Apache HTTP Server Implementation Notes

Table of Contents

Allow Encoded Slashes

As specified in the Image API, slashes (“/”, “\”) in the identifer portion of the base uri MUST be encoded. This may cause problems with some HTTP servers. Apache servers from version 2.2.18 support the AllowEncodedSlashes NoDecode configuration directive which will correctly pass these characters to client applications without rejecting or decoding them.

AllowEncodedSlashes On

Servers using older versions of Apache and local identifiers which include these characters will need to use a workaround such as internally translating or escaping slash and backslash to safe value (perhaps by double URI-encoding them).

Enabling CORS

Both specifications prefer to have cross-origin resource sharing enabled. This may be enabled with the following configuration snippet:

LoadModule headers_module modules/mod_headers.so
Header set Access-Control-Allow-Origin "*"

The Image API states that a server may indicate its compliance level in a link header. This can be done as follows:

Header set Link '<http://iiif.io/api/image/2/level1.json>;rel="profile"'

Conditional Content Types

Both the Image and Presentation APIs state that clients may request JSON-LD, as opposed to plain JSON.

In the Image API, this may be enabled with the following configuration snippet (note that this assumes the compliance level Link header has been set as above):

<FilesMatch "\.json">
    SetEnvIf Accept "application/ld\+json" WANTS_jsonld
    Header set Content-Type "application/ld+json" env=WANTS_jsonld
    Header append Link '<http://iiif.io/api/image/2/context.json>;rel="http://www.w3.org/ns/json-ld#context";type="application/ld+json"' env=!WANTS_jsonld

The above configuration snippet may also be used for Presentation API implementations that have URIs ending in .json, but the line starting Header append Link should be deleted and it will not work for the recommended URI pattern. The following snippet will work for the recommended patterns:

<LocationMatch "^/prefix/(collection/.*|.*/manifest|.*/(sequence|canvas|annotation|list|range|layer)/.*)$">
    SetEnvIf Accept "application/ld\+json" WANTS_jsonld
    Header set Content-Type "application/json"
    Header set Content-Type "application/ld+json" env=WANTS_jsonld