If we talk about the data injestion in the big data streaming pipelines it is fair to say that in the vast majority of cases it is the files in the CSV and other text, easy to parse formats which provide the source data.
Things will become more complex when the task is to read and parse the files in the format such as PDF. One would need to create a reader/receiver capable of parsing the PDF files and feeding the content fragments (the regular text, the text found in the embedded attachments and the file metadata) into the processing pipelines. That was tricky to do right but you did it just fine.
The next morning you get a call from your team lead letting you know the customer actually needs the content injested not only from the PDF files but also from the files in a format you've never heard of before. You spend the rest of the week looking for a library which can parse such files and when you finish writing the code involving that library's not well documented API all you think of is that the weekends have arrived just in time.
On Monday your new task is to ensure that the pipelines have to be initialized from the same network folder where the files in PDF and other format will be dropped. You end up writing a frontend reader code which reads the file, checks the extension, and then chooses a more specific reader.
Next day, when you are told that Microsoft Excel and Word documents which may or may not be zipped will have to be parsed as well, you report back asking for the holidays...
I'm sure you already know I've been preparing you for a couple of good news.
The first one is a well known fact that Apache Tika allows to write a generic code which can collect the data from the massive number of text, binary, image and video formats. One has to prepare or update the dependencies and configuration and have the same code serving the data from the variety of the data formats.
The other and main news is that Apache Beam 2.2.0-SNAPSHOT now ships a new TikaIO module (thanks to my colleague JB for reviewing and merging the PR). With Apache Beam capable of running the pipelines on top of Spark, Flink and other runners and Apache Tika taking care of various file formats, you get the most flexible data streaming system.
Do give it a try, help to improve TikaIO with new PRs, and if you are really serious about supporting a variety of the data formats in the pipelines, start planning on integrating it into your products :-)