Re: [ecf-dev] discovery service help

[Scott Lewis <slewis@xxxxxxxxxxxxx>]

Hi Abhisek,

abhisek saikia wrote:
> Hi
>   I am in a problem of selecting discovery services.Could you please 
> help me in finding which discovery service follows the below 
> specifications.
>
> 1)take a configure list of ips/ports for discovery
>  
> 2) discovery does not depend on "Host should be started before 
> consumer started"
>
> 3)discovery happens again if consumer/host goes down and up again
>
> I tried file based discovery ,which fails for case 2.

So I've got a few distinct responses to this:

1) WRT file-based discovery.  The hello world file-based discovery 
example fails when the consumer is started before the host because for 
the hello example this is the way the file-based discovery is activated 
(i.e. the file-based discovery is automatically started *when the hello 
consumer app starts*).  It is possible to have the file-based discovery 
to start at some *other/later time*, but it's up to you to define 
when/what that later time is (i.e. if not when the consumer starts, 
when?).  Once that later event(s) are defined, whatever it is for your 
use case, then it is trivial to have the file-based discovery read the 
service description and attempt to connect to the remote service at that 
time.  This can/could even be done repeatedly, at regular intervals or 
based upon some other event, if desired.   So what I'm saying is, I 
think that file-based discovery could probably be made to work for your 
use case...as I understand it.

2) I would guess another option is the use of Apache zookeeper-based 
discovery.  I think (but don't know, since I am not yet an expert with 
zookeeper itself), that it could meet these requirements.  The people to 
ask about this are indicated on this bug:

https://bugs.eclipse.org/bugs/show_bug.cgi?id=301854

3) Since your use case has some fairly specific needs/requirements I 
would request that you consider engaging one of the ECF committers 
directly for consulting about the design/develop of your application.  
As much as we would like to, we can only spend so much effort supporting 
the creation of individual applications when they don't involve 
finding/fixing problems in ECF itself.

Scott