HTTP requests and responses have specific structures to help facilitate the exchange of information between a client and a server. These structures encapsulate all of the important information required to instruct the recipient of the message on how to react.
Requests
Requests are comprised of a few core elements that provide information to a server. The core elements that can be expected are:
1) HTTP Method: The HTTP method is usually a verb, such as GET and POST, or a noun such as OPTIONS and HEAD. These methods inform the server of the intent of the request and are used in accurately routing and processing requests. For instance, an HTTP request containing a GET method implies that the client wants to fetch a resource. The list of supported HTTP methods can be found using the http.METHODS property.
2) Path: The path denotes the path of the resource relative to the root URL. For example, making a GET request to https://codecademy.com/api/lessons would strip common elements such as the protocol (https://) and domain (codecademy.com), leaving the path of /api/lessons.
3) HTTP Protocol Version: The version of the HTTP protocol (I.e. HTTP/1.1, HTTP/2, and HTTP/3). We will learn more about this in the next exercise.
4) Headers: Headers are optional and are used to convey additional information that may be important in processing a request by a server. There is an extensive list of standard headers that can be used, as well as custom headers that can be added on a per-application basis.
5) Body: The body contains data required to be sent to the server to process a request. The body is not leveraged for all request types. It is most common to see a body attached to requests with verbs such as POST, PUT, and PATCH.
Responses
Responses are comprised of similar elements to their counterpart requests, with a few differences. The core elements that can be expected in a response are:
1) HTTP Protocol Version: The version of the HTTP protocol, similar to the request.
2) Status Code: The status code indicates if the request was successful and, if not, why it wasn’t successful.
3) Status Message: The status message provides a short description of the corresponding status code.
4) Headers: These response headers are similar to those provided in a request.
5) Body: The body of a response contains data corresponding to the fetched resource. The body is optional and contains data only when necessary to fulfill the request.
Instructions
Visit the same website you visited in the previous exercise. Open the “Network” tab in the developer console once again, but this time further inspect the details of a few of the requests. Try to identify the core parts of their message structure for both the request and corresponding response. Make sure to inspect a few different types of requests if possible to see the differences (i.e. GET, POST, etc.).
What types of requests might you see?
You can further inspect the details of a request by clicking on it from the list of requests in the network tab and viewing the corresponding data in the pane to the right.
