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Building Your API 
for Longevity 
by mike stowe 
l All contents Copyright © 2014, MuleSoft Inc.
Disclaimer 
This talk is not about how to code your 
API, but rather to show you what steps and 
best practices you need t...
About Me 
• API Fanatic 
• Open Source Contributor 
• Author, Speaker, Consultant 
• 10+ years hacking Professional Code 
...
APIs are changing the 
world. 
l All contents Copyright © 2014, MuleSoft Inc.
Over 13,000 PUBLIC APIs 
l All contents Copyright © 2014, MuleSoft Inc.
l All contents Copyright © 2014, MuleSoft Inc.
Today APIs are connecting… 
l All contents Copyright © 2014, MuleSoft Inc.
PHONES 
l All contents Copyright © 2014, MuleSoft Inc.
WATCHES 
l All contents Copyright © 2014, MuleSoft Inc.
GLASSES 
l All contents Copyright © 2014, MuleSoft Inc.
CARS 
l All contents Copyright © 2014, MuleSoft Inc.
REFRIGERATORS 
l All contents Copyright © 2014, MuleSoft Inc.
THERMOSTATS 
l All contents Copyright © 2014, MuleSoft Inc.
l All contents Copyright © 2014, MuleSoft Inc. 
IN HOME 
ROBOTS
AND MORE 
l All contents Copyright © 2014, MuleSoft Inc.
THINK ABOUT THAT… 
l All contents Copyright © 2014, MuleSoft Inc.
In order to work, the IoT 
requires that APIs remain 
persistent. 
l All contents Copyright © 2014, MuleSoft Inc.
l All contents Copyright © 2014, MuleSoft Inc. 
+
Versioning and making 
changes is expensive… 
l All contents Copyright © 2014, MuleSoft Inc.
FOR EVERYONE. 
l All contents Copyright © 2014, MuleSoft Inc.
Thankfully with 5 Simple 
Steps you can build an API 
that is designed to last. 
l All contents Copyright © 2014, MuleSoft...
They are: 
1 – Go in with a long-term mindset 
2 – Understand what you’re building 
3 – Utilize Spec Driven Development 
4...
Think Long-term: 
• Your API is a Contract 
• Versioning is not a solution 
• Understand you suck at design 
• You can pay...
Your Users are Depending on You… 
Your API is a contract, it’s your word to 
your users. Users who are not only 
depending...
This means you need to think through every 
aspect of your API before building it. 
l All contents Copyright © 2014, MuleS...
Thinking things through… 
• Who is your API for? 
• What type of API are you building? 
• How are you going to maintain yo...
Who Will Be Using Your API? 
• Who are your end users? 
- Current customers 
- Business partners 
- Third-party services 
...
What is the Purpose of Your API? 
• List out WHY you are making the API 
- Saying that you’re exposing your data to users ...
List Out What Your Users Need to be able to Do: 
l All contents Copyright 29 © 2014, MuleSoft Inc.
What Type of API Are You Building? 
• Are you building a REST, partial REST, SOAP, or RPC 
based API? 
• Why are you build...
What Type of API Are You Building? 
l All contents Copyright 31 © 2014, MuleSoft Inc.
Do You Understand the REST Constraints? 
• Client-Server 
• Stateless 
• Cacheable 
• Interface/ Uniform Contract 
• Layer...
Most APIs are NOT RESTful. 
l All contents Copyright © 2014, MuleSoft Inc.
This is why it’s so important to understand 
the different types of APIs, why each type is 
different, and why you are cho...
It also means building your API for beyond 
today… 
l All contents Copyright © 2014, MuleSoft Inc.
...people are fairly good at short-term 
design, and usually awful at long-term 
design.” 
“ 
l All contents Copyright 36 ...
Versioning is a necessary evil. 
l All contents Copyright © 2014, MuleSoft Inc.
Problems with Versioning 
• Backwards incompatibilities 
• Multiple Services to Maintain 
• Multiple Systems to Support 
•...
