experimental.noacquisition 1.1.0b1

Introduction

The problem with “acquisition” and publishTraverse is that the current method returns too many different URLs for the same content. For instance here is some potential url for the “kb” page of the plone.org website

• https://plone.org/documentation/kb

• https://plone.org/documentation/manual/kb

• https://plone.org/documentation/kb/manual/kb

• https://plone.org/documentation/manual/spinner.gif/kb

• …

and here is a generic “Plone” site with two content items “a” and “b” (folderish or not)

• http://example.com/Plone/a

• http://example.com/Plone/a/b/a

• http://example.com/Plone/a

• http://example.com/Plone/b/a

• …

All the urls above returns 200 with the same content, while I would like the “canonical url” to return 200 and the other to return 404.

The behaviour described above constitute a problem because:

• multiple url for the same content is a problem for SEO and is confusing to people. For SEO, in the latest versions Plone introduced the canonical META, but IMHO it’s just a workaround. People are confused. For example: sometimes some of my editors ask me: “I can’t remove the http://example.com/Plone/a/b/a/page. Can you do it for me?”

• the page doesn’t seem really the same on all urls: if you open https://plone.org/documentation/kb and https://plone.org/documentation/manual/kb the second has a portlet that the first is missing

• removing page from external cache (varnish or squid), for example after a content modification, will be a pain. This is because for the same content there could be multiple urls without any control or rules (collective.purgebyid solves this)

• when using subsite (or multiple plone site on the same zope app) the problem is even more annoying: suppose that “a” is a subsite (marked with INavigationRoot) for http://a.example.org and “b” for http://b.example.org. Opening the url http://a.example.org/b will probably show the homepage of site “a” inside the “b” site. collective.siteisolation and probably collective.lineage do something to isolate subsite, but IMHO again are only workarounds.

Versions

This is the 1.x series, maintained for Plone 5.2, 6.0, 6.1 and 6.2 (Zope < 6.2). Since Products.CMFCore 3.1 (i.e. Plone 6) Plone also ships a native implementation of this same idea, based on the IPubAfterTraversal event instead of a monkey patch, and the 2.x series of this package builds on that instead. That implementation only inspects the last traversed object, so it misses acquired content reached through a view that consumes further path segments – for instance:

/folder/acquired_image/@@images/image          served by 2.x, 404 with 1.x
/folder/acquired_doc/@types/Document           served by 2.x, 404 with 1.x

The monkey patch used here does not have that gap, because it checks at every traversal step. So 1.x gives more complete coverage than 2.x on every Plone version both support.

Usage

This is a monkey patch for publishTraverse method of Zope2’s ZPublisher.BaseRequest.DefaultPublishTraverse and a monkey patch for Products.Archetypes.BaseObject.BaseObject.__bobo_traverse__

By default invalid traverse is only logged as warning.

For enable raising exceptions, you need to manually modify config.py changing DRYRUN to False.

Or using plone.recipe.zope2instance >= 4.2.14, e.g.:

[instance]
recipe = plone.recipe.zope2instance
eggs =
    experimental.noacquisition
...
initialization =
   from experimental.noacquisition import config
   config.DRYRUN = False

Warning

USE AT YOUR OWN RISK

Don’t use it, if you don’t know exactly what are you doing… at least use leaving DRYRUN = True.

Other solutions

The Products.CMFPlone branch that used to be linked here, based on the IPubAfterTraversal event instead of a monkey patch, was merged into Products.CMFCore itself (3.1+) as Products.CMFCore.explicitacquisition, and is what the 2.x series of this package builds on. It still doesn’t work for all cases, at least when there is a custom traversal at the end of the request (take a look at the tests inside this package) – see Versions above.

There is also other packages with the same event based approach: collective.explicitacquisition and collective.redirectacquired

Changelog