static-ldp

A simple way to expose static assets as a read-only LDP server.

Requirements

• PHP 7.1+
• Composer
• The mbstring extension
• The pcre extension

Installation

To install static-ldp, follow these steps:

1. run composer create-project trellis-ldp/static-ldp
2. create a ./.env.local file like this:

TRELLIS_SOURCE_DIR='/path/to/resources'

Basics

By installing static-ldp and configuring the TRELLIS_SOURCE_DIR to point to the location of your static resources, you have a simple, read-only linked data server.

The web content will be served from the ./public directory.

LDP Resources

Individual files are served as ldp:NonRDFSource resources, and directories are served as ldp:BasicContainer resources. If a static file is a RDF file, then it is served as an ldp:RDFSource.

Describing LDP Non-RDF Resources

It is also possible to describe an ldp:NonRDFSource via the Link: <IRI>; rel="describedby" header. For example, if a JPEG file is named rosid_rosaceae.jpg, then by adding an RDF file with the name rosid_rosaceae.jpg.ttl (or any valid RDF format such as rosid_rosaceae.jpg.jsonld), then requests to rosid_rosaceae.jpg will include a link header pointing to the ldp:RDFSource. Similarly, the ldp:RDFSource will contain a link header (rel="describes") pointing to the ldp:NonRDFSource.

Support for instance digests

All resources support instance digests as defined in RFC 3230. What this means is that the response can include a Digest header so that it is possible to ensure end-to-end data integrity. Requests that include the header: Want-Digest: md5 or Want-Digest: sha1 will include responses that contain a digest corresponding to the on-disk resource.

Only md5 and sha1 algorithms are supported; other algorithms will be ignored. It should be noted that, for large files, Want-Digest requests may perform considerably slower, as the digest will need to be computed before a response is sent.

Configuration

There are many configuration options available. Only the sourceDirectory must be defined. Other options include:

template: default.twig

If you wish to override the HTML template with one of your own design, you can change this value to point to a different location. Alternately, you can edit the default.twig file in the templates directory. Though if you plan to customize the template, it is recommended that you use a separate file.

defaultRdfFormat: turtle

For requests without an Accept header, this is the RDF format used in responses (for ldp:RDFSource and ldp:BasicContainer resources).

contentDisposition: false

For ldp:NonRDFSource resources, this controls whether to include a Content-Disposition header in responses.

extraPropertiesFilename: properties

For each directory that becomes a ldp:BasicContainer resource, an RDF file within that directory with this name will have its contents added to the RDF presented as a response for that resource (instead of becoming a child resource in its own right). This provides a means by which to add user-controlled properties to ldp:BasicContainers.

validRdfFormats:
    turtle:
        mimeType: text/turtle
        extension: ttl
    jsonld:
        mimeType: application/ld+json
        extension: jsonld
    ntriples:
        mimeType: application/n-triples
        extension: nt

Generally speaking, the RDF formats should not be changed unless there is a need to support a serialization that is not included here. The RDF format (e.g. turtle, jsonld) must be an RDF serialization format supported by EasyRdf.

prefixes:
    dc: "http://purl.org/dc/terms/"
    rdf: "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    ...

The default HTML display template will present IRIs in short (prefixed) form if those prefixes are registered. By default a number of common prefixes are included, but any prefix may be registered here.