Azure 服务总线 API 调用示例

编程调用 Azure 服务总线的相关服务,微软有提供基于 .NET 的 dll(Nuget),也有基于 Java 的 Jar 包(Mvnrepository),另外也可以直接调用服务总线 API。这片文章就提供 Azure 服务总线 API 调用示例,以供参考。

如何从策略生成共享访问令牌

当调用服务总线 API 时,必须要提供共享访问令牌(SAS Token)作为 Authorization 头部,以作认证。那么如何生成这个 SAS Token 呢?

SAS Token 的具体构成是这样的:SharedAccessSignature sr={资源地址}&sig={签名}&se={过期时间}&skn={策略名称}

  • 资源地址:要访问资源的 URL 地址,比如 demo 命名空间下的 q1 队列 https://demo.servicebus.chinacloudapi.cn/q1

  • 签名:对由资源地址,换行符和过期时间组成的字符串用策略秘钥通过 SHA-256 哈希后生成的 Base64String。

  • 过期时间:自纪元算起,以秒为单位。

  • 策略名称:相应策略的名称。


static string createToken(string resourceUri, string keyName, string key)
{
    TimeSpan sinceEpoch = DateTime.UtcNow - new DateTime(1970, 1, 1);
    var week = 60 * 60 * 24 * 7;
    var expiry = Convert.ToString((int)sinceEpoch.TotalSeconds + week);
    string stringToSign = HttpUtility.UrlEncode(resourceUri) + "\n" + expiry;
    HMACSHA256 hmac = new HMACSHA256(Encoding.UTF8.GetBytes(key));
    var signature = Convert.ToBase64String(hmac.ComputeHash(Encoding.UTF8.GetBytes(stringToSign)));
    var sasToken = String.Format(CultureInfo.InvariantCulture, 
                "SharedAccessSignature sr={0}&sig={1}&se={2}&skn={3}", 
                HttpUtility.UrlEncode(resourceUri), 
                HttpUtility.UrlEncode(signature), 
                expiry, 
                keyName);
    return sasToken;
}

调用 API 发送消息到服务总线队列

发送消息的 API 具体描述可参照官方文档:Send Message

最关键的就是将 HTTP 请求的 Authorization 头部的值设置为根据拥有发送权限策略生成的 SAS Token。

static async Task SendMessageAsync(ServiceBusHttpMessage message, string token)
{
    var address = $"https://{serviceBusNamespace}.servicebus.chinacloudapi.cn/{queueName}/messages";

    HttpContent postContent = new ByteArrayContent(message.Body);

    // Serialize BrokerProperties. 
    var brokerProps = JsonConvert.SerializeObject(message.SystemProperties,
        Formatting.None,
        new JsonSerializerSettings { NullValueHandling = NullValueHandling.Ignore, 
            DefaultValueHandling = DefaultValueHandling.Ignore });

    postContent.Headers.Add("BrokerProperties", brokerProps);

    // Add custom properties. 
    foreach (string key in message.CustomProperties)
    {
        postContent.Headers.Add(key, message.CustomProperties.GetValues(key));
    }

    var httpClient = new HttpClient();
    httpClient.DefaultRequestHeaders.Add("Authorization", token);
    httpClient.DefaultRequestHeaders.Add("ContentType", "application/atom+xml;type=entry;charset=utf-8");

    // Send message. 
    HttpResponseMessage response = null;
    try
    {
        response = await httpClient.PostAsync($"{address}?timeout=60", postContent);
        response.EnsureSuccessStatusCode();
        Console.WriteLine("SendMessage successfully!");
    }
    catch (HttpRequestException ex)
    {
        Console.WriteLine($"SendMessage failed: {ex.Message}");
    }
    response.Dispose();
}

调用 API 从服务总线队列接收消息

ReceiveAndDelete 模式 API:Receive and Delete Message

PeekLock 模式 API:Peek-Lock Message

两者的区别在于,ReceiveAndDelete 模式消息被接收后就自动从队列中删除了,而 PeekLock 模式只是把消息锁住,然后由客户端来删除。所以两种模式的 API URI 是一致的,只是 HTTP 方法不一样,前者是 DELETE,后者是 POST。

static async Task<ServiceBusHttpMessage> ReceiveMessageAsync(string token, bool deleteMessage = true)
{
    var address = $"https://{serviceBusNamespace}.servicebus.chinacloudapi.cn/{queueName}/messages/head";

    var httpClient = new HttpClient();
    httpClient.DefaultRequestHeaders.Add("Authorization", token);

    HttpResponseMessage response = null;

    try
    {
        if (deleteMessage)
        {
            // receive and delete
            response = await httpClient.DeleteAsync($"{address}?timeout=60");
        }
        else
        {
            // peek lock
            response = await httpClient.PostAsync($"{address}?timeout=60", new ByteArrayContent(new Byte[0]));
        }

        response.EnsureSuccessStatusCode();
        Console.WriteLine($"ReceiveMessage successfully!");
    }
    catch (HttpRequestException ex)
    {
        Console.WriteLine($"ReceiveMessage failed: {ex.Message}");
        return null;
    }

    var message = await ResolveMessageFromResponse(response);
    response.Dispose();
    return message;
}

完整代码:SBRestApiDemo

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