函数计算怎么调用函数

调用类型


您可以采用两种同步和异步两种方式调用函数。

• 同步调用：事件被函数处理后再将结果返回。
• 异步调用：事件在写入到消息队列后则返回。函数计算系统会保证该消息被可靠的处理。
• 同步/异步请求对传入的事件有不同的限制，具体请参考限制项文档。

您可以通过控制台/命令行工具的方式，手动调用函数，具体请参考快速入门中的 相关示例；也可通过 REST API 的方式调用函数，具体请参考 相关文档。我们也提供了各种语言的 SDK，进一步简化您的操作。下例是 Java SDK 的调用示例：

1. [backcolor=transparent]public[backcolor=transparent] [backcolor=transparent]class[backcolor=transparent] [backcolor=transparent]FcSample[backcolor=transparent] [backcolor=transparent]{
2. [backcolor=transparent]    [backcolor=transparent]private[backcolor=transparent] [backcolor=transparent]static[backcolor=transparent] [backcolor=transparent]final[backcolor=transparent] [backcolor=transparent]String[backcolor=transparent] CODE_DIR [backcolor=transparent]=[backcolor=transparent] [backcolor=transparent]"/tmp/fc_code"[backcolor=transparent];
3. [backcolor=transparent]    [backcolor=transparent]private[backcolor=transparent] [backcolor=transparent]static[backcolor=transparent] [backcolor=transparent]final[backcolor=transparent] [backcolor=transparent]String[backcolor=transparent] REGION [backcolor=transparent]=[backcolor=transparent] [backcolor=transparent]"cn-shanghai"[backcolor=transparent];
4. [backcolor=transparent]    [backcolor=transparent]private[backcolor=transparent] [backcolor=transparent]static[backcolor=transparent] [backcolor=transparent]final[backcolor=transparent] [backcolor=transparent]String[backcolor=transparent] SERVICE_NAME [backcolor=transparent]=[backcolor=transparent] [backcolor=transparent]"test_service"[backcolor=transparent];
5. [backcolor=transparent]    [backcolor=transparent]private[backcolor=transparent] [backcolor=transparent]static[backcolor=transparent] [backcolor=transparent]final[backcolor=transparent] [backcolor=transparent]String[backcolor=transparent] FUNCTION_NAME [backcolor=transparent]=[backcolor=transparent] [backcolor=transparent]"test_function"[backcolor=transparent];
7. [backcolor=transparent]    [backcolor=transparent]public[backcolor=transparent] [backcolor=transparent]static[backcolor=transparent] [backcolor=transparent]void[backcolor=transparent] main[backcolor=transparent]([backcolor=transparent]final[backcolor=transparent] [backcolor=transparent]String[backcolor=transparent][][backcolor=transparent] args[backcolor=transparent])[backcolor=transparent] [backcolor=transparent]throws[backcolor=transparent] [backcolor=transparent]IOException[backcolor=transparent] [backcolor=transparent]{
8. [backcolor=transparent]        [backcolor=transparent]String[backcolor=transparent] accessKey [backcolor=transparent]=[backcolor=transparent] [backcolor=transparent]System[backcolor=transparent].[backcolor=transparent]getenv[backcolor=transparent]([backcolor=transparent]"ACCESS_KEY"[backcolor=transparent]);
9. [backcolor=transparent]        [backcolor=transparent]String[backcolor=transparent] accessSecretKey [backcolor=transparent]=[backcolor=transparent] [backcolor=transparent]System[backcolor=transparent].[backcolor=transparent]getenv[backcolor=transparent]([backcolor=transparent]"SECRET_KEY"[backcolor=transparent]);
10. [backcolor=transparent]        [backcolor=transparent]String[backcolor=transparent] accountId [backcolor=transparent]=[backcolor=transparent] [backcolor=transparent]System[backcolor=transparent].[backcolor=transparent]getenv[backcolor=transparent]([backcolor=transparent]"ACCOUNT_ID"[backcolor=transparent]);
11. [backcolor=transparent]        [backcolor=transparent]String[backcolor=transparent] role [backcolor=transparent]=[backcolor=transparent] [backcolor=transparent]System[backcolor=transparent].[backcolor=transparent]getenv[backcolor=transparent]([backcolor=transparent]"ROLE"[backcolor=transparent]);
13. [backcolor=transparent]        [backcolor=transparent]// Initialize FC client
14. [backcolor=transparent]        [backcolor=transparent]FunctionComputeClient[backcolor=transparent] fcClient [backcolor=transparent]=[backcolor=transparent] [backcolor=transparent]new[backcolor=transparent] [backcolor=transparent]FunctionComputeClient[backcolor=transparent]([backcolor=transparent]REGION[backcolor=transparent],[backcolor=transparent] accountId[backcolor=transparent],[backcolor=transparent] accessKey[backcolor=transparent],[backcolor=transparent] accessSecretKey[backcolor=transparent]);
16. [backcolor=transparent]        [backcolor=transparent]// Create a service
17. [backcolor=transparent]        [backcolor=transparent]CreateServiceRequest[backcolor=transparent] csReq [backcolor=transparent]=[backcolor=transparent] [backcolor=transparent]new[backcolor=transparent] [backcolor=transparent]CreateServiceRequest[backcolor=transparent]();
18. [backcolor=transparent]        csReq[backcolor=transparent].[backcolor=transparent]setServiceName[backcolor=transparent]([backcolor=transparent]SERVICE_NAME[backcolor=transparent]);
