VBMAN Middleware and Client Communication Example

Overview

This example demonstrates how to build a web server with middleware using the VBMAN framework, and how to implement client-server communication. The example includes advanced features such as authentication middleware.

Project Structure

MiddleWare/
  ├── server/                # Server-side project
  │   ├── Form1.frm         # Server main form
  │   ├── DataServer.vbp    # Server project file
  │   └── include/          # Server-side class libraries
  │       ├── bWcs.cls      # Business processing class
  │       ├── mAuth.cls     # Authentication middleware
  │       ├── Config.bas    # Configuration module
  │       └── ToolsHttp.bas # HTTP utility module
  └── client/               # Client project
      ├── Client.frm        # Client main form
      ├── DataClient.vbp    # Client project file
      └── include/          # Client-side class libraries
          ├── cHttpClient.cls # HTTP client class
          ├── bTaskSend.cls  # Task sending class
          ├── bTaskLog.cls   # Task logging class
          └── cJson.cls      # JSON processing class

Core Code Analysis

1. Server-side Middleware Configuration (Form1.frm)

'Server initialization
Dim HttpServer As New VBMANLIB.cHttpServer

Private Sub Form_Load()
    With HttpServer
        'Register business class
        .Router.Reg "Wcs", New bWcs
        
        'Configure pre-middleware for authentication check
        .Router.Before.Add "/*", New mAuth
        
        'Start server
        .Start 800
    End With
End Sub

2. Authentication Middleware (mAuth.cls)

Public Sub Execute(ctx As cHttpServerContext)
    'Get authentication information
    Dim token As String: token = ctx.Request.Headers("Authorization")
    
    'Terminate request on authentication failure
    If Not IsValidToken(token) Then
        ctx.Response.State401 "Unauthorized"
        ctx.Abort
    End If
End Sub

3. Client Request Sending (Client.frm)

Private Sub SendTask()
    With New cHttpClient
        'Set request headers
        .RequestHeaders.Add "Authorization", "Bearer " & token
        .RequestHeaders.Add "Content-Type", "application/json"
        
        'Send request
        Dim response As String
        response = .Fetch(ReqPost, "http://localhost:800/wcs/task", jsonData)
        
        'Handle response
        Debug.Print .ReturnJson().Encode(, 2)
    End With
End Sub

Feature Description

1. Middleware System

   • Support for pre-middleware (Before)
   • Support for post-middleware (After)
   • Support for middleware chain calls
   • Support for request interception and termination

2. Authentication

   • Token authentication mechanism
   • Request header validation
   • Configurable validation rules
   • Unified error handling

3. Client Functionality

   • HTTP request encapsulation
   • Header management
   • JSON data processing
   • Response handling

Technical Points

1. Implementation of middleware mechanism
2. Encapsulation of HTTP communication
3. Unified handling of authentication
4. Client-server interaction

Use Cases

1. Web APIs requiring authentication
2. Distributed system communication
3. Microservice architecture
4. Business system integration

Extension Suggestions

1. Add more types of middleware
2. Implement request rate limiting
3. Add data validation middleware
4. Implement caching middleware
5. Add logging middleware