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Nodes

As we learned in Intro, objects in an Islandora repository are represented as nodes in Drupal. Because of this, their metadata profile, display, form (and much more) are configurable through the Drupal UI. This gives repository administrators a huge degree of control over their repository without any need for coding. Much more so than ever before. And since we're using a core Drupal solution for modeling our objects, compatibility with third-party modules is virtually guaranteed. This opens up a plethora of solutions from the Drupal community that will save you untold time and effort when implementing your repository with Islandora.

Properties

Nodes have some basic properties that are common to all nodes, regardless of content type. These properties are not fields. This means that they cannot changed or removed. Their name, what type of data they hold, etc... are all baked in. Here's an example of the basic properties you'll see on a node:

nid: 1
uid: 1
title: "I am an Islandora 8 object"
created: 1550703004
changed: 1550703512
uuid: 02932f2c-e4c2-4b7e-95e1-4aceab78c638
type: islandora_object
status: 1

As you can see, it's all system data used at the Drupal level to track the basics.

Property Value
nid The local ID for a node
uuid The global ID for any entity
title The title for a node
created Timestamp of when node was created
changed Timestamp of when a node was last updated
type Content type (e.g. which group of fields are present on the node)
status Published, unpublished, etc...

Compared to Islandora 7

These node properties directly correspond to following Islandora 7.x object properties:

Islandora 7 Islandora 8
owner uid
dc.title title
PID uuid
status status

Fields

In addition to the basic node properties identified above, Islandora objects (like all Drupal nodes) can have fields. Most of what we would think of as descriptive metadata is stored as fields. Since a specific set of required and optional fields is assigned to a node by giving it a content type, we can think of content types as metadata profiles for our objects. For example, you might have a content type for a set of repository objects that have very specialized metadata requirements but another content type for generic repository objects that share a more general set of metadata fields. The section on metadata describes in more detail how fields on Islandora objects work.

Islandora has a notion of a content model, which is used to identify what type of content is being represented by a node (e.g. an image, a video, a collection of other items, etc...). This is done using a special field, "Model", which accepts taxonomy terms from the "Islandora Models" vocabulary. By applying a term from the Islandora Models vocabulary to a node, Islandora will become aware of how to handle the node in response to certain events, like choosing a viewer or generating derivatives.

Model tags

Compared to Islandora 7

Content models in Islandora 7 were immutable, and contained restrictions as to what types of datastreams could be associated with an object. Islandora 8 imposes no such restrictions. Content models can be changed at any time, and they in no way dictate what types of media can be associated with a node.

Members

Islandora has a notion of membership, which is used to create a parent/child relationship between two nodes. Any two nodes can be related in this way, though typically, the parent node has a content model of Collection. Membership (to a Collection or otherwise) is denoted using another special field, "Member Of". The "Member Of" field can hold multiple references, so it is possible for a single child to belong to multiple parents.

Compared to Islandora 7

In Islandora 7, there was a distinction between belonging to a collection and belonging to a compound object. In Islandora 8, this distinction is not present, essentially making every object a compound object.

For any node, its "Members" tab can be used to see all its members. You can also perform Actions in bulk on members using the check boxes and the Actions drop down.

Members tab

Media

All nodes can contain any number of media. The media for any node can be managed using the "Media" tab when viewing a node. Much like the "Members" tab, Actions can be performed in bulk using the check boxes and Actions drop down.

Media tab