19. [backcolor=transparent]        csReq[backcolor=transparent].[backcolor=transparent]setDescription[backcolor=transparent]([backcolor=transparent]"FC test service"[backcolor=transparent]);
20. [backcolor=transparent]        csReq[backcolor=transparent].[backcolor=transparent]setRole[backcolor=transparent]([backcolor=transparent]role[backcolor=transparent]);
21. [backcolor=transparent]        [backcolor=transparent]CreateServiceResponse[backcolor=transparent] csResp [backcolor=transparent]=[backcolor=transparent] fcClient[backcolor=transparent].[backcolor=transparent]createService[backcolor=transparent]([backcolor=transparent]csReq[backcolor=transparent]);
22. [backcolor=transparent]        [backcolor=transparent]System[backcolor=transparent].[backcolor=transparent]out[backcolor=transparent].[backcolor=transparent]println[backcolor=transparent]([backcolor=transparent]"Created service, request ID "[backcolor=transparent] [backcolor=transparent]+[backcolor=transparent] csResp[backcolor=transparent].[backcolor=transparent]getRequestId[backcolor=transparent]());
24. [backcolor=transparent]        [backcolor=transparent]// Create a function
25. [backcolor=transparent]        [backcolor=transparent]CreateFunctionRequest[backcolor=transparent] cfReq [backcolor=transparent]=[backcolor=transparent] [backcolor=transparent]new[backcolor=transparent] [backcolor=transparent]CreateFunctionRequest[backcolor=transparent]([backcolor=transparent]SERVICE_NAME[backcolor=transparent]);
26. [backcolor=transparent]        cfReq[backcolor=transparent].[backcolor=transparent]setFunctionName[backcolor=transparent]([backcolor=transparent]FUNCTION_NAME[backcolor=transparent]);
27. [backcolor=transparent]        cfReq[backcolor=transparent].[backcolor=transparent]setDescription[backcolor=transparent]([backcolor=transparent]"Function for test"[backcolor=transparent]);
28. [backcolor=transparent]        cfReq[backcolor=transparent].[backcolor=transparent]setMemorySize[backcolor=transparent]([backcolor=transparent]128[backcolor=transparent]);
29. [backcolor=transparent]        cfReq[backcolor=transparent].[backcolor=transparent]setHandler[backcolor=transparent]([backcolor=transparent]"hello_world.handler"[backcolor=transparent]);
30. [backcolor=transparent]        cfReq[backcolor=transparent].[backcolor=transparent]setRuntime[backcolor=transparent]([backcolor=transparent]"nodejs6"[backcolor=transparent]);
31. [backcolor=transparent]        [backcolor=transparent]Code[backcolor=transparent] code [backcolor=transparent]=[backcolor=transparent] [backcolor=transparent]new[backcolor=transparent] [backcolor=transparent]Code[backcolor=transparent]().[backcolor=transparent]setDir[backcolor=transparent]([backcolor=transparent]CODE_DIR[backcolor=transparent]);
32. [backcolor=transparent]        cfReq[backcolor=transparent].[backcolor=transparent]setCode[backcolor=transparent]([backcolor=transparent]code[backcolor=transparent]);
33. [backcolor=transparent]        cfReq[backcolor=transparent].[backcolor=transparent]setTimeout[backcolor=transparent]([backcolor=transparent]10[backcolor=transparent]);
34. [backcolor=transparent]        [backcolor=transparent]CreateFunctionResponse[backcolor=transparent] cfResp [backcolor=transparent]=[backcolor=transparent] fcClient[backcolor=transparent].[backcolor=transparent]createFunction[backcolor=transparent]([backcolor=transparent]cfReq[backcolor=transparent]);
35. [backcolor=transparent]        [backcolor=transparent]System[backcolor=transparent].[backcolor=transparent]out[backcolor=transparent].[backcolor=transparent]println[backcolor=transparent]([backcolor=transparent]"Created function, request ID "[backcolor=transparent] [backcolor=transparent]+[backcolor=transparent] cfResp[backcolor=transparent].[backcolor=transparent]getRequestId[backcolor=transparent]());
37. [backcolor=transparent]        [backcolor=transparent]// Invoke the function with a string as function event parameter, Sync mode
38. [backcolor=transparent]        [backcolor=transparent]InvokeFunctionRequest[backcolor=transparent] invkReq [backcolor=transparent]=[backcolor=transparent] [backcolor=transparent]new[backcolor=transparent] [backcolor=transparent]InvokeFunctionRequest[backcolor=transparent]([backcolor=transparent]SERVICE_NAME[backcolor=transparent],[backcolor=transparent] FUNCTION_NAME[backcolor=transparent]);
39. [backcolor=transparent]        [backcolor=transparent]String[backcolor=transparent] payload [backcolor=transparent]=[backcolor=transparent] [backcolor=transparent]"Hello FunctionCompute!"
40. [backcolor=transparent]        invkReq[backcolor=transparent].[backcolor=transparent]setPayload[backcolor=transparent]([backcolor=transparent]payload[backcolor=transparent].[backcolor=transparent]getBytes[backcolor=transparent]())
41. [backcolor=transparent]        [backcolor=transparent]InvokeFunctionResponse[backcolor=transparent] invkResp [backcolor=transparent]=[backcolor=transparent] fcClient[backcolor=transparent].[backcolor=transparent]invokeFunction[backcolor=transparent]([backcolor=transparent]invkReq[backcolor=transparent]);