You Need to Version When: 
• Backwards incompatible platform changes 
• Your API is no longer extendable 
• Your spec is o...
But You Shouldn’t Version Just Because You: 
• Added new endpoints 
• Added additional data in response 
• Changed technol...
Versioning does not excuse poor design. 
l All contents Copyright © 2014, MuleSoft Inc.
And a poorly designed API will cost you far 
more in the long run, adding months to fix what 
could have been prevented in...
Use Spec Driven Development 
• Define your API before Coding 
• Use Design Patterns/ Code Reuse 
• Mock and get User Feedb...
Spec Driven Development means a hybrid 
between agile and waterfall methodologies. 
You should develop your spec iterative...
Disclaimer: Waterfall refers to the spec and 
changing the spec only! You should still use 
sprints for code development –...
Hybrid Approach 
Design Development 
Continuous, fluid, changeable Static… No turns 
l All contents Copyright 46 © 2014, M...
The Agile Design Cycle 
l All contents Copyright 47 © 2014, MuleSoft Inc.
The goal is that by utilizing agile user 
testing, carefully designing, and 
prototyping your API in an iterative state, 
...
The problem is up until now, designing and 
prototyping an API has been extremely 
costly. Requiring developers to create ...
However, there are several new specs being 
driven by today’s industry leaders making it 
easier define your API: with too...
Some of Today’s Specs: 
• RAML 
• IO Docs 
• Swagger 
• API Blueprint 
l All contents Copyright 51 © 2014, MuleSoft Inc.
Using RAML You Can: 
• You can define your API in just a few lines of code 
• You can see what it would look like as you g...
More Importantly… 
• You can use design patterns 
• You can reuse code (traits, resourceTypes) 
resourceTypes: 
-­‐ 
colle...
The RAML API Designer 
l All contents Copyright 54 © 2014, MuleSoft Inc.
What Does RAML Look Like? 
#%RAML 
0.8 
title: 
World 
Music 
API 
baseUri: 
http://example.api.com/{version} 
version: 
v...
Remember, your spec is not a one-and-done, 
rather it is the blueprint for your API. 
Anytime you do something to your API...
Incorporate Best Practices: 
• Use Nouns 
• Use CRUD 
• Use Hypermedia (HATEOAS) 
• Use Accept/ Content-Type 
• Return Hea...
Use Nouns. 
l All contents Copyright © 2014, MuleSoft Inc.
Use: 
/users 
Not: 
/createUser 
/getUser 
/deleteUser 
l All contents Copyright © 2014, MuleSoft Inc.
Utilize CRUD. 
l All contents Copyright © 2014, MuleSoft Inc.
Create (POST) 
Read (GET) 
Update (PUT/ 
l All contents Copyright © 2014, MuleSoft Inc. 
PATCH) 
Delete (DELETE)
Use Hypermedia. 
l All contents Copyright © 2014, MuleSoft Inc. 
HATEOAS
Most Popular Hypertext Link Specs 
• HAL 
• JSON-LD 
• JSON API 
• Siren 
l All contents Copyright 63 © 2014, MuleSoft Inc...
{ 
"data" 
: 
{ 
"user": 
{ 
"fname":"first", 
"lname":"last" 
} 
}, 
"_links" 
: 
{ 
"edit": 
{ 
"href" 
: 
"/api/user/id...
Use Accept/ Content-Type 
Headers. 
l All contents Copyright © 2014, MuleSoft Inc.
Use Accept/ Content-Type Headers 
Using headers gives you flexibility to support multiple 
types of formats from the same ...
Use Response Codes. 
l All contents Copyright © 2014, MuleSoft Inc.
• 200 – OK 
• 201 – Created 
• 304 – Not modified 
• 400 – Bad Request 
• 401 – Not Authorized 
• 403 – Forbidden 
• 404 –...
Or if you’re feeling super creative… 
• 418 – I’m a Teapot… 
• 420 – Enhance Your Calm 
l All contents Copyright © 2014, M...
