[
https://issues.apache.org/jira/browse/BEAM-6730?focusedWorklogId=214651&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-214651
]
ASF GitHub Bot logged work on BEAM-6730:
----------------------------------------
Author: ASF GitHub Bot
Created on: 18/Mar/19 09:10
Start Date: 18/Mar/19 09:10
Worklog Time Spent: 10m
Work Description: robertwb commented on pull request #7875: [BEAM-6730]
Support configuring transforms externally in Java SDK / Expose Java's
GenerateSequence in Python
URL: https://github.com/apache/beam/pull/7875#discussion_r266343725
##########
File path:
runners/core-construction-java/src/main/java/org/apache/beam/runners/core/construction/expansion/ExpansionService.java
##########
@@ -69,14 +82,123 @@
Map<String, TransformProvider> knownTransforms();
}
+ /**
+ * Exposes Java transforms via {@link
org.apache.beam.sdk.expansion.ExternalTransformRegistrar}.
+ */
+ @AutoService(ExpansionService.ExpansionServiceRegistrar.class)
+ public static class ExternalTransformRegistrarLoader<ConfigT>
+ implements ExpansionService.ExpansionServiceRegistrar {
+
+ @Override
+ public Map<String, ExpansionService.TransformProvider> knownTransforms() {
+ ImmutableMap.Builder<String, ExpansionService.TransformProvider> builder
=
+ ImmutableMap.builder();
+ for (ExternalTransformRegistrar registrar :
+ ServiceLoader.load(ExternalTransformRegistrar.class)) {
+ for (Map.Entry<String, Class<? extends ExternalTransformBuilder<?, ?,
?>>> entry :
+ registrar.knownBuilders().entrySet()) {
+ String urn = entry.getKey();
+ Class<? extends ExternalTransformBuilder<?, ?, ?>> builderClass =
entry.getValue();
+ builder.put(
+ urn,
+ spec -> {
+ try {
+ ExternalTransforms.ExternalConfigurationPayload payload =
+
ExternalTransforms.ExternalConfigurationPayload.parseFrom(spec.getPayload());
+ return translate(payload, builderClass);
+ } catch (Exception e) {
+ throw new RuntimeException(
+ String.format("Failed to build transform %s from spec
%s", urn, spec), e);
+ }
+ });
+ }
+ }
+ return builder.build();
+ }
+
+ private static PTransform translate(
+ ExternalTransforms.ExternalConfigurationPayload payload,
+ Class<? extends ExternalTransformBuilder<?, ?, ?>> builderClass)
+ throws Exception {
+ Preconditions.checkState(
+ ExternalTransformBuilder.class.isAssignableFrom(builderClass),
+ "Provided identifier %s is not an ExternalTransformBuilder.",
+ builderClass.getName());
+
+ Object configObject = initConfiguration(builderClass);
+ populateConfiguration(configObject, payload);
+ return buildTransform(builderClass, configObject);
+ }
+
+ private static Object initConfiguration(
+ Class<? extends ExternalTransformBuilder<?, ?, ?>> builderClass)
throws Exception {
+ for (Method method : builderClass.getMethods()) {
+ if (method.getName().equals("buildExternal")) {
+ Preconditions.checkState(
+ method.getParameterCount() == 1,
+ "Build method for ExternalTransformBuilder %s must have exactly
one parameter, but had %s parameters.",
+ builderClass.getSimpleName(),
+ method.getParameterCount());
+ Class<?> configurationClass = method.getParameterTypes()[0];
+ if (Object.class.equals(configurationClass)) {
+ continue;
+ }
+ return configurationClass.getDeclaredConstructor().newInstance();
+ }
+ }
+ throw new RuntimeException("Couldn't find build method on
ExternalTransformBuilder.");
+ }
+
+ private static void populateConfiguration(
+ Object config, ExternalTransforms.ExternalConfigurationPayload
payload) throws Exception {
+ Converter<String, String> camelCaseConverter =
+ CaseFormat.LOWER_UNDERSCORE.converterTo(CaseFormat.LOWER_CAMEL);
+ for (Map.Entry<String, ExternalTransforms.ConfigValue> entry :
+ payload.getConfigurationMap().entrySet()) {
+ String fieldName = camelCaseConverter.convert(entry.getKey());
+ String coderUrn = entry.getValue().getCoderUrn();
+ final Coder coder;
+ if
(BeamUrns.getUrn(RunnerApi.StandardCoders.Enum.VARINT).equals(coderUrn)) {
Review comment:
Shouldn't we be leveraging the coder rehydration code here? Or is that
implicit in the TODO below (which should be made more explicit)?
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Issue Time Tracking
-------------------
Worklog Id: (was: 214651)
Time Spent: 9.5h (was: 9h 20m)
> Expose Java transforms (specifically IO) in other SDKs
> ------------------------------------------------------
>
> Key: BEAM-6730
> URL: https://issues.apache.org/jira/browse/BEAM-6730
> Project: Beam
> Issue Type: New Feature
> Components: runner-flink, sdk-java-core, sdk-py-core
> Reporter: Maximilian Michels
> Assignee: Maximilian Michels
> Priority: Major
> Time Spent: 9.5h
> Remaining Estimate: 0h
>
> Since https://github.com/apache/beam/pull/7316 we can reference external
> transforms which are transforms only available in a "foreign" SDKs. This
> allows us to fill the gap in terms of missing transforms in the Python and Go
> SDK, specifically IO transforms.
> We can start collecting/exposing transforms that Beam users need. The
> following transforms could be interesting:
> - KafkaIO / KinesisIO
> - CassandraIO / ElasticserchIO / Hbase / Redis
> - JDBC
> - S3 file system
> - GenerateSequence
> See also https://s.apache.org/beam-cross-language-io and BEAM-6485.
> CC [~robertwb] [~chamikara] [~thw]
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