damccorm commented on code in PR #25947:
URL: https://github.com/apache/beam/pull/25947#discussion_r1152254375


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website/www/site/content/en/documentation/ml/side-input-updates.md:
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@@ -0,0 +1,144 @@
+---
+title: "Auto Update ML models using WatchFilePattern"
+---
+<!--
+Licensed 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.
+-->
+
+# Use WatchFilePattern as side input to auto-update ML models in RunInference

Review Comment:
   ```suggestion
   # Use WatchFilePattern to auto-update ML models in RunInference
   ```
   
   I think this is a clearer title for the non-beam user. The "how" (side 
inputs) is sufficiently explained below, so the title can just focus on the 
behavior the user is trying to achieve.



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website/www/site/content/en/documentation/ml/side-input-updates.md:
##########
@@ -0,0 +1,144 @@
+---
+title: "Auto Update ML models using WatchFilePattern"
+---
+<!--
+Licensed 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.
+-->
+
+# Use WatchFilePattern as side input to auto-update ML models in RunInference
+
+The pipeline in this example uses a 
[RunInference](https://beam.apache.org/documentation/transforms/python/elementwise/runinference/)
 `PTransform` with a [side 
input](https://beam.apache.org/documentation/programming-guide/#side-inputs) 
`PCollection` that emits `ModelMetadata` to run inferences on images using 
TensorFlow models.

Review Comment:
   ```suggestion
   The pipeline in this example uses a 
[RunInference](https://beam.apache.org/documentation/transforms/python/elementwise/runinference/)
 `PTransform` to run inference on images using TensorFlow models. It uses a 
[side 
input](https://beam.apache.org/documentation/programming-guide/#side-inputs) 
`PCollection` that emits `ModelMetadata` to update the model.
   ```
   
   Suggestion for clarity - the current form makes it sound like the 
`ModelMetadata` (or maybe the side input) is the thing running inference



##########
website/www/site/content/en/documentation/ml/side-input-updates.md:
##########
@@ -0,0 +1,144 @@
+---
+title: "Auto Update ML models using WatchFilePattern"
+---
+<!--
+Licensed 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.
+-->
+
+# Use WatchFilePattern as side input to auto-update ML models in RunInference
+
+The pipeline in this example uses a 
[RunInference](https://beam.apache.org/documentation/transforms/python/elementwise/runinference/)
 `PTransform` with a [side 
input](https://beam.apache.org/documentation/programming-guide/#side-inputs) 
`PCollection` that emits `ModelMetadata` to run inferences on images using 
TensorFlow models.
+
+Using side inputs, you can update your model (which is passed in the 
`ModelHandler`) in real-time, even while the Beam pipeline is still running. 
This can be done either by leveraging one of Beam's provided patterns, such as 
the `WatchFilePattern`,

Review Comment:
   ```suggestion
   Using side inputs, you can update your model (which is passed in a 
`ModelHandler` configuration object) in real-time, even while the Beam pipeline 
is still running. This can be done either by leveraging one of Beam's provided 
patterns, such as the `WatchFilePattern`,
   ```
   
   This mirrors how we talk about `ModelHandlers` elsewhere in our docs



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website/www/site/layouts/partials/section-menu/en/documentation.html:
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@@ -226,6 +226,7 @@
       <li><a href="/documentation/ml/tensorrt-runinference">Build a custom 
model handler with TensorRT</a></li>
       <li><a href="/documentation/ml/large-language-modeling">Use LLM 
inference</a></li>
       <li><a href="/documentation/ml/multi-language-inference/">Build a 
multi-language inference pipeline</a></li>
+      <li><a href="/documentation/ml/side-input-updates/">Use side inputs to 
automatically update models</a></li>

Review Comment:
   Same thing, I think focusing on the desired behavior vs the mechanism will 
help newer users



