WebView2 CDP Sync Demo - Pure Synchronous CDP Calls

Overview

The CDP Sync demo is a simplified version of the CDP demo, using only synchronous CDP calling mode. Since no event callback handling is needed, the simpler Dim wv As New declaration can be used.

Project Structure

Download Source [ Note: Re-register the DLL file in the bin directory ]

Source code is available in the VBMAN2 project's demos/webview2/cdpSync directory.

cdpSync/
  ├── Form1.frm              # Main form, containing synchronous CDP calls
  ├── vbman2_webview2.vbp    # VB6 project file
  └── vbman2_webview2.vbw    # VB6 workspace file

Core Code Walkthrough

1. Declaration and Initialization (Form1.frm)

Dim wv As New cWebView2Host

Private Sub Form_Load()
    wv.Initialize Me.hWnd, "https://vb6.pro"
End Sub

Note: Uses Dim wv As New for auto-instantiation; synchronous mode doesn't need WithEvents.

2. Pure Synchronous CDP Calls

Private Sub MenuSendCDP_Click()
    ' Execute multiple synchronous CDP calls sequentially
    Dim sTitle As String
    sTitle = wv.CallDevToolsProtocolMethodSync( _
        "Runtime.evaluate", _
        "{""expression"":""document.title""}")
    Debug.Print "[Sync] Title -> " & sTitle
    
    Dim sCookies As String
    sCookies = wv.CallDevToolsProtocolMethodSync( _
        "Network.getCookies", _
        "{}")
    Debug.Print "[Sync] Cookies -> " & sCookies
    
    Dim sUrl As String
    sUrl = wv.CallDevToolsProtocolMethodSync( _
        "Runtime.evaluate", _
        "{""expression"":""document.URL""}")
    Debug.Print "[Sync] URL -> " & sUrl
    
    Dim sVersion As String
    sVersion = wv.CallDevToolsProtocolMethodSync( _
        "Browser.getVersion", _
        "{}")
    Debug.Print "[Sync] Version -> " & sVersion
    
    MsgBox "Title: " & sTitle, vbInformation, "CDP Sync Demo"
End Sub

Feature Description

1. Pure Synchronous CDP Calls

   • All CallDevToolsProtocolMethodSync calls block waiting for results
   • Return values are directly usable, no event handling required

2. Simplified Code Structure

   • No WithEvents declaration needed
   • No event handler functions needed
   • Code logic is linear and straightforward

3. CDP Methods Demonstrated

   • Runtime.evaluate: Execute JS and get return value
   • Network.getCookies: Get cookie information
   • Browser.getVersion: Get browser version

Technical Notes

1. Synchronous vs Asynchronous Choice: Synchronous calls are simpler and more direct, but block the current thread. For fast operations (millisecond-level returns), synchronous mode is preferable
2. No WithEvents Needed: Synchronous mode doesn't use event callbacks; can use Dim wv As New for simplified declaration
3. Sequential Execution: Multiple synchronous calls execute in order; each subsequent call starts only after the previous one completes

Use Cases

1. Quick retrieval of page information (title, URL, cookies)
2. Debugging and diagnostic tools
3. Simple CDP integration without time-consuming operations

Extension Suggestions

1. If you need time-consuming CDP operations (e.g., screenshots), refer to the cdp demo and switch to async mode
2. Commonly used CDP calls can be encapsulated as VB6 helper functions to reduce repetitive code