REST. And now for something completely different. Mike amundsen.com

Transcription

1 REST And now for something completely different Mike amundsen.com

2 Preliminaries Mike Amundsen Developer, Architect, Presenter Hypermedia Junkie I program the Internet Designing Hypermedia APIs with Node and HTML5 O Reilly, Fall 2011

3 And now for something a completely different

4 Excuse me... did you say knives'? City Gent #1 (Michael Palin) The Architects Sketch

5 Consider how often we see software projects begin with adoption of the latest fad in architectural design, and only later discover whether or not the system requirements call for such an architecture Roy T. Fielding, 2000

6 Consider how often we see software projects begin with adoption of the latest fad in architectural design, and only later discover whether or not the system requirements call for such an architecture Roy T. Fielding, 2000

7 Consider how often we see software projects begin with adoption of the latest fad in architectural design, and only later discover whether or not the system requirements call for such an architecture Roy T. Fielding, 2000

8 Representational State Transfer

9 Representational State Transfer

10 These are.?

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14 REST is a style

15 REST is a style of software architecture.

16 In contrast to

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20 HTTP is a Standard

21 HTTP is a Standard Transfer Protocol

22 !=

23 REST!= HTTP

24 Well then, what IS REST?

25 Roy T. Fielding, 2000

26 REST is a coordinated set of architectural constraints that attempts to minimize latency and network communication while at the same time maximizing the independence and scalability of component implementations. Roy T. Fielding, 2000

27 REST is a coordinated set of architectural constraints that attempts to minimize latency and network communication while at the same time maximizing the independence and scalability of component implementations. Roy T. Fielding, 2000

28 REST is a coordinated set of architectural constraints that attempts to minimize latency and network communication while at the same time maximizing the independence and scalability of component implementations. Roy T. Fielding, 2000

29 REST is a coordinated set of architectural constraints that attempts to minimize latency and network communication while at the same time maximizing the independence and scalability of component implementations. Roy T. Fielding, 2000

30 REST attempts to minimize latency while maximizing scalability Roy T. Fielding, 2000

31 Srsly?

32 But some people say

33 REST IS Crafting URIs Identifying Resources Designing Responses (JSON, XML, etc.) HTTP Verbs (GET, PUT, POST, DELETE) Headers (Caching, etc.) HTTP Response Codes (200, 404, 418, etc.)

34 REST IS Crafting URIs Identifying Resources Designing Responses (JSON, XML, etc.) HTTP Verbs (GET, PUT, POST, DELETE) Headers (Caching, etc.) HTTP Response Codes (200, 404, 418, etc.)

35 Actually

36 REST IS NOT Crafting URIs Identifying Resources Designing Responses (JSON, XML, etc.) HTTP Verbs (GET, PUT, POST, DELETE) Headers (Caching, etc.) HTTP Response Codes (200, 404, 418, etc.)

37 REST IS NOT Crafting URIs Identifying Resources Designing Responses (JSON, XML, etc.) HTTP Verbs (GET, PUT, POST, DELETE) Headers (Caching, etc.) HTTP Response Codes (200, 404, 418, etc.)

38 REST IS NOT Crafting URIs Identifying Resources Designing Responses (JSON, XML, etc.) HTTP Verbs (GET, PUT, POST, DELETE) Headers (Caching, etc.) HTTP Response Codes (200, 404, 418, etc.)

39 REST IS NOT Crafting URIs Identifying Resources Designing Responses (JSON, XML, etc.) HTTP Verbs (GET, PUT, POST, DELETE) Headers (Caching, etc.) HTTP Response Codes (200, 404, 418, etc.)

40 But really, what is REST?

41 A set of constraints.

42 Another example

43 Charles Eames

44 "I have never been forced to accept compromises but I have willingly accepted constraints." Charles Eames, Eames Design, 1989

45 "I have never been forced to accept compromises but I have willingly accepted constraints." Charles Eames, Eames Design, 1989

46 "I have never been forced to accept compromises but I have willingly accepted constraints." Charles Eames, Eames Design, 1989

47 Why constraints?

48 Is there anything more intimidating?

49 OK, what are REST s constraints?

50 There are six REST constraints

51 Client-Server Not Peer-to-Peer

52 Stateless No Server-Side Session

53 Cache Don t hit server every time

54 Uniform Interface Same API for everyone

55 Layered System Add hardware any time

56 Code On Demand * Don t hard-code clients, send code to them.

57 REST s Constraints 1. Client-Server 2. Stateless 3. Cache 4. Uniform Interface 5. Layered System 6. Code on Demand

58 Wait, that s it?

59 Well

60 "[REST] is achieved by placing constraints on connector semantics where other styles have focused on component semantics." Roy T. Fielding, 2000

