跟着实例学Oozie
阅读导读：1.如何应用Oozie？
2.提醒邮件的程序如何编写？
3.Oozie各个配置参数的含义？
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我们在此描述的工作流会实现汽车GPS探测数据的获取过程。我们每个小时都会以文件的形式把探测数据传递到指定的HDFS目录中，其中包含有这个小时之内的所有探测数据。探测数据的获取是每天针对一天内所有的24个文件完成的。如果文件的数量是24，那么获取过程就会启动。否则：
当天什么都不做对前一天——最多到7天，发送剩下的内容到探测数据提供程序如果目录的存在时间已达到7天，那么就获取所有可用的探测数据文件。
过程的总体实现请见图1
图1： 过程图
在此，主流程（数据获取流程）首先会为今天以及之前的六天计算出目录的名称，然后启动（fork）七个目录的子过程（子流程）。待所有子过程的状态都变成终止之后，join步骤就会把控制权交给end状态。子过程启动时，首先会获得关于目录的信息——它的日期以及文件数量。基于这条信息，它会决定是获取数据还是把数据归档，或者发送剩下的邮件，或者不做任何工作。Directory子过程实现以下代码负责实现的是directory子过程（代码1）。
<workflow-app xmlns='uri:oozie:workflow:0.1' name='processDir'>
<start to='getDirInfo' />
<!-- STEP ONE -->
<action name='getDirInfo'>
<!--writes 2 properties: dir.num-files: returns -1 if dir doesn't exist,
otherwise returns # of files in dir dir.age: returns -1 if dir doesn't exist,
otherwise returns age of dir in days -->
<java>
<job-tracker>${jobTracker}</job-tracker>
<name-node>${nameNode}</name-node>
<main-class>com.navteq.oozie.GetDirInfo</main-class>
<arg>${inputDir}</arg>
<capture-output />
</java>
<ok to="makeIngestDecision" />
<error to="fail" />
</action>
<!-- STEP TWO -->
<decision name="makeIngestDecision">
<switch>
<!-- empty or doesn't exist -->
<case to="end">
${wf:actionData('getDirInfo')['dir.num-files'] lt 0 ||
(wf:actionData('getDirInfo')['dir.age'] lt 1 and
wf:actionData('getDirInfo')['dir.num-files'] lt 24)}
</case>
<!-- # of files >= 24 -->
<case to="ingest">
${wf:actionData('getDirInfo')['dir.num-files'] gt 23 ||
wf:actionData('getDirInfo')['dir.age'] gt 6}
</case>
<default to="sendEmail"/>
</switch>
</decision>
<!--EMAIL-->
<action name="sendEmail">
<java>
<job-tracker>${jobTracker}</job-tracker>
<name-node>${nameNode}</name-node>
<main-class>com.navteq.oozie.StandaloneMailer</main-class>
<arg>probedata2@navteq.com</arg>
<arg>gregory.titievsky@navteq.com</arg>
<arg>${inputDir}</arg>
<arg>${wf:actionData('getDirInfo')['dir.num-files']}</arg>
<arg>${wf:actionData('getDirInfo')['dir.age']}</arg>
</java>
<ok to="end" />
<error to="fail" />
</action>
<!--INGESTION -->
<action name="ingest">
<java>
<job-tracker>${jobTracker}</job-tracker>
<name-node>${nameNode}</name-node>
<prepare>
<delete path="${outputDir}" />
</prepare>
<configuration>
<property>
<name>mapred.reduce.tasks</name>
<value>300</value>
</property>
</configuration>
<main-class>com.navteq.probedata.drivers.ProbeIngest</main-class>
<arg>-conf</arg>
<arg>action.xml</arg>
<arg>${inputDir}</arg>
<arg>${outputDir}</arg>
</java>
<ok to=" archive-data" />
<error to="ingest-fail" />
</action>
<!—Archive Data -->
<action name="archive-data">
<fs>
<move source='${inputDir}' target='/probe/backup/${dirName}' />
<delete path = '${inputDir}' />
</fs>
<ok to="end" />
<error to="ingest-fail" />
</action>
<kill name="ingest-fail">
<message>Ingestion failed, error
message[${wf:errorMessage(wf:lastErrorNode())}]</message>
</kill>
<kill name="fail">
<message>Java failed, error
message[${wf:errorMessage(wf:lastErrorNode())}]</message>
</kill>
<end name='end' />
</workflow-app>
代码1： Directory子过程
这个子过程的start节点会触发自定义的java节点，这个节点会获得目录信息（代码2）。
package com.navteq.oozie;
import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.util.GregorianCalendar;
import java.util.Properties;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
public class GetDirInfo {
private static final String OOZIE_ACTION_OUTPUT_PROPERTIES = "oozie.action.output.properties";
public static void main(String[] args) throws Exception {
String dirPath = args;
String propKey0 = "dir.num-files";
String propVal0 = "-1";
