remote retriever (#2232)

langchain/retrievers/__init__.py

@@ -1,3 +1,4 @@
 from langchain.retrievers.chatgpt_plugin_retriever import ChatGPTPluginRetriever
+from langchain.retrievers.remote_retriever import RemoteLangChainRetriever
 
-__all__ = ["ChatGPTPluginRetriever"]
+__all__ = ["ChatGPTPluginRetriever", "RemoteLangChainRetriever"]

langchain/retrievers/remote_retriever.py

@@ -0,0 +1,29 @@
+from typing import List, Optional
+
+import aiohttp
+import requests
+from pydantic import BaseModel
+
+from langchain.schema import BaseRetriever, Document
+
+
+class RemoteLangChainRetriever(BaseRetriever, BaseModel):
+    url: str
+    headers: Optional[dict] = None
+    input_key: str = "message"
+    response_key: str = "response"
+
+    def get_relevant_documents(self, query: str) -> List[Document]:
+        response = requests.post(
+            self.url, json={self.input_key: query}, headers=self.headers
+        )
+        result = response.json()
+        return [Document(**r) for r in result[self.response_key]]
+
+    async def aget_relevant_documents(self, query: str) -> List[Document]:
+        async with aiohttp.ClientSession() as session:
+            async with session.request(
+                "POST", self.url, headers=self.headers, json={self.input_key: query}
+            ) as response:
+                result = await response.json()
+        return [Document(**r) for r in result[self.response_key]]