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Posted to github@arrow.apache.org by GitBox <gi...@apache.org> on 2022/04/12 19:16:11 UTC
[GitHub] [arrow] lidavidm commented on a diff in pull request #12847: ARROW-15577: [Java][Doc] Add Arrow Flight documentation
lidavidm commented on code in PR #12847:
URL: https://github.com/apache/arrow/pull/12847#discussion_r848788087
##########
docs/source/java/flight.rst:
##########
@@ -0,0 +1,213 @@
+.. 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.
+
+================
+Arrow Flight RPC
+================
+
+Arrow Flight is an RPC framework for efficient transfer of Arrow data
+over the network.
+
+.. contents::
+
+.. seealso::
+
+ :doc:`Flight protocol documentation <../format/Flight>`
+ Documentation of the Flight protocol, including how to use
+ Flight conceptually.
+
+ `Java Cookbook <https://arrow.apache.org/cookbook/java/flight.html>`_
+ Recipes for using Arrow Flight in Java.
+
+Writing a Flight Service
+========================
+
+Flight servers implement the `FlightProducer`_ interface. For convenience,
+they can subclass `NoOpFlightProducer`_ instead, which offers default
+implementations of all the RPC methods.
+
+.. code-block:: Java
+
+ public class TutorialFlightProducer implements FlightProducer {
+ @Override
+ // Override methods or use NoOpFlightProducer for only methods needed
+ }
+
+Each RPC method always takes a ``CallContext`` for common parameters. To indicate
+failure, pass an exception to the "listener" if present, or else raise an
+exception.
+
+.. code-block:: Java
+
+ // Server
+ @Override
+ public void listFlights(CallContext context, Criteria criteria, StreamListener<FlightInfo> listener) {
+ // ...
+ listener.onError(
+ CallStatus.UNAUTHENTICATED.withDescription(
+ "Custom UNAUTHENTICATED description message.").toRuntimeException());
+ // ...
+ }
+
+ // Client
+ try{
+ Iterable<FlightInfo> flightInfosBefore = flightClient.listFlights(Criteria.ALL);
+ // ...
+ } catch (FlightRuntimeException e){
+ // Catch UNAUTHENTICATED exception
+ }
+
+To start a server, create a `Location`_ to specify where to listen, and then create
+a `FlightServer`_ with an instance of a producer. This will start the server, but
+won't block the rest of the program. Call ``FlightServer.awaitTermination``
+to block until the server stops.
+
+.. code-block:: Java
+
+ class TutorialFlightProducer implements FlightProducer {
+ @Override
+ // Override methods or use NoOpFlightProducer for only methods needed
+ }
+
+ Location location = Location.forGrpcInsecure("0.0.0.0", 0);
+ try(
+ BufferAllocator allocator = new RootAllocator();
+ FlightServer server = FlightServer.builder(
+ allocator,
+ location,
+ new TutorialFlightProducer()
+ ).build();
+ ){
+ server.start();
+ System.out.println("Server listening on port " + server.getPort());
+ server.awaitTermination();
+ } catch (Exception e) {
+ e.printStackTrace();
+ }
+
+.. code-block:: shell
+
+ Server listening on port 58104
+
+Using the Flight Client
+=======================
+
+To connect to a Flight service, create a `FlightClient`_ with a location.
+
+.. code-block:: Java
+
+ Location location = Location.forGrpcInsecure("0.0.0.0", 58104);
+
+ try(BufferAllocator allocator = new RootAllocator();
+ FlightClient client = FlightClient.builder(allocator, location).build()){
+ // ... Consume operations exposed by Flight server
+ } catch (Exception e) {
+ e.printStackTrace();
+ }
+
+Cancellation and Timeouts
+=========================
+
+When making a call, clients can optionally provide `CallOptions`. This allows
+clients to set a timeout on calls. Also, some objects returned by client RPC calls
+expose a cancel method which allows terminating a call early.
