Does it make sense to use Google DataFlow/Apache B

问题:

I am considering Google DataFlow as an option for running a pipeline that involves steps like:

1. Downloading images from the web;
2. Processing images.

I like that DataFlow manages the lifetime of VMs required to complete the job, so I don't need to start or stop them myself, but all examples I came across use it for data mining kind of tasks. I wonder if it is a viable option for other batch tasks like image processing and crawling.

回答1:

This use case is a possible application for Dataflow/Beam.

If you want to do this in a streaming fashion, you could have a crawler generating URLs and adding them to a PubSub or Kafka queue; and code a Beam pipeline to do the following:

1. Read from PubSub
2. Download the website content in a ParDo
3. Parse image URLs from the website in another ParDo*
4. Download each image and process it, again with a ParDo
5. Store the result in GCS, BigQuery, or others, depending on what information you want from the image.

You can do the same with a batch job, just changing the source you're reading the URLs from.

*After parsing those image URLs, you may also want to reshuffle your data, to gain some parallelism.