61 "[REST] is achieved by placing constraints on connector semantics where other styles have focused on component semantics." Roy T. Fielding, 2000

62 "[REST] is achieved by placing constraints on connector semantics where other styles have focused on component semantics." Roy T. Fielding, 2000

63 Connector!= Component

64 Component Database File System Message Queue Transaction Manager Source Code

65 Component == Private

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67 Connector Web Server Browser Agent Proxy Server Shared Cache

68 Connector == Public

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70 Client Connectors Server The Web Components

71 And the best way to ensure Connectors work together is

72 Uniform Interface 1. Identification of Resources 2. Resource Representations 3. Self-Descriptive Messages 4. Hypermedia

73 Uniform Interface 1. Identification of Resources (URIs) 2. Resource Representations 3. Self-Descriptive Messages 4. Hypermedia

74 Uniform Interface 1. Identification of Resources (URIs) 2. Resource Representations (Media-Types) 3. Self-Descriptive Messages 4. Hypermedia

75 Uniform Interface 1. Identification of Resources (URIs) 2. Resource Representations (Media-Types) 3. Self-Descriptive Messages (Header+Body) 4. Hypermedia

76 Uniform Interface 1. Identification of Resources (URIs) 2. Resource Representations (Media-Types) 3. Self-Descriptive Messages (Header+Body) 4. Hypermedia (Links & Forms)

77 URIs A Uniform Resource Identifier (URI) is a compact string of characters for identifying an abstract or physical resource. RFC2396 URI Generic Syntax

78 URIs A Uniform Resource Identifier (URI) is a compact string of characters for identifying an abstract or physical resource. RFC2396 URI Generic Syntax

79 MIME Media Types Specify the nature of the data in the body of a MIME entity and auxiliary information that may be required for certain media types. RFC2046 MIME Media Types

80 MIME Media Types Specify the nature of the data in the body of a MIME entity and auxiliary information that may be required for certain media types. RFC2046 MIME Media Types

81 Header + Body Message[s] consist of a start-line, zero or more header fields (also known as "headers"), an empty line (i.e., a line with nothing preceding the CRLF) indicating the end of the header fields, and possibly a messagebody. RFC2616 Hypertext Transfer Protocol HTTP/1.1

82 Header + Body Message[s] consist of a start-line, zero or more header fields (also known as "headers"), an empty line (i.e., a line with nothing preceding the CRLF) indicating the end of the header fields, and possibly a messagebody. RFC2616 Hypertext Transfer Protocol HTTP/1.1

83 Links & Forms Hypermedia is defined by the presence of application control information embedded within, or as a layer above, the presentation of information. Roy. T. Fielding, 2000

84 Links & Forms Hypermedia is defined by the presence of application control information embedded within, or as a layer above, the presentation of information. Roy. T. Fielding, 2000

85 Seems kinda complicated

86 REST in one slide Read the dissertation, really!

87 Component Connector Connector Component Client Connectors Server The Web Components

88 Those of us who have been trained as architects have this desire perhaps at the very center of our lives: that one day, somewhere, somehow, we shall build one building which is wonderful, beautiful, breathtaking, a place where people can walk and dream for centuries. Christopher Alexander, The Timeless Way of Building

89 Those of us who have been trained as architects have this desire perhaps at the very center of our lives: that one day, somewhere, somehow, we shall build one building which is wonderful, beautiful, breathtaking, a place where people can walk and dream for centuries. Christopher Alexander, The Timeless Way of Building

90 Those of us who have been trained as architects have this desire perhaps at the very center of our lives: that one day, somewhere, somehow, we shall build one building which is wonderful, beautiful, breathtaking, a place where people can walk and dream for centuries. Christopher Alexander, The Timeless Way of Building

91 Those of us who have been trained as architects have this desire perhaps at the very center of our lives: that one day, somewhere, somehow, we shall build one building which is wonderful, beautiful, breathtaking, a place where people can walk and dream for centuries. Christopher Alexander, The Timeless Way of Building

92 So

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102 Excuse me... did you say knives'? City Gent #1 (Michael Palin) The Architects Sketch

103 REST Mike amundsen.com