Thank you, Martin! I got it working now using the same shading rules in my 
project as in Spark.

From: Martin Grund <mar...@databricks.com>
Date: Monday, 28. August 2023 at 17:58
To: Stefan Hagedorn <stefan.haged...@actian.com>
Cc: dev@spark.apache.org <dev@spark.apache.org>
Subject: Re: Spark Connect: API mismatch in SparkSesession#execute
Hi Stefan,

There are some current limitations around how protobuf is embedded in Spark 
Connect. One of the challenges there is that for compatibility reasons we 
currently shade protobuf that then shades the `prototobuf.GeneramtedMessage` 
class. The way to work around this is to shade the protobuf library in your 
code following the same rules as in Spark.

I have a fully working example here: 
https://github.com/grundprinzip/spark-connect-appstate-example/tree/main

We definitely looking forward to improve the usability.

Hope this helps,
Martin

On Mon, Aug 28, 2023 at 4:19 PM Stefan Hagedorn 
<stefan.haged...@actian.com<mailto:stefan.haged...@actian.com>> wrote:
Hi everyone,

Trying my luck here, after no success in the user mailing list :)

I’m trying to use the "extension" feature of the Spark Connect CommandPlugin 
(Spark 3.4.1) [1].

I created a simple protobuf message `MyMessage` that I want to send from the 
connect client-side to the connect server (where I registered my plugin).

The source API for SparkSession class in `spark-connect-client-jvm` provides a 
method `execute` that accepts a `com.google.protobuf.Any` [2], so I packed the 
MyMessage object in an Any:

    val spark = SparkSession.builder().remote("sc://localhost").build()

  val cmd = com.test.MyMessage.newBuilder().setBlubb("hello world").build()
  val googleAny = com.google.protobuf.Any.pack(cmd)

  spark.execute(googleAny)


This compiles, but during execution I receive a NoSuchMethodError:
java.lang.NoSuchMethodError: 'void 
org.apache.spark.sql.SparkSession.execute(com.google.protobuf.Any)'

After looking around for a while after decompiling I found that 
spark-connect-client-jvm_2.12-3.4.1.jar!SparkSession#execute accepts a 
`org.sparkproject.connect.client.com.google.protobuf.Any` (instead of only the 
com.google.protobuf.Any).

Am I missing something, how am I supposed to use this? Is there an additional 
build step or should I use a specific plugin? I'm using the sbt-protoc [3] 
plugin in my setup.

Packing my message object `cmd` into an 
org.sparkproject.connect.client.com.google.protobuf.Any does not compile.

Thanks,
Stefan


[1] https://github.com/apache/spark/pull/39291
[2] 
https://github.com/apache/spark/blob/64c26b7cb9b4c770a3e056404e05f6b6603746ee/connector/connect/client/jvm/src/main/scala/org/apache/spark/sql/SparkSession.scala#L444
[3] https://github.com/thesamet/sbt-protoc

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