Use Descriptive Error Messages. 
l All contents Copyright © 2014, MuleSoft Inc.
The more information you provide, the easier it will be 
for developers to integrate your API without contacting 
Support....
Also be sure to keep your documentation up 
to date and simple enough for developers to 
quickly find and implement soluti...
Finally, when adding new things 
to your API, be sure to: 
l All contents Copyright © 2014, MuleSoft Inc.
Finally, when adding new things 
to your API, be sure to: 
1 – Go in with a long-term mindset 
2 – Understand what you’re ...
It only takes ONE little thing to significantly 
reduce your API’s life span. Every action you 
make on your API must be c...
Remember... 
l All contents Copyright © 2014, MuleSoft Inc.
Building an API is easy. 
l All contents Copyright © 2014, MuleSoft Inc.
Designing an API is hard. 
l All contents Copyright © 2014, MuleSoft Inc.
l All contents Copyright © 2014, MuleSoft Inc. 
read more @ 
blogs.mulesoft.org
l All contents Copyright © 2014, MuleSoft Inc. 
@MuleDev 
www.mulesoft.com
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Building Your API for Longevity

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This is not about how to code your API, but rather to show you what steps and best practices you need to utilize to build a successful, long-lived API. Thankfully with 5 Simple Steps you can build an API that is designed to last.

1 – Go in with a long-term mindset
2 – Understand what you’re building
3 – Utilize Spec Driven Development
4 – Incorporate Best Practices
5 – Repeat steps 1-4 for all new features

Published in: Technology

Building Your API for Longevity

  1. 1. Building Your API for Longevity by mike stowe l All contents Copyright © 2014, MuleSoft Inc.
  2. 2. Disclaimer This talk is not about how to code your API, but rather to show you what steps and best practices you need to utilize to build a successful, long-lived API to the extent that we can in 45 minutes. l All contents Copyright © 2014, MuleSoft Inc.
  3. 3. About Me • API Fanatic • Open Source Contributor • Author, Speaker, Consultant • 10+ years hacking Professional Code • Dev Relations Manager at MuleSoft l All contents Copyright © 2014, MuleSoft Inc.
  4. 4. APIs are changing the world. l All contents Copyright © 2014, MuleSoft Inc.
  5. 5. Over 13,000 PUBLIC APIs l All contents Copyright © 2014, MuleSoft Inc.
  6. 6. l All contents Copyright © 2014, MuleSoft Inc.
  7. 7. Today APIs are connecting… l All contents Copyright © 2014, MuleSoft Inc.
  8. 8. PHONES l All contents Copyright © 2014, MuleSoft Inc.
  9. 9. WATCHES l All contents Copyright © 2014, MuleSoft Inc.
  10. 10. GLASSES l All contents Copyright © 2014, MuleSoft Inc.
  11. 11. CARS l All contents Copyright © 2014, MuleSoft Inc.
  12. 12. REFRIGERATORS l All contents Copyright © 2014, MuleSoft Inc.
  13. 13. THERMOSTATS l All contents Copyright © 2014, MuleSoft Inc.
  14. 14. l All contents Copyright © 2014, MuleSoft Inc. IN HOME ROBOTS
  15. 15. AND MORE l All contents Copyright © 2014, MuleSoft Inc.
  16. 16. THINK ABOUT THAT… l All contents Copyright © 2014, MuleSoft Inc.
  17. 17. In order to work, the IoT requires that APIs remain persistent. l All contents Copyright © 2014, MuleSoft Inc.
  18. 18. l All contents Copyright © 2014, MuleSoft Inc. +
  19. 19. Versioning and making changes is expensive… l All contents Copyright © 2014, MuleSoft Inc.
  20. 20. FOR EVERYONE. l All contents Copyright © 2014, MuleSoft Inc.
  21. 21. Thankfully with 5 Simple Steps you can build an API that is designed to last. l All contents Copyright © 2014, MuleSoft Inc.
