建立和使用卸載的作業

Apache Sling Discovery功能提供Java API，可讓您建立使用JobManager作業和JobConsumer服務。

有關建立卸載拓撲和配置主題消耗的資訊，請參閱卸載作業。

處理作業負載

卸載框架定義了用於標識作業裝載的兩個作業屬性。 卸載複製代理使用這些屬性來標識要複製到拓撲中實例的資源：

• offloading.job.input.payload:以逗號分隔的內容路徑清單。內容會複製到執行作業的執行個體。
• offloading.job.output.payload:以逗號分隔的內容路徑清單。作業執行完成後，作業裝載將複製到建立作業的執行個體上的這些路徑。

使用OffloadingJobProperties列舉來參照屬性名稱：

• OffloadingJobProperties.INPUT_PAYLOAD.propertyName()
• OffloadingJobProperties.OUTPUT_PAYLOAD.propetyName()

作業不需要裝載。 但是，如果作業需要操作資源，並且作業被卸載到未建立該作業的電腦上，則需要裝載。

建立卸載作業

建立調用JobManager.addJob方法的客戶端，以建立自動選擇的JobConsumer執行的作業。 提供以下資訊以建立作業：

• 主題：工作主題。
• 名稱：（可選）
• 屬性映射：Map<String, Object>物件，包含任何數量的屬性，例如輸入有效負載路徑和輸出有效負載路徑。 此映射對象可用於執行該作業的JobConsumer對象。

下列範例服務會為指定主題和輸入裝載路徑建立工作。

package com.adobe.example.offloading;

import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Service;
import org.apache.felix.scr.annotations.Reference;

import java.util.HashMap;

import org.apache.sling.event.jobs.Job;
import org.apache.sling.event.jobs.JobManager;

import org.apache.sling.api.resource.ResourceResolverFactory;
import org.apache.sling.api.resource.ResourceResolver;

import com.adobe.granite.offloading.api.OffloadingJobProperties;

@Component
@Service
public class JobGeneratorImpl implements JobGenerator  {

 @Reference
 private JobManager jobManager;
 @Reference ResourceResolverFactory resolverFactory;

 public String createJob(String topic, String payload) throws Exception {
  Job offloadingJob;

  ResourceResolver resolver = resolverFactory.getResourceResolver(null);
  if(resolver.getResource(payload)!=null){

   HashMap<String, Object> jobprops = new HashMap<String, Object>();
   jobprops.put(OffloadingJobProperties.INPUT_PAYLOAD.propertyName(), payload);

   offloadingJob = jobManager.addJob(topic, null, jobprops);
  } else {
   throw new Exception("Payload for job cannot be found");
  }
  if (offloadingJob == null){
   throw new Exception ("Offloading job could not be created");
  }
  return offloadingJob.getId();
 }
}

當為com/adobe/example/offloading主題和/content/geometrixx/de/services裝載調用JobGeneratorImpl.createJob時，日誌包含以下消息：

10.06.2013 15:43:33.868 *INFO* [JobHandler: /etc/workflow/instances/2013-06-10/model_1554418768647484:/content/geometrixx/en/company] com.adobe.example.offloading.JobGeneratorImpl Received request to make job for topic com/adobe/example/offloading and payload /content/geometrixx/de/services

開發工作消費者

若要使用作業，請開發實作org.apache.sling.event.jobs.consumer.JobConsumer介面的OSGi服務。 使用JobConsumer.PROPERTY_TOPICS屬性識別要使用的主題。

下列JobConsumer實作範例會註冊至com/adobe/example/offloading主題。 使用者只會將裝載內容節點的「已使用」屬性設為true。

package com.adobe.example.offloading;

import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Property;
import org.apache.felix.scr.annotations.Reference;
import org.apache.felix.scr.annotations.Service;
import org.apache.sling.api.resource.ResourceResolver;
import org.apache.sling.api.resource.ResourceResolverFactory;
import org.apache.sling.event.jobs.Job;
import org.apache.sling.event.jobs.JobManager;
import org.apache.sling.event.jobs.consumer.JobConsumer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.jcr.Session;
import javax.jcr.Node;

import com.adobe.granite.offloading.api.OffloadingJobProperties;

@Component
@Service
public class MyJobConsumer implements JobConsumer {

 public static final String TOPIC = "com/adobe/example/offloading";

 @Property(value = TOPIC)
 static final String myTopic = JobConsumer.PROPERTY_TOPICS; 

 @Reference
 private ResourceResolverFactory resolverFactory;

 @Reference
 private JobManager jobManager;

 private final Logger log = LoggerFactory.getLogger(getClass());

 public JobResult process(Job job) {
  JobResult result = JobResult.FAILED;
  String topic = job.getTopic();
  log.info("Consuming job of topic: {}", topic);
  String payloadIn =  (String) job.getProperty(OffloadingJobProperties.INPUT_PAYLOAD.propertyName());
  String payloadOut =  (String) job.getProperty(OffloadingJobProperties.OUTPUT_PAYLOAD.propertyName());

  log.info("Job has Input Payload {} and Output Payload {}",payloadIn, payloadOut);

  ResourceResolver resolver = null;
  try {
   resolver = resolverFactory.getAdministrativeResourceResolver(null);
   Session session = resolver.adaptTo(Session.class);
   Node inNode = session.getNode(payloadIn);
   inNode.getNode(Node.JCR_CONTENT).setProperty("consumed",true);
   result = JobResult.OK;
  }catch (Exception e){
   log.info("ERROR -- JOB RESULT IS FAILURE " + e.getMessage());
   result = JobResult.FAILED;
  }
  log.info("Job OK for payload {}",payloadIn);
  return result;
 }
}

MyJobConsumer類別會為/content/geometrixx/de/services的輸入裝載產生下列記錄訊息：

10.06.2013 16:02:40.803 *INFO* [pool-7-thread-17-<main queue>(com/adobe/example/offloading)] com.adobe.example.offloading.MyJobConsumer Consuming job of topic: com/adobe/example/offloading
10.06.2013 16:02:40.803 *INFO* [pool-7-thread-17-<main queue>(com/adobe/example/offloading)] com.adobe.example.offloading.MyJobConsumer Job has Input Payload /content/geometrixx/de/services and Output Payload /content/geometrixx/de/services
10.06.2013 16:02:40.884 *INFO* [pool-7-thread-17-<main queue>(com/adobe/example/offloading)] com.adobe.example.offloading.MyJobConsumer Job OK for payload /content/geometrixx/de/services

可使用CRXDE Lite來觀察已使用屬性：

Maven依賴項

將下列相依性防禦項目新增至您的pom.xml檔案，讓Maven可解析卸載相關類別。

<dependency>
   <groupId>org.apache.sling</groupId>
   <artifactId>org.apache.sling.event</artifactId>
   <version>3.1.5-R1485539</version>
   <scope>provided</scope> 
</dependency>
<dependency>
   <groupId>com.adobe.granite</groupId>
   <artifactId>com.adobe.granite.offloading.core</artifactId>
   <version>1.0.4</version>
   <scope>provided</scope>
</dependency>

前面的示例還需要以下依賴項定義：

<dependency>
   <groupId>org.apache.sling</groupId>
   <artifactId>org.apache.sling.api</artifactId>
   <version>2.4.3-R1488084</version>
   <scope>provided</scope>
</dependency>

<dependency>
   <groupId>org.apache.sling</groupId>
   <artifactId>org.apache.sling.jcr.jcr-wrapper</artifactId>
   <version>2.0.0</version>
   <scope>provided</scope>
</dependency>