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From Evan Weaver <ewea...@gmail.com>
Subject Re: Alternative wire protocols
Date Tue, 30 Jun 2009 22:22:25 GMT
I will see what I can cook up in the Ruby client: http://bit.ly/12okYX

That will help inform my opinions at least on what a more final RPC
should be. For example, as a start, I unified all the getters (but
don't support slice options yet): http://bit.ly/18iZCv

This is similar to above but figures out the list/scalar division for you.

Evan

On Tue, Jun 30, 2009 at 1:54 PM, Jonathan Ellis<jbellis@gmail.com> wrote:
> I don't know.  I'd need to see how it didn't end up being a crazy mess
> where it was very difficult to tell what kind of filter you needed to
> perform, like we had before Jun split ReadCommand up into different
> classes.  (https://issues.apache.org/jira/browse/CASSANDRA-95)
>
> (This was an internal change, the thrift api has always been what it is.)
>
> -Jonathan
>
> On Tue, Jun 30, 2009 at 1:55 PM, Evan Weaver<eweaver@gmail.com> wrote:
>> Since the API is so thorny right now, it would be extremely difficult
>> to automate filter calls. What if we had something like follows
>> (pardon my bogus syntax):
>>
>> resultUnion_n get_one(column_family:string, key:string,
>> [super_column:string], [column:string], [options:Something_t])
>> list<resultUnion_n> get_all(column_family:string, key:string,
>> [super_column:string], [column:string], [options:Something_t])
>>
>> where resultUnion_n is: (scalar | Column_t | SuperColumn_t)
>>
>> Ideally Column_t and SuperColumn_t could be merged, but that's not a big deal.
>>
>> The options struct/dict could have the composable filters of various kinds.
>>
>> Is this even remotely possible?
>>
>> Evan
>>
>> On Sun, Jun 28, 2009 at 5:49 AM, Bill de hOra<bill@dehora.net> wrote:
>>> Evan Weaver wrote:
>>>>
>>>> I wanted to start a small discussion to see if there is any interest
>>>> in supporting alternative wire protocols or perhaps junking Thrift to
>>>> some degree.
>>>>
>>>> Some options:
>>>>  * Use JSON over HTTP
>>>>  * Use BSON over...something (http://www.mongodb.org/display/DOCS/BSON)
>>>>  * Use ASN.1 over...something
>>>>  * Use Protocol Buffers over...something
>>>>  * Use Thrift, but package Cassandra-specific clients for each language
>>>>
>>>> I have not thought too coherently about this but generic Thrift seems
>>>> to be a pain point for everybody.
>>>
>>> Hi Evan,
>>>
>>> I've been playing around again with Cassandra recently and I agree Thrift is
>>> a pain point, and that was the case when I looked at the project originally.
>>> But I think it's not so much Thrift as how the data is presented to clients.
>>>
>>> Much more important to me is that to use Cassandra means reading and
>>> understanding the service api calls in cassandra.thrift. Personally I
>>> wouldn't have designed a fine grained API over the generic data structures
>>> implied by a colum store, where simple filters and selects become a litany
>>> of get_by_X calls. For example, 4 methods return list<column_t>, 2 return
>>> list<string>, 2 return list<superColumn_t>, there are 5 get_slice
and 4
>>> get_column variants. And typical of RPC, none of this stuff composes. In
>>> something like Django there are chained filter() calls (Hibernate has
>>> similar Criteria calls) which makes for a stable programming API, where what
>>> you need to figure out the criteria to pass. With Cassandra you have to do
>>> that and find the right method; the API surface is much bigger. Simple
>>> keystores and dynamo style models get away with fine grained RPC as there's
>>> nothing much to do except the key lookup and multiget usecases. They're not
>>> a design sweetspot for column stores APIs imvho.
>>>
>>> I think the question for Cassandra is not so much about serialization
>>> techniques and speed as whether RPC is the best way to expose the data.
>>>
>>> Bill
>>>
>>
>>
>>
>> --
>> Evan Weaver
>>
>



-- 
Evan Weaver

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