  22. 22. They are: 1 – Go in with a long-term mindset 2 – Understand what you’re building 3 – Utilize Spec Driven Development 4 – Incorporate Best Practices 5 – Repeat steps 1-4 for all new features l All contents Copyright © 2014, MuleSoft Inc.
  23. 23. Think Long-term: • Your API is a Contract • Versioning is not a solution • Understand you suck at design • You can pay a little now, or much more later • You need to think things through • Mind-set is everything l All contents Copyright © 2014, MuleSoft Inc.
  24. 24. Your Users are Depending on You… Your API is a contract, it’s your word to your users. Users who are not only depending on a working API to integrate with your service, but in order to provide food for their families. l All contents Copyright 24 © 2014, MuleSoft Inc.
  25. 25. This means you need to think through every aspect of your API before building it. l All contents Copyright © 2014, MuleSoft Inc.
  26. 26. Thinking things through… • Who is your API for? • What type of API are you building? • How are you going to maintain your API? • How are you going to document your API? • How are you going to let users interact with your API? • How are you going to manage authentication, provisioning, throttling, and developer security? • How are you going to protect your servers against attacks, developer misuse, etc? • How are you going to manage support? l All contents Copyright 26 © 2014, MuleSoft Inc.
  27. 27. Who Will Be Using Your API? • Who are your end users? - Current customers - Business partners - Third-party services • What actions do they need access to? - This means sitting down and talking to them! • How can you involve them in the design process? - Your users should be involved from Day One. l All contents Copyright 27 © 2014, MuleSoft Inc.
  28. 28. What is the Purpose of Your API? • List out WHY you are making the API - Saying that you’re exposing your data to users is not good enough- explain HOW they will use it • Explain how your API will interact with existing services • List out the actions the API needs to be able to handle - Users: add, edit, reset password, delete, etc… - Messages: draft, send, retrieve, archive, etc… • Do only what is NECESSARY • DON’T get fancy. l All contents Copyright 28 © 2014, MuleSoft Inc.
  29. 29. List Out What Your Users Need to be able to Do: l All contents Copyright 29 © 2014, MuleSoft Inc.
  30. 30. What Type of API Are You Building? • Are you building a REST, partial REST, SOAP, or RPC based API? • Why are you building your API in that format? • What does that mean for development? • What does that mean for usability? • What does that mean for longevity? l All contents Copyright 30 © 2014, MuleSoft Inc.
  31. 31. What Type of API Are You Building? l All contents Copyright 31 © 2014, MuleSoft Inc.
  32. 32. Do You Understand the REST Constraints? • Client-Server • Stateless • Cacheable • Interface/ Uniform Contract • Layered System • Code on Demand (optional) l All contents Copyright 32 © 2014, MuleSoft Inc.
  33. 33. Most APIs are NOT RESTful. l All contents Copyright © 2014, MuleSoft Inc.
  34. 34. This is why it’s so important to understand the different types of APIs, why each type is different, and why you are choosing one over the other. l All contents Copyright © 2014, MuleSoft Inc.
  35. 35. It also means building your API for beyond today… l All contents Copyright © 2014, MuleSoft Inc.
  36. 36. ...people are fairly good at short-term design, and usually awful at long-term design.” “ l All contents Copyright 36 © 2014, MuleSoft Inc. -Dr. Roy Fielding
  37. 37. Versioning is a necessary evil. l All contents Copyright © 2014, MuleSoft Inc.
  38. 38. Problems with Versioning • Backwards incompatibilities • Multiple Services to Maintain • Multiple Systems to Support • Creates confusion among developers • Developer adoption is nearly impossible l All contents Copyright 38 © 2014, MuleSoft Inc.
  39. 39. You Need to Version When: • Backwards incompatible platform changes • Your API is no longer extendable • Your spec is out dated (ie SOAP) l All contents Copyright 39 © 2014, MuleSoft Inc.
  40. 40. But You Shouldn’t Version Just Because You: • Added new endpoints • Added additional data in response • Changed technologies (java toruby) • Changed your application’s services (code) l All contents Copyright 40 © 2014, MuleSoft Inc.
