<h2 id="asynchronous-operations">Asynchronous Operations</h2>
Certain types of operations might require processing of the request in an asynchronous manner (e.g. validating a bank account, processing an image, etc.) in order to avoid long delays on the client side and prevent long-standing open client connections waiting for the operations to complete. For such use cases, APIs MUST employ the following pattern:
For POST
requests:
202 Accepted
HTTP response code.GET
request to that URI in order to obtain the completed resource. Until the resource is ready, the final URI SHOULD return the HTTP status code 404 Not Found
.`{ "rel": "self", "href": "/v1/namespace/resources/{resource_id}", "method": "GET" }`
* A temporary request queue URI where the status of the operation may be obtained via some temporary identifier. Clients SHOULD make an HTTP `GET` request to obtain the status of the operation which MAY include such information as completion state, ETA, and final URI once it is completed.
`{ "rel": "self", "href": "/v1/queue/requests/{request_id}, "method": "GET" }"`
For PUT
/PATCH
/DELETE
/GET
requests:
Like POST
, you can support PUT/PATCH
/DELETE
/GET
to be asynchronous. The behaviour would be as follows:
202 Accepted
HTTP response code.GET
request to obtain the status of the operation which MAY include such information as completion state, ETA, and final URI once it is completed.
`{ "rel": "self", "href": "/v1/queue/requests/{request_id}, "method": "GET" }"`
APIs that support both synchronous and asynchronous processing for an URI:
APIs that support both synchronous and asynchronous operations for a particular URI and an HTTP method combination, MUST recognize the Prefer
header and exhibit following behavior:
Prefer=respond-async
header, the service MUST switch the processing to asynchronous mode. Prefer=respond-async
header, the service MUST process the request synchronously.It is desirable that all APIs that implement asynchronous processing, also support webhooks as a mechanism of pushing the processing status to the client.
资料引自:paypal/API Design Patterns And Use Cases:asynchronous-operations
好像也没什么讲了....
全文结束吧.
时序图大概长这样:
RequestService.cs
// RequestService.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using CorrelationId;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json.Linq;
using StackExchange.Redis;
using static StackExchange.Redis.RedisChannel;
namespace MTQueue.Service
{
public class RequestService
{
private readonly ICorrelationContextAccessor _correlationContext;
private readonly ConnectionMultiplexer _redisMultiplexer;
private readonly IServiceProvider _services;
private readonly ILogger<RequestService> _logger;
public RequestService(ICorrelationContextAccessor correlationContext,
ConnectionMultiplexer redisMultiplexer, IServiceProvider services,
ILogger<RequestService> logger)
{
_correlationContext = correlationContext;
_redisMultiplexer = redisMultiplexer;
_services = services;
_logger = logger;
}
public long? AddRequest(JToken data)
{
var requestId = _correlationContext.CorrelationContext.CorrelationId;
var redisDB = _redisMultiplexer.GetDatabase(CommonConst.DEFAULT_DB);
var index = redisDB.SortedSetRank(CommonConst.REQUESTS_SORT_SETKEY, requestId);
if (index == null)
{
data["requestId"] = requestId;
redisDB.SortedSetAdd(CommonConst.REQUESTS_SORT_SETKEY, requestId, GetTotalSeconds());
PushRedisMessage(data.ToString());
}
return redisDB.SortedSetRank(CommonConst.REQUESTS_SORT_SETKEY, requestId);
}
public static long GetTotalSeconds()
{
return (long)(DateTime.Now.ToLocalTime() - new DateTime(1970, 1, 1).ToLocalTime()).TotalSeconds;
}
private void PushRedisMessage(string message)
{
Task.Run(() =>
{
try
{
using (var scope = _services.CreateScope())
{
var multiplexer = scope.ServiceProvider.GetRequiredService<ConnectionMultiplexer>();
multiplexer.GetSubscriber().PublishAsync(CommonConst.REQUEST_CHANNEL, message);
}
}
catch (Exception ex)
{
_logger.LogError(-1, ex, message);
}
});
}
