IIS 7.0 模組化架構與端到端擴展性實作

IIS 7.0 核心架構革新

IIS 7.0 採用全模組化架構，所有功能（靜態檔案服務、驗證、壓縮、ASP.NET 執行）皆為可替換的模組。請求處理管線整合 ASP.NET，使 managed code 可參與所有請求階段，不限於 .aspx 檔案。

兩種模組開發路徑

Managed 模組開發實作：回應修改模組

1. 實作 IHttpModule

public class ResponseModifierModule : IHttpModule {
    public void Init(HttpApplication context) {
        context.ReleaseRequestState += OnReleaseRequestState;
    }

    private void OnReleaseRequestState(object sender, EventArgs e) {
        HttpApplication app = (HttpApplication)sender;
        HttpResponse response = app.Response;
        
        // 僅處理 HTML 回應
        if (response.ContentType?.StartsWith("text/html") == true) {
            response.Filter = new ResponseModifierStream(response.Filter, GetRules());
        }
    }

    private List GetRules() {
        // 從設定檔讀取替換規則
        return ConfigurationManager.GetSection("responseModifier/rules") as List;
    }

    public void Dispose() { }
}

2. 自訂 Stream 進行內容替換

public class ResponseModifierStream : Stream {
    private readonly Stream _baseStream;
    private readonly List _rules;
    private readonly MemoryStream _buffer = new MemoryStream();

    public ResponseModifierStream(Stream baseStream, List rules) {
        _baseStream = baseStream;
        _rules = rules;
    }

    public override void Write(byte[] buffer, int offset, int count) {
        _buffer.Write(buffer, offset, count);
    }

    public override void Close() {
        _buffer.Position = 0;
        using (var reader = new StreamReader(_buffer, Encoding.UTF8)) {
            string html = reader.ReadToEnd();
            
            // 套用所有替換規則
            foreach (var rule in _rules) {
                html = Regex.Replace(html, rule.Pattern, rule.Replacement, rule.Options);
            }
            
            byte[] data = Encoding.UTF8.GetBytes(html);
            _baseStream.Write(data, 0, data.Length);
        }
        _baseStream.Close();
    }
    // 其他 Stream 抽象方法轉給 _baseStream...
}

自定義設定區段與 IIS Manager 整合

1. 定義設定區段

<configSections>
    <section name="responseModifier" 
             type="ResponseModifier.Configuration.ResponseModifierSection, ResponseModifier" />
</configSections>

<responseModifier>
    <rules>
        <add pattern="<!--\s*DEBUG\s*-->" replacement="" 
           options="IgnoreCase" description="移除 DEBUG 註解" />
        <add pattern="https://oldsite\.com" replacement="https://newsite.com" 
           description="網域遷移" />
        <add pattern="</body>" replacement="<script src='/tracking.js'></script></body>" 
           description="植入追蹤碼" />
    </rules>
</responseModifier>

2. 設定區段類別

public class ResponseModifierSection : ConfigurationSection {
    [ConfigurationProperty("rules")]
    public ReplaceRuleCollection Rules => (ReplaceRuleCollection)this["rules"];
}

[ConfigurationCollection(typeof(ReplaceRule), AddItemName = "add")]
public class ReplaceRuleCollection : ConfigurationElementCollection {
    protected override ConfigurationElement CreateNewElement() => new ReplaceRule();
    protected override object GetElementKey(ConfigurationElement element) 
        => ((ReplaceRule)element).Pattern;
}

public class ReplaceRule : ConfigurationElement {
    [ConfigurationProperty("pattern", IsRequired = true)]
    public string Pattern => (string)this["pattern"];
    
    [ConfigurationProperty("replacement", IsRequired = true)]
    public string Replacement => (string)this["replacement"];
    
    [ConfigurationProperty("options", DefaultValue = RegexOptions.None)]
    public RegexOptions Options => (RegexOptions)this["options"];
    
    [ConfigurationProperty("description")]
    public string Description => (string)this["description"];
}

IIS Manager 管理介面開發

1. 模組註冊 (web.config 或 applicationHost.config)

<system.webServer>
    <modules>
        <add name="ResponseModifier" 
             type="ResponseModifier.ResponseModifierModule, ResponseModifier" 
             preCondition="managedHandler" />
    </modules>
</system.webServer>

2. 建立 IIS Manager UI 模組

• 參考 Microsoft.Web.Management.dll
• 實作 IModule、IModuleProvider
• 使用 WinForms/WPF 建立規則編輯介面
• 透過 ConfigurationService 讀寫設定

部署策略

效能最佳化建議

1. 非同步模組：實作 IHttpAsyncHandler 避免阻塞執行緒
2. 快取編譯規則：Regex 物件建立成本高，啟動時預編譯並快取
3. 限制處理範圍：透過 preCondition 或程式碼判斷 Content-Type、URL 路徑
4. 串流處理：大型回應使用串流式替換，避免完整緩衝到記憶體
5. 監控指標：記錄處理耗時、替換次數、錯誤率至 ETW/EventLog

遷移自 ISAPI Filter/Extension 的關鍵點

• ISAPI Filter → IHttpModule (事件模型相似)
• ISAPI Extension → IHttpHandler + 路由對應
• 原生 C++ 程式碼可透過 P/Invoke 或 C++/CLI 混合模組重用
• 註冊方式從註冊表改為 system.webServer/modules