42. [backcolor=transparent]        [backcolor=transparent]System[backcolor=transparent].[backcolor=transparent]out[backcolor=transparent].[backcolor=transparent]println[backcolor=transparent]([backcolor=transparent]new[backcolor=transparent] [backcolor=transparent]String[backcolor=transparent]([backcolor=transparent]invkResp[backcolor=transparent].[backcolor=transparent]getContent[backcolor=transparent]()));
44. [backcolor=transparent]        [backcolor=transparent]// Invoke the function, Async mode
45. [backcolor=transparent]        invkReq[backcolor=transparent].[backcolor=transparent]setInvocationType[backcolor=transparent]([backcolor=transparent]Const[backcolor=transparent].[backcolor=transparent]INVOCATION_TYPE_ASYNC[backcolor=transparent]);
46. [backcolor=transparent]        invkResp [backcolor=transparent]=[backcolor=transparent] fcClient[backcolor=transparent].[backcolor=transparent]invokeFunction[backcolor=transparent]([backcolor=transparent]invkReq[backcolor=transparent]);
47. [backcolor=transparent]        [backcolor=transparent]if[backcolor=transparent] [backcolor=transparent]([backcolor=transparent]HttpURLConnection[backcolor=transparent].[backcolor=transparent]HTTP_ACCEPTED [backcolor=transparent]==[backcolor=transparent] invkResp[backcolor=transparent].[backcolor=transparent]getStatus[backcolor=transparent]())[backcolor=transparent] [backcolor=transparent]{
48. [backcolor=transparent]            [backcolor=transparent]System[backcolor=transparent].[backcolor=transparent]out[backcolor=transparent].[backcolor=transparent]println[backcolor=transparent]([backcolor=transparent]"Async invocation has been queued for execution, request ID: "[backcolor=transparent] [backcolor=transparent]+[backcolor=transparent] invkResp[backcolor=transparent].[backcolor=transparent]getRequestId[backcolor=transparent]());
49. [backcolor=transparent]        [backcolor=transparent]}[backcolor=transparent] [backcolor=transparent]else[backcolor=transparent] [backcolor=transparent]{
50. [backcolor=transparent]            [backcolor=transparent]System[backcolor=transparent].[backcolor=transparent]out[backcolor=transparent].[backcolor=transparent]println[backcolor=transparent]([backcolor=transparent]"Async invocation was not accepted"[backcolor=transparent]);
51. [backcolor=transparent]        [backcolor=transparent]}
53. [backcolor=transparent]        [backcolor=transparent]// Delete the function
54. [backcolor=transparent]        [backcolor=transparent]DeleteFunctionRequest[backcolor=transparent] dfReq [backcolor=transparent]=[backcolor=transparent] [backcolor=transparent]new[backcolor=transparent] [backcolor=transparent]DeleteFunctionRequest[backcolor=transparent]([backcolor=transparent]SERVICE_NAME[backcolor=transparent],[backcolor=transparent] FUNCTION_NAME[backcolor=transparent]);
55. [backcolor=transparent]        [backcolor=transparent]DeleteFunctionResponse[backcolor=transparent] dfResp [backcolor=transparent]=[backcolor=transparent] fcClient[backcolor=transparent].[backcolor=transparent]deleteFunction[backcolor=transparent]([backcolor=transparent]dfReq[backcolor=transparent]);
56. [backcolor=transparent]        [backcolor=transparent]System[backcolor=transparent].[backcolor=transparent]out[backcolor=transparent].[backcolor=transparent]println[backcolor=transparent]([backcolor=transparent]"Deleted function, request ID "[backcolor=transparent] [backcolor=transparent]+[backcolor=transparent] dfResp[backcolor=transparent].[backcolor=transparent]getRequestId[backcolor=transparent]());
58. [backcolor=transparent]        [backcolor=transparent]// Delete the service
59. [backcolor=transparent]        [backcolor=transparent]DeleteServiceRequest[backcolor=transparent] dsReq [backcolor=transparent]=[backcolor=transparent] [backcolor=transparent]new[backcolor=transparent] [backcolor=transparent]DeleteServiceRequest[backcolor=transparent]([backcolor=transparent]SERVICE_NAME[backcolor=transparent]);
60. [backcolor=transparent]        [backcolor=transparent]DeleteServiceResponse[backcolor=transparent] dsResp [backcolor=transparent]=[backcolor=transparent] fcClient[backcolor=transparent].[backcolor=transparent]deleteService[backcolor=transparent]([backcolor=transparent]dsReq[backcolor=transparent]);
61. [backcolor=transparent]        [backcolor=transparent]System[backcolor=transparent].[backcolor=transparent]out[backcolor=transparent].[backcolor=transparent]println[backcolor=transparent]([backcolor=transparent]"Deleted service, request ID "[backcolor=transparent] [backcolor=transparent]+[backcolor=transparent] dsResp[backcolor=transparent].[backcolor=transparent]getRequestId[backcolor=transparent]());
62. [backcolor=transparent]    [backcolor=transparent]}
63. [backcolor=transparent]}

