HTTP
HTTP
So far, most of our programs have worked with information that comes from sensors, buttons, displays, and devices connected directly to our microcontroller.
But what if we want information from the internet?
What if we want to:
- Read weather data from a website
- Send sensor readings to a cloud service
- Retrieve information from an online database
- Communicate with web applications
- Connect an IoT project to the internet
To do these things, we use HTTP.
Introduction
When you open a website in a web browser, something ha
ppens behind the scenes.
Your device sends a request asking for information.
The website receives that request and sends information back.
The same thing can happen between a D1 R32 and a web server.
D1 R32
↓
HTTP Request
↓
Web Resource
↓
HTTP Response
↓
Program
This type of communication is the foundation of the modern internet.
Every day, websites, mobile apps, games, smart devices, and cloud services use HTTP to exchange information.
What Is HTTP?
HTTP stands for:
HyperText Transfer Protocol
While the full name sounds complicated, the basic idea is simple:
HTTP is a way for computers and devices to communicate across a network.
Think of HTTP as a conversation.
Your program asks a question.
The web server sends back an answer.
Everyday Example
Imagine asking a librarian for a book.
Request
You ask:
"Can I have the science encyclopedia?"
Response
The librarian replies:
"Here it is."
HTTP works in a very similar way.
Program
↓
Request
↓
Server
↓
Response
↓
Program
Why Use HTTP?
HTTP allows your projects to communicate with systems beyond the microcontroller itself.
Examples include:
- Weather services
- Online databases
- Cloud dashboards
- Smart home systems
- IoT platforms
- Web applications
- Educational APIs
- Mobile apps
Without HTTP, your project can only work with nearby hardware.
With HTTP, your project can interact with the entire internet.
HTTP Category
[INSERT CATEGORY IMAGE HERE: HTTP Category]
Figure 12.1 - Blocks available in the HTTP category.
The HTTP category includes blocks for:
- Sending requests
- Storing responses
- Reading response information
- Retrieving text and JSON data
- Checking status codes
- Accessing headers and cookies
Understanding Requests and Responses
Before learning the blocks, it is important to understand the two most important HTTP concepts.
Request
A request is information sent from your program to a web resource.
The request may ask for information or send information.
Program
↓
Request
↓
Web Resource
Response
A response is the information returned by the web resource.
Web Resource
↓
Response
↓
Program
Complete Communication Cycle
Request
↓
Web Resource
↓
Response
Every HTTP interaction follows this pattern.
HTTP Request and Response Block
[INSERT BLOCK IMAGE HERE: HTTP Request + Response]
This block sends an HTTP request and stores the returned result inside a variable called:
responseConceptually:
Send Request
↓
Receive Response
↓
Store Response
The stored response can then be examined using other HTTP blocks.
Why Store the Response?
The response contains important information.
For example:
- Returned text
- Response status
- JSON data
- Header information
- Cookies
By saving the response, the program can use this information later.
HTTP Methods
When sending an HTTP request, one of several request methods can be selected.
Each method has a different purpose.
GET Request
urequests.get(...)GET is the most common HTTP request.
Its purpose is simple:
Request information.
Example
D1 R32
↓
GET Request
↓
Weather Website
↓
Current Temperature
Most beginner projects start with GET requests.
Beginner Rule
If you want information from the internet, start with GET.
POST Request
urequests.post(...)POST sends information to a server.
Instead of asking for information, the device provides information.
Example
Temperature Sensor
↓
POST Request
↓
Cloud Database
A sensor reading could be sent to an online dashboard for storage.
PUT Request
urequests.put(...)PUT is commonly used when updating existing information.
Example
Current Value
↓
Update Server Data
↓
Store New Value
DELETE Request
urequests.delete(...)DELETE requests are used to remove information from a server.
Example
Request
↓
Delete Data
↓
Server Removes Data
HEAD Request
urequests.head(...)A HEAD request asks for information about a resource without requesting the complete content.
This is a more advanced HTTP operation.
Students typically do not need it when first learning HTTP.
OPTION Request
urequests.option(...)The OPTION request operation is provided by Clu-Blocks Pro.
Like HEAD, it is considered more advanced and is rarely needed in beginner projects.
Recommended Learning Progression
When learning HTTP:
- Learn GET
- Read the response text
- Check the status code
- Work with JSON
- Explore POST requests
- Learn PUT and DELETE
- Explore advanced methods
Reading a Response
[INSERT BLOCK IMAGE HERE: Response Content]
Once a request has been completed, the response can be examined.
The Response Content block allows you to choose which part of the response you want.
HTTP Request
↓
Response
↓
Choose Information
Available options include:
- text
- status_code
- headers
- cookies
- content
- json
Response Text
response.textText is often the easiest type of response for beginners to understand.
