API – Application Programming Interface

Let’s learn about API as it takes over the entire digital market place.

Design Process of an API

While designing an API its important to understand API basics and concepts of CRUD operations.

You will come across the term CURL when using APIs:
cURL – Client URL is a command line tool used to send and received data from an endpoint of a server. 
CURL can be used to submit API queries. 

Each request typically consists of the following four components:

HEADERS: it includes metadata information about the request such as the content type, user agent and other details.

 BODY: which is the actual message and, if any data is being sent, contains it. It is also known as payload. The body is typically used with POST and PUT operations.

ENDPOINT: An endpoint is the location (URL) to which the request is being sent.

HTTP Methods (VERBS) :–  GET, POST, PUT, PATCH and DELETE are the most often used techniques.

 

HTTP Verbs and CRUD Operations

HTTP verbs are methods used in HTTP requests (like GET, POST, PUT, PATCH, and DELETE) that tell the server what action to perform on a resource.

CRUD, on the other hand, stands for Create, Read, Update, and Delete, and represents the four basic actions that can be performed on data in a database or other data storage system. These operations are often mapped to HTTP verbs in web applications.

Let me try to break down the mapping process for your better understanding about this concept.

In web applications, it is common to map the CRUD operations (Create, Read, Update, Delete) to HTTP verbs. This means that each CRUD operation is associated with a specific HTTP verb.

For example, when a user wants to create a new resource (such as a blog post), the application will send a request to the server with the HTTP verb “POST”. The server will then handle the request and create the new resource.

Similarly, when a user wants to read a resource (such as a blog post), the application will send a request to the server with the HTTP verb “GET”. The server will then retrieve the requested resource and send it back to the application.

By mapping CRUD operations to HTTP verbs, web applications can use a standard set of methods to perform all the necessary actions on resources, making it easier to build and maintain the application.

 

While CRUD operations can be implemented using HTTP verbs, HTTP verbs are not limited to CRUD operations and can be used for other types of actions as well. Additionally, not all HTTP verbs map directly to CRUD operations.

HTTP verbs can be used for a variety of actions beyond CRUD operations. Here are some examples:

  1. OPTIONS: This HTTP verb is used to retrieve information about the communication options available for a resource.

  2. HEAD: This HTTP verb is similar to GET, but it only retrieves the headers of the resource, without the body.

  3. CONNECT: This HTTP verb is used to establish a network connection to a resource.

  4. TRACE: This HTTP verb is used to retrieve a diagnostic trace of the actions performed by the server on a request.

  5. PATCH: This HTTP verb is used to partially update a resource.

  6. COPY: This HTTP verb is used to make a copy of a resource.

  7. MOVE: This HTTP verb is used to move a resource to a different location.

In summary, while CRUD operations are often implemented using HTTP verbs, HTTP verbs have a broader range of uses beyond CRUD operations and can be used for various types of actions in web applications.

What is an API Gateway?

An API gateway is a server that acts as a central entry point for client applications to access multiple backend services or APIs. It acts as a reverse proxy that receives incoming API requests from clients, routes them to the appropriate backend services, and then returns the responses back to the clients.

API gateways can provide a number of benefits, such as:

  1. Simplifying client access to multiple backend services by providing a unified API endpoint
  2. Enforcing security policies and access controls for API requests
  3. Caching and rate-limiting to improve API performance and prevent overloading of backend services
  4. Transforming API requests and responses to different formats, such as JSON or XML
  5. Monitoring and logging API traffic to provide visibility into API usage and performance

API gateways are commonly used in microservices architectures, where different services are developed and deployed independently. By using an API gateway, client applications can access these services without needing to know the details of each individual service or its API.

How to access API using python

Python might make accessing APIs appear scary, but it’s actually quite simple. Here’s a how-to manual to get you going: 

Choose an 
API:Python allows you to access a wide range of APIs. 

To authenticate your requests, you’ll need to provide this key, which is often a lengthy string of characters, in your Python code. 

