-Re: Reader / Writer terminology
Doug Cutting 2013-06-08, 07:44
Originally I used the term 'actual' for the schema of the data written and
'expected' for the schema that the reader of the data wished to see it as.
Some found those terms confusing and suggested that 'writer' and 'reader'
were more intuitive, so we started using those instead. That unfortunately
seems not to have resolved the confusion entirely.
Perhaps we should improve the documentation around this? Do you have any
specific suggestions about how that might be done?
On Jun 7, 2013 10:12 PM, "Gregory (Grisha) Trubetskoy" <[EMAIL PROTECTED]>
> I'm curious how the "Reader" and "Writer" terminology came about, and,
> most importantly, whether it's as confusing to the rest of you as it is to
> As I understand it, the principal analogy here is from the RPC world - a
> process A writes some Avro to process B, in which case A is the writer and
> B is the reader.
> And there is the possibility that the schema which B may be expecting
> isn't what A is providing, thus B may have to do some conversion on its end
> to grok it, and Avro schema resolution rules may make this possible.
> So far so good. This is where it becomes confusing. I am lost on how the
> act of reading or writing is relevant to the task at hand, which is
> conversion of a value from one schema to another.
> As I read stuff on the lists and the docs, I couldn't help noticing words
> such as "original", "first", "second", "actual, "expected" being using
> alongside "reader" and "writer" as clarification.
> Why would be wrong with a "source" and "destination" schmeas?
> Consider the following line (from Avro-C):
> writer_iface = avro_resolved_writer_new(**writer_schema,
> Here "writer" in resolved_writer and writer_schema are unrelated. The
> former refers to the fact that this interface will be modifying (writing
> to) an object, the latter is referring to the writer (source, original,
> a.k.a actual) schema.
> Wouldn't this read better as:
> writer_iface = avro_resolved_writer_new(**source_schema, dest_schema);
> Anyway - I just want to know if I'm missing something obvious when I think
> that reader/writer is confusing.