##########
website/www/site/content/en/documentation/ml/side-input-updates.md:
##########
@@ -0,0 +1,144 @@
+---
+title: "Auto Update ML models using WatchFilePattern"
+---
+<!--
+Licensed 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.
+-->
+
+# Use WatchFilePattern as side input to auto-update ML models in RunInference
+
+The pipeline in this example uses a 
[RunInference](https://beam.apache.org/documentation/transforms/python/elementwise/runinference/)
 `PTransform` with a [side 
input](https://beam.apache.org/documentation/programming-guide/#side-inputs) 
`PCollection` that emits `ModelMetadata` to run inferences on images using 
TensorFlow models.
+
+Using side inputs, you can update your model (which is passed in the 
`ModelHandler`) in real-time, even while the Beam pipeline is still running. 
This can be done either by leveraging one of Beam's provided patterns, such as 
the `WatchFilePattern`,
+or by configuring a custom side input `PCollection` that defines the logic for 
the model update.
+
+For more information about side inputs, see the [Side 
inputs](https://beam.apache.org/documentation/programming-guide/#side-inputs) 
section in the Apache Beam Programming Guide.
+
+This example uses 
[`WatchFilePattern`](https://beam.apache.org/releases/pydoc/current/apache_beam.ml.inference.utils.html#apache_beam.ml.inference.utils.WatchFilePattern)
 as a side input. `WatchFilePattern` is used to watch for the file updates 
matching the `file_pattern`
+based on timestamps. It emits the latest 
[`ModelMetadata`](https://beam.apache.org/documentation/transforms/python/elementwise/runinference/),
 which is used in
+the RunInference `PTransform` to automatically update the ML model without 
stopping the Beam pipeline.
+
+## Set up the source
+
+To read the image names, use a Pub/Sub topic as the source.
+ * The Pub/Sub topic emits a `UTF-8` encoded model path that is used to read 
and preprocess images to run the inference.
+
+## Models for image segmentation
+
+For the purpose of this example, use TensorFlow models saved in 
[HDF5](https://www.tensorflow.org/tutorials/keras/save_and_load#hdf5_format) 
format.
+
+
+## Pre-process images for inference
+The Pub/Sub topic emits an image path. We need to read and preprocess the 
image to use it for RunInference. The `read_image` function is used to read the 
image for inference.
+
+```python
+import io
+from PIL import Image
+from apache_beam.io.filesystems import FileSystems
+import numpy
+import tensorflow as tf
+
+def read_image(image_file_name):
+  with FileSystems().open(image_file_name, 'r') as file:
+    data = Image.open(io.BytesIO(file.read())).convert('RGB')
+  img = data.resize((224, 224))
+  img = numpy.array(img) / 255.0
+  img_tensor = tf.cast(tf.convert_to_tensor(img[...]), dtype=tf.float32)
+  return img_tensor
+```
+
+Now, let's jump into the pipeline code.
+
+**Pipeline steps**:
+1. Get the image names from the Pub/Sub topic.
+2. Read and pre-process the images using the `read_image` function.
+3. Pass the images to the RunInference `PTransform`. RunInference takes 
`model_handler` and `model_metadata_pcoll` as input parameters.
+
+For the 
[`model_handler`](https://github.com/apache/beam/blob/07f52a478174f8733c7efedb7189955142faa5fa/sdks/python/apache_beam/ml/inference/base.py#L308),
 we use 
[TFModelHandlerTensor](https://github.com/apache/beam/blob/186973b110d82838fb8e5ba27f0225a67c336591/sdks/python/apache_beam/ml/inference/tensorflow_inference.py#L184).
+```python
+from apache_beam.ml.inference.tensorflow_inference import TFModelHandlerTensor
+# initialize TFModelHandlerTensor with a .h5 model saved in a directory 
accessible by the pipeline.
+tf_model_handler = 
TFModelHandlerTensor(model_uri='gs://<your-bucket>/<model_path.h5>')
+```
+
+The `model_metadata_pcoll` is a [side 
input](https://beam.apache.org/documentation/programming-guide/#side-inputs) 
`PCollection` to the RunInference `PTransform`. This side input is used to 
update the models in the `model_handler` without needing to stop the beam 
pipeline.