  41. 41. Versioning does not excuse poor design. l All contents Copyright © 2014, MuleSoft Inc.
  42. 42. And a poorly designed API will cost you far more in the long run, adding months to fix what could have been prevented in weeks. There are no shortcuts or quick fixes, you can either build your API the right way to begin with, or pay substantially for it in the long-run. l All contents Copyright © 2014, MuleSoft Inc.
  43. 43. Use Spec Driven Development • Define your API before Coding • Use Design Patterns/ Code Reuse • Mock and get User Feedback • Make Necessary Changes • Start Coding – to the Spec • DO NOT DEVIATE! l All contents Copyright © 2014, MuleSoft Inc.
  44. 44. Spec Driven Development means a hybrid between agile and waterfall methodologies. You should develop your spec iteratively, incorporating agile user testing. However, the actual development (coding) of your API should be static, driven by the spec with no deviation. l All contents Copyright © 2014, MuleSoft Inc.
  45. 45. Disclaimer: Waterfall refers to the spec and changing the spec only! You should still use sprints for code development – just at this point the spec should not be changing. l All contents Copyright © 2014, MuleSoft Inc.
  46. 46. Hybrid Approach Design Development Continuous, fluid, changeable Static… No turns l All contents Copyright 46 © 2014, MuleSoft Inc.
  47. 47. The Agile Design Cycle l All contents Copyright 47 © 2014, MuleSoft Inc.
  48. 48. The goal is that by utilizing agile user testing, carefully designing, and prototyping your API in an iterative state, that most design related issues have already been discovered and resolved. Allowing you to develop fearlessly. l All contents Copyright © 2014, MuleSoft Inc.
  49. 49. The problem is up until now, designing and prototyping an API has been extremely costly. Requiring developers to create a mock API through extensive coding, and without any real constraints/ pattern reuse. l All contents Copyright © 2014, MuleSoft Inc.
  50. 50. However, there are several new specs being driven by today’s industry leaders making it easier define your API: with tools to design, prototype, document, and allow user interaction. l All contents Copyright © 2014, MuleSoft Inc.
  51. 51. Some of Today’s Specs: • RAML • IO Docs • Swagger • API Blueprint l All contents Copyright 51 © 2014, MuleSoft Inc.
  52. 52. Using RAML You Can: • You can define your API in just a few lines of code • You can see what it would look like as you go • You can quickly prototype it for devs to try • You can quickly make tweaks/ changes • You can easily document your API • You can let developers try your API online • You can let developers interact with your and other APIs • Generate SDKs/ client libraries for your API (APIMatic.io) l All contents Copyright 52 © 2014, MuleSoft Inc.
  53. 53. More Importantly… • You can use design patterns • You can reuse code (traits, resourceTypes) resourceTypes: -­‐ collection: description: Collection of available <<resourcePathName>> in Jukebox. get: description: Get a list of <<resourcePathName>>. responses: 200: body: application/json: example: | <<exampleCollection>> l All contents Copyright 53 © 2014, MuleSoft Inc.
  54. 54. The RAML API Designer l All contents Copyright 54 © 2014, MuleSoft Inc.
  55. 55. What Does RAML Look Like? #%RAML 0.8 title: World Music API baseUri: http://example.api.com/{version} version: v1 /playlists: get: responses: 200: body: application/json: example: | { “playlistID” : 1, “playlistName” : “My Awesome Playlist”, “genre” : “top40”, “songs” : 40 } l All contents Copyright 55 © 2014, MuleSoft Inc.
  56. 56. Remember, your spec is not a one-and-done, rather it is the blueprint for your API. Anytime you do something to your API you should be modifying the spec and going through user testing before writing code. You should never have code that does something not defined by your spec. l All contents Copyright © 2014, MuleSoft Inc.
  57. 57. Incorporate Best Practices: • Use Nouns • Use CRUD • Use Hypermedia (HATEOAS) • Use Accept/ Content-Type • Return Header Codes • Return Descriptive Error Messages l All contents Copyright © 2014, MuleSoft Inc.
