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Managing Deliverable-Specific Link Anchors: New Suggested Best Practice for Keys


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How to define and maintain publicly-linkable anchors in deliverables produced from DITA source

Presented originally at DITA North America 2015

Published in: Software
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Managing Deliverable-Specific Link Anchors: New Suggested Best Practice for Keys

  1. 1. Managing Deliverable-Specific Link Anchors: New Suggested Best Practice for Keys How to define and maintain publicly- linkable anchors in deliverables produced from DITA source 4/29/2015 Contrext, LLC 1 Eliot Kimber Contrext, LLC DITA North America 2015
  2. 2. About the Author • Independent consultant focusing on DITA analysis, design, and implementation • Doing SGML and XML for cough 30 years cough • Founding member of the DITA Technical Committee • Founding member of the XML Working Group • Co-editor of HyTime standard (ISO/IEC 10744) • Primary developer and founder of the DITA for Publishers project • Author of DITA for Practitioners, Vol 1 (XML Press) 4/29/2015 Contrext, LLC 2
  3. 3. Agenda • What are "public anchors"? • Navigation vs resource keys • Key definition and usage best practice • Generating public deliverable anchors 4/29/2015 Contrext, LLC 3
  4. 4. Executive Summary • Use keys for everything • Principle: Exactly one URI reference to each resource across all maps • Put unique keys on each navigation topicref you want to be publicly linkable or xref to • Use navigation keys to determine deliverable anchors • Don’t change navigation keys unnecessarily 4/29/2015 Contrext, LLC 4
  5. 5. What are Public Anchors? • Anything that can be linked to from outside the deliverable: – HTML files – HTML @id values – PDF named destinations – Help topic IDs • Need to be reliably persistent • Should not change from release to release for the same logical component (topic or element) 4/29/2015 Contrext, LLC 5
  6. 6. Navigation vs Resource keys • Two types of topicrefs: – "normal": contribute to the navigation tree or to reltables – "resource-only": Establish a dependency on a resource but don’t put it in the navigation tree • @processing-role on topicref: – processing-role="normal" – processing-role="resource-only" • <keydef> is resource-only by default 4/29/2015 Contrext, LLC 6
  7. 7. Resource-Only Keys • Establish context-independent keys for topics • Can be unique across all maps if required or map- or scope-specific • Key-defining maps serve as catalogs of topics or other resources (images, etc.) • Should be used for conrefs • Not useful for cross reference targets: no navigation use context 4/29/2015 Contrext, LLC 7
  8. 8. Normal-Role (Navigation) Key • Identifies the unique uses of a given topic • Only appropriate target for cross references • By the nature of keys, are globally unique within a single root map. 4/29/2015 Contrext, LLC 8
  9. 9. Key Definition and Usage Best Practice • Define resource-only keys in standalone "key- definition" maps <keydef keys="topic-000123r5" href="topics/t-57623-934.dita"/> • Use resource-only keys from navigation topicrefs: <chapter keys="chap-01" keyref="topic-000123r5"/> • Put keys on either all navigation topicrefs or • Put keys on all navigation topicrefs you want to be publicly linkable 4/29/2015 Contrext, LLC 9
  10. 10. Exactly One URI Reference For Each Resource • For images and external Web resources: – Always define a key – Refer to the key (and only the key) from topics • For topics that are or are likely to be reused: – Define resource-only keys in a separate key- defining map • For topics that are only ever used in a single map: – Put @keys on the topicref to the topic 4/29/2015 Contrext, LLC 10
  11. 11. Keys for Single-Use Topics • A topic used only once across all maps may not justify the cost of separate resource-only key definition • Define two keys on the topicref: – One that reflects that use of the topic: "ch-01-ss-01" – One that represents the topic in any context: "topic-1235" • Example: <topicref keys="installation topic-1234" href="topics/topic-1234.dita" /> • If the topic is ever reused, create resource-only topicref and move context-independent key to that definition 4/29/2015 Contrext, LLC 11
  12. 12. NOTE: DITA OT Limitation • As of OT 2.1 and earlier: – @copy-to on navigation topicrefs that use keyref doesn't work – Copy-to processing is done before key space construction • Fixing this will require rethinking entire preprocessing approach – Rethink required for DITA 1.3 anyway – Non-trivial to implement • Workaround: Use separate keydefs for each required copy-to: <keydef keys="key-01" href="topic-01.dita"/> <keydef keys="key-01-copy-to-c01s01" href="topic-01.dita" copy-to="ch01-sec01.dita"/> … <topicref keys="ch01-sec01" keyref="key-01-copy-to-c01s01"/> 4/29/2015 Contrext, LLC 12
  13. 13. Example: Publication root map <map> <title>Prod1 Product Guide</title> <mapref href="keysdefs-01.ditamap"/> <topicref keys="pubroot" keyref="topic-ABC001" > <topicref keys="chapter-01" keyref="topic-ABC123" > <topicref keys="ch01-overview" keyref="topic-ABC456" > </topicref> … </topicref> … </map> 4/29/2015 Contrext, LLC 13
  14. 14. Example: keydefs-01.ditamap <map> <title>Keydefs for Group 1</title> <keydef keys="topic-ABC001" href="topic-ABC001.dita" /> <keydef keys="topic-ABC002" href="topic-ABC002.dita" /> … </map> 4/29/2015 Contrext, LLC 14
  15. 15. Cross Reference Example <p>See <xref keyref="chapter-01"/>… <p>See <xref keyref="chapter-01/fig-01"/> 4/29/2015 Contrext, LLC 15
  16. 16. Generating Public Deliverable Anchors • Two basic use cases: – Multi-file outputs (HTML, online help) – Monolithic outputs (PDF, EPUB, etc.) • General problem: anchors for non-topic elements – Only unique within a single topic – Not necessarily unique within result documents • Must combine keys with element IDs in some cases 4/29/2015 Contrext, LLC 16
  17. 17. Multi-File Outputs (HTML) • Use navigation keys to determine result filenames: <topicref keys="chapter-01" keyref="topic-ABC123" > becomes chapter-01.html • Use navigation key plus element ID to construct in-document anchors 4/29/2015 Contrext, LLC 17
  18. 18. Monolithic Outputs (PDF) • Use navigation key for topic anchors • Use navigation key+element ID for non-topic anchors • For PDF, need to use a separator that uses legal URL characters, e.g. "_._", "-.-" – Needs to be more than "-" or "_" to avoid accidental collisions 4/29/2015 Contrext, LLC 18
  19. 19. Preprocessing Extensions • DITA Community project • Extends base preprocessing to add @copy-to to topicrefs as required – Second and subsequent reference to a given topic – Will eventually use keys for the filename value • Some subtle complexities • Haven't had time to implement yet 4/29/2015 Contrext, LLC 19
  20. 20. Summary • Always use keys for all references – To topics – To images – To peer maps (DITA 1.3) • Put keys on navigation topicrefs • Crossrefs should point to navigation keys • Use navigation keys to generate anchors in deliverables 4/29/2015 Contrext, LLC 20
  21. 21. Resources • Paper: community/paper-dita-keys-as-public-anchor- ids • Preprocessing extensions: community.preprocess-extensions • Me:, 4/29/2015 Contrext, LLC 21