Conceptually:
Website
↓
Response
↓
Text
↓
Program
Example
HTTP Request
↓
Response Text
↓
Serial Port
↓
Computer Screen
Students can immediately see the information being returned.
Response Status Code
response.status_codeThe status code tells the program whether the request was successful.
Conceptually:
Send Request
↓
Receive Response
↓
Check Status
Why Is This Important?
Imagine sending a request to a weather service.
If something goes wrong, the response may not contain the information you expected.
Checking the status code helps confirm whether the communication worked correctly.
Beginner Rule
Always check the result before assuming a request succeeded.
Response Headers
response.headersHeaders provide extra information about the response.
Examples of information commonly found in headers include:
- Content type
- Server information
- Data format
- Communication details
Headers are useful for more advanced projects.
Response Cookies
response.cookiesCookies are pieces of information associated with communication between systems.
Many websites use cookies to remember settings, preferences, or user-related information.
For beginner projects, cookies are considered an advanced topic.
Response Content
response.contentThe content option provides access to the response's raw content.
This option becomes useful when working with files, images, binary data, or more advanced communication systems.
JSON Responses
response.jsonJSON is one of the most common formats used to exchange information on the internet.
Many web APIs return information as JSON.
Example
A weather service might send:
Temperature: 22
Humidity: 65
Condition: Sunny
JSON helps organize information into a format that programs can easily understand.
Conceptual Flow
HTTP Request
↓
JSON Response
↓
Program Reads Data
↓
Display or Use Information
HTTP Requests Without Storing a Response
[INSERT BLOCK IMAGE HERE: HTTP Request]
The HTTP category also includes a request block that does not visibly save the response.
Instead of:
response = GET(...)the request is simply performed:
GET(...)When Should You Store the Response?
Store the response when you want to:
- Read returned text
- Check the status code
- Process JSON data
- Examine headers
- Access cookies
When Might You Not Store It?
In simple situations where the program only needs to trigger an action and does not need information returned.
However, most beginner HTTP projects will benefit from storing the response.
HTTP Requires a Network Connection
HTTP communication only works when a network connection is available.
The overall process is:
D1 R32
↓
Wi-Fi
↓
HTTP Request
↓
Web Resource
↓
HTTP Response
↓
Program
Without a network connection, HTTP requests cannot reach their destination.
HTTP and the Serial Port
The Serial Monitor is an excellent learning tool when working with HTTP.
A recommended beginner workflow is:
Connect to Wi-Fi
↓
Send GET Request
↓
Receive Response
↓
Display Response Text
↓
Observe Results
Using the Serial Monitor allows students to see exactly what information is being returned.
HTTP in Internet of Things (IoT) Projects
HTTP is one of the technologies that makes IoT possible.
Example:
Temperature Sensor
↓
HTTP POST
↓
Cloud Service
↓
Store Reading
Or:
Weather API
↓
HTTP GET
↓
Receive Forecast
↓
Display on OLED Screen
This allows microcontrollers to interact with online services and real-world data.
Key Distinction: Request vs Response
Students often confuse these terms.
Request
Program → Server
The program asks for something.
Response
Server → Program
The server replies.
Memory Tip
Request = Ask
Response = Answer
Key Distinction: GET vs POST
Another common point of confusion is the difference between GET and POST.
GET
I want information.
Examples:
- Weather data
- Current time
- Sensor history
- Data from a website
POST
I want to send information.
Examples:
- Sensor readings
- Form submissions
- Device updates
- IoT measurements
Key Vocabulary
| Term | Definition |
|---|---|
| HTTP | A protocol used for communication over the web |
| Request | Information sent by a program |
| Response | Information returned by a web resource |
| GET | Request information |
| POST | Send information |
| PUT | Update information |
| DELETE | Remove information |
| Response Text | Text returned by a response |
| Status Code | Indicates the result of a request |
| Header | Additional response information |
| Cookie | Information associated with communication |
| JSON | A structured format for exchanging data |
Summary
In this lesson, you learned how HTTP allows programs to communicate with web resources across a network.
You explored how to:
Send HTTP requests
Receive responses
Use GET requests
Store responses
Read text data
Check status codes
Access JSON information
Connect IoT projects to online services
HTTP is one of the most important technologies behind the internet. It enables microcontrollers, websites, mobile apps, cloud platforms, and smart devices to exchange information and work together.
Key Takeaway
HTTP allows a program to communicate with the internet by sending requests and receiving responses.
Once connected to a network, your Clu-Blocks projects can go beyond sensors and hardware, allowing them to retrieve information, share data, interact with cloud services, and become part of a larger connected world.