A presentatino by wouter Danes

1. Faceted Navigation on Related Documents
A tale of Daemons
Wouter Danes – Hippo Gettogether – 20 april 2012
Vrijdag 20 april 2012 | Copyright ©2012 HintTech B.V. All rights reserved 1

2. Agenda
• About me
• User story: faceted navigation for site wide search
• Problem: practice doesn’t follow theory
• Possible solution: Derived Data Engine
• Better solution: Daemons!
• Some stuff we learned
• How to improve Hippo to make this easier
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3. About me – Wouter Danes
• Hired via Orange11 @Rijksoverheid.nl
• Java (10yrs experience) & Hippo Developer
• Competence Manager Java & Hippo @ Hinttech
• Merciless refactorer
• Loves Test Driven Development
• Hippo CMS Committer
• Experience as a Software Architect
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4. Faceted Navigation for Site Wide Search
• Rijksoverheid.nl needed a new side wide search
• It had to allow a drill down via four facets:
Responsible Department(s), Document Type
Applicable Theme(s), Document Date
• This is pretty easy with Hippo
• It supports faceted navigation out of the box
• At least, if all facets are properties on the
document…
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5. Problem: Practice doesn’t follow theory
We would like to see:
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6. Problem: Practice doesn’t follow theory
We would like to see: The horrible truth:
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7. Possible solution: Derived Data Engine
• Derived Data Engine allows you to define input
properties and then populate some output
properties
• You can even point to a single property on ONE
related Document (property name is secretly a
relative path… shhh!) f.ex: “common:subject/@title”
• You cannot point to a property on multiple
related Documents
• Crap! Foiled again!
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8. We Were About to Give Up…
When Jeroen and me came up with this idea…
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9. Daemon Modules
• Hippo CMS supports Daemon Modules
• Daemon modules are services that run in the
Hippo Repository in their own (admin) session
• We could let this daemon module derive stuff for
us, all we have to do is send it the UUID of the
node…
• Let’s see how that works!
!! WARNING: DO NOT TRY THIS AT HOME !!
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10. Sequence Diagram
Now show us some code..!!
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11. Nothing Like the Smell of a Good Hack!
(unless you are Hippo Support and got 50+ clients doing this…)
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12. Stuff We Learned
1. Make Sure Your Daemon Module is Thread Safe
2. When you Refresh a Session, any Nodes it
Supplied Become Useless
3. If a Derived Data Function Throws an Exception,
any Action that Triggered the Node.save() Fails
4. This Will Break (Delayed) Publishing!
1 + 2 + 3 + 4 == Weird Artifacts
….That took us ages to debug
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13. How to improve Hippo to make this easier
• Improve Derived Data Engine to Supply a
Decorated Read Only Node instead of Input &
Output Properties
• Read Only is Good, Because You Don’t Want the
Derived Data Engine to Modify/Save other Nodes
• Output Concept Can Stay Like it Is
• Or… Wait for SOLR Integration
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14. Wouter Danes
@wouterdanes
Tel: +31–(0)88–268 25 00 Address: Delftechpark 37i
Mob: +31-(0) 6 1158 8264 2628 XJ Delft
E-mail: Wouter.danes@hinttech.com The Netherlands
Delft San Francisco Novi Sad Nordic United Kingdom
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