Hypermedia and forms | Glenn Block. Updated (with a lot of new content) One challenge when building REST based systems is how can the client determine what it can do next? There can be any number of clients each which need to interact with a system. How do they know HOW to interact? The WSDL approach is to offer a static snapshot of method calls on an API. That approach couples the client heavily to knowing everything about the server, including being coupled as to how things get processed. It inhibits evolvability. A change to the server usually results in breaking all clients. Hypermedia (also referred to as Hypertext) is an answer. ) were envisioning the Web, linking was a key component of that design. With a hypermedia approach your server doesn’t only return data. Above the server returned a link for adding an item.
What about evolvability? Older clients won’t know about the wish list. An additional benefit of the link approach has to do with the urls themselves. So now we have links. Now imagine there is no human. Which bit?: Giving an Enterprise Application a REST. I work in a product development group with a software product in use at over 600 companies, which they depend on for their mission critical record keeping. One day, not so long ago, we woke up and the world had changed.
No, this was not the financial crisis. It was far more significant for our development team. We discovered that our users’ perception of what was a good application had changed. The ones they liked could browse, mash-up, poke, and prod any number of resources. But our Enterprise Application couldn’t. We were practically selling legacy software. As we found out, to satisfy a modern Enterprise Application user it is no longer sufficient to transact with a single application based on queries from a single data source.
Figure 1 Enterprise Application mash-ups and callouts After some deep thought, we decided on a change to our architecture that seemed to satisfy all our requirements. Figure 2 Original Architecture Figure 3 An early evolution of our architecture Resources. S blog: Linking in JSON. Friday, 25 November 2011 To be a full-fledged format on the Web, you need to support links -- something sorely missing in JSON, which many have noticed lately. In fact, too many; everybody seems to be piling on with their own take on how a link should look in JSON. Rather than adding to the pile (just yet), I thought I'd look around a bit first.
What am I looking for? 5988 isn't perfect by any stretch (primarily because it was an after-the-fact compromise), but it does sketch out a path for typed links to become a first-class, format-independent part of the Web -- as they well should be, since URIs are the most important leg holding up the Web. My immediate use case is being able to generically pull links out of JSON documents so that I can "walk" an HTTP API, as alluded to previously. I'm also going in with a bit of caution, because we have at least one proof that getting a generic linking convention to catch on is hard; see XLink. Now, to the contenders. JSON-LD: JSON for Linking Data. Lib/backbone.hal.coffee at master · mikekelly/backbone.hal. HAL enhanced OAuth 2.0 response – Making OAuth 2.0 slightly more RESTful : =nat. Many people claim that OAuth 2.0 is JSON and REST. Well, yes, it is RESTish, but not quite REST.
It notably misses the hyperlink capability. With this response alone, you do not know where it came from, and where it can be used in the next step. This actually stems from one of the weakness of JSON itself. There are several attempts to mitigate it. This is a very simple spec to convert the conventional JSON document to Hyper-Linked REST response.
To denote hyperlinks, it proposes to insert a top level JSON object called “_links”. e.g., Inserting it in the OAuth response, it will become: Since it was an OpenID Connect token endpoint response, the resource that the client was going to access with the access_token was primarily UserInfo endpoint, so I have denoted it like above, but if the protected resource in question was like photo service, then it could have been like: Now, in the above examples, I was using URI template (RFC6570). Changes. Rest - HATEOAS: concise description. Hateoas « This week in REST. Wilde-profile-link-02 - The \x27profile\x27 Link Relation Type. [Docs] [txt|pdf|xml|html] [Tracker] [Email] [Diff1] [Diff2] [Nits] Versions: 00 01 02 03 04 RFC 6906 Network Working Group E.
Wilde Internet-Draft EMC Corporation Intended status: Standards Track June 7, 2012 Expires: December 9, 2012 Abstract This specification defines the 'profile' link relation type that allows resource representations to indicate that they are following one or more profiles. A profile is defined to not alter the semantics of the resource representation itself, but to allow clients to learn about additional semantics (constraints, conventions, extensions) that are associated with the resource representation, in addition to those defined by the media type and possibly other mechanisms.