+
+.. code-block:: Java
+
+ Location location = Location.forGrpcInsecure("0.0.0.0", 58609);
+
+ try(BufferAllocator allocator = new RootAllocator();
+ FlightClient tutorialFlightClient = FlightClient.builder(allocator, location).build()){
+
+ Iterator<Result> resultIterator = tutorialFlightClient.doAction(
+ new Action("test-timeout"),
+ CallOptions.timeout(2, TimeUnit.SECONDS)
+ );
+ } catch (Exception e) {
+ e.printStackTrace();
+ }
+
+On the server side, timeouts are transparent. For cancellation, the server needs to manually poll
+``setOnCancelHandler`` or ``isCancelled`` to check if the client has cancelled the call,
+and if so, break out of any processing the server is currently doing.
+
+.. code-block:: Java
+
+ // Client
+ Location location = Location.forGrpcInsecure("0.0.0.0", 58609);
+ try(BufferAllocator allocator = new RootAllocator();
+ FlightClient tutorialFlightClient = FlightClient.builder(allocator, location).build()){
+ try(FlightStream flightStream = flightClient.getStream(new Ticket(new byte[]{}))) {
+ // ...
+ flightStream.cancel("tutorial-cancel", new Exception("Testing cancellation option!"));
+ }
+ } catch (Exception e) {
+ e.printStackTrace();
+ }
+ // Server
+ @Override
+ public void getStream(CallContext context, Ticket ticket, ServerStreamListener listener) {
+ // ...
+ listener.setOnCancelHandler(()->{
+ // Implement logic to handle cancellation option
+ });
+ }
+
+Enabling TLS
+============
+
+TLS can be enabled when setting up a server by providing a
+certificate and key pair to ``FlightServer.Builder.useTls``.
+
+On the client side, use ``Location.forGrpcTls`` to create the Location for the client.
+
+Enabling Authentication
+=======================
+
+.. warning:: Authentication is insecure without enabling TLS.
+
+Handshake-based authentication can be enabled by implementing
+Handlers on the client and server side (i.e.: ``ServerAuthHandler``).
+There are two options available user/password and token.
Review Comment:
Both user/password and token authentication are separate - IMO let's not talk about them here, there's some work needed to document all the auth methods available in Flight and explain why you might need to use each, and I don't want to make this confusing.
##########
docs/source/java/flight.rst:
##########
@@ -0,0 +1,213 @@
+.. 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.
+
+================
+Arrow Flight RPC
+================
+
+Arrow Flight is an RPC framework for efficient transfer of Arrow data
+over the network.
+
+.. contents::
+
+.. seealso::
+
+ :doc:`Flight protocol documentation <../format/Flight>`
+ Documentation of the Flight protocol, including how to use
+ Flight conceptually.
+
+ `Java Cookbook <https://arrow.apache.org/cookbook/java/flight.html>`_
+ Recipes for using Arrow Flight in Java.
+
+Writing a Flight Service
+========================
+
+Flight servers implement the `FlightProducer`_ interface. For convenience,
+they can subclass `NoOpFlightProducer`_ instead, which offers default
+implementations of all the RPC methods.
+
+.. code-block:: Java
+
+ public class TutorialFlightProducer implements FlightProducer {
+ @Override
+ // Override methods or use NoOpFlightProducer for only methods needed
+ }
+
+Each RPC method always takes a ``CallContext`` for common parameters. To indicate
+failure, pass an exception to the "listener" if present, or else raise an
+exception.
+
+.. code-block:: Java
+
+ // Server
+ @Override
+ public void listFlights(CallContext context, Criteria criteria, StreamListener<FlightInfo> listener) {
+ // ...
+ listener.onError(
+ CallStatus.UNAUTHENTICATED.withDescription(
+ "Custom UNAUTHENTICATED description message.").toRuntimeException());
+ // ...
+ }
+
+ // Client
+ try{
+ Iterable<FlightInfo> flightInfosBefore = flightClient.listFlights(Criteria.ALL);
+ // ...
