This is an node.js, Express-based REST API for discovering information about resources at the other end of URLs.
$ npm install
The server is configured by setting environment variables. These settings include:
PORT- The Port number to use for the server. Defaults to8888.REDIS_URL,REDISCLOUD_URL, orREDISTOGO_URL- The URL of the Redis server used for caching. Defaults to none.MEMCACHED_URL- The URL of the Memcached server used for caching. Defaults to none.CACHE_EXPIRE- The number of seconds to cache responses. Defaults to3600seconds (i.e., 1 hour).
$ node server.js
There are a number of things you can lookup based on a URL. The server provides the following end-points:
mime- find the content-type and actual URL (i.e., follow redirects) for a given URLmeta- likemime, but also extract Open Graph, Twitter Card, and other social metadata from the resourceimg- find the type (i.e., content-type), actual URL (i.e., follow redirects) and size (i.e., width, height) of an image for a given URL
The server expects a URL in the following form:
http://localhost:<PORT>/mime/<url>
The server takes the URL and attempts to do two things. First, it gets the actual URL in the case that a URL shortener has been used, or other redirects. Second, it requests the HTTP headers for this resource, and determins the content-type that is being used. Both pieces of information are returned as JSON.
Assuming a server running on http://localhost:8888, the following are valid API calls:
http://localhost:8888/mime/http://google.com
{
"href": "http://www.google.ca/",
"contentType": "text/html; charset=ISO-8859-1"
}
http://localhost:8888/mime/http://bit.ly/900913
{
"href": "http://www.google.ca/",
"contentType": "text/html; charset=ISO-8859-1"
}
http://localhost:8888/mime/http://i.imgur.com/syPS3rG.jpg
{
"href": "http://i.imgur.com/syPS3rG.jpg",
"contentType": "image/jpeg"
}
http://localhost:8888/mime/http://archive.org/download/PET1018_R-2_LA/PET1018_R-2_LA.mp4
{
"href": "http://ia700805.us.archive.org/2/items/PET1018_R-2_LA/PET1018_R-2_LA.mp4",
"contentType": "video/mp4"
}
The server expects a URL in the following form:
http://localhost:<PORT>/meta/<url>
The server attempts to download the document at <url>. If it is not HTML, an error will occur. If it is HTML, the document's Open Graph, Twitter Card, Dublin Core, and other metadata will be extracted and returned as JSON. In the case that there is no data that can be extracted, the following will be returned:
{
"href": "http://example.com/some-url.html",
"contentType": "text/html"
}Often a document at least has a title, and if it does, this will be added:
{
"href": "http://example.com/some-url.html",
"contentType": "text/html",
"title": "The Document's title"
}Then, depending on the presense of various namespaced metadata properites (i.e., og:*, twitter:*, dc.*, and dcterms.*), objects will be added for any known namespaces found, with all of the namespaced properites as children. If a namespace is not found, it will not appear in the result (i.e., you can do checks like if ( result.og )...). For example, if only og:* metadata is found, only the og object will be available:
{
"href": "http://example.com/some-url.html",
"contentType": "text/html",
"og": {
"og:title": "Open Graph title found for this page",
...
}
"title": "The Document's title"
}http://localhost:8888/meta/http://google.com
{
"href": "http://www.google.ca/",
"contentType": "text/html; charset=ISO-8859-1",
"meta": {
"title": "Google"
}
}
http://localhost:8888/meta/http://twitter.com
{
"href": "https://twitter.com/",
"contentType": "text/html; charset=utf-8",
"meta": {
"description": "Instantly connect to what's most important to you. Follow your friends, experts, favorite celebrities, and breaking news.",
"title": "Twitter"
}
}
http://localhost:8888/meta/http://ogp.me/
{
"href": "http://ogp.me/",
"contentType": "text/html",
"meta": {
"og": {
"og:title": "Open Graph protocol",
"og:type": "website",
"og:url": "http://ogp.me/",
"og:image": "http://ogp.me/logo.png",
"og:image:type": "image/png",
"og:image:width": "300",
"og:image:height": "300",
"og:description": "The Open Graph protocol enables any web page to become a rich object in a social graph."
},
"title": "The Open Graph protocol"
}
}
http://localhost:8888/meta/https://developer.mozilla.org/en-US/docs/HTML/WebVTT
{
"href": "https://developer.mozilla.org/en-US/docs/HTML/WebVTT",
"contentType": "text/html; charset=utf-8",
"meta": {
"og": {
"og:title": "WebVTT",
"og:type": "website",
"og:image": "https://developer.mozilla.org/media/img/mdn-logo-sm.png",
"og:site_name": "Mozilla Developer Network",
"og:url": "https://developer.mozilla.org/en-US/docs/HTML/WebVTT",
"og:description": "WebVTT is a format for displaying timed text tracks (e.g. subtitles) with the track element. The primary purpose of WebVTT files is to add subtitles to a video."