Review Comment:
   @rszper this following section has a lot of code blocks which collectively 
make it kinda hard to read IMO 
(http://apache-beam-website-pull-requests.storage.googleapis.com/25947/documentation/ml/side-input-updates/index.html),
 but I don't know of a great way around it - any ideas on how we could make 
this section a little cleaner looking/easier to read? The content itself is 
correct



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website/www/site/content/en/documentation/ml/side-input-updates.md:
##########
@@ -0,0 +1,144 @@
+---
+title: "Auto Update ML models using WatchFilePattern"
+---
+<!--
+Licensed 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.
+-->
+
+# Use WatchFilePattern as side input to auto-update ML models in RunInference
+
+The pipeline in this example uses a 
[RunInference](https://beam.apache.org/documentation/transforms/python/elementwise/runinference/)
 `PTransform` with a [side 
input](https://beam.apache.org/documentation/programming-guide/#side-inputs) 
`PCollection` that emits `ModelMetadata` to run inferences on images using 
TensorFlow models.
+
+Using side inputs, you can update your model (which is passed in the 
`ModelHandler`) in real-time, even while the Beam pipeline is still running. 
This can be done either by leveraging one of Beam's provided patterns, such as 
the `WatchFilePattern`,
+or by configuring a custom side input `PCollection` that defines the logic for 
the model update.
+
+For more information about side inputs, see the [Side 
inputs](https://beam.apache.org/documentation/programming-guide/#side-inputs) 
section in the Apache Beam Programming Guide.
+
+This example uses 
[`WatchFilePattern`](https://beam.apache.org/releases/pydoc/current/apache_beam.ml.inference.utils.html#apache_beam.ml.inference.utils.WatchFilePattern)
 as a side input. `WatchFilePattern` is used to watch for the file updates 
matching the `file_pattern`
+based on timestamps. It emits the latest 
[`ModelMetadata`](https://beam.apache.org/documentation/transforms/python/elementwise/runinference/),
 which is used in
+the RunInference `PTransform` to automatically update the ML model without 
stopping the Beam pipeline.
+
+## Set up the source
+
+To read the image names, use a Pub/Sub topic as the source.
+ * The Pub/Sub topic emits a `UTF-8` encoded model path that is used to read 
and preprocess images to run the inference.
+
+## Models for image segmentation
+
+For the purpose of this example, use TensorFlow models saved in 
[HDF5](https://www.tensorflow.org/tutorials/keras/save_and_load#hdf5_format) 
format.
+
+
+## Pre-process images for inference
+The Pub/Sub topic emits an image path. We need to read and preprocess the 
image to use it for RunInference. The `read_image` function is used to read the 
image for inference.
+
+```python
+import io
+from PIL import Image
+from apache_beam.io.filesystems import FileSystems
+import numpy
+import tensorflow as tf
+
+def read_image(image_file_name):
+  with FileSystems().open(image_file_name, 'r') as file:
+    data = Image.open(io.BytesIO(file.read())).convert('RGB')
+  img = data.resize((224, 224))
+  img = numpy.array(img) / 255.0
+  img_tensor = tf.cast(tf.convert_to_tensor(img[...]), dtype=tf.float32)