+ } catch (FlightRuntimeException e){
+ // Catch UNAUTHENTICATED exception
+ }
+
+To start a server, create a `Location`_ to specify where to listen, and then create
+a `FlightServer`_ with an instance of a producer. This will start the server, but
+won't block the rest of the program. Call ``FlightServer.awaitTermination``
+to block until the server stops.
+
+.. code-block:: Java
+
+ class TutorialFlightProducer implements FlightProducer {
+ @Override
+ // Override methods or use NoOpFlightProducer for only methods needed
+ }
+
+ Location location = Location.forGrpcInsecure("0.0.0.0", 0);
+ try(
+ BufferAllocator allocator = new RootAllocator();
+ FlightServer server = FlightServer.builder(
+ allocator,
+ location,
+ new TutorialFlightProducer()
+ ).build();
+ ){
+ server.start();
+ System.out.println("Server listening on port " + server.getPort());
+ server.awaitTermination();
+ } catch (Exception e) {
+ e.printStackTrace();
+ }
+
+.. code-block:: shell
+
+ Server listening on port 58104
+
+Using the Flight Client
+=======================
+
+To connect to a Flight service, create a `FlightClient`_ with a location.
+
+.. code-block:: Java
+
+ Location location = Location.forGrpcInsecure("0.0.0.0", 58104);
+
+ try(BufferAllocator allocator = new RootAllocator();
+ FlightClient client = FlightClient.builder(allocator, location).build()){
+ // ... Consume operations exposed by Flight server
+ } catch (Exception e) {
+ e.printStackTrace();
+ }
+
+Cancellation and Timeouts
+=========================
+
+When making a call, clients can optionally provide `CallOptions`. This allows
+clients to set a timeout on calls. Also, some objects returned by client RPC calls
+expose a cancel method which allows terminating a call early.
+
+.. code-block:: Java
+
+ Location location = Location.forGrpcInsecure("0.0.0.0", 58609);
+
+ try(BufferAllocator allocator = new RootAllocator();
+ FlightClient tutorialFlightClient = FlightClient.builder(allocator, location).build()){
+
+ Iterator<Result> resultIterator = tutorialFlightClient.doAction(
+ new Action("test-timeout"),
+ CallOptions.timeout(2, TimeUnit.SECONDS)
+ );
+ } catch (Exception e) {
+ e.printStackTrace();
+ }
+
+On the server side, timeouts are transparent. For cancellation, the server needs to manually poll
+``setOnCancelHandler`` or ``isCancelled`` to check if the client has cancelled the call,
+and if so, break out of any processing the server is currently doing.
+
+.. code-block:: Java
+
+ // Client
+ Location location = Location.forGrpcInsecure("0.0.0.0", 58609);
+ try(BufferAllocator allocator = new RootAllocator();
+ FlightClient tutorialFlightClient = FlightClient.builder(allocator, location).build()){
+ try(FlightStream flightStream = flightClient.getStream(new Ticket(new byte[]{}))) {
+ // ...
+ flightStream.cancel("tutorial-cancel", new Exception("Testing cancellation option!"));
+ }
+ } catch (Exception e) {
+ e.printStackTrace();
+ }
+ // Server
+ @Override
+ public void getStream(CallContext context, Ticket ticket, ServerStreamListener listener) {
+ // ...
+ listener.setOnCancelHandler(()->{
+ // Implement logic to handle cancellation option
+ });
+ }
+
+Enabling TLS
+============
+
+TLS can be enabled when setting up a server by providing a
+certificate and key pair to ``FlightServer.Builder.useTls``.
+
+On the client side, use ``Location.forGrpcTls`` to create the Location for the client.
+
+Enabling Authentication
+=======================
+
+.. warning:: Authentication is insecure without enabling TLS.
+
+Handshake-based authentication can be enabled by implementing
+Handlers on the client and server side (i.e.: ``ServerAuthHandler``).
+There are two options available user/password and token.
