml .
-RUN mvn dependency:go-offline -B
-COPY src ./src
-RUN mvn clean package -DskipTests
+RUN apk add --no-cache wget
+RUN wget -q "https://search.maven.org/remotecontent?filepath=org/zeromq/jeromq/0.6.0/jeromq-0.6.0.jar" -O /opt/jeromq.jar
+COPY *.java .
+RUN javac -cp /opt/jeromq.jar *.java
 
 #runtime stage
-FROM eclipse-temurin:17-jdk-alpine
+FROM eclipse-temurin:17-jre-alpine
 
 WORKDIR /app
-
-# Copy the JAR from the build stage
-COPY --from=builder /build/target/concore-*.jar /app/concore.jar
-EXPOSE 3000
-CMD ["java", "-jar", "/app/concore.jar"]
\ No newline at end of file
+COPY --from=builder /build/*.class /app/
+COPY --from=builder /opt/jeromq.jar /app/jeromq.jar
\ No newline at end of file
diff --git a/concoredocker.java b/concoredocker.java
index 96cf6ee..226865f 100644
--- a/concoredocker.java
+++ b/concoredocker.java
@@ -5,6 +5,7 @@
 import java.util.Map;
 import java.util.ArrayList;
 import java.util.List;
+import org.zeromq.ZMQ;
 
 /**
  * Java implementation of concore Docker communication.
@@ -24,6 +25,8 @@ public class concoredocker {
     private static String inpath = "/in";
     private static String outpath = "/out";
     private static Map<String, Object> params = new HashMap<>();
+    private static Map<String, ZeroMQPort> zmqPorts = new HashMap<>();
+    private static ZMQ.Context zmqContext = null;
     // simtime as double to preserve fractional values (e.g. "[0.0, ...]")
     private static double simtime = 0;
     private static double maxtime;
@@ -49,6 +52,7 @@ public class concoredocker {
             params = new HashMap<>();
         }
         defaultMaxTime(100);
+        Runtime.getRuntime().addShutdownHook(new Thread(concoredocker::terminateZmq));
     }
 
     /**
@@ -292,7 +296,7 @@ public static void write(int port, String name, Object val, int delta) {
                 }
                 content.append("]");
                 // simtime must not be mutated here.
-                // Mutation breaks cross-language determinism (see issue #385).
+                // Mutation breaks cross-language determinism.
             } else if (val instanceof Object[]) {
                 // Legacy support for Object[] arguments
                 Object[] arrayVal = (Object[]) val;
@@ -304,7 +308,7 @@ public static void write(int port, String name, Object val, int delta) {
                 }
                 content.append("]");
                 // simtime must not be mutated here.
-                // Mutation breaks cross-language determinism (see issue #385).
+                // Mutation breaks cross-language determinism.
             } else {
                 System.out.println("write must have list or str");
                 return;
@@ -336,6 +340,113 @@ public static List<Object> initVal(String simtimeVal) {
         return val;
     }
 
