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Choosing between glossary.module and g2.module

G2 is not intended as a direct replacement for the glossary module already available with drupal for quite some time now. It is designed for slightly different needs, and this page is here to help you choose which module you should probably be using, or if you should really write your own.

Feature	Glossary	G2
Drupal-related
Drupal 4.7.x	Yes	Yes
Drupal 4.6.x	Yes	No
AJAX	No	Entry selector
architecture	term-based	node-based
Services provided
multiple glossaries on one site	Yes	No
RSS feeds on entries	Yes, Drupal core	No
RSS feeds on additional vocabularies	No	Yes, Drupal core
classify entries using taxonomy	No	Yes, Drupal core
commenting on entries	No	Yes, Drupal core
private editorial information	No	Yes
feature blocks	No	alphabar latest top random word of the day
XML-RPC services provided	No	alphabar latest top random word of the day
Security	Drupal core	Drupal core XML-RPC access control XML-RPC throttling
alphabar maintenance	automatic	manual
content filtering	automatic	dfn elements
Performance
memory needs/number of entries	proportional	constant
speed on small glossaries	faster	slower
speed on large glossaries	slower with size	remains constant
Themeability	search form node overview	Drupal core node themeing Independent themeing for all 5 feature blocks Independent themeing for all parts of a term definition

Obviously, in all cases, a “No” actually means: “roll your own”, as in all Open Source software.

Rationale for G2 specificities

Optimization for large glossaries: this is the need expressed by OSInet, which funded development, to support its 5000+ term glossary of computing, for which glossary.module, even when coupled with flexinode to bind blob content to terms, is not really efficient enough.
Single glossary: multiple glossaries were not necessary to OSInet, which funded development
Explicit linking to terms with dfn elements:
- limits system workload
- allows invisible marking of entries made of other entries. Think: XML-RPC, points to XML and to RPC with glossary.module and various wiki filters, but can point to 'XML-RPC' with G2. Wrapping XML-RPC in quotes is necessary to allow linking to this entry in glossary, but the quotes remain visible, degrading the UI.
- allows redactor-level choice of
  - whether to link to an entry: glossary always links if the term matches, which is not always meaningful (“and” can be present in a glossary and you don't want “and” to be linked from in all nodes on the site).
  - where to link to an entry: glossary allows only a predefined set of positions (first, last or all matches)
nodes vs terms: this is the most salient difference.
- Using custom nodes (g2_entry in g2.module) allows large definitions, with the complete drupal feature set for nodes,
- Using terms (glossary.module) allows definitions to be bound to custom nodes instead of being nodes on their own
Alphabar maintenance: large glossaries will most of the time use all available initials, so the processing cost of maintaining it is not justifiable