http/python: Add simple HTTP GET example with FastAPI and Uvicorn (#37)
* Add FastAPI + Uvicorn server
Co-authored-by: Arun Pa <arunppsg@gmail.com>
* Use getbuffer() not getvalue()
---------
Co-authored-by: Arun Pa <arunppsg@gmail.com>
diff --git a/http/get_simple/python/server/fastapi_uvicorn/README.md b/http/get_simple/python/server/fastapi_uvicorn/README.md
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+<!---
+ Licensed to the Apache Software Foundation (ASF) under one
+ or more contributor license agreements. See the NOTICE file
+ distributed with this work for additional information
+ regarding copyright ownership. The ASF licenses this file
+ to you 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.
+-->
+
+# HTTP GET Arrow Data: Simple Python Server Example with FastAPI and Uvicorn
+
+This directory contains a minimal example of an HTTP server implemented in Python using the [FastAPI](https://fastapi.tiangolo.com) framework and the [Uvicorn](https://www.uvicorn.org) web server. This example:
+1. Creates a list of record batches and populates it with synthesized data.
+2. Listens for HTTP GET requests from clients.
+3. Upon receiving a request, sends an HTTP 200 response with the body containing an Arrow IPC stream of record batches.
+
+To run this example:
+
+```sh
+pip install fastapi
+pip install "uvicorn[standard]"
+pip install pyarrow
+uvicorn server:app --port 8008
+```
+
+> [!NOTE]
+> This example requires Starlette 0.38.0 or newer, which added support for `memoryview` in `StreamingResponse`. If using an older version of Starlette, change both instances of:
+> ```py
+> with sink.getbuffer() as buffer:
+> yield buffer
+> ```
+> to:
+> ```py
+> yield sink.getvalue()
+> ```
diff --git a/http/get_simple/python/server/fastapi_uvicorn/server.py b/http/get_simple/python/server/fastapi_uvicorn/server.py
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+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you 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.
+
+import pyarrow as pa
+from random import randbytes
+import io
+from fastapi import FastAPI
+from fastapi.responses import StreamingResponse
+
+schema = pa.schema([
+ ("a", pa.int64()),
+ ("b", pa.int64()),
+ ("c", pa.int64()),
+ ("d", pa.int64())
+])
+
+
+def GetPutData():
+ total_records = 100000000
+ length = 4096
+ ncolumns = 4
+
+ arrays = []
+
+ for x in range(0, ncolumns):
+ buffer = pa.py_buffer(randbytes(length * 8))
+ arrays.append(pa.Int64Array.from_buffers(
+ pa.int64(), length, [None, buffer], null_count=0))
+
+ batch = pa.record_batch(arrays, schema)
+ batches = []
+
+ records = 0
+ while records < total_records:
+ if records + length > total_records:
+ last_length = total_records - records
+ batches.append(batch.slice(0, last_length))
+ records += last_length
+ else:
+ batches.append(batch)
+ records += length
+
+ return batches
+
+
+def generate_bytes(schema, batches):
+ with pa.RecordBatchReader.from_batches(schema, batches) as source, \
+ io.BytesIO() as sink, \
+ pa.ipc.new_stream(sink, schema) as writer:
+ for batch in source:
+ sink.seek(0)
+ writer.write_batch(batch)
+ sink.truncate()
+ with sink.getbuffer() as buffer:
+ yield buffer
+
+ sink.seek(0)
+ writer.close()
+ sink.truncate()
+ with sink.getbuffer() as buffer:
+ yield buffer
+
+
+batches = GetPutData()
+
+app = FastAPI()
+
+
+@app.get("/")
+def main():
+ return StreamingResponse(
+ generate_bytes(schema, batches),
+ media_type="application/vnd.apache.arrow.stream"
+ )
