Layouts represent the structure of the content that a user sees when they log into uPortal. As of version 2.5 of uPortal the following layout management approaches are available:
SLM
Simple Layout Management was the original layout management approach. It provides nearly complete control to end users to customize their layout. They own all portions of the layout. Some aspects of layouts could be locked in place but such locks had to be applied in the "template" layout from which user's received their initial copy when first logging into the portal. And such locks had to be applied within the layout in the database directly. There was no UI for applying locks. Once a layout was copied for an end user it was owned completely by them so changes made to the template user layout only affected new users that logged in after the change was made.
ALM
Aggregated Layout Management was introduced in version 2.2. It provided the means of creating layouts, fragments, that could be pushed to users based on group membership and merged into their owned portions of the layout. It also provided pulled fragments that could be subscribed to by the end user if they desired. The difference from SLM was that changes made to the pushed or pulled fragments would appear in the layout of the user of that fragment. A differentiating capability of ALM is that these fragments can not be altered by the end user thereby enforcing the pushed content being visible. See Fragments for more information.
DLM
Distributed Layout Management was designed by Sungard SCT in the 2.1 uPortal release timeframe but was only available in the version of uPortal included in Sungard SCT's Luminis product. The DLM Administrator's Guide is located here 02 DLM Administration Guide. DLM was contributed back to the uPortal code base in uPortal version 2.5. It is an extension of SLM and uses SLM's User Preferences channel for modifying a user's layout and editing fragment contents. DLM provides the ability to define fragments that get pushed to end users but allows the maintainer of the fragment to determine just how much of the pushed fragment can be edited by the end user. If such restrictions are later changed then changes made to a fragment by the users will be replaced with the original content of the fragment. See 03 Distributed Layout Management for more information.