Re: [sca-assembly] issue 243: is default channel configurable? Proposals

[Eric Johnson <eric@tibco.com>]

Hi Anish,

On 11/8/11 8:52 AM, Anish Karmarkar wrote:

I took an AI to provide two competing proposals for resolving issue 243.

Proposal 1: allow the default channel to be configurable.

In section 5.9 of WD06, add the following --
The default domain channel, like any domain channel, can be configured. Configuring the default domain channel requires one to deploy a domain composite containing a channel with the 'name' attribute value set to "/". Note that since the default domain channel always exists, configuring the default domain channel in a running system is equivalent to reconfiguring an existing channel and will be subject to restrictions and conditions imposed by a runtime on reconfiguration of domain channels.

I was wondering whether you'd fall into the trap/pitfall you hit. I meant to send you an email reminder about that, but I forgot.

This proposal doesn't work, because channel names are declared as "xs:NCName", and you can't name a channel "/". We had an issue about "/" in the names of channels.

Perhaps something like this?
The default domain channel, like any domain channel, can be configured. Note that how it is configured is determined by the implementation, because it cannot be deployed like other channels ("/" is not a valid channel name). Also note that since the default domain channel always exists, configuring the default domain channel in a running system is equivalent to reconfiguring an existing channel and will be subject to restrictions and conditions imposed by a runtime on reconfiguration of domain channels.

Or, more simply:
"This specification does not define any way to configure the default domain channel."

[In any spec, what the spec explicitly or implicitly chooses not to define is, by implication, left to an implementation. I'm not sure we need to bludgeon readers with more words, or that they add value here.]

I think, instead, if we wish for the default channel to have some spec'd way to be configured, then we have to come up with some spec'd way to name it, perhaps (borrowing from C) such as "__DEFAULT__".

Proposal 2: do not allow the default channel to be configured.

In section 5.9 of WD06, add the following --
Since the default channel always exists, one is not allowed to deploy and configure the default channel using a domain composite. This does not prohibit runtimes from defining implementation-specific ways of statically or dynamically specifying configuration of the default channel.

Given the fact that you cannot, as currently spec'd, name the default channel in order to deploy and configure, this new proposal just seems like a variation, "configuring the default channel is outside the SCA Assembly spec."

Comments?

Nope, none.

;-)

-Eric.

-Anish
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