批次處理要求

本文說明如何批次處理 API 呼叫，以減少用戶端必須建立的 HTTP 連線數量。

本文專門說明如何透過傳送 HTTP 要求來提交批次要求。如果您是使用 Google 用戶端程式庫提交批次要求，請參閱用戶端程式庫的說明文件。

總覽

用戶端的每個 HTTP 連線都會造成一定程度的負擔。Google Classroom API 支援批次作業，可讓用戶端在單一 HTTP 要求中加入數個 API 呼叫。

以下是您可能想要使用批次作業的狀況範例：

• 擷取大量課程的學生名單。
• 大量建立或更新課程。
• 新增大量課程名單。
• 擷取大量使用者的課程清單。

在任一案例中，都不需要個別傳送每一個呼叫，只需將這些呼叫分組後組成單一 HTTP 要求。所有內部要求都必須前往相同的 Google API。

單一批次要求最多能包含 50 個呼叫，如果您發出的呼叫數量超過這個上限，請使用多個批次要求。

注意：Google Classroom API 的批次系統使用的語法與 OData 批次處理系統相同，但語意不同。

批次詳細資料

批次要求是由多個 API 呼叫合併成一個 HTTP 要求，系統會將這個要求傳送至 API 探索文件中指定的 batchPath。預設路徑為 /batch/api_name/api_version。本節詳細說明批次語法，並在後半段提供範例。

注意：組成批次的 n 個要求在用量限制中會算成 n 個要求，而不是一個要求。在這個處理之前，批次要求會拆分成一組要求。

批次要求的格式

批次要求是單一標準 HTTP 要求，內含多個使用 multipart/mixed 內容類型的 Google Classroom API 呼叫。在主要 HTTP 要求中，每個分部都含有一個巢狀的 HTTP 要求。

每個部分都以自己的 Content-Type: application/http HTTP 標頭開始。也可以有選用的 Content-ID 標頭。不過，分部標頭只是用來標記零件的開頭，與巢狀要求無關。伺服器將批次要求展開為個別要求後，就會忽略部分標頭。

每個部分的主體都是完整的 HTTP 要求，各有專屬的動詞、網址、標頭和主體。HTTP 要求只能包含 URL 的路徑部分；批次要求禁止納入完整的 URL。

外部批次要求的 HTTP 標頭會套用於批次中的每項要求，但 Content- 標頭 (例如 Content-Type) 除外。如果您在外部要求和個別呼叫中均指定所提供的 HTTP 標頭，則個別呼叫標頭的值會覆寫外部批次要求標頭的值。個別呼叫的標頭只會套用於該呼叫。

例如，如果您提供 Authorization 標頭用於特定呼叫，則該標頭只會套用於該呼叫。如果您提供 Authorization 標頭用於外部要求，則除非個別呼叫以自己的 Authorization 標頭覆寫所提供的標頭，否則所提供的 Authorization 標頭會套用於所有個別呼叫。

當伺服器收到批次要求時，即會將外部要求的查詢參數和標頭 (在適用情況下) 套用至每一個分部，然後將每個分部視為不同的 HTTP 要求。

回應批次要求

伺服器回應是含有 multipart/mixed 內容類型的單一標準 HTTP 回應，每個部分都是批次要求中其中一個要求的回應，與要求的順序相同。

就像要求中的分部一樣，每個回應分部都含有完整的 HTTP 回應，包括狀態碼、標頭和內文；就像要求中的部分一樣，每個回應部分前面都會加上 Content-Type 標頭，標示部分的開頭。

如果要求的特定部分含有 Content-ID 標頭，則回應的對應部分就會含有相符的 Content-ID 標頭，原始值前方會加上字串 response-，如以下範例所示。

注意：伺服器可能會以任意順序執行您的呼叫。不要期望呼叫會按您的指定順序執行。如果您想要確保兩個呼叫依指定順序執行，就不能以單一要求傳送它們，而要先傳送第一個呼叫，然後等到第一個呼叫的回應後才能傳送第二個呼叫。

範例

以下範例說明如何使用 Google Classroom API 進行批次作業。

批次要求範例

POST https://classroom.googleapis.com/batch HTTP/1.1
Authorization: Bearer your_auth_token
Content-Type: multipart/mixed; boundary=batch_foobarbaz
Content-Length: total_content_length

--batch_foobarbaz
Content-Type: application/http
Content-Transfer-Encoding: binary
MIME-Version: 1.0
Content-ID: <item1:[e-mail]>

