Portable JSON serializer (Java) (#280)

Allow Java to interoperate with TS/Py via simple JSON serialization to
the workflow_status and other tables

---------

Co-authored-by: Harry Pierson <harry.pierson@dbos.dev>

Author: chuck-dbos

transact/src/main/java/dev/dbos/transact/DBOS.java

@@ -19,6 +19,7 @@
 import dev.dbos.transact.workflow.ForkOptions;
 import dev.dbos.transact.workflow.ListWorkflowsInput;
 import dev.dbos.transact.workflow.Queue;
+import dev.dbos.transact.workflow.SerializationStrategy;
 import dev.dbos.transact.workflow.StepInfo;
 import dev.dbos.transact.workflow.StepOptions;
 import dev.dbos.transact.workflow.Workflow;
@@ -144,7 +145,13 @@ private void registerClassWorkflows(
 
       String name = wfTag.name().isEmpty() ? method.getName() : wfTag.name();
       workflowRegistry.register(
-          className, name, target, instanceName, method, wfTag.maxRecoveryAttempts());
+          className,
+          name,
+          target,
+          instanceName,
+          method,
+          wfTag.maxRecoveryAttempts(),
+          wfTag.serializationStrategy());
       return name;
     }
 
@@ -545,6 +552,17 @@ public static <T, E extends Exception> T getResult(@NonNull String workflowId) t
     return executor("getWorkflowStatus").getWorkflowStatus(workflowId);
   }
 
+  /**
+   * Get the serialization format of the current workflow context.
+   *
+   * @return the serialization format name (e.g., "portable_json", "java_jackson"), or null if not
+   *     in a workflow context or using default serialization
+   */
+  public static @Nullable SerializationStrategy getSerialization() {
+    var ctx = DBOSContextHolder.get();
+    return ctx != null ? ctx.getSerialization() : null;
+  }
+
   /**
    * Send a message to a workflow
    *
@@ -558,8 +576,33 @@ public static void send(
       @NonNull Object message,
       @NonNull String topic,
       @Nullable String idempotencyKey) {
+    send(destinationId, message, topic, idempotencyKey, null);
+  }
+
+  /**
+   * Send a message to a workflow with serialization strategy
+   *
+   * @param destinationId recipient of the message
+   * @param message message to be sent
+   * @param topic topic to which the message is send
+   * @param idempotencyKey optional idempotency key for exactly-once send
+   * @param serialization serialization strategy to use (null for default)
+   */
+  public static void send(
+      @NonNull String destinationId,
+      @NonNull Object message,
+      @NonNull String topic,
+      @Nullable String idempotencyKey,
+      @Nullable SerializationStrategy serialization) {
+    if (serialization == null) serialization = SerializationStrategy.DEFAULT;
     executor("send")
-        .send(destinationId, message, topic, instance().internalWorkflowsService, idempotencyKey);
+        .send(
+            destinationId,
+            message,
+            topic,
+            instance().internalWorkflowsService,
+            idempotencyKey,
+            serialization);
   }
 
   /**
@@ -571,7 +614,7 @@ public static void send(
    */
   public static void send(
       @NonNull String destinationId, @NonNull Object message, @NonNull String topic) {
-    DBOS.send(destinationId, message, topic, null);
+    DBOS.send(destinationId, message, topic, null, null);
   }
 
   /**
@@ -586,13 +629,29 @@ public static void send(
   }
 
   /**
-   * Call within a workflow to publish a key value pair
+   * Call within a workflow to publish a key value pair. Uses the workflow's serialization format.
    *
    * @param key identifier for published data
    * @param value data that is published
    */
   public static void setEvent(@NonNull String key, @NonNull Object value) {
-    executor("setEvent").setEvent(key, value);
+    setEvent(key, value, null);
+  }
+
+  /**
+   * Call within a workflow to publish a key value pair with a specific serialization strategy.
+   *
+   * @param key identifier for published data
+   * @param value data that is published
+   * @param serialization serialization strategy to use (null to use workflow's default)
+   */
+  public static void setEvent(
+      @NonNull String key, @NonNull Object value, @Nullable SerializationStrategy serialization) {
+    // If no explicit serialization specified, use the workflow context's serialization
+    if (serialization == null) {
+      serialization = getSerialization();
+    }
+    executor("setEvent").setEvent(key, value, serialization);
   }
 
   /**