1. Building RESTful Interfaces
Steve Shaw

2. We will Cover What is REST? The precepts of a RESTful Interface
Security
Show how to implement a REST interface within the InterSystems Platform

3. What is REST
Architectural style for web Applications introduced by Roy Fielding
“Representational State Transfer is intended to evoke an image of how a well-designed web application behaves: a network of web pages (a virtual state- machine), where the user progresses through an application by selecting links (state transitions), resulting in the next page (representing the next state of the application) being transferred to the user and rendered for their use.”

4. Or…
"REST emphasizes scalability of component interactions, generality of interfaces, independent deployment of components, and intermediary components to reduce interaction latency, enforce security, and encapsulate legacy systems. ”
- Webopedia

5. Even Better…
"Representational state transfer (REST) is a distributed system framework that uses Web protocols and technologies. The REST architecture involves client and server interactions built around the transfer of resources. The Web is the largest REST implementation
- Techopedia

6. REST
Rest is not a standard or protocol, REST is an architectural style.
REST makes use of existing web standards such as HTTP, URL, XML, JSON, etc..
REST is resource oriented. Resources or pieces of information, are addressed by URIs and passed from server to client or vice versa

7. Principles of REST
Uniform interface: simplifies and decouples the architecture, which enables each part to evolve independently.
Stateless: no client context being stored on the server between requests. Each request all of the information necessary to service the request
Cacheable: Well-managed caching partially or completely eliminates some client–server interactions, further improving scalability and performance.

8. RESTful Web Service
A RESTful web service is a web API implemented using HTTP and the principles of REST.
A collection of resources identified by a directory structure-like URI
E.g.:
Operations based explicitly on HTTP methods (GET, POST, PUT, DELETE)
Information transfer based on Internet media types, commonly JSON. Other types include XML,HTML, CSV (text)

9. CRUD operations
REST operations fall under 4 types (CRUD) which are defined as http protocol methods:
REST
HTTP
Create
Post
POST
Read
Get
GET
Update
Put
PUT
Delete
DELETE

10. REST Advantages REST Simplicity (easy to use, maintain and test)
Many options for representations(JSON, CSV, HTML, XML)
Human Readable Results
Performance
Scalable architecture
Lightweight requests and responses
Easier response parsing
Saves bandwidth(Caching, Conditional GET..)
Well suited clients using JSON representations

11. REST Advantages Soap request REST request <?xml version=“1.0”?>
<soap:Envelope xmlns:soap= soap:encodingStyle=
<soap:Body ord=“
<ord:GetOrderDetails>
<ord:OrderNumber>12345</ord:OrderNumber>
</ord:GetOrderDetails>
</soap:Body>
</soap:Envelope>
REST request

12. URL / URI REST interfaces are defined via a URL/URI
URI – Uniform Resource Identifier
Identifies a specific Resource on the network
Example:
URL – Uniform Resource Locator
Provides access to a specific representation of a resource on the network or

13. Security Security is up to the Interface developer
REST has no predefined methods for Security
Security should take advantage of what is already available for Web Applications
SSL/TLS (
OpenId Authorization (Oauth)
Hash-based Message Authentication Code (HMAC)

14. Security
REST is exposed to all the same vulnerabilities as an other Web based Applications
Encrypt any sensitive payload or static keys
Note HMAC does not encrypt data, a common miss- conception
Sophisticated security models can be difficult to implement

15. Cache Implementation New class in 2014.1 - %CSP.REST
In SMP register the Dispatch Class which matches your REST application base URL
System>Security Management>Web Applications>Edit Web Application
New web application /csp/samples/globalsummit
Dispatch Class: Rest.Broker
Use the UrlMap Xdata block to route requests to HTTP operation and target class method
XData UrlMap { <Routes> <Route Url="/employee/html/list" Method="GET" Call="Rest.HTML:GetAllEmployees"/>
</Routes>}

16. Example: Hello World Redux
This service will provide access to a translation of “HELLO WORLD” into other languages.
In this example we will:
Configure the Web application
Show the setup of a REST interface dispatch class
Show the implementation options for the service resources (methods)
Show the results

17. Q & A
Any Questions?