PATCH /v1/courses/134529639?updateMask=name HTTP/1.1
Content-Type: application/json; charset=UTF-8
Authorization: Bearer your_auth_token

{
  "name": "Course 1"
}
--batch_foobarbaz
Content-Type: application/http
Content-Transfer-Encoding: binary
MIME-Version: 1.0
Content-ID: <item2:[e-mail]>

PATCH /v1/courses/134529901?updateMask=section HTTP/1.1
Content-Type: application/json; charset=UTF-8
Authorization: Bearer your_auth_token
{
  "section": "Section 2"
}
--batch_foobarbaz--

批次回應範例

這是前一節中範例要求的回應。

HTTP/1.1 200
Content-Length: response_total_content_length
Content-Type: multipart/mixed; boundary=batch_foobarbaz

--batch_foobarbaz
Content-Type: application/http
Content-ID: <response-item1:[e-mail]>

HTTP/1.1 200 OK
Content-Type application/json
Content-Length: response_part_1_content_length

{
  "id": "134529639",
  "name": "Course 1",
  "section": "Section 1",
  "ownerId": "116269102540619633451",
  "creationTime": "2015-06-25T14:23:56.535Z",
  "updateTime": "2015-06-25T14:33:06.583Z",
  "enrollmentCode": "6paeflo",
  "courseState": "PROVISIONED",
  "alternateLink": "http://classroom.google.com/c/MTM0NTI5NjM5"
}
--batch_foobarbaz
Content-Type: application/http
Content-ID: <response-item2:[e-mail]>

HTTP/1.1 200 OK
Content-Type: application/json
Content-Length: response_part_2_content_length

{
  "id": "134529901",
  "name": "Course 1",
  "section": "Section 2",
  "ownerId": "116269102540619633451",
  "creationTime": "2015-06-25T14:23:08.761Z",
  "updateTime": "2015-06-25T14:33:06.490Z",
  "enrollmentCode": "so75ha5",
  "courseState": "PROVISIONED",
  "alternateLink": "http://classroom.google.com/c/MTM0NTI5OTAx"
}
--batch_foobarbaz--

使用用戶端程式庫

下列程式碼範例示範如何使用 Google API 用戶端程式庫提出批次要求。如要進一步瞭解如何安裝及設定程式庫，請參閱各自的快速入門指南。

.NET

classroom/snippets/ClassroomSnippets/BatchAddStudents.cs

前往 GitHub 查看

using Google;
using Google.Apis.Auth.OAuth2;
using Google.Apis.Classroom.v1;
using Google.Apis.Classroom.v1.Data;
using Google.Apis.Requests;
using Google.Apis.Services;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;

namespace ClassroomSnippets
{
    // Class to demonstrate the use of Classroom Batch Add Students API
    public class BatchAddStudents
    {
        /// <summary>
        /// Add multiple students in a specified course.
        /// </summary>
        /// <param name="courseId">Id of the course to add students.</param>
        /// <param name="studentEmails">Email address of the students.</param>
        public static void ClassroomBatchAddStudents(string courseId,
            List<string> studentEmails)
        {
            try
            {
                /* Load pre-authorized user credentials from the environment.
                 TODO(developer) - See https://developers.google.com/identity for 
                 guides on implementing OAuth2 for your application. */
                GoogleCredential credential = GoogleCredential.GetApplicationDefault()
                    .CreateScoped(ClassroomService.Scope.ClassroomRosters);

                // Create Classroom API service.
                var service = new ClassroomService(new BaseClientService.Initializer
                {
                    HttpClientInitializer = credential,
                    ApplicationName = "Classroom Snippets"
                });

                var batch = new BatchRequest(service, "https://classroom.googleapis.com/batch");
                BatchRequest.OnResponse<Student> callback = (student, error, i, message) =>
                {
                    if (error != null)
                    {
                        Console.WriteLine("Error adding student to the course: {0}", error.Message);
                    }
                    else
                    {
                        Console.WriteLine("User '{0}' was added as a student to the course.",
                            student.Profile.Name.FullName);
                    }
                };
                foreach (var studentEmail in studentEmails)
                {
                    var student = new Student() {UserId = studentEmail};
                    var request = service.Courses.Students.Create(student, courseId);
                    batch.Queue<Student>(request, callback);
                }

                Task.WaitAll(batch.ExecuteAsync());
            }
            catch (Exception e)
            {
                // TODO(developer) - handle error appropriately
                if (e is AggregateException)
                {
                    Console.WriteLine("Credential Not found");
                }
                else if (e is GoogleApiException)
                {
                    Console.WriteLine("Course does not exist.");
                }
                else
                {
                    throw;
                }
            }
        }
    }
}

