@startuml
skinparam dpi 100
skinparam classFontSize 8
skinparam classFontName Helvetica
autonumber

box "Application" #LightGreen
    participant "Application" as application
end box

box "Third-party \n Library" #LightPink
    participant "http-parser" as parser
end box

box "Libraries" #LightBlue
    participant "HTTP Client" as http
    participant "JSON Client" as json
    participant "SigV4 Client" as sigv4
end box

box "HTTP Server" #Yellow
    participant "HTTP Server" as server
end box

activate application

application -> parser : Parse configured AWS IOT Credential provider URL to extract\n AWS IOT credential provider host address
activate parser
parser -> application : Return AWS IOT credential provider server host address
deactivate parser

loop until session established or all attempts exhausted
application -> server : Establish TLS session to AWS IOT credential provider server\n (client verifies server's certificate)
server -> application : Session established (no client authentication)
end

application -> parser : Parse configured AWS IOT Credential provider URL to extract\n URL path
activate parser
parser -> application : Return path string with request-URI
deactivate parser

application -> application: Set request info parameters
application -> http: Initialize request headers\n (HTTPClient_InitializeRequestHeaders)
activate http
http -> application : Write request headers to user-provided buffer
deactivate http

application -> http : Send HTTP GET request (HTTPClient_Send)
activate http
http -> server: Send payload of request through transport interface
http -> application : Write response to user-provided buffer
deactivate http

application -> json: Parse response to obtain temporary credentials
activate json
json-> application  : Write parsed temporary credentials to the user buffer
deactivate json

application -> http: Parse date header from response to obtain date
activate http
http -> application : Write parsed date to the user provide buffer
deactivate http

application -> sigv4: Convert Date retrieved to ISO8601 format
activate sigv4
http -> application : Write formatted date to the user provide buffer
deactivate sigv4

application -> server: End TLS session and disconnect from server

application -> parser : Parse configured AWS S3 URL to extract\n S3 host address
activate parser
parser -> application : Return server host address
deactivate parser

loop until session established or all attempts exhausted
application -> server : Establish TLS session\n (client verifies server's certificate)
server -> application : Session established (no client authentication)
end

application -> parser : Parse configured AWS S3 URL to extract\n URL path
activate parser
parser -> application : Return path string with request-URI
deactivate parser

application -> application: Set request info parameters
application -> application: Set sigv4 parameters
activate sigv4
application -> sigv4: Generate HTTP Authorization header (Sigv4_GenerateHTTPAuthorization)
sigv4 -> application : Write HTTP Authorization header to user-provided buffer
deactivate sigv4
application -> http: Initialize request headers\n (HTTPClient_InitializeRequestHeaders)
activate http
http -> application : Write request headers to user-provided buffer
deactivate http

application -> http : Send HTTP GET request (HTTPClient_Send)
activate http
http -> server: Send payload of request through transport interface
http -> application : Write response to user-provided buffer
deactivate http
application -> application: Parse content-range\n header from response to obtain file size

loop until entire file is downloaded
activate sigv4
application -> sigv4: Generate HTTP Authorization header (Sigv4_GenerateHTTPAuthorization)
sigv4 -> application : Write HTTP Authorization header to user-provided buffer
deactivate sigv4
application -> http: Initialize request headers\n (HTTPClient_InitializeRequestHeaders)
activate http
http -> application : Write request headers to user-provided buffer
deactivate http
application -> http: Add range header\n (HTTPClient_AddRangeHeader)
activate http
http -> application : Add range header to user-provided buffer
deactivate http
application -> http : Send HTTP GET request (HTTPClient_Send)\n to download requested bytes of the file
activate http
http -> server: Send payload of request through transport interface
http -> application : Write response to user-provided buffer
deactivate http
application -> application: Log response from contents of buffer
end

application -> server: End TLS session and disconnect from server

deactivate application
@enduml