[Index]

bus:bus

Links components in a data pipeline. Components provide data by accepting an java.util.function.Consumer either by being an org.oddjob.beanbus.Outbound or by marking a setter with the org.oddjob.beanbus.Destination annotation. Components accept data by being a java.util.function.Consumer. Components can be both.

This component parent provides the following features over other component parents such as sequential:

Components will be automatically linked to the next component unless this is disabled.
Any plain java.util.function.Consumer will appear in the bus as a service with appropriate icons and state.
Components will be run (or started) in reverse order so destinations are ready to receive data before it is sent by the previous components.
Components will be stopped in order so components that send data are stopped before the destinations that receive the data.
If a component has a property setter of type java.lang.AutoCloseable then one will be set automatically allowing the component to stop the bus.
If a component has a property setter of type java.io.Flushable then one will be set automatically allowing the component to flush the bus.
Any component that is java.io.Flushable will be flushed when a component flushes the bus. Flush will be called in component order. Flush will always be called when the bus stops, unless it crashes.
If a component wishes to both stop and flush the bus, and doesn't mind a dependency on this framework it can provide a property setter of type org.oddjob.beanbus.BusConductor and one will be set automatically
If a component enters an Exception state the bus will crash. Other components will be stopped in order.

Property Summary

busConductor	Provides coordination facilities to the components of a bus.
count
name	A name, can be any text.
noAutoLink	Bus components will automatically be linked unless this is true.
of	The components of a Bus.
services	Provides services to other components of a bus.
stop	Read only view of the internal stop flag.
to	An onward consumer so that bus services may be nested.

Example Summary

Example 1	A simple bus of 3 components.
Example 2	Shows how a bus can be nested to create side branches.

Property Detail

busConductor

Configured By	ELEMENT
Access	READ_WRITE
Required	No.

Provides coordination facilities to the components of a bus. Set automatically and exposed for advance use only.

count

Access

READ_ONLY

name

Configured By	ATTRIBUTE
Access	READ_WRITE
Required	No.

A name, can be any text.

noAutoLink

Configured By	ATTRIBUTE
Access	READ_WRITE
Required	No, defaults to false.

Bus components will automatically be linked unless this is true.

of

Configured By	ELEMENT
Access	WRITE_ONLY
Required	No, but pointless if missing.

The components of a Bus.

services

Access	READ_ONLY
Required	Read Only.

Provides services to other components of a bus. Exposed for advance use only.

stop

Access

READ_ONLY

Read only view of the internal stop flag. This flag is cleared with a reset.

to

Configured By	ELEMENT
Access	READ_WRITE
Required	No.

An onward consumer so that bus services may be nested.

Examples

Example 1

A simple bus of 3 components. The first component is the bus driver that sends 3 beans down the pipe. The second component is a function that doubles the price and the last component collects the results.

<oddjob>
    <job>
        <bus:bus id="bean-bus" xmlns:bus="oddjob:beanbus">
            <of>
                <bus:driver>
                    <values>
                        <list>
                            <values>
                                <value value="#{25.5}"/>
                                <value value="#{36.2}"/>
                                <value value="#{40.4}"/>
                            </values>
                        </list>
                    </values>
                </bus:driver>
                <bus:map>
                    <function>
                        <value value="#{ function(x) { return x * 2 } }"/>
                    </function>
                </bus:map>
                <bus:collect id="results"/>
            </of>
        </bus:bus>
    </job>
</oddjob>

Example 2

Shows how a bus can be nested to create side branches. The data is passed to each branch in turn.

<oddjob>
    <job>
        <cascade>
            <jobs>
                <bus:bus id="bus" xmlns:bus="oddjob:beanbus">
                    <of>
                        <bus:driver>
                            <values>
                                <list>
                                    <values>
                                        <value value="red"/>
                                        <value value="red"/>
                                        <value value="blue"/>
                                        <value value="green"/>
                                    </values>
                                </list>
                            </values>
                        </bus:driver>
                        <bus:bus>
                            <of>
                                <bus:filter id="filterRed">
                                    <predicate>
                                        <value value="#{ function(x) { return 'red' == x }}"/>
                                    </predicate>
                                </bus:filter>
                            </of>
                        </bus:bus>
                        <bus:bus>
                            <of>
                                <bus:filter id="filterBlue">
                                    <predicate>
                                        <value value="#{ function(x) { return 'blue' == x }}"/>
                                    </predicate>
                                </bus:filter>
                            </of>
                        </bus:bus>
                    </of>
                </bus:bus>
                <check value="${filterRed.passed}" eq="2"/>
                <check value="${filterBlue.passed}" eq="1"/>
            </jobs>
        </cascade>
    </job>
</oddjob>