+  return img_tensor
+```
+
+Now, let's jump into the pipeline code.
+
+**Pipeline steps**:
+1. Get the image names from the Pub/Sub topic.
+2. Read and pre-process the images using the `read_image` function.
+3. Pass the images to the RunInference `PTransform`. RunInference takes 
`model_handler` and `model_metadata_pcoll` as input parameters.
+
+For the 
[`model_handler`](https://github.com/apache/beam/blob/07f52a478174f8733c7efedb7189955142faa5fa/sdks/python/apache_beam/ml/inference/base.py#L308),
 we use 
[TFModelHandlerTensor](https://github.com/apache/beam/blob/186973b110d82838fb8e5ba27f0225a67c336591/sdks/python/apache_beam/ml/inference/tensorflow_inference.py#L184).
+```python
+from apache_beam.ml.inference.tensorflow_inference import TFModelHandlerTensor
+# initialize TFModelHandlerTensor with a .h5 model saved in a directory 
accessible by the pipeline.
+tf_model_handler = 
TFModelHandlerTensor(model_uri='gs://<your-bucket>/<model_path.h5>')
+```
+
+The `model_metadata_pcoll` is a [side 
input](https://beam.apache.org/documentation/programming-guide/#side-inputs) 
`PCollection` to the RunInference `PTransform`. This side input is used to 
update the models in the `model_handler` without needing to stop the beam 
pipeline.
+We will use `WatchFilePattern` as side input to watch a glob pattern matching 
`.h5` files.
+
+`model_metadata_pcoll` expects a `PCollection[ModelMetadata]` compatible with 
[`AsSingleton`](https://beam.apache.org/releases/pydoc/2.4.0/apache_beam.pvalue.html#apache_beam.pvalue.AsSingleton)
 view. Because the pipeline uses `WatchFilePattern` as side input, it will take 
care of windowing and wrapping the output into `ModelMetadata`.
+
+
+After the pipeline starts processing data and when you see some outputs 
emitted from the RunInference `PTransform`, upload a `.h5` `TensorFlow` model 
that matches the `file_pattern` to the Google Cloud Storage bucket. 
RunInference will update the `model_uri` of `TFModelHandlerTensor` using 
`WatchFilePattern` as a side input.
+
+**Note**: Side input update frequency is non-deterministic and can have longer 
intervals between updates.
+
+```python
+import apache_beam as beam
+from apache_beam.ml.inference.utils import WatchFilePattern
+from apache_beam.ml.inference.base import RunInference
+with beam.Pipeline() as pipeline:
+
+  file_pattern = 'gs://<your-bucket>/*.h5'
+  pubsub_topic = '<topic_emitting_image_names>'
+
+  side_input_pcoll = (
+    pipeline
+    | "FilePatternUpdates" >> WatchFilePattern(file_pattern=file_pattern))
+
+  images_pcoll = (
+    pipeline
+    | "ReadFromPubSub" >> beam.io.ReadFromPubSub(topic=pubsub_topic)
+    | "DecodeBytes" >> beam.Map(lambda x: x.decode('utf-8'))
+    | "PreProcessImage" >> beam.Map(read_image)
+  )
+
+  inference_pcoll = (
+    images_pcoll
+    | "RunInference" >> RunInference(
+    model_handler=tf_model_handler,
+    model_metadata_pcoll=side_input_pcoll))
+
+```
+
+
+## Post-process the `PredictionResult` object
+
+When the inference is complete, RunInference outputs a `PredictionResult` 
object that contains `example`, `inference`, and `model_id`. Here, the 
`model_id` is used to identify which model is used for running the inference.

