Feat: refine dataflow and initialize dataflow app (#9952)

### What problem does this PR solve?

Refine dataflow and initialize dataflow app.

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

rag/flow/file.py

@@ -0,0 +1,50 @@
+#
+#  Copyright 2025 The InfiniFlow Authors. All Rights Reserved.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+#
+from api.db.services.document_service import DocumentService
+from api.db.services.file2document_service import File2DocumentService
+from api.db.services.file_service import FileService
+from rag.flow.base import ProcessBase, ProcessParamBase
+from rag.utils.storage_factory import STORAGE_IMPL
+
+
+class FileParam(ProcessParamBase):
+    def __init__(self):
+        super().__init__()
+
+    def check(self):
+        pass
+
+    def get_input_form(self) -> dict[str, dict]:
+        return {}
+
+
+class File(ProcessBase):
+    component_name = "File"
+
+    async def _invoke(self, **kwargs):
+        if self._canvas._doc_id:
+            e, doc = DocumentService.get_by_id(self._canvas._doc_id)
+            if not e:
+                self.set_output("_ERROR", f"Document({self._canvas._doc_id}) not found!")
+                return
+
+            b, n = File2DocumentService.get_storage_address(doc_id=self._canvas._doc_id)
+            self.set_output("blob", STORAGE_IMPL.get(b, n))
+            self.set_output("name", doc.name)
+        else:
+            file = kwargs.get("file")
+            self.set_output("name", file["name"])
+            self.set_output("blob", FileService.get_blob(file["created_by"], file["id"]))