com.arjuna.services.framework.startup

Class Sequencer

java.lang.Object

com.arjuna.services.framework.startup.Sequencer

public class Sequencer
extends Object

A manager which allows initializaton callabcks for a suite of related web apps to be registered and subsequently run in a fixed order, irrespective of the order in which the application server initializes the web apps. Sequencer maintains two lists of independently managed callbacks, one for the WSCOOR 1.0 web app suite and one for the WSCOOR 1.1 web app suite. When registering a callback listeners or servlets for a given web app supply a sequence id and a web app id to identify i) the required sequence and ii) the entry in the sequence at which the callback should be stored. If a web app registers multiple callbacks they are stored in the sequence entry as a list in registration order. Once a web app has registered all its callbacks it closes the relevant entry. When all entries in a sequence have been closed the entries are traversed in order and the callbacks in each entry are triggered, thus ensuring that callbacks for web apps with lower sequence indices complete before callbacks with higher indices are called. This version also includes a global latch which can be used to ensure that no callbacks are not processed until a client lifts the latch. If the latch has already been lifted when the final element of a sequencer is closed the callbacks are run straight away. If the latch is closed then the sequencer is installed in a deferred list. When the latch is lifted the deferred list is scanned and callbacks are run for each sequencer found in the list. User: adinn Date: Nov 30, 2007 Time: 4:05:13 PM

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Sequencer.Callback a callback class specialised by client web apps to execute startup code

Field Summary

Fields

Modifier and Type	Field and Description
static int	SEQUENCE_MAX count of independent startup sequences.
static int	SEQUENCE_WSCOOR10 index of startup sequence used for serialization of WSCOOR 1.0 initialization callbacks
static int	SEQUENCE_WSCOOR11 index of startup sequence used for serialization of WSCOOR 1.1 initialization callbacks
static int	WEBAPP_MAX10 there are four startup apps in the 1.0 sequence
static int	WEBAPP_MAX11 there are three startup apps in the 1.1 sequence
static int	WEBAPP_WSC10 index of WS-C web app which initialises first in 1.0
static int	WEBAPP_WSC11 index of WS-C web app which initialises first in 1.1
static int	WEBAPP_WSCF10 index of WSCF web app which intiialises third in 1.0
static int	WEBAPP_WSCF11 index of WSCF web app which intiialises third in 1.1
static int	WEBAPP_WST10 index of WS-T web app which initialises second in 1.0
static int	WEBAPP_WST11 index of WS-T web app which initialises second in 1.1
static int	WEBAPP_WSTX10 index of WSTX web app which initialises last in 1.0
static int	WEBAPP_WSTX11 index of WSTX web app which intiialises fourth in 1.1

Method Summary

Modifier and Type	Method and Description
static void	close(int sequence, int webapp) notify end of callback registration for a web app associated with a given sequence
static void	unlatch() undo the latch which initially delays running of any callback sequences.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

SEQUENCE_WSCOOR10

public static final int SEQUENCE_WSCOOR10

index of startup sequence used for serialization of WSCOOR 1.0 initialization callbacks

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Constant Field Values

SEQUENCE_WSCOOR11

public static final int SEQUENCE_WSCOOR11

index of startup sequence used for serialization of WSCOOR 1.1 initialization callbacks

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Constant Field Values

SEQUENCE_MAX

public static final int SEQUENCE_MAX

count of independent startup sequences.

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Constant Field Values

WEBAPP_WSC10

public static final int WEBAPP_WSC10

index of WS-C web app which initialises first in 1.0

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Constant Field Values

WEBAPP_WST10

public static final int WEBAPP_WST10

index of WS-T web app which initialises second in 1.0

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Constant Field Values

WEBAPP_WSCF10

public static final int WEBAPP_WSCF10

index of WSCF web app which intiialises third in 1.0

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Constant Field Values

WEBAPP_WSTX10

public static final int WEBAPP_WSTX10

index of WSTX web app which initialises last in 1.0

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Constant Field Values

WEBAPP_MAX10

public static final int WEBAPP_MAX10

there are four startup apps in the 1.0 sequence

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Constant Field Values

WEBAPP_WSC11

public static final int WEBAPP_WSC11

index of WS-C web app which initialises first in 1.1

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Constant Field Values

WEBAPP_WST11

public static final int WEBAPP_WST11

index of WS-T web app which initialises second in 1.1

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Constant Field Values

WEBAPP_WSCF11

public static final int WEBAPP_WSCF11

index of WSCF web app which intiialises third in 1.1

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Constant Field Values

WEBAPP_WSTX11

public static final int WEBAPP_WSTX11

index of WSTX web app which intiialises fourth in 1.1

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Constant Field Values

WEBAPP_MAX11

public static final int WEBAPP_MAX11

there are three startup apps in the 1.1 sequence

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Constant Field Values

Method Detail

close

public static final void close(int sequence,
                               int webapp)

notify end of callback registration for a web app associated with a given sequence

Parameters:

webapp -

unlatch

public static void unlatch()

undo the latch which initially delays running of any callback sequences. this is provided to enable the Service start routine to configure any necessary parameters before the listener callbacks are run.