20160321 - Meeting minutes, Monday 21th March 2016 - Discussion on cache mechanism

 

Estimated: 11:00 to 12:00 CET.

Performed: 11:05  to 12:05 CET

Agenda

Open discussion

Location

  • AdobeConnect:

http://ec-wacs.adobeconnect.com/openncp/
Room Passcode:  markus.kalliola or michele.foucart
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S

Joao Cunha

Kostas Karkaletsis

Massimiliano Masi

Marcello Melgara

YacoubouY

michele.foucart

Support documents

https://openncp.atlassian.net/wiki/pages/viewpage.action?spaceKey=ncp&title=Cache+implementation+through+ConfigurationManager+refactoring


  1. Introduction of the context of the meeting:
    1. Idea was on Friday SMP/SML meeting to agree on solution proposed by the DSI owner.
      1. Solution chosen by the eHDSI SP because limited impact on code, effort etc.
      2. But impact was challenged during the SMP/SML meeting, reason of the tenue of this meeting
  2. S explains the solution proposed, its advantages, impacts...
    1. Solution proposed is "enough" for our needs
      1. static data that do not change and end points that change once every 6 months
      2. Redis gives better results but maybe not necessary needed for our needs (get 60 properties...)
    2. Limited impact on code/effort: 1 additional class or 1 annotation, 1/2 day development
    3. No new installation/configuration needed
    4. "Effort" is the key reason for this choice since we don't have resources available now for this, the project has already other priorities (SMP/SML, Terminology...)...
  3. Massimiliano Masi:
    1. change proposal is supposed to be used for change of specs, based on objective results. So challenging objective
      1. Is this a change? Distinction between software bugs, change of specs, or improvement of something existing
    2. From a technical point of view, the publisher subscriber system will lead to better performance
    3. Missing measures from the CP, solution should be documented/shared on Confluence
  4.  Marcello Melgara: any change must converge to something that is stable and useful for MS. For every change it must reach an agreement, if agreement not reach we need to escalate. 
  5. Massimiliano Masi: question of complexity:
    1. product useful for MS
    2. We don't know yet the size (how many messages, patients, documents...), so we should do the best
      1. Reality for CEF:
      2. 21 countries applied
      3. 1 million EU citizens...
      4. Results? We don't know because not a comparison of the same thing
  6. Impact of the proposed CP: 1/2 day effort
    1. Massimiliano Masi:
      1. Not sure according to Massi, because keeping the DB and...more complex than the other solutions. 
        1. S: 3 or 4 calls to the db, simple hashmap.
      2. In addition it would not help for SMP/SML...
       Get properties to the conf manager is called every time, should be one of the top priority
      1. Keep the value in memory as long as it changes
      2. With DB approach (micro cache), use DB every time the cache is expired => DH hit more often than we think
  7. Question from Joao Cunha: Each cache in hibernate or also microcache? Idea was to use both (IH? Hibernate? cache + micro cache) => not clear in the proposal
    • context of the properties which won't change so much, so even if refresh once start day, 1 call to the database...
    • Tests microcache 
  8. The solutions should be compared
  9. Next steps:
    1. Proposition to add a dimension in the table of conclusion, which is "effort", and also 2 lines with the KEY advantages and disadvantages of each solution
    2. The solution described in the CP will be published in Confluence (including updates following today's meeting, additional info...) and share tests results
    3. Organise a new meeting to make a new status on this topic
      1. michele.foucart will organize, waiting S's GO