+    private static ZMQ.Context getZmqContext() {
+        if (zmqContext == null) {
+            zmqContext = ZMQ.context(1);
+        }
+        return zmqContext;
+    }
+
+    public static void initZmqPort(String portName, String portType, String address, String socketTypeStr) {
+        if (zmqPorts.containsKey(portName)) return;
+        int sockType = zmqSocketTypeFromString(socketTypeStr);
+        if (sockType == -1) {
+            System.err.println("initZmqPort: unknown socket type '" + socketTypeStr + "'");
+            return;
+        }
+        zmqPorts.put(portName, new ZeroMQPort(portType, address, sockType));
+    }
+
+    public static void terminateZmq() {
+        for (Map.Entry<String, ZeroMQPort> entry : zmqPorts.entrySet()) {
+            entry.getValue().socket.close();
+        }
+        zmqPorts.clear();
+        if (zmqContext != null) {
+            zmqContext.term();
+            zmqContext = null;
+        }
+    }
+
+    private static int zmqSocketTypeFromString(String s) {
+        switch (s.toUpperCase()) {
+            case "REQ":  return ZMQ.REQ;
+            case "REP":  return ZMQ.REP;
+            case "PUB":  return ZMQ.PUB;
+            case "SUB":  return ZMQ.SUB;
+            case "PUSH": return ZMQ.PUSH;
+            case "PULL": return ZMQ.PULL;
+            case "PAIR": return ZMQ.PAIR;
+            default:     return -1;
+        }
+    }
+
+    /**
+     * Reads data from a ZMQ port. Same wire format as file-based read:
+     * expects [simtime, val1, val2, ...], strips simtime, returns the rest.
+     */
+    public static List<Object> read(String portName, String name, String initstr) {
+        List<Object> defaultVal = new ArrayList<>();
+        try {
+            List<?> parsed = (List<?>) literalEval(initstr);
+            if (parsed.size() > 1) {
+                defaultVal = new ArrayList<>(parsed.subList(1, parsed.size()));
+            }
+        } catch (Exception e) {
+        }
+        ZeroMQPort port = zmqPorts.get(portName);
+        if (port == null) {
+            System.err.println("read: ZMQ port '" + portName + "' not initialized");
+            return defaultVal;
+        }
+        String msg = port.recvWithRetry();
+        if (msg == null) {
+            System.err.println("read: ZMQ recv timeout on port '" + portName + "'");
+            return defaultVal;
+        }
+        s += msg;
+        try {
+            List<?> inval = (List<?>) literalEval(msg);
+            if (!inval.isEmpty()) {
+                simtime = Math.max(simtime, ((Number) inval.get(0)).doubleValue());
+                return new ArrayList<>(inval.subList(1, inval.size()));
+            }
+        } catch (Exception e) {
+            System.out.println("Error parsing ZMQ message '" + msg + "': " + e.getMessage());
+        }
+        return defaultVal;
+    }
+
+    /**
+     * Writes data to a ZMQ port. Prepends [simtime+delta] to match file-based write behavior.
+     */
+    public static void write(String portName, String name, Object val, int delta) {
+        ZeroMQPort port = zmqPorts.get(portName);
+        if (port == null) {
+            System.err.println("write: ZMQ port '" + portName + "' not initialized");
+            return;
+        }
+        String payload;
+        if (val instanceof List) {
+            List<?> listVal = (List<?>) val;
+            StringBuilder sb = new StringBuilder("[");
+            sb.append(toPythonLiteral(simtime + delta));
+            for (Object o : listVal) {
+                sb.append(", ");
+                sb.append(toPythonLiteral(o));
+            }
+            sb.append("]");
+            payload = sb.toString();
+            // simtime must not be mutated here
+        } else if (val instanceof String) {
+            payload = (String) val;
+        } else {
+            System.out.println("write must have list or str");
+            return;
+        }
+        port.sendWithRetry(payload);
+    }
+
     /**
      * Parses a Python-literal string into Java objects using a recursive descent parser.
      * Supports: dict, list, int, float, string (single/double quoted), bool, None, nested structures.
@@ -354,6 +465,44 @@ static Object literalEval(String s) {
         return result;
     }
 
+    /**
+     * ZMQ socket wrapper with bind/connect, timeouts, and retry.
+     */
+    private static class ZeroMQPort {
+        final ZMQ.Socket socket;
+        final String address;
+
+        ZeroMQPort(String portType, String address, int socketType) {
+            this.address = address;
+            ZMQ.Context ctx = getZmqContext();
+            this.socket = ctx.socket(socketType);
+            this.socket.setReceiveTimeOut(2000);
+            this.socket.setSendTimeOut(2000);
+            this.socket.setLinger(0);
+            if (portType.equals("bind")) {
+                this.socket.bind(address);
+            } else {
+                this.socket.connect(address);
+            }
+        }
+
+        String recvWithRetry() {
+            for (int attempt = 0; attempt < 5; attempt++) {
+                String msg = socket.recvStr();
+                if (msg != null) return msg;
+                try { Thread.sleep(500); } catch (InterruptedException e) { Thread.currentThread().interrupt(); break; }
+            }
+            return null;
+        }
+
+        void sendWithRetry(String message) {
+            for (int attempt = 0; attempt < 5; attempt++) {
+                if (socket.send(message)) return;
+                try { Thread.sleep(500); } catch (InterruptedException e) { Thread.currentThread().interrupt(); break; }
+            }
+        }
+    }
+
     /**
      * Recursive descent parser for Python literal expressions.
      * Handles: dicts, lists, tuples, strings, numbers, booleans, None.