Review Comment:
   ```suggestion
   When the inference is complete, RunInference outputs a `PredictionResult` 
object that contains `example`, `inference`, and `model_id` fields. The 
`model_id` is used to identify which model is used for running the inference.
   ```



##########
website/www/site/content/en/documentation/ml/side-input-updates.md:
##########
@@ -0,0 +1,144 @@
+---
+title: "Auto Update ML models using WatchFilePattern"
+---
+<!--
+Licensed 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.
+-->
+
+# Use WatchFilePattern as side input to auto-update ML models in RunInference
+
+The pipeline in this example uses a 
[RunInference](https://beam.apache.org/documentation/transforms/python/elementwise/runinference/)
 `PTransform` with a [side 
input](https://beam.apache.org/documentation/programming-guide/#side-inputs) 
`PCollection` that emits `ModelMetadata` to run inferences on images using 
TensorFlow models.
+
+Using side inputs, you can update your model (which is passed in the 
`ModelHandler`) in real-time, even while the Beam pipeline is still running. 
This can be done either by leveraging one of Beam's provided patterns, such as 
the `WatchFilePattern`,
+or by configuring a custom side input `PCollection` that defines the logic for 
the model update.
+
+For more information about side inputs, see the [Side 
inputs](https://beam.apache.org/documentation/programming-guide/#side-inputs) 
section in the Apache Beam Programming Guide.
+
+This example uses 
[`WatchFilePattern`](https://beam.apache.org/releases/pydoc/current/apache_beam.ml.inference.utils.html#apache_beam.ml.inference.utils.WatchFilePattern)
 as a side input. `WatchFilePattern` is used to watch for the file updates 
matching the `file_pattern`
+based on timestamps. It emits the latest 
[`ModelMetadata`](https://beam.apache.org/documentation/transforms/python/elementwise/runinference/),
 which is used in
+the RunInference `PTransform` to automatically update the ML model without 
stopping the Beam pipeline.
+
+## Set up the source
+
+To read the image names, use a Pub/Sub topic as the source.
+ * The Pub/Sub topic emits a `UTF-8` encoded model path that is used to read 
and preprocess images to run the inference.
+
+## Models for image segmentation
+
+For the purpose of this example, use TensorFlow models saved in 
[HDF5](https://www.tensorflow.org/tutorials/keras/save_and_load#hdf5_format) 
format.
+
+
+## Pre-process images for inference
+The Pub/Sub topic emits an image path. We need to read and preprocess the 
image to use it for RunInference. The `read_image` function is used to read the 
image for inference.
+
+```python
+import io
+from PIL import Image
+from apache_beam.io.filesystems import FileSystems
+import numpy
+import tensorflow as tf
+
+def read_image(image_file_name):
+  with FileSystems().open(image_file_name, 'r') as file:
+    data = Image.open(io.BytesIO(file.read())).convert('RGB')
+  img = data.resize((224, 224))
+  img = numpy.array(img) / 255.0
+  img_tensor = tf.cast(tf.convert_to_tensor(img[...]), dtype=tf.float32)
+  return img_tensor
+```
+
+Now, let's jump into the pipeline code.
+
+**Pipeline steps**:
+1. Get the image names from the Pub/Sub topic.
+2. Read and pre-process the images using the `read_image` function.
+3. Pass the images to the RunInference `PTransform`. RunInference takes 
`model_handler` and `model_metadata_pcoll` as input parameters.
+
+For the 
[`model_handler`](https://github.com/apache/beam/blob/07f52a478174f8733c7efedb7189955142faa5fa/sdks/python/apache_beam/ml/inference/base.py#L308),
 we use 
[TFModelHandlerTensor](https://github.com/apache/beam/blob/186973b110d82838fb8e5ba27f0225a67c336591/sdks/python/apache_beam/ml/inference/tensorflow_inference.py#L184).
+```python
+from apache_beam.ml.inference.tensorflow_inference import TFModelHandlerTensor