+
+Authentication consists of two parts: on
+initial client connection, the server and client authentication
+implementations can perform any negotiation needed; then, on each RPC
+thereafter, the client provides a token. The client set an ID result
+of user/password through ``CallHeaders`` / ``Metadata`` these IDs is
+recovered by the server side to do validation. The server authentication
+handler validates the token and provides the identity of the
+client. This identity can be obtained from the
+``CallContext.peerIdentity``.
+
Review Comment:
As evidence of what I mean, this is mixing up how different authentication schemes work. Again, the other PR already explains the basic, handshake-based authentication - let's stick to just explaining that instead of trying to explain all three schemes at once.
##########
docs/source/java/flight.rst:
##########
@@ -0,0 +1,213 @@
+.. 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.
+
+================
+Arrow Flight RPC
+================
+
+Arrow Flight is an RPC framework for efficient transfer of Arrow data
+over the network.
+
+.. contents::
+
+.. seealso::
+
+ :doc:`Flight protocol documentation <../format/Flight>`
+ Documentation of the Flight protocol, including how to use
+ Flight conceptually.
+
+ `Java Cookbook <https://arrow.apache.org/cookbook/java/flight.html>`_
+ Recipes for using Arrow Flight in Java.
+
+Writing a Flight Service
+========================
+
+Flight servers implement the `FlightProducer`_ interface. For convenience,
+they can subclass `NoOpFlightProducer`_ instead, which offers default
+implementations of all the RPC methods.
+
+.. code-block:: Java
+
+ public class TutorialFlightProducer implements FlightProducer {
+ @Override
+ // Override methods or use NoOpFlightProducer for only methods needed
+ }
+
+Each RPC method always takes a ``CallContext`` for common parameters. To indicate
+failure, pass an exception to the "listener" if present, or else raise an
+exception.
+
+.. code-block:: Java
+
+ // Server
+ @Override
+ public void listFlights(CallContext context, Criteria criteria, StreamListener<FlightInfo> listener) {
+ // ...
+ listener.onError(
+ CallStatus.UNAUTHENTICATED.withDescription(
+ "Custom UNAUTHENTICATED description message.").toRuntimeException());
+ // ...
+ }
+
+ // Client
+ try{
+ Iterable<FlightInfo> flightInfosBefore = flightClient.listFlights(Criteria.ALL);
+ // ...
+ } catch (FlightRuntimeException e){
+ // Catch UNAUTHENTICATED exception
+ }
+
+To start a server, create a `Location`_ to specify where to listen, and then create
+a `FlightServer`_ with an instance of a producer. This will start the server, but
+won't block the rest of the program. Call ``FlightServer.awaitTermination``
+to block until the server stops.
+
+.. code-block:: Java
+
+ class TutorialFlightProducer implements FlightProducer {
+ @Override
+ // Override methods or use NoOpFlightProducer for only methods needed
+ }
+
+ Location location = Location.forGrpcInsecure("0.0.0.0", 0);
+ try(
+ BufferAllocator allocator = new RootAllocator();
+ FlightServer server = FlightServer.builder(
+ allocator,
+ location,
+ new TutorialFlightProducer()
+ ).build();
+ ){
+ server.start();
+ System.out.println("Server listening on port " + server.getPort());
+ server.awaitTermination();
+ } catch (Exception e) {
+ e.printStackTrace();
+ }
+
+.. code-block:: shell
+
+ Server listening on port 58104
+
+Using the Flight Client
+=======================
+
+To connect to a Flight service, create a `FlightClient`_ with a location.
+
+.. code-block:: Java
+
+ Location location = Location.forGrpcInsecure("0.0.0.0", 58104);
+
+ try(BufferAllocator allocator = new RootAllocator();
+ FlightClient client = FlightClient.builder(allocator, location).build()){
+ // ... Consume operations exposed by Flight server
+ } catch (Exception e) {
+ e.printStackTrace();
+ }
+
+Cancellation and Timeouts
+=========================
+
+When making a call, clients can optionally provide `CallOptions`. This allows
Review Comment:
```suggestion
When making a call, clients can optionally provide ``CallOptions``. This allows
```
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