Ok, that's where the confusion is coming in :). I envision protocol
buffer objects replacing the POJOs in both the wire api and the Meta API.
Trying to do both seems without gain for me (again, aside from
preserving backwards compatibility with existing releases). If that
requires a different Meta interface+impl (or a translation layer),
that's fine too -- just extra work (and a slight performance hit on
whichever is treated as the reference object).
Does that make sense?
Julian Hyde wrote:
Yes, the POJOs are needed. The service layer (which for a particular
client may or may not be backed by RPC) consists of methods that take
complex arguments and return complex results. Those arguments and
results are expressed as POJOs.
One example:
Frame fetch(StatementHandle h, List<TypedValue> parameterValues, long offset,
int fetchMaxRowCount);
class Frame {
public final long offset;
public final boolean done;
public final Iterable<Object> rows;
}
public class TypedValue {
public final ColumnMetaData.Rep type;
public final Object value;
}
The POJOs are definitely needed for the Java API Meta and appear in
some form by whatever the wire protocol is.
Julian
On Tue, Aug 11, 2015 at 10:16 AM, Josh Elser<[email protected]> wrote:
Pulling this out to email to avoid cluttering JIRA. I feel like I might not
be on the same page.
I see CALCITE-839 and CALCITE-840 being one in the same change, or at least
the root cause being solved by it.
Julian, I'm getting the impression that you envision protocol buffer
encoding being just another option for encoding requests and responses. My
opinion is that using protocol buffers to define these requests and
responses completely invalidates the need to support these POJOs. These
objects should be usable cross-language, so aside from support the releases
of Calcite which shipped only these POJOs, I don't see a need to maintain
them.
I am admittedly hedging my bet that the PB devs will release a new version
that has the advertised JSON-esque serialization format (instead of just a
binary format). If this ultimately falls through, POJOs that just wrap the
PB classes could also be done.
I just wanted to make sure I'm not dancing by myself and that we're all in
agreement on a general direction.
-------- Original Message --------
Subject: [jira] [Commented] (CALCITE-839) Remove Jackson annotations from
POJO classes in Meta
Date: Tue, 11 Aug 2015 05:41:45 +0000 (UTC)
From: Julian Hyde (JIRA)<[email protected]>
Reply-To: [email protected]
To: [email protected]
[
https://issues.apache.org/jira/browse/CALCITE-839?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14681279#comment-14681279
]
Julian Hyde commented on CALCITE-839:
-------------------------------------
Well then, I've assigned CALCITE-840 to you.
Remove Jackson annotations from POJO classes in Meta
----------------------------------------------------
Key: CALCITE-839
URL: https://issues.apache.org/jira/browse/CALCITE-839
Project: Calcite
Issue Type: Bug
Components: avatica
Reporter: Julian Hyde
Assignee: Julian Hyde
The Meta interface contains several POJO classes that represent RPC
requests or responses. Currently a few of those classes have Jackson
annotations such as @JsonCreator, @JsonProperty to help Jackson serialize
the POJO to JSON and de-serialize from JSON to the object.
As [~ndimiduk] pointed out in
http://mail-archives.apache.org/mod_mbox/incubator-calcite-dev/201503.mbox/%3CCANZa=gvkgd+bkj4+ejmuo6ivhs+okgskg1vwdazcy-zijyy...@mail.gmail.com%3E
these annotations are a "code smell" and should be removed. It makes it look
as if Jackson is the only possible transport, which is not the case. We can
continue to use Jackson as a transport, just specify the mappings elsewhere,
not as annotations.
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