Editorial Note (to be removed by RFC Editor) Please discuss this draft on the apps-discuss@ietf.org mailing list. Internet-Draft "profile" Link Type June 2012 ( in effect on the date of publication of this document. 1. 2. 3. 3.1. 3.2. 4. 5. 5.2. Kelly-json-hal-03 - JSON Hypermedia API Language. [Docs] [txt|pdf|xml|html] [Tracker] [Email] [Diff1] [Diff2] [Nits] Versions: 00 01 02 03 05 06 Network Working Group M. Kelly Internet-Draft Stateless Intended status: Informational July 1, 2012 Expires: January 2, 2013 Abstract This document proposes a media type for representing resources and their relations as hypermedia.
Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Internet-Draft JSON Hypermedia API Language July 2012 Table of Contents 1. Internet-Draft JSON Hypermedia API Language July 2012 1. There is an emergence of non-HTML HTTP applications ("Web APIs") which use hypermedia to direct clients around their resources. 2. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 3. 4. 4.1. 5. 6. Www.iana.org/assignments/media-types/application/vnd.hal+json. WRML. Three Ways to Think About API Design. Is MIME a problem for REST? As REST (and REST-over-HTTP) adoption grows for more than just running your favourite Web server, we are seeing more and more people bring their real-world experiences to a wider community.
In this case Benjamin Carlyle asks whether MIME types are holding back REST? A significant weakness of HTTP in my view is its dependence on the MIME standard for media type identification and on the related iana registry. This registry is a limited bottleneck that does not have the capacity to deal with the media type definition requirements of individual enterprises or domains. Machine-centric environments rely in a higher level of semantics than the human-centric environment of the Web.
The problem as Benjamin points out, is that getting universal adoption of various MIME types is extremely difficult and doesn't scale. The ability to experimentally define and evolve these standards outside the Web is essential to a healthy adoption of the REST style and related styles beyond the Web. API v3. This describes the resources that make up the official GitHub API v3. If you have any problems or requests please contact support. Current Version There are two versions of the GitHub API: beta and v3.
By default, all requests receive the beta version: Accept: application/vnd.github.beta+json Soon, v3 will become the default version. We encourage you to request a specific version via the Accept header. Schema All API access is over HTTPS, and accessed from the api.github.com domain (or through yourdomain.com/api/v3/ for enterprise) . $ curl -i HTTP/1.1 200 OK Server: nginx Date: Fri, 12 Oct 2012 23:33:14 GMT Content-Type: application/json; charset=utf-8 Connection: keep-alive Status: 200 OK ETag: "a00049ba79152d03380c34652f2cb612" X-GitHub-Media-Type: github.beta X-RateLimit-Limit: 5000 X-RateLimit-Remaining: 4987 X-RateLimit-Reset: 1350085394 Content-Length: 5 Cache-Control: max-age=0, private, must-revalidate X-Content-Type-Options: nosniff []
API v3. This describes the resources that make up the official GitHub API v3. If you have any problems or requests please contact support. Current Version There are two versions of the GitHub API: beta and v3. By default, all requests receive the beta version: Accept: application/vnd.github.beta+json Soon, v3 will become the default version. We encourage you to request a specific version via the Accept header. Schema All API access is over HTTPS, and accessed from the api.github.com domain (or through yourdomain.com/api/v3/ for enterprise)
. $ curl -i HTTP/1.1 200 OK Server: nginx Date: Fri, 12 Oct 2012 23:33:14 GMT Content-Type: application/json; charset=utf-8 Connection: keep-alive Status: 200 OK ETag: "a00049ba79152d03380c34652f2cb612" X-GitHub-Media-Type: github.beta X-RateLimit-Limit: 5000 X-RateLimit-Remaining: 4987 X-RateLimit-Reset: 1350085394 Content-Length: 5 Cache-Control: max-age=0, private, must-revalidate X-Content-Type-Options: nosniff [] REST is OVER! Yep. Sorry to have to inform you. REST is totally over. The cool kids are moving on. We're building "Hypermedia APIs" now. Such is life. A lesson from the anti-globalization movement Way back in the day, COINTELPRO was at the forefront of America's fight against "subersive" organizations and individuals. In 2008, for the Republican National Convention in St. At an anti-RNC conference held over the weekend of February 9th and 10th, a broad spectrum of groups revealed what are being called the “St.