You must create an account with the API provider and adhere to their key-obtaining instructions in order to obtain an API key.

Install requests library: The requests library is a popular Python library for making HTTP requests, which is what you’ll be using to access the API. You can install it using pip, which is the Python package manager.

Open up your terminal and type the following command: python code to install Requests Module

pip install requests

Make a request: Once you have your API key and have installed the requests library, you can start making requests to the API. The requests library provides several methods for making different types of HTTP requests, such as GET, POST, PUT, and DELETE. In most cases, you’ll be using the GET method to retrieve data from the API.

Here’s an example of how to make a GET request to the OpenWeatherMap API:

import requests

api_key = ‘your_api_key_here’
city = ‘New York’

response = requests.get(f’https://api.openweathermap.org/data/2.5/weather?q={city}&appid={api_key}’)

print(response.json())

In this example, we’re using the requests.get method to make a GET request to the OpenWeatherMap API to get the current weather data for New York. We’re including our API key in the request URL, and using f-strings to dynamically insert the city name and API key into the URL. The response.json() method is used to convert the response data into a Python dictionary.

Note: You should never hardcode your API key into your code. Instead, you should store it in a separate file or environment variable and load it into your code as needed.

Parse the response: Once you’ve made a request to the API, you’ll need to parse the response data to extract the information you’re interested in. In the example above, we’re using the response.json() method to convert the response data into a Python dictionary, which we can then access like any other dictionary in Python.

Here’s an example of how to extract the temperature and weather description from the OpenWeatherMap response:

data = response.json()

temperature = data[‘main’][‘temp’]
weather_description = data[‘weather’][0][‘description’]

print(f’The temperature in {city} is {temperature} Kelvin, and the weather is {weather_description}.’)

In this example, we’re accessing the temperature and weather description data from the response dictionary using nested keys. We’re using f-strings to dynamically insert the data into a string for printing.

And that’s it! Those are the basic steps for accessing an API using Python. Of course, the specifics will depend on the API you’re working with, but the general process will be similar. Happy coding!

Tweepy: A Twitter API

How to Access Twitter API
 
How to use Twitter API: We will try to make a product using this tweepy api of the twitter platform.

At first, you need to get access from Twitter’s platform for developers.
You will then see a page with options shown in above screenshot. You can opt for the suitable option as per your need. 
 
Common issues:

pip install tweepy
import tweepy

client = tweepy.Client(“AAAAAAAAAAAA—BreakToken—-DDkrt2lBZX3GbJxxhyrh7VFkiZpdi”)  

AttributeError: module ‘tweepy’ has no attribute ‘Client’

resulting in an error —  while creating client = AttributeError: module ‘tweepy’ has no attribute ‘Client’   Reason

The error “AttributeError: module ‘tweepy’ has no attribute ‘Client'” typically occurs when you try to reference a ‘Client’ object in Tweepy, but Tweepy does not have a ‘Client’ attribute. This is likely due to a mistake in your code where you are trying to access a non-existent attribute in the Tweepy module.

Here are a few approaches to solve this issue:

  1. Double-check the code: Review your code and ensure that you are using the correct syntax and referencing the correct attributes and objects in Tweepy. The ‘Client’ attribute is not a valid attribute in Tweepy, so make sure that you are not mistakenly trying to access it.

  2. Verify the Tweepy version: Tweepy has gone through some updates and changes in different versions. Make sure that you are using the correct version of Tweepy that is compatible with your code. The ‘Client’ attribute may have been deprecated or removed in certain versions of Tweepy, so check the official Tweepy documentation or release notes to confirm the availability of ‘Client’ in the version you are using.

