This document discusses services and REST APIs in Drupal 8. It defines key concepts like web services, REST, and the Richardson Maturity model. It explains the components of a REST request and how requests work. Drupal 8 introduces a new routing system based on Symfony, and resources are exposed via plugins that define routes for CRUD operations. Serialization and normalization convert entities to JSON/HAL. Authentication is decoupled from sessions. Overall the document provides an overview of the RESTful services architecture in Drupal 8.

1. Services in Drupal 8
Andrei Jechiu
andrei.jechiu@gmail.com
http://wearepropeople.com

2. Definitions
Web Services
A method of communication between two applications
over the World Wide Web.
REST (Representational State Transfer)
An architecture style for designing networked
applications.

3. Components of the REST request
Base Format
HTTP Verbs
URI
Media Type (MIME type)

4. REST request
Base Format

5. REST request
HTTP Verbs
GET - retrieve whatever data is identified by the URI.
POST - create a resource.
PATCH - update a resource.
DELETE - remove a resource.
/node/3/get
GET /node/3
/node/add
POST /node

6. REST request
URI
Resource
http://example.com/entity/node/1
Post /endpoint
http://example.com/node/1
{id:1}
Link Relation
http://example.com/node/article/field_tags
http://drupal.org/rest/relations/field-configuration

7. REST request
Media Type (MIME type)
application/json
application/hal+json
node/3.json
node/3.hal_json
Headers
Accept: application/json
Content-Type: application/json

8. Richardson Maturity Model

9. Services Drupal 7
http://drupal.org/project/services
Endpoint concept with custom URL paths
Caters for RPC and SOAP also
Uses drupal_form_submit() for write operations
Only covers hard coded entities like nodes, comments, users
Explicit authentication info hooks.
No hypermedia controls

10. RESTWS and Services Entity API Drupal 7
RESTWS http://drupal.org/project/restws
Relies on Entity API and metadata about entities
No endpoints: uses /node/1.json or /node/1.xml
No configuration: exposes any entity type out of the box
Access control on top of Entity API and Field API
Standard user authentication over session cookies or HTTP Basic
Auth submodule
Services Entity API http://drupal.org/project/services_entity
Combines approaches from Services and RESTWS
Configurable endpoints + Entity API for data management

11. Modules in Drupal 8 core
RESTful Web Services (REST module)
Serialization
HAL

12. Resources and operations
A resource is the object of interest. Example: the node resource.
An operation is an action to read or manipulate a resource.
Operation
HTTP request method
path
Create
POST
/entity/node
Read
GET
/entity/node/1
Update
PATCH
/entity/node/1
Delete
DELETE
/entity/node/1

13. REST in core
New Entity API with field metadata
REST API support can be enabled for any content entity
known to the system
Access control on the entity level
Access control on the field level

14. Configure permissions

15. Fetch the node with cURL
With cURL from PHP

16. Fetch the node with Guzzle

17. The node response
{
"_links":
"self":
"href":
},
"type":
"href":
},
{
{
"http://drupal8.loc/node/1"
{
"http://drupal8.loc/rest/type/node/article"
…
"body": [
{
"value": "<p>Article used for REST web services
tests.</p>rn",
"format": "basic_html",
"summary": ""
}
]
}

18. Drupal 7 routing
based on paths (menu_get_item($path))
tied up with menu links (tables menu_router,
menu_links)

19. Drupal 7 routing
hook_menu()
hook_menu_alter()

20. Drupal 8 routing
mymodule.routing.yml

21. Dynamic routes
Example: Generate dynamic routes for various block pages.

22. Dynamic routes
Route subscribers have to be registered in the dependency injection container
by adding an entry in example.services.yml:

23. Routing
Drupal 7
Path only
Tied with menu links
Drupal 8
Heavily used
Symfony
Mime type
Http method
...

24. Resource plugins
DrupalmodulenamePluginrestresource
Classes where specially named methods correspond
to HTTP methods (get, post, patch, delete, ...)
Annotation with id and description

25. Resource plugin example

26. Serialization

27. Serialization

28. Normalizers
ImageItemNormalizer
EntityReferenceItemNormalizer
FieldItemNormalizer
FieldNormalizer
EntityNormalizer

29. CSRF protection
Each non-safe call (not GET, HEAD,
OPTIONS, TRACE methods) should be done
with ‘X-CSRF-Token’ header with token

30. Services in Drupal 8
Own plugin (extends Resources from REST).
Each method as own route (not tied with http
method names).
Use annotations to describe your routes.
Validation of arguments.

31. Services example

32. Authentication
No more dependent on Cookie Session
Authentication providers
Access check if authentication provider allowed
Multiple authentication providers - 400 Bad Request

33. Resources
https://groups.drupal.org/wscci
https://drupal.org/documentation/modules/rest
https://portland2013.drupal.org/session/rest-and-serialization-drupal-8
http://martinfowler.com/articles/richardsonMaturityModel.html
http://www.slideshare.net/ygerasimov/drupal-8-routing

34. Thank You!