A Raspberry Pi HTTP REST software stack

2.1   nginx

Use apt-get or aptitude. E.g. with aptitude, you can do:

$ sudo aptitude install nginx

2.2   uwsgi

Use apt-get or aptitude. E.g. with aptitude, you can do:

$ sudo aptitude install uwsgi

2.3   flask and flask-restful

I suggest that you use a virtualenv. Do the following:

$ pip install virtualenv
$ cd where/you/want/your/virtualenvs
$ virtualenv -p /usr/bin/pyton3 restplatform3    # identify as Python 3
$ source restplatform3/bin/activate              # activate this virtual environment
$ pip install flask flask_restful

Notes:

• After activating the virtual environment, you will be running the version of Python in that virtual environment whenever you run a script or you execute $ python. And, whenever you install a Python package, e.g. with pip, it will be installed inside the virtual environment directory that you have just created. You can check this (on Linux) by running:

  $ which python
  

• The above commands create a virtual environment containing Python 3. If you prefer Python 2, omit the "-p" option and its argument.

You should also consider using pip to install a few useful things like ipython, lxml, etc.

3.1   nginx

3.2   uwsgi

5.1   curl

Examples:

get-one-document.sh:

#!/bin/bash
# get-one-document.sh
# Retrieve a single document from the database.
curl -v http://localhost:8001/documents/getdocument/$1

list-documents.sh:

#!/bin/bash
# list-documents.sh
# Retrieve a list of all existing documents.
http://localhost:8001/documents/getdocument

add-document.sh:

#!/bin/bash
# add-document.sh
# Create a new document; add it to the database.
curl -v -X POST http://localhost:8001/documents/adddocument -d "document=$1"

update-document.sh:

#!/bin/bash
# update-document.sh
# Update an existing document.
curl -v -X PUT http://localhost:8001/documents/updatedocument/$1 -d "document=$2"

delete-document.sh:

#!/bin/bash -x
# delete-document.sh
# Delete an existing document; remove it from the database.
http://localhost:8001/documents/delete/$1

5.2   httpie

httpie is a pleasant command line HTTP client and can be used as an alternative to curl. The actual command line name is "http". If you are a Python user, you can install it with pip:

$ pip install httpie

Or, on Linux, you can install it with apt-get or aptitude.

Here are several examples using httpie:

# Get a list of all documents
$ http GET http://localhost:8001/documents/getdocument
# Get one document by its ID
$ http GET http://localhost:8001/documents/getdocument/91a3b86fcbc59cc5f4a855d7894cb3be46546dccc18f5e833d24824ff4e4bf95

5.3   Python and requests

A test driver -- You can write a simple application using the requests module (which can be installed using pip). Here is some sample code to get you started.

rook_request.py:

#!/usr/bin/env python

from __future__ import print_function
import requests

def rook_request():
    #
    # Request HTML.
    response = requests.get('http://rook.local:5000')
    content = response.content.decode('utf-8')
    print('html content: {}'.format(content))
    print('-' * 60)
    #
    # Request JSON.
    headers = {'content-type': 'application/json'}
    response = requests.get('http://rook.local:5000', headers=headers)
    content = response.content.decode('utf-8')
    print('json content: {}'.format(content))

def main():
    rook_request()

if __name__ == '__main__':
    #import ipdb; ipdb.set_trace()
    main()

Timing -- You can get some estimates of response time using IPyton and the %timeit magic command. For example, the following uses the above Python code (in rook_request.py) and executes 10 loops with 1 call to rook_request.rook_request in each loop:

$ ipython
Python 3.6.0 (default, Dec 26 2016, 10:27:00)
Type "copyright", "credits" or "license" for more information.

IPython 5.1.0 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object', use 'object??' for extra details.
In [1]:
In [1]: import rook_request
In [2]: %timeit -n 10 -r 1 rook_request.rook_request()
    o
    o
    o
html content: <html>
<head>
<title>Flask test app on rook</title>
</head>
<body>
<h1>rook test 1</h1>
<p>Current time: Fri Mar 24 16:23:43 2017</p>
</body>
</html>

------------------------------------------------------------
json content: {"time": "Fri Mar 24 16:23:43 2017"}
10 loops, best of 1: 117 ms per loop
In [3]: