為了防止并發(fā)對(duì)數(shù)據(jù)修改造成差異，dapr使用了etag標(biāo)簽來(lái)作為版本號(hào)，對(duì)數(shù)據(jù)修改進(jìn)行驗(yàn)證。

下面是對(duì)etag的一個(gè)demo

appsettings.json中的url配置

"StateUrl": "http://localhost:3500/v1.0/state/statestore"

在PaymentSystem項(xiàng)目中添加兩個(gè)action

[HttpPost("/writekeyswithetag")]public async Task<IActionResult> WriteKeysWithEtag([FromBody] KeyEntityWithEtag[] keys){var client = _clientFactory.CreateClient();var jsonContent = System.Text.Json.JsonSerializer.Serialize(keys);var?content?=?new?StringContent(jsonContent);var response = await client.PostAsync(_stateUrl, content);return Ok(await response.Content.ReadAsStringAsync());}[HttpGet("/readekeywithetag/{key}")]public async Task<IActionResult> ReadKeyWithEtag(string key){var client = _clientFactory.CreateClient();var?response?=?await?client.GetAsync($"{_stateUrl}/{key}");??????var dataString = await response.Content.ReadAsStringAsync();var data = (string.IsNullOrEmpty(dataString) ? null : System.Text.Json.JsonSerializer.Deserialize<OrderPayment>(dataString));return new JsonResult(new { result = true, data = new { data = data, etag = response.Headers.SingleOrDefault(s => s.Key.ToLower() == "etag") }, host = Dns.GetHostName() });}

實(shí)體類

public class OrderPayment {public string PayOrder { get; set; }public decimal PayTotal { get; set; }public string PayType { get; set; }public DateTime PayTime { get; set; } } public class KeyEntityWithEtag {public string Key { get; set; }public OrderPayment Value { get; set; }public string Etag { get; set; } }

docker-compose.yml

version: '3.4'services:#┌─────────────────────────┐#│ Dapr placement1 service │#└─────────────────────────┘ placement:image: "daprio/dapr"command: ["./placement", "-port", "50006"]ports:- "50006:50006"networks:- b2c-dapr#┌────────────────────┐#│ Redis1 state store │#└────────────────────┘ redis:image: "redis:latest"ports:- "6380:6379"networks:- b2c-dapr#┌───────────────────────────────────┐#│ paymentsystem1 app + Dapr sidecar │#└───────────────────────────────────┘ paymentsystem1:image: ${DOCKER_REGISTRY-}paymentsystemdepends_on:- redis- placementbuild:context: ../dockerfile: /PaymentSystem/Dockerfileports:- "3601:3500"volumes: - ../PaymentSystem:/PaymentSystem networks:- b2c-dapr paymentsystem1-dapr:image: "daprio/daprd:latest"command: [ "./daprd", "-app-id", "pay", "-app-port", "80","-placement-host-address", "placement:50006","-components-path","/components" ]build:context: ../depends_on:- paymentsystem1network_mode: "service:paymentsystem1"volumes: - ../components:/components #┌───────────────────────────────────┐#│ paymentsystem2 app + Dapr sidecar │#└───────────────────────────────────┘ paymentsystem2:image: ${DOCKER_REGISTRY-}paymentsystemdepends_on:- redis- placement build:context: ../dockerfile: /PaymentSystem/Dockerfilevolumes: - ../PaymentSystem:/PaymentSystem ports:- "3602:3500"networks:- b2c-dapr paymentsystem2-dapr:image: "daprio/daprd:latest"command: [ "./daprd", "-app-id", "pay", "-app-port", "80" ,"-placement-host-address", "placement:50006","-components-path","/components"]build:context: ../depends_on:- paymentsystem2network_mode: "service:paymentsystem2"volumes: - ../components:/components networks:b2c-dapr:

提交帶有etag標(biāo)簽的數(shù)據(jù)，多提交幾次，可以把etag頂起來(lái)

查看etag為非1

這時(shí)再次提交就會(huì)報(bào)錯(cuò)，如果另外的服務(wù)更新了這個(gè)值，本次提交就會(huì)失敗，需要再次查詢后更新，或作別的業(yè)務(wù)邏輯處理。

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