cHttpClient Component Overview

Introduction

cHttpClient is an HTTP client component based on WinHTTP that provides complete HTTP request functionality, supporting sync/async requests, chainable calls, JSON processing, Cookie management, and more. Also provides cSSEClient for SSE (Server-Sent Events) real-time message reception.

Features

Feature	Description
HTTP Methods	Supports GET/POST/PUT/DELETE/OPTIONS
Data Formats	JSON, Form-UrlEncoded, Text auto-processing
Sync/Async	Supports sync and async request modes
Chainable API	Fluent API design with chainable operations
Cookie Management	Auto parse and set Cookies
SSL Support	Auto ignore SSL certificate errors
Encoding	Supports UTF-8 encoding auto-conversion
Debug Mode	Provides detailed request/response debug info
SSE Support	Independent SSE client for real-time messages

Quick Start

HTTP GET Request

Dim http As New cHttpClient
Dim result As String

' Simple GET request
result = http.SendGet("https://api.example.com/users").ReturnText()

' GET request with query parameters
result = http.SendGet("https://api.example.com/users") _
    .AddQueryParam("page", "1") _
    .AddQueryParam("limit", "10") _
    .ReturnText()

HTTP POST Request (JSON)

Dim http As New cHttpClient
Dim json As cJson
Set json = New cJson
json.AddItem "name", "John"
json.AddItem "age", 25

Set http.RequestDataJson = json

Dim response As cJson
Set response = http.SendPost("https://api.example.com/users").ReturnJson()

HTTP POST Request (Form)

Dim http As New cHttpClient

http.RequestDataForm("username") = "admin"
http.RequestDataForm("password") = "123456"

Dim result As String
result = http.SendPost("https://api.example.com/login").ReturnText()

Async Request

Private WithEvents HttpClient As cHttpClient

Private Sub StartAsyncRequest()
    Set HttpClient = New cHttpClient
    HttpClient.Async(True).SendGet("https://api.example.com/data")
End Sub

Private Sub HttpClient_OnResponseFinished()
    Debug.Print "Response complete: " & HttpClient.ReturnText()
End Sub

Private Sub HttpClient_OnError(ByVal ErrorNumber As Long, ByVal ErrorDescription As String)
    Debug.Print "Error: " & ErrorDescription
End Sub

SSE (Server-Sent Events)

Private WithEvents SSE As cSSEClient

Private Sub InitializeSSE()
    Set SSE = New cSSEClient
    SSE.AutoReconnect = True
    SSE.ReconnectInterval = 3000  ' 3 second reconnect interval
    SSE.MaxReconnectAttempts = 10
    Call SSE.Connect("https://api.example.com/events")
End Sub

Private Sub SSE_OnOpen()
    Debug.Print "SSE connection established"
End Sub

Private Sub SSE_OnMessage(EventName As String, Data As String, Id As String)
    Debug.Print "Received message: " & EventName & " = " & Data
End Sub

Private Sub SSE_OnError(Description As String, ErrorNumber As Long)
    Debug.Print "SSE error: " & Description
End Sub

Private Sub SSE_OnClose()
    Debug.Print "SSE connection closed"
End Sub

References

• Microsoft WinHTTP Services, version 5.1
• Microsoft Scripting Runtime
• cJson.cls
• cTimer.cls (required for SSE)

File Structure

File	Description
cHttpClient.cls	HTTP client main class
cSSEClient.cls	SSE client implementation
mSSEDemo.bas	SSE usage example
SSE_Client_使用文档.md	SSE detailed documentation

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Last Updated: 2026-05-17