并发执行


并发执行是指在任意指定时间您的函数代码同时执行的数量。您可以用下述公式来估算并发的函数调用数。
请求速率 * 函数执行时间
其中，请求速率是指函数被调用的速率，单位为“每秒请求数/事件数”。例如，考虑一个处理阿里云 OSS 事件的函数。假定函数平均用时 3 秒，OSS 每秒发布 10 个事件。因此，您的函数有 30 个并发执行。

安全限制


在某些情况下，由于用户的错误设置，函数执行可能会失控。考虑如下场景，您设置了 OSS 触发器，当图片文件上传到 OSS 上的 foo bucket 后，会调用相关函数处理。该函数将原图片调整为3张不同分辨率的图片，并将结果错误地写回到了 foo bucket 下。因此又会造成新的函数被调用，无限循环下去。为了避免因为失控函数导致财务损失，函数计算在每个账户粒度设置了并发执行限制，默认为100。您可以通过函数在 云监控中的相关指标（throttles）来观察流控行为。如果您需要提高该限制，请提交工单。

流控错误处理


根据调用方式，流控错误的处理方式有所不同。

• 
  同步调用：发出调用的应用程序会收到 429 错误，并将负责执行重试操作。如果您通过 API 网关调用函数，您需要确保将函数计算的响应错误映射到 API 网关的错误代码上。如果您直接调用该函数（例如使用函数计算的 SDK 或者 CLI），则您的客户端将会收到 429 错误，您可以根据实际需求选择是否重试。
• 
  异步调用：如果您的函数被异步调用并被流控，函数计算会自动重试受限制的事件，最长六个小时，并在重试之间有一定的延迟。在使用异步事件来调用函数之前，会将它们排队。