rest in good! - devcon 2017
TRANSCRIPT
REST in good!
André Goliath
[skip motivation, because REST]
REST is an abbreviation for…
a) Really Strange Topic
b) Relational Enterprise Scheme Trade
c) Representational State Transfer
d) ??? [use “send a comment”]
Representational State Transfer
Building Blocks: HTTP(as far as this talk is concerned,
HTTP and HTTP/2 are the same)
URIs (Uniform Resource Identifier)
vs.
URLs (Uniform Resource Locator)
URLs locate resources
(“something that we can talk about
and that has ‘properties’ ”)
Verbs or methods
operate on resources
safe idempotent
GET
HEAD
OPTIONS
PUT
PATCH
DELETE
POST
HEAD and GET are the same,
except HEAD not sending the actual body
Browsers use OPTIONS to implement
Cross-Origin Resource Sharing (CORS)
OPTIONS and CORS Preflights
Use PUT to create or replace resources
if you know their exact URL
Otherwise, POST to the parent resource
Use PUT to replace a whole resource at once,
PUT operations must be idempotent!
Use PATCH to update partial data
We have a list of items, e.g. /messages
How do we get the number of all messages?
a) GET /messages and {…count: 5…}
b) GET /messages/count
c) GET /messages?count
d) ??? [use “send a comment”]
We have a list of items, e.g. /messages
How do we get the number of all messages?
> HEAD /messages
< …
< X-COUNT: 5
We GET the current temperature from
/house/livingroom/temp. But the sensor is
kinda unstable and needs to be power-cycled
from time to time. How would you do it?
a) POST /house/livingroom/temp/reset
b) PUT /house/livingroom/temp/reset
c) DELETE /house/livingroom/temp
d) ??? [use “send a comment”]
We GET the current temperature from
/house/livingroom/temp. But the sensor is
kinda unstable and needs to be power-cycled
from time to time. How would you do it?
> POST /house/scheduledTasks
> {
> time: ‘now’,
> action: ‘reset’,
> target: ‘livingroom/temp’
> }
HTTP is kinda bad
for long-running processes
No, you´re just
using it wrong
> POST /house/scheduledTasks
> {
> time: ‘in 2 hours’,
> action: ‘reset’,
> target: ‘livingroom/temp’
> }
> POST /house/scheduledTasks
> {
> time: ‘in 2 hours’,
> action: ‘reset’,
> target: ‘livingroom/temp’
> }
< HTTP/1.1 201 Created
< Location: https://…/scheduledTasks/7dhe9u
< HTTP/1.1 201 Created
< Location: https://…/scheduledTasks/7dhe9u
> GET /house/scheduledTasks/7dhe9u
< Cache-Control "max-age=3600, must-revalidate"
< {
< time: ‘2017-11-10T13:15:28+02:00’,
< action: ‘reset’,
< target: ‘livingroom/temp’,
< status: ‘scheduled’
< }
… two hours later …
> GET /house/scheduledTasks/7dhe9u
< {
< time: ‘2017-11-10T13:15:32+02:00’,
< action: ‘reset’,
< target: ‘livingroom/temp’,
< status: ‘done’,
< result: 200
< }
… one eternity later …
> GET /house/scheduledTasks/7dhe9u
< HTTP/1.1 404 Not Found
> GET /house/scheduledTasks/7dhe9u
< ???
a) 404 – Not Found
b) 202 - Accepted
c) 204 – No Content
d) 410 – Gone
e) ??? [use “send a comment”]
> GET /house/scheduledTasks/7dhe9u
< HTTP/1.1 410 Gone
> GET /house/scheduledTasks/1234567890
< HTTP/1.1 404 Not Found
HTTP
Status Codes
(just RTFM)
Why 404 has no ‘double meaning’
> GET /house/scheduledTasks/1234567890
< HTTP/1.1 404 Not Found
> GET /house/scheduledTasks/7dhe9u
< HTTP/1.1 410 Gone
> GET /house/scheduledTasks/8fks3k
< HTTP/1.1 200 OK
> GET /house/scheduledTasks/9edm4d
< HTTP/1.1 200 OK
Why 404 has no ‘double meaning’
> GET /houes/scheduledTasks/1234567890
< HTTP/1.1 404 Not Found
> GET /houes/scheduledTasks/7dhe9u
< HTTP/1.1 404 Not Found
> GET /houes/scheduledTasks/8fks3k
< HTTP/1.1 404 Not Found
> GET /houes/scheduledTasks/9edm4d
< HTTP/1.1 404 Not Found
Level Up your API!
The Richardson Maturity Model
https://martinfowler.com/articles/richardsonMaturityModel.html
Hypertext as the Engine of Application State
(HATEOAS)
https://github.com/farrelmr/introtospringdatarest