  3. Import the correct module: Tweepy has several submodules, and it’s possible that you may be trying to reference a ‘Client’ object from a wrong submodule. Double-check your import statement and ensure that you are importing the correct submodule that contains the ‘Client’ object. 

    import tweepy
    from tweepy.streaming import StreamClient

    # Create a StreamClient instance
    client = StreamClient(consumer_key, consumer_secret, access_token, access_token_secret)

    # Use the StreamClient object to access streaming API
    client.filter(track=[‘keyword’])

  4. For example, Tweepy has a ‘Stream’ submodule for streaming API, and you may be mistakenly trying to reference ‘Client’ instead of ‘StreamClient’.

  5. Here’s an example of how you can use the ‘StreamClient’ from the ‘Stream’ submodule in Tweepy:

or you can try to install the module through below mentioned ways:   pip install tweepy==4.10.1 pip3 install –upgrade git+https://github.com/tweepy/tweepy.git

 

pip freeze command

With the pip freeze command, you may examine what modules you have installed by using the pip install command.
The command pip freeze is quite helpful because it shows you the versions of the modules you currently have installed on your machine as well as which ones you have installed using pip install.
The incompatibility of some modules with others results into modules may not be working together.

 

Custom HTTP Headers and Query Parameters

Let’s understand what are Cookies and Headers first. 

When you visit a website, your browser sends a request to the server that hosts the website. This request contains a set of headers, which provide information about your browser and the type of content you are requesting.

 

Headers are pieces of data that are sent as part of an HTTP request or response. They provide additional information about the request or response, such as the content type, encoding, and language.

Cookies, on the other hand, are small pieces of data that are stored on your computer by websites that you visit. These cookies can be used to track your activity on the website, remember your preferences, and personalize your experience.

Here’s a step-by-step guide on how cookies and headers work:

  1. When you type a website address into your browser’s address bar and hit enter, your browser sends an HTTP request to the server that hosts the website.

  2. This request contains a set of headers, which provide information about your browser and the type of content you are requesting. For example, the User-Agent header tells the server what type of browser you are using, while the Accept-Language header tells the server what language you prefer.

  3. The server responds to the request with an HTTP response, which also contains a set of headers. These headers provide information about the content that is being sent back to your browser, such as the content type, encoding, and length.

  4. If the server wants to store information on your computer, it can do so by setting a cookie in the HTTP response. Cookies are usually used to remember your preferences or track your activity on the website.

  5. The next time you visit the website, your browser sends an HTTP request that includes the cookies that were set by the website. This allows the website to personalize your experience and remember your preferences.

It’s important to note that not all websites use cookies, and some browsers allow you to block or delete cookies if you don’t want websites to store information on your computer. Additionally, some websites may use other methods of tracking your activity, such as browser fingerprinting or device recognition.

HTTP headers and HTTP parameters are two important components of an HTTP request. While headers contain metadata, parameters hold actual data. Headers are manually escaped/encoded at the client-side and need to be manually unescaped/decoded at the server-side, whereas parameters are automatically unescaped/decoded by HTTP servers. Headers are hidden to end-users, whereas parameters can be seen in the URL.

An HTTP request is composed of the URL, HTTP method, and HTTP headers, among others. The query parameters are within the URL, while the headers are not. Headers are part of the HTTP message, which is sent through a TCP connection in string format.

Headers are appropriate for information about the request or client, while parameters are appropriate for the content of the request itself, such as some details that identify the item to be returned or saved on the web server.

To construct an HTTP request using URLComponents, the URL, HTTP method, and headers can be added using the URLRequest class. Query parameters can be added using the URLQueryItem class.

urllib module of Python

In Python, the urllib module provides classes and functions to handle URLs (Uniform Resource Locators), including making requests to web servers and parsing their responses.

The urllib.request module defines classes like Request and urlopen to make URL requests. The Request class allows you to construct an HTTP request with various parameters, such as headers, data, and request method. Once you have constructed the request, you can use the urlopen function to send it and get the response.

Here is an example of using Request and urlopen to send a GET request:

import urllib.request

url = ‘https://www.example.com’
req = urllib.request.Request(url)
response = urllib.request.urlopen(req)
print(response.read())