openDCIM has a RESTful API interface which can be accessed by other applications.
Development of the API is happening in stages, and as such this specification is subject to change. If you are unfamiliar with what a RESTful API is, a good place to start is the Wikipedia Entry.
Data Format
openDCIM data will always be returned in JSON format, with no pagination. This is open source, so if you need your output in another format, such as XML, you can modify the appropriate function in the application.
Authentication
RESTful APIs by definition are stateless, but do still need some form of authentication. It is suggested that you create a separate account for the API to use, rather than piggy-backing off of an existing user account.
At a minimum, the account created for the API must have Global Read Access. Working with the inner guts of openDCIM will certainly increase the risk of data corruption, so it's not something that should be opened up lightly.