+# initialize TFModelHandlerTensor with a .h5 model saved in a directory 
accessible by the pipeline.
+tf_model_handler = 
TFModelHandlerTensor(model_uri='gs://<your-bucket>/<model_path.h5>')
+```
+
+The `model_metadata_pcoll` is a [side 
input](https://beam.apache.org/documentation/programming-guide/#side-inputs) 
`PCollection` to the RunInference `PTransform`. This side input is used to 
update the models in the `model_handler` without needing to stop the beam 
pipeline.
+We will use `WatchFilePattern` as side input to watch a glob pattern matching 
`.h5` files.
+
+`model_metadata_pcoll` expects a `PCollection[ModelMetadata]` compatible with 
[`AsSingleton`](https://beam.apache.org/releases/pydoc/2.4.0/apache_beam.pvalue.html#apache_beam.pvalue.AsSingleton)
 view. Because the pipeline uses `WatchFilePattern` as side input, it will take 
care of windowing and wrapping the output into `ModelMetadata`.
+
+
+After the pipeline starts processing data and when you see some outputs 
emitted from the RunInference `PTransform`, upload a `.h5` `TensorFlow` model 
that matches the `file_pattern` to the Google Cloud Storage bucket. 
RunInference will update the `model_uri` of `TFModelHandlerTensor` using 
`WatchFilePattern` as a side input.
+
+**Note**: Side input update frequency is non-deterministic and can have longer 
intervals between updates.
+
+```python
+import apache_beam as beam
+from apache_beam.ml.inference.utils import WatchFilePattern
+from apache_beam.ml.inference.base import RunInference
+with beam.Pipeline() as pipeline:
+
+  file_pattern = 'gs://<your-bucket>/*.h5'
+  pubsub_topic = '<topic_emitting_image_names>'
+
+  side_input_pcoll = (
+    pipeline
+    | "FilePatternUpdates" >> WatchFilePattern(file_pattern=file_pattern))
+
+  images_pcoll = (
+    pipeline
+    | "ReadFromPubSub" >> beam.io.ReadFromPubSub(topic=pubsub_topic)
+    | "DecodeBytes" >> beam.Map(lambda x: x.decode('utf-8'))
+    | "PreProcessImage" >> beam.Map(read_image)
+  )
+
+  inference_pcoll = (
+    images_pcoll
+    | "RunInference" >> RunInference(
+    model_handler=tf_model_handler,
+    model_metadata_pcoll=side_input_pcoll))
+
+```
+
+
+## Post-process the `PredictionResult` object
+
+When the inference is complete, RunInference outputs a `PredictionResult` 
object that contains `example`, `inference`, and `model_id`. Here, the 
`model_id` is used to identify which model is used for running the inference.
+
+```python
+from apache_beam.ml.inference.base import PredictionResult
+
+class PostProcessor(beam.DoFn):
+  """
+  Process the PredictionResult to get the predicted label and model id used 
for inference.
+  """
+  def process(self, element: PredictionResult) -> typing.Iterable[str]:
+    predicted_class = numpy.argmax(element.inference[0], axis=-1)
+    labels_path = tf.keras.utils.get_file(
+        'ImageNetLabels.txt',
+        
'https://storage.googleapis.com/download.tensorflow.org/data/ImageNetLabels.txt'
+    )
+    imagenet_labels = numpy.array(open(labels_path).read().splitlines())
+    predicted_class_name = imagenet_labels[predicted_class]
+    return predicted_class_name.title(), element.model_id
+
+post_processor_pcoll = (inference_pcoll | "PostProcessor" >> PostProcessor())
+```
+
+## Run the pipeline
+```python
+result = pipeline.run().wait_until_finish()
+```
+**Note**: The `model_name` of the `ModelMetaData` object will be attached as 
prefix to the 
[metrics](https://beam.apache.org/documentation/ml/runinference-metrics/) 
calculated by the RunInference `PTransform`.
+
+## Final remarks
+Use this example as a pattern when using side inputs with the RunInference 
`PTransform` to auto-update the models without stopping the pipeline. You can 
see a similar example for PyTorch on 
[GitHub](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/examples/inference/pytorch_image_classification_with_side_inputs.py).