},
"twitter": {
"twitter:card": "summary",
"twitter:url": "https://developer.mozilla.org/en-US/docs/HTML/WebVTT",
"twitter:title": "WebVTT",
"twitter:image": "https://developer.cdn.mozilla.net/media/img/mdn-logo-sm.png",
"twitter:site": "@mozhacks",
"twitter:creator": "@mozhacks",
"twitter:description": "WebVTT is a format for displaying timed text tracks (e.g. subtitles) with the track element. The primary purpose of WebVTT files is to add subtitles to a video."
},
"title": "WebVTT - HTML | MDN"
}
}
http://localhost:8888/meta/http://www.tutorialsonline.info/Common/DublinCore.html
{
"href": "http://www.tutorialsonline.info/Common/DublinCore.html",
"contentType": "text/html",
"meta": {
"dc": {
"dc.format": "text/html",
"dc.creator": "Alan Kelsey",
"dc.publisher": "Alan Kelsey, Ltd.",
"dc.publisher.address": "[email protected]",
"dc.contributor": "Alan Kelsey",
"dc.date": "2005-01-06",
"dc.type": "Text.Homepage.Organizational",
"dc.relation": "TutorialOnline.info",
"dc.coverage": "Hennepin Technical College",
"dc.rights": "Copyright 2012, Alan Kelsey, Ltd. All rights reserved.",
"dc.date.x-metadatalastmodified": "2013-01-12",
"dc.language": "EN",
"dc.title": "Dublin Core Tutorial",
"dc.identifier": "http://tutorialsonline.info/Common/DublinCore.html",
"dc.subject": "Dublin Core Meta Tags"
},
"title": "Dublin Core Tutorial"
}
}
http://localhost:8888/meta/https://developer.cdn.mozilla.net/media/img/mdn-logo-sm.png
{
"error": "Unable to read Social Graph or metadata for URL."
}
The server expects a URL in the following form:
http://localhost:<PORT>/img/<url>
The server attempts to download the image at <url>--no images are saved on the server. If it is not an image, an error will occur. If it is an image, the image's width and height will be determined and returned as JSON.
http://localhost:8888/img/http://url.shortener.com/abcd3
{
"href": "http://example.com/some-image.png",
"contentType": "image/png",
"size": {
"width": 800,
"height": 400
}
}If the caller provides a callback=<callbackFn> query string parameter, the result will be JSONP instead of pure JSON:
http://localhost:8888/mime/http://google.com?callback=foo
foo && foo({
"href": "http://www.google.ca/",
"contentType": "text/html; charset=ISO-8859-1"
});
Note: if the URL being passed to the API end-points also includes ?callback=..., remember to encode the URL such that ? becomes %3F and is not interpreted as part of the API call. Consider:
// URL with ?callback param used as part of API call (JSONP)
http://localhost:8888/mime/http://foo.com?callback=bar
// URL containing ?callback param (not part of API call)
http://localhost:8888/mime/http%3A%2F%2Ffoo.com%3Fcallback%3Dfn
// URL containing ?callback param with API using JSONP callback param bar
http://localhost:8888/mime/http%3A%2F%2Ffoo.com%3Fcallback%3Dfn?callback=bar
A number of situations can cause errors. In all such cases, the API end-points will return a 500 result code, and JSON of the following form:
{
"error": "Error message..."
}
Current errors include:
Expected url param, found none.-- no url was specified to the API call.Unable to determine content type.-- the url was unusable, or the resource's content type could not be determined for some reason.Unable to read Social Graph or metadata for URL.-- the resource at the given url could not be read or parsed for some reason.
If no error message is given, an unknown error occurred.
You can run the tests locally by doing the following from the project's root directory:
$ npm test
The tests depend on a network connection being available (some real URLs are used).
In order to test the server's cache support, you have to run the tests with some extra environment variables. First, install and start redis-server and/or memcached locally, then run the tests like so:
$ EXPECT_CACHED=1 REDIS_URL=127.0.0.1 npm test
...
$ EXPECT_CACHED=1 MEMCACHED_URL=127.0.0.1 npm test
To enable New Relic, set the NEW_RELIC_ENABLED environment variable and add a config file, or set the relevant environment variables.
For more information on configuring New Relic, see: https://github.com/newrelic/node-newrelic/#configuring-the-agent
Copyright 2013 David Humphrey [email protected]
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.