ACTIVEMQ Analysis (i) Start-up process

Activemq startup is very simple.

Such as

1. Booting from a binary release package

On Windows:

CD [ACTIVEMQ_INSTALL_DIR]BIN\ACTIVEMQ Start

2. Start from source mode

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Main Class:org.apache.activemq.console.Main

Arguments:start Xbean:activemq2.xml

One of the simplest configuration files for activemq2.xml content

<beans  xmlns= "Http://www.springframework.org/schema/beans"   xmlns:amq= "http// Activemq.apache.org/schema/core "  xmlns:xsi=" Http://www.w3.org/2001/XMLSchema-instance "   Xsi:schemalocation= "http://www.springframework.org/schema/beans http://www.springframework.org/schema/ beans/spring-beans-2.0.xsd  http://activemq.apache.org/schema/core http://activemq.apache.org/ schema/core/activemq-core.xsd  http://activemq.apache.org/camel/schema/spring http:// Activemq.apache.org/camel/schema/spring/camel-spring.xsd ">  <!-- allows us to  use system properties as variables in this configuration file  -->  <bean class= " Org.springframework.beans.factory.config.PropertyPlaceholderConfigurer "/>  <broker xmlns= "Http://activemq.apache.org/schema/core"  brokername= "localhost"  datadirectory= "${activemq.basE}/data ">    <!-- the transport connectors activemq will  listen to -->    <transportConnectors>        <transportconnector name= "Openwire"  uri= "tcp://localhost:61616"  />     </transportConnectors>  </broker></beans>

Command List

There are many commands, the start command is just one of them.

tasks:    browse                    - Display selected messages in a  specified destination.    bstat                     - Performs a predefined  Query that displays useful statistics regarding the specified broker     create                    - creates a runnable broker instance in  the specified path.    decrypt                   - Decrypts given text     encrypt                  -  encrypts given text    export                    - Exports a stopped  brokers data files to an archive file    list                       - lists all available brokers in the specified jmx context     purge                     - delete selected destination ' s messages  that matches the message selector    query                     - display selected broker  Component ' s attributes and statistics.    start                     - creates  and starts a broker using a configuration file, or a  broker uri.    stop                      - Stops a running broker  Specified by the broker name.

Start process sequence diagram

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View the Main method entry by analyzing the Activemq*.jar. Navigate to Org.apache.activemq.console.Main.

By reflection, call the Main method of Shellcommand

public static final string task_default_class =  " Org.apache.activemq.console.command.ShellCommand ";p Ublic void runtaskclass (list<string>  Tokens)  throws Throwable {...    ClassLoader cl =  getClassLoader ();     thread.currentthread (). Setcontextclassloader (CL);     // Use reflection to run the task.    try {         string[] args = tokens.toarray (new String[ Tokens.size ()]);        class<?> task =  Cl.loadclass (task_default_class);         method runtask =  task.getmethod ("main", new class[] {             string[].class, inputstream.class, printstream.class        });         Runtask.invoke (Task.newinstance (),  args, system.in, system.out);    }  catch  (invocationtargetexception e)  {        throw  e.getcause ();     }}

Step 2

Org.apache.activemq.console.command.ShellCommand:main method

Construct the run context and formatter

Public static int main (String[] args, inputstream in, printstream out)  {    commandcontext context = new commandcontext ();     context.setformatter (New commandshelloutputformatter (out));    //  convert arguments to list for easier management    list< String> tokens = new arraylist<string> (Arrays.aslist (args));     shellcommand main = new shellcommand ();    try {         main.setcommandcontext (context);         main.execute (Tokens);        return 0;     } catch  (exception e)  {         Context.printexception (e);        return -1;    }} 

Step 3:

Org.apache.activemq.console.command.ShellCommand:runTask

Find the appropriate command, process the request

Protected void runtask (List<string> tokens)  throws Exception {     // Process task token    if  (Tokens.size ()  >  0)  {        Command command=null;         String taskToken =  (String) tokens.remove (0);         for ( command c: getcommands ()  )  {             if ( tasktoken.equals (C.getname ())  )  {// According to the name and parameter of each command                  command = c;                 break;            }        &nbsP;}         if ( command == null )  {             if  (Tasktoken.equals ("Help")  {                 printhelp ();             } else {                 printhelp ();             }        }         if ( command!=null )  {             command.setcommandcontext (context);             command.execute (tokens);         }     } else {        printhelp ();     }} 

Step 5:org.apache.activemq.console.command.startcommand:runtask

To start the broker, first determine if the parameters are Brokeruri

Protected void runtask (List<string> brokeruris)  throws Exception {     try {        // if no config  uri, use default setting        if  ( Brokeruris.isempty ())  {             Setconfiguri (New uri (Default_config_uri));             startbroker (Getconfiguri ());             // set configuration data, if available, which in this case             // would be the  config uri        } else {             string strconfiguri;            while  (! Brokeruris.isempty ())  {                 strConfigURI =  (String) brokeruris.remove (0);                 try {                     setconfiguri (New URI ( Strconfiguri));                 } catch  (urisyntaxexception e)  {                     context.printexception (e);                      return;                }                 startbroker (Getconfiguri ());             }        }         // Prevent the main thread from  exiting unless it is terminated        //  elsewhere    } catch  (exception e)  {         context.printexception (New runtimeexception ("Failed to execute start  task. Reason:  " + e, e");         throw  new exception (e);    }        //  The broker start up fine.  if this unblocks it ' s cause they were stopped     // and this would occur because of an internal  error  (Like the db going offline)     waitforshutdown ();}

Class diagram

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ACTIVEMQ Analysis (i) Start-up process