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Date: Tue, 29 May 2012 23:04:44 -0700
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Subject: Scala API
From: Christophe Taton <taton@wibidata.com>
To: user@avro.apache.org
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Hi people,

Is there interest in a custom Scala API for Avro records and protocols?
I am currently working on an schema compiler for Scala, but before I go
deeper, I would really like to have external feedback.
I would especially like to hear from anyone who has opinions on how to map
Avro types onto Scala types.
Here are a few hints on what I've been trying so far:

   - Records are compiled into two forms: mutable and immutable.
   - To avoid collisions with Java generated classes, scala classes are
   generated in a .scala sub-package.
   - Avro arrays are translated to Seq/List when immutable and
   Buffer/ArrayBuffer when mutable.
   - Avro maps are translated to immutable or mutable Map/HashMap.
   - Bytes/Fixed are translated to Seq[Byte] when immutable and
   Buffer[Byte] when mutable.
   - Avro unions are currently translated into Any, but I plan to:
   - translate union{null, X} into Scala Option[X]
      - compile union {T1, T2, T3} into a custom case classes to have
      proper type checking and pattern matching.
   - Scala records provide a method encode(encoder) to serialize as binary
   into a byte stream (appears ~30% faster than SpecificDatumWriter).
   - Scala mutable records provide a method decode(decoder) to deserialize
   a byte stream (appears ~25% faster than SpecificDatumReader).
   - Scala records implement the SpecificRecord Java interface (with some
   overhead), so one may still use the SpecificDatumReader/Writer when the
   custom encoder/decoder methods cannot be used.
   - Mutable records can be converted to immutable (ie. can act as
   builders).

Thanks,
Christophe

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Hi people,<div><br></div><div>Is there interest in a custom Scala API for A=
vro records and protocols?</div><div>I am currently working on an schema co=
mpiler for Scala, but before I go deeper, I would really like to have exter=
nal feedback.</div>
<div>I would especially like to hear from anyone who has opinions on how to=
 map Avro types onto Scala types.</div><div>Here are a few hints on what I&=
#39;ve been trying so far:</div><div><ul><li>Records are compiled into two =
forms: mutable and immutable.<br>
</li><li>To avoid collisions with Java generated classes, scala classes are=
 generated in a .scala sub-package.</li>
<li>Avro arrays are translated to Seq/List when immutable and Buffer/ArrayB=
uffer when mutable.</li><li>Avro maps are translated to immutable or mutabl=
e Map/HashMap.</li><li>Bytes/Fixed are translated to Seq[Byte] when immutab=
le and Buffer[Byte] when mutable.</li>
<li>Avro unions are currently translated into Any, but I plan to:<br></li><=
ul><li>translate union{null, X} into Scala Option[X]</li><li>compile union =
{T1, T2, T3} into a custom case classes to have proper type checking and pa=
ttern matching.</li>
</ul><li>Scala records provide a method encode(encoder) to serialize as bin=
ary into a byte stream (appears ~30% faster than SpecificDatumWriter).</li>
<li>Scala mutable records provide a method decode(decoder) to deserialize a=
 byte stream (appears ~25% faster than SpecificDatumReader).</li><li>Scala =
records implement the SpecificRecord Java interface (with some overhead), s=
o one may still use the SpecificDatumReader/Writer when the custom encoder/=
decoder methods cannot be used.</li>
<li>Mutable records can be converted to immutable (ie. can act as builders)=
.</li></ul><div>Thanks,</div><div>Christophe</div></div><div><br></div>

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