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Re: [sca-assembly] [Issue 253]: (1.2) Must a global domain channel bedeployed before it can be used?
Eric, My view is that global channels - indeed any channels - are more than a name - they have configuration associated with them. A system which does not require them to be declared makes it difficult to provide required configuration. Yours, Mike Dr Mike Edwards Mail Point 146, Hursley Park STSM Winchester, Hants SO21 2JN SCA & Services Standards United Kingdom Co-Chair OASIS SCA Assembly TC IBM Software Group Phone: +44-1962 818014 Mobile: +44-7802-467431 (274097) e-mail: From: Eric Johnson <> To: Anish Karmarkar <> Cc: Date: 04/02/2011 17:14 Subject: Re: [sca-assembly] [Issue 253]: (1.2) Must a global domain channel be deployed before it can be used? On 2/4/11 1:37 AM, Anish Karmarkar wrote: > I don't see this being different than say requiring that a variable be > declared before it is used. <eej> Which might be a perfect analogy. If the only point of a global channel is to establish a name, then there's actually minimal value to declaring it before it is used. Many dynamic languages work this way - Python & Ruby. In the case of global domain channels, for many use cases, filters and bindings don't make sense, so the channel just becomes a name. At which point, declaration before use looks like ceremony over substance. </eej> > > -Anish > -- > > On 2/1/2011 10:11 AM, Danny van der Rijn wrote: >> An interesting argument for tight coupling... >> >> On 2/1/2011 6:19 AM, Anish Karmarkar wrote: >>> I think this is a fine issue to raise, but I don't quite support the >>> auto-creation proposal. The only global channel that is >>> 'auto-deployed' or always exists is the default channel. >>> >>> I would want the runtime to tell me if I referenced a channel that has >>> not been deployed (unless it is the default channel, which is the >>> exception). If I want a producer and consumer (especially if they are >>> in different composites) to communicate over a common channel, I would >>> want the system to catch typos. For example, if the producer is >>> connected to the channel "//omg" and the consumer is connected to >>> "//zomg", they would be deployed fine but my application would not >>> work correctly. >>> >>> -Anish >>> -- >>> >>> On 1/31/2011 10:19 AM, Eric Johnson wrote: >>>> Hi Peter, >>>> >>>> On 1/31/11 10:02 AM, Peter Niblett wrote: >>>>> Eric >>>>> >>>>> You said.. >>>>> >>>>> Neither of the above indicate whether or not the global domain >>>>> channel >>>>> can be used before it is referenced. >>>> >>>> Ah yes, the joys of a muddled brain on Monday morning. You're >>>> correct - >>>> the question is whether or not the global domain channel can be used >>>> before it is *created* via a contribution. >>>> >>>> Thanks for catching my circularity. >>>> >>>> -Eric. >>>>> >>>>> I'm not sure how you can "use" a channel without referencing it (I >>>>> assume "reference" means "wire to/from"), but I think the question >>>>> you >>>>> are asking is the one in the title - "can you reference a channel >>>>> that >>>>> hasn't been defined to the SCA assembly?". I think this is one place >>>>> where the current spec is clear.. you can't reference a domain >>>>> channel >>>>> that hasn't been defined. >>>>> >>>>> So it looks as though your issue is to say that we should change the >>>>> spec to say that it permits (in fact requires) autocreation of domain >>>>> channels. Presumably these channels would have to be created with >>>>> default attributes (though I know you think they shouldn't have >>>>> attributes at all). >>>>> >>>>> Regards >>>>> >>>>> Peter Niblett >>>>> IBM Senior Technical Staff Member >>>>> Member of the IBM Academy of Technology >>>>> +44 1962 815055 >>>>> +44 7825 657662 (mobile) >>>>> >>>>> >>>>> >>>>> >>>>> From: Eric Johnson<> >>>>> To: OASIS SCA Assembly<> >>>>> Date: 31/01/2011 17:19 >>>>> Subject: [sca-assembly] NEW ISSUE: (1.2) Must a global domain channel >>>>> be deployed before it can be used? >>>>> ------------------------------------------------------------------------ >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> Title: Must a global domain channel be deployed before it can be >>>>> used? >>>>> >>>>> Target: Assembly 1.2 WD 03 >>>>> >>>>> Description: >>>>> >>>>> Via the "@target" and "@source" attributes defined on a consumer& >>>>> producer, the assembler can reference global domain channels. >>>>> >>>>> In section 5.8, the presumed to be normative text reads "SCA runtimes >>>>> MUST support the use of domain channels [ASM????]." That is followed >>>>> by: >>>>> >>>>> "To create a Domain Channel, deploy a composite containing a channel >>>>> directly to the SCA Domain (i.e., do not use that composite as the >>>>> implementation of some component in the Domain)." >>>>> >>>>> Neither of the above indicate whether or not the global domain >>>>> channel >>>>> can be used before it is referenced. >>>>> >>>>> Proposal: >>>>> >>>>> General theme: do not require the global domain channel to exist >>>>> before >>>>> it can be used. >>>>> >>>>> Specific text (needs refinement?): >>>>> >>>>> In section 5.8, Paragraph #2, append: >>>>> >>>>> When contributing artifacts to a domain that contain references to >>>>> global domain channels that have not been created, the SCA runtime >>>>> MUST >>>>> automatically create said global domain channels, and cannot reject >>>>> such >>>>> contributions [ASM????]. >>>>> >>>>> >>>>> >>>>> --------------------------------------------------------------------- >>>>> To unsubscribe from this mail list, you must leave the OASIS TC that >>>>> generates this mail. Follow this link to all your TCs in OASIS at: >>>>> https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> ------------------------------------------------------------------------ >>>>> >>>>> >>>>> >>>>> / >>>>> / >>>>> >>>>> /Unless stated otherwise above: >>>>> IBM United Kingdom Limited - Registered in England and Wales with >>>>> number 741598. >>>>> Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire >>>>> PO6 >>>>> 3AU/ >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>> >>> --------------------------------------------------------------------- >>> To unsubscribe from this mail list, you must leave the OASIS TC that >>> generates this mail. Follow this link to all your TCs in OASIS at: >>> https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php >> > > --------------------------------------------------------------------- > To unsubscribe from this mail list, you must leave the OASIS TC that > generates this mail. Follow this link to all your TCs in OASIS at: > https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php --------------------------------------------------------------------- To unsubscribe from this mail list, you must leave the OASIS TC that generates this mail. Follow this link to all your TCs in OASIS at: https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
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