org.jivesoftware.smack.provider
Class ProviderManager

java.lang.Object
  org.jivesoftware.smack.provider.ProviderManager

public class ProviderManager
extends Object

Manages providers for parsing custom XML sub-documents of XMPP packets. Two types of providers exist:

• IQProvider -- parses IQ requests into Java objects.
• PacketExtension -- parses XML sub-documents attached to packets into PacketExtension instances.

IQProvider

By default, Smack only knows how to process IQ packets with sub-packets that are in a few namespaces such as:

• jabber:iq:auth
• jabber:iq:roster
• jabber:iq:register

Because many more IQ types are part of XMPP and its extensions, a pluggable IQ parsing mechanism is provided. IQ providers are registered programatically or by creating a smack.providers file in the META-INF directory of your JAR file. The file is an XML document that contains one or more iqProvider entries, as in the following example:

 <?xml version="1.0"?>
 <smackProviders>
     <iqProvider>
         <elementName>query</elementName>
         <namespace>jabber:iq:time</namespace>
         <className>org.jivesoftware.smack.packet.Time</className>
     </iqProvider>
 </smackProviders>

Each IQ provider is associated with an element name and a namespace. If multiple provider entries attempt to register to handle the same namespace, the first entry loaded from the classpath will take precedence. The IQ provider class can either implement the IQProvider interface, or extend the IQ class. In the former case, each IQProvider is responsible for parsing the raw XML stream to create an IQ instance. In the latter case, bean introspection is used to try to automatically set properties of the IQ instance using the values found in the IQ packet XML. For example, an XMPP time packet resembles the following:

 <iq type='result' to='joe@example.com' from='mary@example.com' id='time_1'>
     <query xmlns='jabber:iq:time'>
         <utc>20020910T17:58:35</utc>
         <tz>MDT</tz>
         <display>Tue Sep 10 12:58:35 2002</display>
     </query>
 </iq>

In order for this packet to be automatically mapped to the Time object listed in the providers file above, it must have the methods setUtc(String), setTz(String), and setDisplay(String). The introspection service will automatically try to convert the String value from the XML into a boolean, int, long, float, double, or Class depending on the type the IQ instance expects.

A pluggable system for packet extensions, child elements in a custom namespace for message and presence packets, also exists. Each extension provider is registered with a name space in the smack.providers file as in the following example:

 <?xml version="1.0"?>
 <smackProviders>
     <extensionProvider>
         <elementName>x</elementName>
         <namespace>jabber:iq:event</namespace>
         <className>org.jivesoftware.smack.packet.MessageEvent</className>
     </extensionProvider>
 </smackProviders>

If multiple provider entries attempt to register to handle the same element name and namespace, the first entry loaded from the classpath will take precedence. Whenever a packet extension is found in a packet, parsing will be passed to the correct provider. Each provider can either implement the PacketExtensionProvider interface or be a standard Java Bean. In the former case, each extension provider is responsible for parsing the raw XML stream to contruct an object. In the latter case, bean introspection is used to try to automatically set the properties of the class using the values in the packet extension sub-element. When an extension provider is not registered for an element name and namespace combination, Smack will store all top-level elements of the sub-packet in DefaultPacketExtension object and then attach it to the packet.

It is possible to provide a custom provider manager instead of the default implementation provided by Smack. If you want to provide your own provider manager then you need to do it before creating any XMPPConnection by sending the static setInstance(ProviderManager) message. Trying to change the provider manager after an XMPPConnection was created will result in an IllegalStateException error.

Author:

Matt Tucker

Method Summary

void	addExtensionProvider(String elementName, String namespace, Object provider) Adds an extension provider with the specified element name and name space.
void	addIQProvider(String elementName, String namespace, Object provider) Adds an IQ provider (must be an instance of IQProvider or Class object that is an IQ) with the specified element name and name space.
Object	getExtensionProvider(String elementName, String namespace) Returns the packet extension provider registered to the specified XML element name and namespace.
Collection<Object>	getExtensionProviders() Returns an unmodifiable collection of all PacketExtensionProvider instances.
static ProviderManager	getInstance() Returns the only ProviderManager valid instance.
Object	getIQProvider(String elementName, String namespace) Returns the IQ provider registered to the specified XML element name and namespace.
Collection<Object>	getIQProviders() Returns an unmodifiable collection of all IQProvider instances.
protected void	initialize()
void	removeExtensionProvider(String elementName, String namespace) Removes an extension provider with the specified element name and namespace.
void	removeIQProvider(String elementName, String namespace) Removes an IQ provider with the specified element name and namespace.
static void	setInstance(ProviderManager providerManager) Sets the only ProviderManager valid instance to be used by all XMPPConnections.

