2. SDN - Software defined
networking
uses software to define/modify
networks.
Before SDN:
the data plane and control plane were
tied together as one.
3. What SDN does:
on a network device, data enters & leaves
through the data plane
decisions of what to do with the data are
made by the control plane
this allows network configuration &
decisions to be completed through a remote
control plane.
to make SDN features on these devices
accessible over the network, they are
exposed through an API
4. API: Application Programming Interface
REST: REpresentational State Transfer
An API enables 2 pieces of software to
communicate with each other.
5. What is REST?
REST is an API framework built on HTTP
when you combine REST and API, you see a
simple service interface that enables
applications or people to use HTTP protocol to
request objects/information
a REST API service sends all requests &
responses over TCP/TLS connections using text
6. A Look under the hood at REST
Protocol: http:// or https:// indicates whether the server
host is open (http) or secured (https).
Domain name: maps.googleapis.com is the domain name of the
server or host that is providing the web service, and may include port
number such as :8080.
Resource Path: /maps/api/geocode/json is the resource path
of the API call. This path tends to use plural nouns and English-
language descriptive words.
Parameter: ?address=sanjose is a parameter that provides
details for the service to filter, scope, or paginate the response data.
Often, parameters are optional.
7. HTTP verb CRUD action
POST create
GET read
PUT update
PATCH update
DELETE delete
8. A valid REST API request typically gets a 200 OK response
whereas an invalid request gets a 404 Not Found
Some REST APIs do not require authentication, but many do
Requests and responses may use headers to pass
information to form the service
Some APIs use custom headers for authentication
Some headers carry metadata to help define the request or
response
To know more about REST headers: https://www.ibm.com/
support/knowledgecenter/en/SSQP76_8.10.x/
com.ibm.odm.itoa.ref/topics/ref_rest_headers_codes.html
9. REST Payloads
Body of request/response may include a
payload that carries data to & from the
service
Data format of the payload: JSON or XML
JSON: JavaScript Object Notation
XML: eXtensible Markup Language
10. In JSON, the object is an unordered set of name-
value pairs.
An object begins with { (left brace) & ends with }
(right brace)
You can check the “Content-Type” header to
know for certain what the service is sending
11. Getting started with REST APIs
When documenting REST APIs, the trend is to use
open standards such as OpenAPI(Swagger) or
RAML to document requests, responses, headers &
parameters.
Read more about OpenAPI: https://swagger.io/
docs/specification/about/
Read more about RAML: https://raml.org/about-
raml
1. Finding the API documentation
2. Figuring out authentication
Read the documentation for the API
12. An endpoint is the URI where you send an HTTP
request. The path of an endpoint can include
notable information.
e.g. to ensure compatibility, your API provider
might specify a particular version of the API in the
endpoint itself.
An API provider can make an endpoint URI private
and accessible only through a VPN or make it
completely public on the Internet.
You can learn which end points are available by
reading the documentation.
3. Determining the end points
13. GET, POST, PUT, DELETE
Many API documentation sites use color-coding
for each verb.
To compose a request:
• determine the verb that reflects the action you
want to perform
• determine the endpoint upon which you want to
perform the action
4. Understanding REST API verbs
14. parameters help to scope, filter or clarify a
request
Pagination(returning pages of data from a
request) is sometimes implemented by using
query parameters in the URI
e.g.
• max: to specify max no. of items to return
• &: used between 2 parameters
5. Understanding REST API parameters
15. When sending a request, data formats are aka
payloads.
e.g. JSON, XML
For each data format, the data maybe
contained in the body of the request
POST, PUT, PATCH requests typically include
data requests or optional parameters as part
of the request.
GET responses nearly always include data.
6. Understanding REST API data formats
16. 1. cURL: linux command line application
2. Postman: Chrome browser plugin &
application
3. Python Requests: Python library for
scripting
4. OpenAPI/Swagger: Dynamic API
documentation
Some REST API tools