Review Comment:
   ```suggestion
   You can use this example as a pattern when using side inputs with the 
RunInference `PTransform` to auto-update the models without stopping the 
pipeline. You can see a similar example for PyTorch on 
[GitHub](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/examples/inference/pytorch_image_classification_with_side_inputs.py).
   ```
   
   Nit: consistency of style with the next sentence.



##########
website/www/site/layouts/partials/section-menu/en/documentation.html:
##########
@@ -226,6 +226,7 @@
       <li><a href="/documentation/ml/tensorrt-runinference">Build a custom 
model handler with TensorRT</a></li>
       <li><a href="/documentation/ml/large-language-modeling">Use LLM 
inference</a></li>
       <li><a href="/documentation/ml/multi-language-inference/">Build a 
multi-language inference pipeline</a></li>
+      <li><a href="/documentation/ml/side-input-updates/">Use side inputs to 
automatically update models</a></li>

Review Comment:
   ```suggestion
         <li><a href="/documentation/ml/side-input-updates/">Update your model 
during pipeline execution</a></li>
   ```



##########
website/www/site/content/en/documentation/ml/side-input-updates.md:
##########
@@ -0,0 +1,144 @@
+---
+title: "Auto Update ML models using WatchFilePattern"
+---
+<!--
+Licensed 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.
+-->
+
+# Use WatchFilePattern as side input to auto-update ML models in RunInference
+
+The pipeline in this example uses a 
[RunInference](https://beam.apache.org/documentation/transforms/python/elementwise/runinference/)
 `PTransform` with a [side 
input](https://beam.apache.org/documentation/programming-guide/#side-inputs) 
`PCollection` that emits `ModelMetadata` to run inferences on images using 
TensorFlow models.
+
+Using side inputs, you can update your model (which is passed in the 
`ModelHandler`) in real-time, even while the Beam pipeline is still running. 
This can be done either by leveraging one of Beam's provided patterns, such as 
the `WatchFilePattern`,
+or by configuring a custom side input `PCollection` that defines the logic for 
the model update.
+
+For more information about side inputs, see the [Side 
inputs](https://beam.apache.org/documentation/programming-guide/#side-inputs) 
section in the Apache Beam Programming Guide.
+
+This example uses 
[`WatchFilePattern`](https://beam.apache.org/releases/pydoc/current/apache_beam.ml.inference.utils.html#apache_beam.ml.inference.utils.WatchFilePattern)
 as a side input. `WatchFilePattern` is used to watch for the file updates 
matching the `file_pattern`
+based on timestamps. It emits the latest 
[`ModelMetadata`](https://beam.apache.org/documentation/transforms/python/elementwise/runinference/),
 which is used in
+the RunInference `PTransform` to automatically update the ML model without 
stopping the Beam pipeline.
+
+## Set up the source
+
+To read the image names, use a Pub/Sub topic as the source.
+ * The Pub/Sub topic emits a `UTF-8` encoded model path that is used to read 
and preprocess images to run the inference.
+
+## Models for image segmentation
+
+For the purpose of this example, use TensorFlow models saved in 
[HDF5](https://www.tensorflow.org/tutorials/keras/save_and_load#hdf5_format) 
format.
+
+
+## Pre-process images for inference
+The Pub/Sub topic emits an image path. We need to read and preprocess the 
image to use it for RunInference. The `read_image` function is used to read the 
image for inference.
+
+```python
+import io
+from PIL import Image
+from apache_beam.io.filesystems import FileSystems
+import numpy
+import tensorflow as tf
+
+def read_image(image_file_name):
+  with FileSystems().open(image_file_name, 'r') as file:
+    data = Image.open(io.BytesIO(file.read())).convert('RGB')
+  img = data.resize((224, 224))
+  img = numpy.array(img) / 255.0
+  img_tensor = tf.cast(tf.convert_to_tensor(img[...]), dtype=tf.float32)
+  return img_tensor
+```
+
+Now, let's jump into the pipeline code.
+
+**Pipeline steps**:
+1. Get the image names from the Pub/Sub topic.
+2. Read and pre-process the images using the `read_image` function.
+3. Pass the images to the RunInference `PTransform`. RunInference takes 
`model_handler` and `model_metadata_pcoll` as input parameters.
+
+For the 
[`model_handler`](https://github.com/apache/beam/blob/07f52a478174f8733c7efedb7189955142faa5fa/sdks/python/apache_beam/ml/inference/base.py#L308),
 we use 
[TFModelHandlerTensor](https://github.com/apache/beam/blob/186973b110d82838fb8e5ba27f0225a67c336591/sdks/python/apache_beam/ml/inference/tensorflow_inference.py#L184).
+```python
+from apache_beam.ml.inference.tensorflow_inference import TFModelHandlerTensor
+# initialize TFModelHandlerTensor with a .h5 model saved in a directory 
accessible by the pipeline.
+tf_model_handler = 
TFModelHandlerTensor(model_uri='gs://<your-bucket>/<model_path.h5>')
+```
+
+The `model_metadata_pcoll` is a [side 
input](https://beam.apache.org/documentation/programming-guide/#side-inputs) 
`PCollection` to the RunInference `PTransform`. This side input is used to 
update the models in the `model_handler` without needing to stop the beam 
pipeline.
+We will use `WatchFilePattern` as side input to watch a glob pattern matching 
`.h5` files.
+
+`model_metadata_pcoll` expects a `PCollection[ModelMetadata]` compatible with 
[`AsSingleton`](https://beam.apache.org/releases/pydoc/2.4.0/apache_beam.pvalue.html#apache_beam.pvalue.AsSingleton)
 view. Because the pipeline uses `WatchFilePattern` as side input, it will take 
care of windowing and wrapping the output into `ModelMetadata`.

Review Comment:
   ```suggestion
   `model_metadata_pcoll` expects a `PCollection` of ModelMetadata compatible 
with 
[AsSingleton](https://beam.apache.org/releases/pydoc/2.4.0/apache_beam.pvalue.html#apache_beam.pvalue.AsSingleton)
 view. Because the pipeline uses `WatchFilePattern` as side input, it will take 
care of windowing and wrapping the output into `ModelMetadata`.
   ```
   
   I think this reads/renders more cleanly (code block links don't render well, 
see this line in 
http://apache-beam-website-pull-requests.storage.googleapis.com/25947/documentation/ml/side-input-updates/index.html)



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