Please draw your attention to the third principle. 'Solidarity' kinda goes out the window when you're busy arguing about each other's drama.Every second you have in the media is precious. So, keeping that all in mind, why are we arguing about what REST means all the time? The real problem is that REST is just bad branding. Uses HTTP correctly.Serves hypermedia responses. HTTP does most of the heavy lifting in terms of bringing us into REST compliance. We just really shouldn't fight. REST API Design: Put the “Type” in “Content-Type” This guest post comes from Mark Massé, Senior Director of Engineering at ESPN. Mark has fourteen years of engineering, management, and architecture experience with The Walt Disney Company and received a “Disney Inventor Award” in 2008. Greetings Programs!
Well-designed REST APIs can be leveraged to create balanced client-server web applications; where the client’s responsibilities extend far beyond simply rendering a server-generated HTML document. Web sites and applications have been slowly shifting to this architecture since Internet Explorer 5’s inclusion of the core AJAX mechanics, DOM scripting and XHR. More recently, the architectural shift has been accelerated by significant advances in standards (e.g. This architecture is attractive to organizations for a number of reasons, such as: In order to support the increasing complexity of web applications being built with this architecture, the design and development practices applied to REST APIs must continue to mature. Sergey Shishkin. RFC 5988 - Web Linking. [Docs] [txt|pdf] [draft-nottingham-...] [Diff1] [Diff2] [Errata] PROPOSED STANDARD Errata Exist Internet Engineering Task Force (IETF) M. Nottingham Request for Comments: 5988 October 2010 Updates: 4287 Category: Standards Track ISSN: 2070-1721 Abstract This document specifies relation types for Web links, and defines a registry for them.
It also defines the use of such links in HTTP headers with the Link header field. Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). RFC 5988 Web Linking October 2010 This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. RFC 5988 Web Linking October 2010 1. 2. RFC 5988 Web Linking October 2010 3.
RFC 5988 Web Linking October 2010 4. In the simplest case, a link relation type identifies the semantics of a link. 4.1. 4.2. 5. 5.1. 5.2. 5.3. JSON descriptors. JSON templates. Examples of RESTful API calls for E-commerce platforms. These examples are type 3 RESTful API requests and responses. The JSON-HAL specification is used to implement HATEOAS. Some of the examples are based on my work as architect of the RESTful API at All proprietary information has been removed.
Relevant links Examples Add Item to Cart A POST request to /member/109087/cart will create a cart resource for the member (if one did not exist) and add the inventory item to the cart. Get Cart Contents A GET request to /member/109087/cart will respond with the cart resource and list the contents of the cart items as embedded resources.
Calculate Payment A GET request to /payment will calculate the total amount owed by the member based on the contents in the members cart. The choice of shipping and billing addresses to be used during payment are sent back as well. Place Order A POST request to /orders will create an order resource based on the contents of the members cart. Hypermedia-Oriented Design. Hypermedia-Oriented Design An Approach for Supporting Evolvable Distributed Network Applications A Review of Common Application Designs Distributed network application implementations rely on a small number of well-known design approaches. This section focuses on three broad categories of design: RPC-Oriented DesignObject-Oriented DesignURI-Oriented Design While each of these patterns has advantages, they all focus on sharing understanding between client and server by requiring both parties to use an implementation model based on a predefined list of procedure calls, object graphs, or URI-construction rules.
In RPC-Oriented designs, clients and servers share a list of procedure signatures including the parameters and their data types. In RPC-Oriented models, the client is "bound" to the procedure list. Object-Oriented designs focus on making sure clients and servers share the same object model (objects, properties, hierarchies, etc.). Evolving Common Implementations The Hypermedia Alternative. Etgryphon/stativus. Stop Using Backbone As If It Were A Stateless Web Server. In the web development world with MVC based back-end servers, nearly everything is kicked off with routes. Look at rails for example. If you want a list of items, you hit /items and the router executes the index method on ItemsController.
Add a new item, view an item, edit an item and post the updates back to the server – even deleting an item works with a route. Unfortunately I see the same patterns emerging in a lot of sample code for javascript MVC frameworks, like Backbone. Stop doing that. Why It Works For The Server A web application is a stateless system. Because of the stateless nature of web servers, it makes sense for every action you want to do to have a route associated with it. State. A Backbone app is closer to a desktop client application than a web application in a few respects. Because of the stateful nature of a Backbone application, there are times when it doesn’t make sense to use a route, though it technically works. Problem: Routing A Delete Yes, this is functional. Best practice regarding StateManager in Ember.js. Ember.js API Docs. The Software Simpleton: Ember.js - Model, View, StateMachine?
SproutCore: Statecharts vs Controllers « Frozen Canuck. FrozenCanuck/Ki.