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This meeting is a hybrid teleconference and IRC chat. Anyone is welcome to join...here's the info:

Attendees 

Agenda

  1. New Fedora committer: Aaron Birkland
  2. Fedora 4.6.0 (Last ModeShape4) - release testing status
  3. Weak/Strong ETags for Containers and the If-Match header
    1. See:  FCREPO-2115 - Getting issue details... STATUS
    2. See also this comment: https://github.com/fcrepo4/fcrepo4/pull/1089#issuecomment-238892821
  4. Recent versioning issues: 
    1. FCREPO-2117 - Getting issue details... STATUS
    2. FCREPO-2118 - Getting issue details... STATUS
  5. Review Import/Export design priorities
  6. Review and contribute to "Fedora value proposition" statements
  7. New bug:  FCREPO-2104 - Getting issue details... STATUS
  8. Work on FCREPO-2105 - Getting issue details... STATUS
  9. ...
  10. Status of "in-flight" tickets

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Ticket Summaries

  1. Please squash a bug!

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  2. Tickets resolved this week:

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  3. Tickets created this week:

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Minutes

  • Congratulations and welcome to New Fedora committer Aaron Birkland.
  • Fedora 4.6.0 (Last ModeShape4) - release testing status
    • Testing is ongoing for Fedora 4.6.0 (last Modeshape 4 release). A. Soroka: thanks to everyone who has been helping with testing, and thanks to those doing the tedious work of manual testing in web browsers.
  • Weak/Strong ETags for Containers and the If-Match header
    • See  FCREPO-2115 - Getting issue details... STATUS
    • See also this comment: https://github.com/fcrepo4/fcrepo4/pull/1089#issuecomment-238892821
    • The LDP spec says we should use If-Match when performing an update to make sure it does not overwrite another update. The HTTP spec currently does not allow weak e-tags on update. Currently, if a client uses strong e-tags, If-Match works. If the client uses weak e-tags, it returns “condition unsatisfied.  Tom Johnson commented on this issue, Fedora attempting to use strong validators: https://github.com/fcrepo4/fcrepo4/pull/1089#issuecomment-23918773.  There is a stringent list of requirements for strong e-tags. Not sure if there is a way to meet them for RDF unless you implement some method of internal version control.
    • Proposed solution: use the timestamp to indicate updates in a method similar to e-tags functionality. This provides a workable alternative to the e-tags If-Match method of avoiding conflicts. This recommendation could go to the LDP community and be offered for consideration as a proof-of-concept workflow for RDF resources to protect edits.
    • Any LDP clients that are using the recommendation and are written to spec, when updating resources via PUTS, would be incompatible with Fedora in this implementation. However, Fedora is already incompatible. Any LDP client that is trying to faithfully follow the spec won’t be able to make updates unless they attempt If-Match, recognize the failure, and try another method, i.e. the header method. If a to-spec LDP client gets a weak e-tag in the response, it shouldn’t accept it for validation. There is not currently a way for things to Just Work as they exist.
    • The software in its current state allows you to accept a weak e-tag and scrub the W/ to pass it along as a strong e-tag. This is a loophole that should be closed, but there is a concern about blocking off functionality to do so. Correcting client behavior on the server side should be a policy-driven decision, not a software-driven one. The PR's purpose is primarily to make this more explicit with a more useful error message, and close a loophole.
    • Additionally, the way e-tags are used is not a back-and-forth, but two stateless requests that take place at two separate times. Scrubbing the W/ from the weak e-tag doesn’t make it match the spec.
    • In sacrificing this, we sacrifice caching and weak concurrency. If we no longer accept weak e-tags (do we? have we ever?), the weak concurrency is taken up by the If-Not-Modified header, which is practical. Caching is all right as well because the tags are still out there for utilization.
    • The LDP community discussed in the RFC-7232 process that weak e-tags should be allowed. The spec processes for these two things overlapped in a way that caused LDP to make an impracticable recommendation that is under review. LDP says server should require If-Match, but if they’re not sending strong e-tags (which no one has figured out how to do), it makes it impossible to require If-Match. This may hopefully be resolved in discussions in the LDP group.
    • Immediate-term resolution: do nothing. Raise this with the LDP group and see if we can come up with a better solution in the next few weeks. We may be overlooking a nasty edge case by leaving this in for now, but let’s try to come up with a bigger solution that’s generally accepted, and implement that in the near term.
  • Recent versioning issues: 
    1. FCREPO-2117 - Getting issue details... STATUS
    2. FCREPO-2118 - Getting issue details... STATUS
    • Not a blocker for 4.6.0 release. Versioning works, improvement is needed but not pressing.
  • Review Import/Export design priorities
    • Nick Ruest has been been spearheading.  Looking for consensus on proposed priorities.  If you have not yet done so, please review the design priorities.
    • No pushback from those who responded, just consensus so far.  Scheduling the sprint for Phase 1 priorities soon.
  • Review and contribute to "Fedora value proposition" statements
    • David Wilcox has put together a voting system with a variety of phrases that describe what Fedora is/does. 
    • People are encouraged to vote on the ones that resonate with them, add comments if any.
    • Timeframe for voting and submissions: within the next week or so. Folks on a Steering Group call on Tuesday will be going through the data that's there.
    • The goal of this is to figure out which phrases Fedora stakeholders find the most important.  Statements are about "what is Fedora?" and not "what could Fedora be?"
  • New bug:  FCREPO-2104 - Getting issue details... STATUS
    • This bug is at the Modeshape level, an exception causes a thread to die, and it has not yet been determined if this can be caught at the Fedora level.
  • Work on  FCREPO-2105 - Getting issue details... STATUS
    • First subticket: Process of resolving reference properties into URIs is very expensive in Modeshape, iterates through most of the nodes to return the ones needed.  To address the issue, Modeshape queries need to be optimized to not do this, targeting the actual resolution to use query resolution facility where possible, to cut down on node iteration.  Ben has done some work around this and had some positive performance findings.  Esmé trying to replicate Ben's performance findings without success. This could mean the performance is impacted by something deeper in the stack. 
    • Second subticket: preventing additional jcr:node lookups with data we already have (was this correct?)
      • Esmé & Aaron working on this.  Looking for volunteers to help with this work on in its current state.
      • Two complexities: 1) the path and URI are not a perfect match, 2) the node lookup for the subject is not at issue, the lookups of N child nodes are. In order to put an identifier in the triple, you have to get the node to get that identifier. This work aims to make it so that the application does not need to get the node to get the identifier for child node references.



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