chamikaramj commented on code in PR #23047:
URL: https://github.com/apache/beam/pull/23047#discussion_r974312230
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website/www/site/content/en/documentation/programming-guide.md:
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@@ -7364,13 +7370,37 @@ When an SDK-specific wrapper isn't available, you will
have to access the cross-
| beam.ExternalTransform(
TEST_PREFIX_URN,
ImplicitSchemaPayloadBuilder({'data': u'0'}),
- <Address of expansion service>))
+ <expansion service>))
assert_that(res, equal_to(['0a', '0b']))
```
For additional examples, see
[addprefix.py](https://github.com/apache/beam/blob/master/examples/multi-language/python/addprefix.py)
and
[javacount.py](https://github.com/apache/beam/blob/master/examples/multi-language/python/javacount.py).
-4. After the job has been submitted to the Beam runner, shut down the
expansion service by terminating the expansion service process.
+4. After the job has been submitted to the Beam runner, shut down any manually
started expansion services by terminating the expansion service process.
+
+**Using the JavaExternalTransform class**
+
+Python has the ability to invoke Java-defined transforms via [proxy
objects](https://beam.apache.org/releases/pydoc/current/apache_beam.transforms.external.html#apache_beam.transforms.external.JavaExternalTransform)
+as if they were Python transforms.
+These are invoked as follows
+
+ ```py
+ MyJavaTransform = beam.JavaExternalTransform('fully.qualified.ClassName',
classpath=[jars])
+
+ with pipeline as p:
+ res = (
+ p
+ | beam.Create(['a', 'b']).with_output_types(unicode)
+ | MyJavaTransform(javaConstructorArg, ...).builderMethod(...)
+ assert_that(res, equal_to(['0a', '0b']))
+ ```
+
+Python's `getattr` method can be used if the method names in java are reserved
Review Comment:
We should also mention the withExtraPackages() method here.
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