String propKey1 = "dir.age";
String propVal1 = "-1";
System.out.println("Directory path: '"+dirPath+"'");
Configuration conf = new Configuration();
FileSystem fs = FileSystem.get(conf);
Path hadoopDir = new Path(dirPath);
if (fs.exists(hadoopDir)){
FileStatus[] files = FileSystem.get(conf).listStatus(hadoopDir);
int numFilesInDir = files.length;
propVal0 = Integer.toString(numFilesInDir);
long timePassed, daysPassedLong;
int daysPassed;
String dirName = hadoopDir.getName();
String[] dirNameArray = dirName.split("-");
if (dirNameArray.length == 3) {
int year = Integer.valueOf(dirNameArray);
int month = Integer.valueOf(dirNameArray) - 1; //months are 0 based
int date = Integer.valueOf(dirNameArray);
GregorianCalendar dirCreationDate = new GregorianCalendar(year,
month, date);
timePassed = (new GregorianCalendar()).getTimeInMillis()
- dirCreationDate.getTimeInMillis();
daysPassed = (int) = timePassed / 1000 / 60 / 60 / 24;;
propVal1 = Integer.toString(daysPassed);
}
}
String oozieProp = System.getProperty(OOZIE_ACTION_OUTPUT_PROPERTIES);
if (oozieProp != null) {
File propFile = new File(oozieProp);
Properties props = new Properties();
props.setProperty(propKey0, propVal0);
props.setProperty(propKey1, propVal1);
OutputStream os = new FileOutputStream(propFile);
props.store(os, "");
os.close();
} else
throw new RuntimeException(OOZIE_ACTION_OUTPUT_PROPERTIES
+ " System property not defined");
}
}
代码2： 获得目录信息的节点
这个类会获得目录名作为输入的参数，并首先检查该目录是否存在。如果目录不存在，那么存在时间（age）和文件数量都会返回-1，否则，这两个值就会返回给子过程。子过程的下一步是一个switch（决定）声明，它会决定如何处理目录。如果目录不存在（文件数 < 0），或者是当前日期（存在时间 < 1）并且文件数量少于24（文件数 < 24），那么子过程就会直接转换到终止状态。如果所有文件都位于子目录中（文件数 > 23）或者目录是在至少七天前创建的（存在时间 > 6），那么就会有如下操作：
[*]使用现存的Map/reduce程获取数据
[*]目录会备份在数据归档中，然后删除
对action节点的其它配置
获取动作向你展示了另外一些Oozie配置参数，包括：
[*]Prepare——如果出现了prepare参数，就意味着在启动作业（job）之前会删除路径列表。这应该专门用于清理目录。删除操作会在fs.default.name文件系统中执行。
[*]Configuration——如果出现了configuration元素，它其中就会包含针对Map/Reduce 作业的JobConf属性。它不仅可以用于map/reduce动作， 而且还可以用于启动map/reduce作业的java动作。
如果不是以上两种情况，那么子过程就会发送剩余的邮件，然后退出。邮件是作为另一个java主类实现的（代码3）。
package com.navteq.oozie;
import java.util.Properties;
import javax.mail.Message;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
public class StandaloneMailer {
private static String _mServer = "imailchi.navtech.com";
private static Properties _props = null;
private StandaloneMailer(){}
public static void init(String mServer){
_mServer = mServer;
_props = new Properties();
_props.setProperty("mail.smtp.host", _mServer);
}
public static void SendMail(String subject, String message, String from, String to) throws Exception {
// create some properties and get the default Session
Session session = Session.getDefaultInstance(_props, null);
// create a message
Message msg = new MimeMessage(session);
// set the from and to address
InternetAddress addressFrom = new InternetAddress(from);
msg.setFrom(addressFrom);
String [] recipients = new String[] {to};
InternetAddress[] addressTo = new InternetAddress;
for (int i = 0; i < recipients.length; i++){
addressTo = new InternetAddress(recipients);
}
msg.setRecipients(Message.RecipientType.TO, addressTo);
// Setting the Subject and Content Type
msg.setSubject(subject);
msg.setContent(message, "text/plain");
Transport.send(msg);
}
public static void main (String[] args) throws Exception {
if (args.length ==5){
init(_mServer);
StringBuilder subject = new StringBuilder();
StringBuilder body = new StringBuilder();
subject.append("Directory ").append(args).append(" contains").append(args).append("
files.");
body.append("Directory ").append(args).append(" is ").append(args).