Methods inherited from class java.lang.Object

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

Method Detail

getInstance

public static ProviderManager getInstance()

Returns the only ProviderManager valid instance. Use setInstance(ProviderManager) to configure your own provider manager. If non was provided then an instance of this class will be used.

Returns:

the only ProviderManager valid instance.

setInstance

public static void setInstance(ProviderManager providerManager)

Sets the only ProviderManager valid instance to be used by all XMPPConnections. If you want to provide your own provider manager then you need to do it before creating any XMPPConnection. Otherwise an IllegalStateException will be thrown.

Parameters:

providerManager - the only ProviderManager valid instance to be used.

Throws:

IllegalStateException - if a provider manager was already configued.

initialize

protected void initialize()

getIQProvider

public Object getIQProvider(String elementName,
                            String namespace)

Returns the IQ provider registered to the specified XML element name and namespace. For example, if a provider was registered to the element name "query" and the namespace "jabber:iq:time", then the following packet would trigger the provider:

 <iq type='result' to='joe@example.com' from='mary@example.com' id='time_1'>
     <query xmlns='jabber:iq:time'>
         <utc>20020910T17:58:35</utc>
         <tz>MDT</tz>
         <display>Tue Sep 10 12:58:35 2002</display>
     </query>
 </iq>

Note: this method is generally only called by the internal Smack classes.

Parameters:

elementName - the XML element name.

namespace - the XML namespace.

Returns:

the IQ provider.

getIQProviders

public Collection<Object> getIQProviders()

Returns an unmodifiable collection of all IQProvider instances. Each object in the collection will either be an IQProvider instance, or a Class object that implements the IQProvider interface.

Returns:

all IQProvider instances.

addIQProvider

public void addIQProvider(String elementName,
                          String namespace,
                          Object provider)

Adds an IQ provider (must be an instance of IQProvider or Class object that is an IQ) with the specified element name and name space. The provider will override any providers loaded through the classpath.

Parameters:

elementName - the XML element name.

namespace - the XML namespace.

provider - the IQ provider.

removeIQProvider

public void removeIQProvider(String elementName,
                             String namespace)

Removes an IQ provider with the specified element name and namespace. This method is typically called to cleanup providers that are programatically added using the addIQProvider method.

Parameters:

elementName - the XML element name.

namespace - the XML namespace.

getExtensionProvider

public Object getExtensionProvider(String elementName,
                                   String namespace)

Returns the packet extension provider registered to the specified XML element name and namespace. For example, if a provider was registered to the element name "x" and the namespace "jabber:x:event", then the following packet would trigger the provider:

 <message to='romeo@montague.net' id='message_1'>
     <body>Art thou not Romeo, and a Montague?</body>
     <x xmlns='jabber:x:event'>
         <composing/>
     </x>
 </message>

Note: this method is generally only called by the internal Smack classes.

Parameters:

elementName - element name associated with extension provider.

namespace - namespace associated with extension provider.

Returns:

the extenion provider.

addExtensionProvider

public void addExtensionProvider(String elementName,
                                 String namespace,
                                 Object provider)

Adds an extension provider with the specified element name and name space. The provider will override any providers loaded through the classpath. The provider must be either a PacketExtensionProvider instance, or a Class object of a Javabean.

Parameters:

elementName - the XML element name.

namespace - the XML namespace.

provider - the extension provider.

removeExtensionProvider

public void removeExtensionProvider(String elementName,
                                    String namespace)

Removes an extension provider with the specified element name and namespace. This method is typically called to cleanup providers that are programatically added using the addExtensionProvider method.

Parameters:

elementName - the XML element name.

namespace - the XML namespace.

getExtensionProviders

public Collection<Object> getExtensionProviders()

Returns an unmodifiable collection of all PacketExtensionProvider instances. Each object in the collection will either be a PacketExtensionProvider instance, or a Class object that implements the PacketExtensionProvider interface.

Returns:

all PacketExtensionProvider instances.