add registry for workflow and state def

core/src/main/java/iwf/core/Registry.java

@@ -0,0 +1,44 @@
+package iwf.core;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class Registry {
+    // workflow type -> workflow
+    private final Map<String,Workflow> workflowStore = new HashMap<>();
+
+    // (workflow type, stateId)-> StateDef
+    private final Map<String, StateDef> workflowStateStore = new HashMap<>();
+
+    private static final String DELIMITER = "_";
+
+    public void addWorkflow(final Workflow wf){
+        String workflowType = wf.getClass().getSimpleName();
+
+        if (workflowStore.containsKey(workflowType)) {
+            throw new RuntimeException(String.format("Workflow type %s already exists", workflowType));
+        }
+        workflowStore.put(workflowType, wf);
+
+        for (StateDef stateDef: wf.getStates()) {
+            String key = getStateDefKey(workflowType, stateDef.getWorkflowState().getStateId());
+            if (workflowStateStore.containsKey(key)) {
+                throw new RuntimeException(String.format("Workflow state definition %s already exists", key));
+            } else {
+                workflowStateStore.put(key, stateDef);
+            }
+        }
+    }
+
+    public Workflow getWorkflow(final String workflowType){
+        return workflowStore.get(workflowType);
+    }
+
+    public StateDef getWorkflowState(final String workflowType, final String stateId){
+        return workflowStateStore.get(getStateDefKey(workflowType, stateId));
+    }
+
+    private String getStateDefKey(final String workflowType, final String stateId) {
+        return workflowType + DELIMITER + stateId;
+    }
+}