append(" days old and contains only ").append(args).append(" files instead of 24.");
SendMail(subject.toString(), body.toString(), args, args);
}
else throw new Exception("Invalid number of parameters provided for email");
}
}列表3： 发送提醒邮件
这是使用了javax.mail API的简单实现，用于发送邮件。主过程的实现我们已经实现了子过程，然后，对主过程的实现就变得非常简单了（列表4）
<workflow-app xmlns='uri:oozie:workflow:0.1' name='processDirsWF'>
<start to='getDirs2Process' />
<!-- STEP ONE -->
<action name='getDirs2Process'>
<!--writes 2 properties: dir.num-files: returns -1 if dir doesn't exist,
otherwise returns # of files in dir dir.age: returns -1 if dir doesn't exist,
otherwise returns age of dir in days -->
<java>
<job-tracker>${jobTracker}</job-tracker>
<name-node>${nameNode}</name-node>
<main-class>com.navteq.oozie.GenerateLookupDirs</main-class>
<capture-output />
</java>
<ok to="forkSubWorkflows" />
<error to="fail" />
</action>
<fork name="forkSubWorkflows">
<path start="processDir0"/>
<path start="processDir1"/>
<path start="processDir2"/>
<path start="processDir3"/>
<path start="processDir4"/>
<path start="processDir5"/>
<path start="processDir6"/>
<path start="processDir7"/>
</fork>
<action name="processDir0">
<sub-workflow>
<app-path>hdfs://sachicn001:8020/user/gtitievs/workflows/ingest</app-path>
<configuration>
<property>
<name>inputDir</name>
<value>hdfs://sachicn001:8020/user/data/probedev/files/${wf:actionData
('getDirs2Process')['dir0']}</value>
</property>
<property>
<name>outputDir</name>
<value>hdfs://sachicn001:8020/user/gtitievs/probe-output/${wf:actionData
('getDirs2Process')['dir0']}</value>
</property>
<property>
<name>jobTracker</name>
<value>${jobTracker}</value>
</property>
<property>
<name>nameNode</name>
<value>${nameNode}</value>
</property>
<property>
<name>activeDir</name>
<value>hdfs://sachicn001:8020/user/gtitievs/test-activeDir</value>
</property>
<property>
<name>dirName</name>
<value>${wf:actionData('getDirs2Process')['dir0']}</value>
</property>
</configuration>
</sub-workflow>
<ok to="joining"/>
<error to="fail"/>
</action>
….
<action name="processDir7">
<sub-workflow>
<app-path>hdfs://sachicn001:8020/user/gtitievs/workflows/ingest</app-path>
<configuration>
<property>
<name>inputDir</name>
<value>hdfs://sachicn001:8020/user/data/probedev/files/${wf:actionData
('getDirs2Process')['dir7']}</value>
</property>
<property>
<name>outputDir</name>
<value>hdfs://sachicn001:8020/user/gtitievs/probe-output/${wf:actionData
('getDirs2Process')['dir7']}</value>
</property>
<property>
<name>dirName</name>
<value>${wf:actionData('getDirs2Process')['dir7']}</value>
</property>
</configuration>
</sub-workflow>
<ok to="joining"/>
<error to="fail"/>
</action>
<join name="joining" to="end"/>
<kill name="fail">
<message>Java failed, error
message[${wf:errorMessage(wf:lastErrorNode())}]</message>
</kill>
<end name='end' />
</workflow-app>代码4： 数据获取主过程
这个过程首先会触发java节点，计算需要处理的目录列表（列表5），然后对每个目录执行子过程，从而处理给定的目录。
package com.navteq.oozie;
import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.Properties;
public class GenerateLookupDirs {
public static final long dayMillis = 1000 * 60 * 60 * 24;
private static final String OOZIE_ACTION_OUTPUT_PROPERTIES = "oozie.action.output.properties";
public static void main(String[] args) throws Exception {
Calendar curDate = new GregorianCalendar();
int year, month, date;
String propKey, propVal;
String oozieProp = System.getProperty(OOZIE_ACTION_OUTPUT_PROPERTIES);
if (oozieProp != null) {
File propFile = new File(oozieProp);
Properties props = new Properties();
for (int i = 0; i<8; ++i)
{
year = curDate.get(Calendar.YEAR);
month = curDate.get(Calendar.MONTH) + 1;
date = curDate.get(Calendar.DATE);
propKey = "dir"+i;
propVal = year + "-" +
(month < 10 ? "0" + month : month) + "-" +
(date < 10 ? "0" + date : date);
props.setProperty(propKey, propVal);
curDate.setTimeInMillis(curDate.getTimeInMillis() - dayMillis);
}
OutputStream os = new FileOutputStream(propFile);
props.store(os, "");
os.close();
} else
throw new RuntimeException(OOZIE_ACTION_OUTPUT_PROPERTIES
+ " System property not defined");
}
}代码5： 目录计算程序
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