  58. 58. Use Nouns. l All contents Copyright © 2014, MuleSoft Inc.
  59. 59. Use: /users Not: /createUser /getUser /deleteUser l All contents Copyright © 2014, MuleSoft Inc.
  60. 60. Utilize CRUD. l All contents Copyright © 2014, MuleSoft Inc.
  61. 61. Create (POST) Read (GET) Update (PUT/ l All contents Copyright © 2014, MuleSoft Inc. PATCH) Delete (DELETE)
  62. 62. Use Hypermedia. l All contents Copyright © 2014, MuleSoft Inc. HATEOAS
  63. 63. Most Popular Hypertext Link Specs • HAL • JSON-LD • JSON API • Siren l All contents Copyright 63 © 2014, MuleSoft Inc.
  64. 64. { "data" : { "user": { "fname":"first", "lname":"last" } }, "_links" : { "edit": { "href" : "/api/user/id/1" }, "message": { "href" : "/api/message/id/1/lname/last" } } } l All contents Copyright © 2014, MuleSoft Inc. HAL
  65. 65. Use Accept/ Content-Type Headers. l All contents Copyright © 2014, MuleSoft Inc.
  66. 66. Use Accept/ Content-Type Headers Using headers gives you flexibility to support multiple types of formats from the same resource without worrying about breaking backwards compatibility. Most common: • application/json - wider language support • application/xml l All contents Copyright 66 © 2014, MuleSoft Inc.
  67. 67. Use Response Codes. l All contents Copyright © 2014, MuleSoft Inc.
  68. 68. • 200 – OK • 201 – Created • 304 – Not modified • 400 – Bad Request • 401 – Not Authorized • 403 – Forbidden • 404 – Page/ Resource Not Found • 405 – Method Not Allowed • 415 – Unsupported Media Type • 500 – Internal Server Error l All contents Copyright © 2014, MuleSoft Inc.
  69. 69. Or if you’re feeling super creative… • 418 – I’m a Teapot… • 420 – Enhance Your Calm l All contents Copyright © 2014, MuleSoft Inc.
  70. 70. Use Descriptive Error Messages. l All contents Copyright © 2014, MuleSoft Inc.
  71. 71. The more information you provide, the easier it will be for developers to integrate your API without contacting Support. { 'exception' { 'code' : 'e3526', 'message' : 'Missing UserID', 'description' : 'A UserID is required to edit a user.', 'link' : 'http://docs.mysite.com/errors/e3526/' } } l All contents Copyright © 2014, MuleSoft Inc.
  72. 72. Also be sure to keep your documentation up to date and simple enough for developers to quickly find and implement solutions to even the most complex problems. Poor documentation has been the death of many an API. l All contents Copyright © 2014, MuleSoft Inc.
  73. 73. Finally, when adding new things to your API, be sure to: l All contents Copyright © 2014, MuleSoft Inc.
  74. 74. Finally, when adding new things to your API, be sure to: 1 – Go in with a long-term mindset 2 – Understand what you’re building 3 – Utilize Spec Driven Development 4 – Incorporate Best Practices l All contents Copyright © 2014, MuleSoft Inc.
  75. 75. It only takes ONE little thing to significantly reduce your API’s life span. Every action you make on your API must be carefully thought out and tested BEFORE being pushed to production. l All contents Copyright © 2014, MuleSoft Inc.
  76. 76. Remember... l All contents Copyright © 2014, MuleSoft Inc.
  77. 77. Building an API is easy. l All contents Copyright © 2014, MuleSoft Inc.
  78. 78. Designing an API is hard. l All contents Copyright © 2014, MuleSoft Inc.
  79. 79. l All contents Copyright © 2014, MuleSoft Inc. read more @ blogs.mulesoft.org
  80. 80. l All contents Copyright © 2014, MuleSoft Inc. @MuleDev www.mulesoft.com

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