http/get_simple/README.md

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# HTTP GET Arrow Data: Simple Examples

This directory contains a set of minimal examples of HTTP clients and servers implemented in several languages. These examples demonstrate:
- How a client can send a GET request to a server and receive a response from the server containing an Arrow IPC stream of record batches.
- How a server can respond to a GET request from a client and send the client a response containing an Arrow IPC stream of record batches.

The examples here assume that the server cannot determine the exact length in bytes of the full Arrow IPC stream before sending it, so they cannot set the `Content-Length` header or serve Range requests.

Most of the client examples here assume that the client needs to hold the full received data in memory in an Arrow data structure for further in-memory processing. The case in which the client simply writes the result directly to a file is much simpler and is demonstrated by the [curl client example](curl/client).

To enable performance comparisons to Arrow Flight RPC, the server examples generate the data in exactly the same way as in [`flight_benchmark.cc`](https://github.com/apache/arrow/blob/7346bdffbdca36492089f6160534bfa2b81bad90/cpp/src/arrow/flight/flight_benchmark.cc#L194-L245) as cited in the [original blog post introducing Flight RPC](https://arrow.apache.org/blog/2019/10/13/introducing-arrow-flight/). But note that Flight example sends four concurrent streams.

If you are collaborating on the set of examples in this directory, please follow these guidelines:
- Each new example must be implemented as minimally as possible. For example, error handling should be minimized or omitted.
- Each new client example must be tested to ensure that it works with each existing server example.
- Each new server example must be tested to ensure that it works with each existing client example.
- To the greatest extent possible, each new server example should be functionally equivalent to each existing server example (generating equivalent data with the same schema, size, shape, and distribution of values; sending the same HTTP headers; and so on).
- Each new client example must print timing and size information before exiting. If possible this must include the number of seconds elapsed (rounded to the second decimal place) and the number of record batches received.