feat/enhance the multi-modal support (#8818)

api/core/workflow/nodes/enums.py

@@ -0,0 +1,24 @@
+from enum import Enum
+
+
+class NodeType(str, Enum):
+    START = "start"
+    END = "end"
+    ANSWER = "answer"
+    LLM = "llm"
+    KNOWLEDGE_RETRIEVAL = "knowledge-retrieval"
+    IF_ELSE = "if-else"
+    CODE = "code"
+    TEMPLATE_TRANSFORM = "template-transform"
+    QUESTION_CLASSIFIER = "question-classifier"
+    HTTP_REQUEST = "http-request"
+    TOOL = "tool"
+    VARIABLE_AGGREGATOR = "variable-aggregator"
+    VARIABLE_ASSIGNER = "variable-assigner"  # TODO: Merge this into VARIABLE_AGGREGATOR in the database.
+    LOOP = "loop"
+    ITERATION = "iteration"
+    ITERATION_START = "iteration-start"  # Fake start node for iteration.
+    PARAMETER_EXTRACTOR = "parameter-extractor"
+    CONVERSATION_VARIABLE_ASSIGNER = "assigner"
+    DOCUMENT_EXTRACTOR = "document-extractor"
+    LIST_OPERATOR = "list-operator"