Document Search: Uploading documents via frontend

[fmatthies]

We talked about giving users (admins) the option to upload documents via the frontend and thereby creating a new data source. This would mean that there needn't necessarily be a pre-populated search index (e.g. Elasticsearch). Questions that arise are the following:

1. can documents be uploaded to an existent data source or does this entail the creation of a new one
2. who can upload documents and therefore create indices
3. should there be a default server or should a user specify this
4. an adapter configuration file needs to be created automatically