13:58:33 <RRSAgent> RRSAgent has joined #xproc
13:58:33 <RRSAgent> logging to http://www.w3.org/2015/09/23-xproc-irc
13:58:34 <Norm> rrsagent, set logs world-visible
13:58:34 <Norm> Meeting: XML Processing Model WG
13:58:34 <Norm> Date: 23 September 2015
13:58:34 <Norm> Meeting: 278
13:58:35 <Norm> Chair: Norm
13:58:36 <Norm> Scribe: Norm
13:58:38 <Norm> ScribeNick: Norm
13:59:14 <Norm> Regrets: Henry
13:59:32 <ht> ht has joined #xproc
13:59:43 <ht> liam, what is meeting room password?
13:59:46 <Norm> s/Regrets:/Non-regrets:/
14:00:03 <Norm> p:call I believe
14:00:31 <Norm> is the password ht
14:01:41 <Norm> s/p:call/SEKRIT/
14:08:03 <Norm> Topic: Accept this agenda?
14:08:03 <Norm> -> http://www.w3.org/XML/XProc/2015/09/23-agenda
14:08:06 <Norm> Accepted.
14:08:09 <Norm> Topic: Accept minutes from the previous meeting?
14:08:10 <Norm> -> http://www.w3.org/XML/XProc/2015/09/09-minutes
14:08:13 <Norm> Accepted.
14:08:16 <Norm> Topic: Next meeting, 7 October 2015 (skipping 30 September)
14:08:44 <Norm> No regrets heard.
14:09:35 <Norm> Topic: Jim's revised proposal for an error port
14:09:37 <jfuller> https://github.com/xproc/specification/issues/136
14:09:43 <Norm> -> https://github.com/xproc/specification/issues/136#issuecomment-128004501
14:10:12 <Norm> Jim: I did a draft a few months ago; this is the result of comments from that review.
14:10:24 <Norm> ...I simplified to a single 'errors' port and I've tried to simplify some other things.
14:10:31 <Norm> Jim summarizes the proposal.
14:15:07 <Norm> Norm: Do we want to allow steps that succeed to write to the error port.
14:15:24 <Norm> Henry: The most obvious problem it's trying to solve seems to be that I run a pipeline and I don't get any output.
14:15:33 <Norm> ...In order to solve that problem, percolation is necessary.
14:16:17 <Norm> ...In shell-land, if someone writes to STDERR you see it, unless active steps have been take to redirect it.
14:17:14 <Norm> Norm: the other problem to solve is to let steps produce diagnostic output *without* failing.
14:19:46 <Norm> Norm attempts to summarize a plausible "percolating story"
14:21:30 <Norm> Norm mumbles a bit about the distinction between loggers in the Java environment vs stderr in the unix shell.
14:22:51 <Norm> Norm: steps send to the error port information they want the pipe to react to, they can log anything they want.
14:23:03 <Norm> Henry: Putting the error information into the pipeline doesn't make a lot of sense.
14:24:15 <Norm> Norm: But catching validation errors is common...
14:24:34 <Norm> Henry: The idea that what comes out on the error port is likely to be processed *by other steps* is very unlikely.
14:24:57 <Norm> ...Going back to the logger example, the stuff that gets logged is for humans or third party apps.
14:25:03 <Norm> Murray: Except when it does.
14:25:50 <Norm> Norm: I'm not sure I agree. I think processing stderr output is not uncommon.
14:26:11 <Norm> Murray: You can use loggers and try/catch and all the other methods you have to build your pipeline.
14:26:26 <Norm> ...My concern about stderr is that any given step could call a shell script, etc.
14:26:34 <Norm> ...How do I get those messages from stderr.
14:26:41 <ht> Good point
14:27:05 <Norm> ...I could do all those things probably better if I had another script and a try catch. ETc.
14:27:21 <Norm> ...The point is, unless you write a lot of code to catch stderr, you're not going to see it.
14:27:36 <Norm> ... If you could see the messages on the console, you might be able to quickly figure out what went wrong.
14:27:47 <Norm> ...You're typically not going to design a pipeline to rely on stderr.
14:28:33 <Norm> Norm: What do you mean by capture? The human or the pipeline?
14:28:36 <Norm> Murray: One or the other.
14:29:53 <Norm> Norm: So I think you're supporting what Henry said earlier. Let it percolate up, but also be able to catchint.
14:29:57 <Norm> s/chatcint/catch it/
14:31:05 <Norm> Norm: I think that's consistent with what Jim proposed. I think we want to say that steps can write to stderr without failing.
14:31:53 <Norm> Jim: What are the constraints on what is produced?
14:32:37 <Norm> Norm: I think a sequence of c:error elements with some required attributes and an ANY body
14:33:27 <Norm> Jim: If a try catch fails and then gets handled, do we still report to the errors report the failure.
14:34:15 <Norm> Norm: I think the catch gets all the error output and it doesn't get passed along unless the catch does so.
14:34:36 <Norm> Norm: Jim, do you want to try to put this in the spec.
14:35:09 <Norm> Norm: How do we make the percolation go through compound steps.
14:35:33 <Norm> Jim/Henry: I think it's implicit.
14:36:16 <Norm> Norm: Does that mean we're taking the name "errors" away from people?
14:39:20 <Norm> ...I suppose we could call it #errors so it's not declarable by mortals.
14:39:56 <Norm> Jim: I think we can just take that name.
14:40:26 <Norm> Henry: As long as we call it something other than "errors", it's probably ok. Call it "stderr" for the time being.
14:40:40 <Norm> ...On the basis that it's a name that won't have been used.
14:42:34 <Norm> Norm attempts to summarize the proposal.
14:42:55 <Norm> Murray: Can we separate stderr from one step. Say I've got step 12 that's 7 layers down.
14:43:14 <Norm> ...can I redirect that.
14:43:55 <Norm> Norm: Yes, by grabbing it like any ordinary port.
14:43:59 <Norm> Murray: Can I 'tee' it.
14:44:04 <Norm> Norm: Uhm...that might require some work.
14:44:42 <Norm> ...I'll add that to the issue.
14:48:27 <Norm> Norm hypothisizes about using p:error to do the tee.
14:48:50 <Norm> Topic: Any other business?
14:49:04 <Norm> None heard.
14:49:45 <Norm> rrsagent, draft minutes
14:49:45 <RRSAgent> I have made the request to generate http://www.w3.org/2015/09/23-xproc-minutes.html Norm