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CGI ('Context-Guided-Ingest') is an attempt the remedy this problem, and improve ingest functionality generally, by providing a small set of service APIs and implementations that constitute more flexible and extensible equivalents to the content API wrappers. To ensure compatibility with previous work, as well as enhance general system modularity, CGI will be offered as a separate add-on or module and require no changes to the content API. Of course to utilize these services, new application code will have to be written. Over time, if CGI services prove useful, it may make sense to begin to abandon or deprecate the wrapper - approach, but it this will not be a requirement of using CGIan immediate requirement of using CGI.

Concepts

To best describe the services, we will introduce a few terms with specific meaning in the domain model of CGI. First, an IngestContext (or merely context when contextually clear ) means a container of persistent state with a determinate life-cycle associated with a specific DSpace item. One could imagine other contexts (for Collections, etc), but since Items are the units of ingest, the range of the IngestContexts is restricted to them. An attribute is a simple name/value pair that belongs to the persistent state of the context. Generally, the life-cycle of an IngestContext begins whenever an API call asserting an attribute on a DSpace item occurs, and ends whenever the item is installed in the repository. The intent is that the context will live for the duration of the ingest, and then be discarded. This is very important to understand, that the IngestContext does not represent any kind of permanent 'extended item metadata' facility, although it can of course hold metadata for the item. Finally, an IngestResource (again, usually just resource), is an instance of any class that can be utilized to perform ingest functions (in UI, workflow, etc) that is not specific to an item. Examples of resources might be metadata templates, input forms, submission steps, curation task sets, etc. CGI places no restrictions on what could count as a resource.

In broad strokes then, CGI provides the following service APIS (and clients):

• IngestContext attribute management for items during ingest (ingest code)
• IngestResource mapping: attaching lookup keys to resources (repository or collection managers, typically)

Combining these 2 services allows application code to select appropriate resources based on context attributes: thus have context help guide ingest.