| <!-- |
| ~ 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. |
| --> |
| |
| <html> |
| <h2>Composite Transform</h2> |
| <p> |
| Transforms can have a nested structure, where a complex transform performs multiple simpler |
| transforms (such as more than one ParDo, Combine, GroupByKey, or even other composite transforms). |
| These transforms are called composite transforms. Nesting multiple transforms inside a single |
| composite transform can make your code more modular and easier to understand. |
| </p> |
| <p> |
| To create your own composite transform, create a subclass of the PTransform class and override |
| the expand method to specify the actual processing logic. You can then use this transform just as |
| you would a built-in transform from the Beam SDK. For the PTransform class type parameters, you |
| pass the PCollection types that your transform takes as input, and produces as output. Within |
| your PTransform subclass, you’ll need to override the expand method. The expand method is where |
| you add the processing logic for the PTransform. Your override of expand must accept the |
| appropriate type of input PCollection as a parameter, and specify the output PCollection as the |
| return value. |
| </p> |
| <p> |
| <b>Kata:</b> Please implement a composite transform "ExtractAndMultiplyNumbers" that extracts |
| numbers from comma separated line and then multiplies each number by 10. |
| </p> |
| <br> |
| <div class="hint"> |
| Refer to <a href="https://beam.apache.org/releases/javadoc/current/org/apache/beam/sdk/transforms/PTransform.html"> |
| PTransform</a>. |
| </div> |
| <div class="hint"> |
| Refer to the Beam Programming Guide |
| <a href="https://beam.apache.org/documentation/programming-guide/#composite-transforms"> |
| "Composite transforms"</a> section for more information. |
| </div> |
| </html> |
