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From Bill Graham <>
Subject Re: Cluster-specific Adaptors
Date Tue, 21 Sep 2010 18:17:07 GMT
+1 on staying stateless.

I think the challenge we're facing is that we're trying to support a
syntax that is simple and readable and can be done with a single line
(i.e. for the initial_adaptors file, the telnet API, the command line,
etc), but the configs can potentially be not-so-simple.

For example, here's how you might configure the JMS adaptor which used
dependency injection. That's a lot for a single line and there's
nowhere to add new global configs in front of the adaptor specific
configs without breaking things.

add jms.JMSAdaptor jms-events
-q -s "id_type IN ('162')" -x
jms.JMSMessagePropertyTransformer -p
"event_time,id_type,id,srcurl,xref,xrq,title -r event_time,id_type,id"

What if we were to adopt a few flags into the syntax:

add [name =] <adaptor_class_name> <datatype> [--tags <tags>]
[--adaptor-params <adaptor specific params>|--adaptor-config-file
<initial offset>

The '--*' flags could be reserved. This would allow us to keep with a
one-line syntax where that approach works, but allow for expansion.
Also, if an adaptor config got to complex, those configs could be
specified in a file if needed.

On Mon, Sep 20, 2010 at 9:52 PM, Jerome Boulon <> wrote:
> Hi,
> If I had to implement this, I will add an extra parameter
> (?extraParams=xyz).
> The adaptorImp will be the only one responsible for parsing this adaptor’s
> specific info.
> I don’t think that we could/should add new complexity in the parsing.
> The same think should be done for getCurrentStatus(), a public result, that
> is the same for all adaptors in order to know if the adaptors is working or
> not and a private section that will give extra information.
> Also, moving to a json input should simplify everything.
> /Jerome.
> On 9/20/10 5:15 PM, "Bill Graham" <> wrote:
> I'd like to hear Ari's take on this, but this does feel a bit hacky to
> me. Plus, it would put the responsibility of parsing tags on each
> adaptor impl and would require a refactor of how each one currently
> parses args.
> Actually, we might be able to intercept the call to parseArgs in
> AbstractAdaptor and pull out the tags if they exist and pass the rest
> to the subclass, which would be none the wiser. Not the cleanest, but
> at lease not as intrusive on the adaptor implementations.
> Ari, also what about the getCurrentStatus() method? I'd think all the
> impls would somehow need to incorporate tags into that response as
> well, since AFAIR that's what's used to do Adaptor SerDe with the
> checkpoints file.
> On Mon, Sep 20, 2010 at 3:57 PM, Eric Yang <> wrote:
>> Hi Bill,
>> This might be hacky but it should be possible to have adaptor specific
>> params to include tags.  Ari, what do you think?
>> Regards,
>> Eric
>> On 9/20/10 2:58 PM, "Bill Graham" <> wrote:
>> Hi,
>> In CHUKWA-515 we discussed the possibility being able to add an
>> adaptor bound to a given cluster:
>> I can actually see this being useful, especially now that it's easier
>> to add/remove agents with the Adaptor REST API. Looking into the code
>> it doesn't seem like it would be that hard to do, but I want to make
>> sure I'm not overlooking anything.
>> It seems like we could support this with a few small changes:
>> - Add the concept of tags to the Adaptor interface.
>> - AbstractAdator would support a getTags method which would return the
>> union of tags set on the Adaptor and the default tags on the
>> DataFactory.
>> - Internal tag implementations on each would change to store tags in
>> maps, instead of concat'ed strings. This would allow for a "last in
>> wins" type of functionality so tags could be overriden. This assumes
>> of course that there should never be more than one of the same tag key
>> value, which I _assume_ is the case.
>> - The ChunkImpl constructor will call getTags on the agent, instead of
>> getDefaultTags the data factory.
>> The trickiest part as I see it is figuring out how to change the add
>> adaptor string syntax in ChukwaAgetn.processAddCommandE in a way that
>> both makes sense and doesn't break things. In it's current form it
>> doesn't have room for easy expansion except at the end of the line:
>> add [name =] <adaptor_class_name> <datatype> <adaptor specific params>
>> <initial offset>
>> Any thoughts or suggestions? There's also a potential gotcha with all
>> the impls of Adaptor.parseArgs either breaking or needing to
>> change....
>> thanks,
>> Bill

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