Or perhaps the other way around? If you have a Schema we can auto-generate the associated builder on the PTransform? Either way, more DRY.
On Tue, May 30, 2023 at 10:59 AM Robert Bradshaw via dev < dev@beam.apache.org> wrote: > +1 to this simplification, it's a historical artifact that provides no > value. > > I would love it if we also looked into ways to auto-generate the > SchemaTransformProvider (e.g. via introspection if a transform takes a > small number of arguments, or uses the standard builder pattern...), > ideally with something as simple as adding a decorator to the PTransform > itself. > > > On Tue, May 30, 2023 at 7:42 AM Ahmed Abualsaud via dev < > dev@beam.apache.org> wrote: > >> Hey everyone, >> >> I was looking at how we use SchemaTransforms in our expansion service. >> From what I see, there may be a redundant step in developing >> SchemaTransforms. Currently, we have 3 pieces: >> - SchemaTransformProvider [1] >> - A configuration object >> - SchemaTransform [2] >> >> The API is generally used like this: >> 1. The SchemaTransformProvider takes a configuration object and returns a >> SchemaTransform >> 2. The SchemaTransform is used to build a PTransform according to the >> configuration >> >> In these steps, the SchemaTransform class seems unnecessary. We can >> combine the two steps if we have SchemaTransformProvider return the >> PTransform directly. >> >> We can then remove the SchemaTransform class as it will be obsolete. This >> should be safe to do; the only place it's used in our API is here [3], and >> that can be simplified if we make this change (we'd just trim ` >> .buildTransform()` off the end as `provider.from(configRow)` will >> directly return the PTransform). >> >> I'd like to first mention that I was not involved in the design process >> of this API so I may be missing some information on why it was set up this >> way. >> >> A few developers already raised questions about how there's seemingly >> unnecessary boilerplate involved in making a Java transform portable. I >> wasn't involved in the design process of this API so I may be missing some >> information, but my assumption is this was designed to follow the pattern >> of the previous iteration of this API (SchemaIO): SchemaIOProvider[4] -> >> SchemaIO[5] -> PTransform. However, with the newer >> SchemaTransformProvider API, we dropped a few methods and reduced the >> SchemaTransform class to have a generic buildTransform() method. See the >> example of PubsubReadSchemaTransformProvider [6], where the >> SchemaTransform interface and buildTransform method are implemented just >> to satisfy the requirement that SchemaTransformProvider::from return a >> SchemaTransform. >> >> I'm bringing this up because if we are looking to encourage contribution >> to cross-language use cases, we should make it simpler and less convoluted >> to develop portable transforms. >> >> There are a number of SchemaTransforms already developed, but applying >> these changes to them should be straightforward. If people think this is a >> good idea, I can open a PR and implement them. >> >> Best, >> Ahmed >> >> [1] >> https://github.com/apache/beam/blob/master/sdks/java/core/src/main/java/org/apache/beam/sdk/schemas/transforms/SchemaTransformProvider.java >> [2] >> https://github.com/apache/beam/blob/master/sdks/java/core/src/main/java/org/apache/beam/sdk/schemas/transforms/SchemaTransform.java >> [3] >> https://github.com/apache/beam/blob/d7ded3f07064919c202c81a2c786910e20a834f9/sdks/java/expansion-service/src/main/java/org/apache/beam/sdk/expansion/service/ExpansionServiceSchemaTransformProvider.java#L138 >> [4] >> https://github.com/apache/beam/blob/master/sdks/java/core/src/main/java/org/apache/beam/sdk/schemas/io/SchemaIOProvider.java >> [5] >> https://github.com/apache/beam/blob/master/sdks/java/core/src/main/java/org/apache/beam/sdk/schemas/io/SchemaIO.java >> [6] >> https://github.com/apache/beam/blob/ed1a297904d5f5c743a6aca1a7648e3fb8f02e18/sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/pubsub/PubsubReadSchemaTransformProvider.java#L133-L137 >> >
