STAM Daemon

This is a webservice for working with stand-off annotation of text. It uses the STAM model, but can also serve W3C Web Annotations using a limited subset of the Web Annotation Protocol, if the underlying model supports it.

Description & Features

A RESTful API is offered with several end-points. The full OpenAPI specification can be consulted interactively at the /swagger-ui/ endpoint once stamd is running.

stamd is a memory-backed service: models or annotation stores (i.e. annotations and the full underlying texts), will be loaded into memory when first needed, and automatically unloaded again when they haven't been used for a while. This allows for very fast response times once a model is loaded, at the cost of limited scalability with regard to the annotation store size and number of models serves simultaneously.

Annotation stores can be queried via STAMQL, a powerful query language designed specifically for stand-off text annotation. Queries are used not just to read information from the annotation stores, but also to add/edit/delete information. The latter behaviour can be disallowed via the --read-only parameter.

Web API

Endpoints in this webservice return up to four different output formats, the format is requested via regular HTTP content negotation:

• STAM JSON - application/json - This is STAM's canonical data format. It is returned by most of the endpoints.
• plain text - text/plain - Whenever output can be reduced to a plain text representation, this content type can be requested. It is also the default representation for the /*/resources/ endpoints.
• HTML - text/html - This is only supported by the /query/ and provides a complete HTML visualisation. In the query you can specify exactly what annotations to highlight. Read further details here.
• W3C Web Annotations (JSON-LD) - application/ld+json - This representation is allow on queries for annotations (/query/) and on the /*/annotations/ endpoints. It returns the W3C Web Annotation representation in JSON-LD. The underlying STAM model must respect certain extra constraints, as formulated in the STAM specification, in order for this conversion to work.

The following endpoints are available, consult the /swagger-ui/ endpoint for a more formal and complete specification.

• GET / - Returns either a simple JSON list of all available annotation stores in this server, or a crude HTML form that allows you to interactively query any of the available stores.
• GET /{store_id}/?query= - Runs a STAMQL query on an annotation store. This is the go-to endpoint that provides 90% of all functionality.
• POST /query - Same as above but takes all paramters as form-encoded data via a POST request
• POST /{store_id} - Create a new annotation store
• GET /{store_id}/annotations - Returns the public identifiers of all available annotations in the store.
• GET /{store_id}/annotations/{annotation_id} - Returns an annotation given its identifier.
• GET /{store_id}/resources - Returns the public identifiers of all available resources in the store.
• GET /{store_id}/resources/{resource_id} - Returns a resource given its identifier.
• POST /{store_id}/resources/{resource_id} - Create a new resource in a given store.
• GET /{store_id}/resources/{resource_id}/{begin}/{end} - Returns a text selection inside a resource. Offset are 0-indexed, unicode points, end is non inclusive.
• GET /swagger-ui - Serves an interactive webinterface explaining the RESTful API specification.
• GET /api-doc/openapi.json - Machine parseable OpenAPI specification.

Installation

From source

$ cargo install stamd

Usage

Run stamd to start the webservice, see stamd --help for various parameters.

Security

This webservice is NOT meant to be directly opened up to the internet, as it does not provide any authentication mechanism and can be easily abused as a file hosting service. It is intended as a backend service for dedicated frontends to communicate with. Make sure it is behind a firewall or on a private network segment. If you do expose it to the internet, make sure to launch stamd with the --readonly parameter.