public Tuple<JToken, long?> GetRequest(string requestId)
{
var redisDB = _redisMultiplexer.GetDatabase(CommonConst.DEFAULT_DB);
var keyIndex = redisDB.SortedSetRank(CommonConst.REQUESTS_SORT_SETKEY, requestId);
var response = redisDB.StringGet(requestId);
if (response.IsNull)
{
return Tuple.Create<JToken, long?>(default(JToken), keyIndex);
}
return Tuple.Create<JToken, long?>(JToken.Parse(response), keyIndex);
}
}
}
// RedisMQListener.cs
using System;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using MTQueue.Model;
using MTQueue.Service;
using Newtonsoft.Json.Linq;
using StackExchange.Redis;
using static StackExchange.Redis.RedisChannel;
namespace MTQueue.Listener
{
public class RedisMQListener : IHostedService
{
private readonly ConnectionMultiplexer _redisMultiplexer;
private readonly IServiceProvider _services;
private readonly ILogger<RedisMQListener> _logger;
public RedisMQListener(IServiceProvider services, ConnectionMultiplexer redisMultiplexer,
ILogger<RedisMQListener> logger)
{
_services = services;
_redisMultiplexer = redisMultiplexer;
_logger = logger;
}
public Task StartAsync(CancellationToken cancellationToken)
{
Register();
return Task.CompletedTask;
}
public virtual bool Process(RedisChannel ch, RedisValue message)
{
_logger.LogInformation("Process start,message: " + message);
var redisDB = _services.GetRequiredService<ConnectionMultiplexer>()
.GetDatabase(CommonConst.DEFAULT_DB);
var messageJson = JToken.Parse(message);
var requestId = messageJson["requestId"]?.ToString();
if (string.IsNullOrEmpty(requestId))
{
_logger.LogWarning("requestId not in message.");
return false;
}
var mtAgent = _services.GetRequiredService<ZhihuClient>();
var text = mtAgent.GetZhuanlan(messageJson);
redisDB.StringSet(requestId, text.ToString(), CommonConst.RESPONSE_TS);
_logger.LogInformation("Process finish,requestId:" + requestId);
redisDB.SortedSetRemove(CommonConst.REQUESTS_SORT_SETKEY, requestId);
return true;
}
public void Register()
{
var sub = _redisMultiplexer.GetSubscriber();
var channel = CommonConst.REQUEST_CHANNEL;
sub.SubscribeAsync(channel, (ch, value) =>
{
Process(ch, value);
});
}
public void DeRegister()
{
// this.connection.Close();
}
public Task StopAsync(CancellationToken cancellationToken)
{
// this.connection.Close();
return Task.CompletedTask;
}
}
}
// RequestsController.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using CorrelationId;
using Microsoft.AspNetCore.Mvc;
using MTQueue.Service;
using Newtonsoft.Json.Linq;
namespace MTQueue.Controllers
{
[Route("v1/[controller]")]
[ApiController]
public class RequestsController : ControllerBase
{
private readonly ICorrelationContextAccessor _correlationContext;
private readonly RequestService _requestService;
private readonly ZhihuClient _mtAgentClient;
public RequestsController(ICorrelationContextAccessor correlationContext,
RequestService requestService, ZhihuClient mtAgentClient)
{
_correlationContext = correlationContext;
_requestService = requestService;
_mtAgentClient = mtAgentClient;
}
[HttpGet("{requestId}")]
public IActionResult Get(string requestId)
{
var result = _requestService.GetRequest(requestId);
var resource = $"/v1/requests/{requestId}";
if (result.Item1 == default(JToken))
{
return NotFound(new { rel = "self", href = resource, method = "GET", index = result.Item2 });
}
return Ok(result.Item1);
}
[HttpPost]
public IActionResult Post([FromBody] JToken data, [FromHeader(Name = "Prefer")]string prefer)
{
if (!string.IsNullOrEmpty(prefer) && prefer == "respond-async")
{
var index = _requestService.AddRequest(data);
var requestId = _correlationContext.CorrelationContext.CorrelationId;
var resource = $"/v1/requests/{requestId}";
return Accepted(resource, new { rel = "self", href = resource, method = "GET", index = index });
}
return Ok(_mtAgentClient.GetZhuanlan(data));
}
}
}
原创声明:本文系作者授权腾讯云开发者社区发表,未经许可,不得转载。
如有侵权,请联系 cloudcommunity@tencent.com 删除。
原创声明:本文系作者授权腾讯云开发者社区发表,未经许可,不得转载。
如有侵权,请联系 cloudcommunity@tencent.com 删除。