Java

classroom/snippets/src/main/java/BatchAddStudents.java

前往 GitHub 查看

import com.google.api.client.googleapis.batch.BatchRequest;
import com.google.api.client.googleapis.batch.json.JsonBatchCallback;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.googleapis.json.GoogleJsonError;
import com.google.api.client.http.HttpHeaders;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.gson.GsonFactory;
import com.google.api.services.classroom.Classroom;
import com.google.api.services.classroom.ClassroomScopes;
import com.google.api.services.classroom.model.Student;
import java.io.IOException;
import java.security.GeneralSecurityException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/* Class to demonstrate the use of Classroom Batch Add Students API */
public class BatchAddStudents {

  /* Scopes required by this API call. If modifying these scopes, delete your previously saved
  tokens/ folder. */
  static ArrayList<String> SCOPES =
      new ArrayList<>(Arrays.asList(ClassroomScopes.CLASSROOM_ROSTERS));

  /**
   * Add multiple students in a specified course.
   *
   * @param courseId - Id of the course to add students.
   * @param studentEmails - Email address of the students.
   * @throws IOException - if credentials file not found.
   * @throws GeneralSecurityException - if a new instance of NetHttpTransport was not created.
   */
  public static void batchAddStudents(String courseId, List<String> studentEmails)
      throws GeneralSecurityException, IOException {

    // Create the classroom API client.
    final NetHttpTransport HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
    Classroom service =
        new Classroom.Builder(
                HTTP_TRANSPORT,
                GsonFactory.getDefaultInstance(),
                ClassroomCredentials.getCredentials(HTTP_TRANSPORT, SCOPES))
            .setApplicationName("Classroom samples")
            .build();

    BatchRequest batch = service.batch();
    JsonBatchCallback<Student> callback =
        new JsonBatchCallback<>() {
          public void onSuccess(Student student, HttpHeaders responseHeaders) {
            System.out.printf(
                "User '%s' was added as a student to the course.\n",
                student.getProfile().getName().getFullName());
          }

          public void onFailure(GoogleJsonError error, HttpHeaders responseHeaders) {
            System.out.printf("Error adding student to the course: %s\n", error.getMessage());
          }
        };
    for (String studentEmail : studentEmails) {
      Student student = new Student().setUserId(studentEmail);
      service.courses().students().create(courseId, student).queue(batch, callback);
    }
    batch.execute();
  }
}

PHP

classroom/snippets/src/ClassroomBatchAddStudents.php

前往 GitHub 查看

use Google\Client;
use Google\Service\Classroom;
use Google\Service\Classroom\Student;
use Google\Service\Exception;

function batchAddStudents($courseId, $studentEmails)
{
    /* Load pre-authorized user credentials from the environment.
    TODO(developer) - See https://developers.google.com/identity for
     guides on implementing OAuth2 for your application. */
    $client = new Client();
    $client->useApplicationDefaultCredentials();
    $client->addScope("https://www.googleapis.com/auth/classroom.profile.emails");
    $service = new Classroom($client);
    $service->getClient()->setUseBatch(true);
    //create batch
    $batch = $service->createBatch();
    foreach ($studentEmails as $studentEmail) {
        $student = new Student([
            'userId' => $studentEmail
        ]);
        $request = $service->courses_students->create($courseId, $student);
        $requestId = $studentEmail;
        $batch->add($request, $requestId);
    }
    //executing request
    $results = $batch->execute();
    foreach ($results as $responseId => $student) {
        $studentEmail = substr($responseId, strlen('response-') + 1);
        if ($student instanceof Exception) {
            $e = $student;
            printf("Error adding user '%s' to the course: %s\n", $studentEmail,
                $e->getMessage());
        } else {
            printf("User '%s' was added as a student to the course.\n",
                $student->profile->name->fullName, $courseId);
        }
    }
    $service->getClient()->setUseBatch(false);
    return $results;
}

Python

course_id = '123456'
student_emails = ['[e-mail]', '[e-mail]']
def callback(request_id, response, exception):
    if exception is not None:
        print 'Error adding user "{0}" to the course course: {1}'.format(
            request_id, exception)
    else:
        print 'User "{0}" added as a student to the course.'.format(
            response.get('profile').get('name').get('fullName'))
batch = service.new_batch_http_request(callback=callback)
for student_email in student_emails:
    student = {
        'userId': student_email
    }
    request = service.courses().students().create(courseId=course_id,
                                                  body=student)
    batch.add(request, request_id=student_email)
batch.execute(http=http)