Package org.cometd.bayeux

Class ChannelId

java.lang.Object

org.cometd.bayeux.ChannelId

public class ChannelId
extends Object

Reification of a channel id with methods to test properties and compare with other ChannelIds.

A ChannelId breaks the channel id into path segments so that, for example, /foo/bar breaks into ["foo","bar"].

ChannelId can be wild, when they end with one or two wild characters "*"; a ChannelId is shallow wild if it ends with one wild character (for example /foo/bar/*) and deep wild if it ends with two wild characters (for example /foo/bar/**).

ChannelId can be a template, when a segment contains variable names surrounded by braces, for example /foo/{var_name}. Variable names can only be made of characters defined by the \w regular expression character class.

Field Summary

Fields

Modifier and Type	Field	Description
static final String	DEEPWILD
static final String	WILD

Constructor Summary

Constructors

Constructor	Description
ChannelId(String id)	Constructs a new ChannelId with the given id

Method Summary

Modifier and Type	Method	Description
Map<String,String>	bind(ChannelId target)	If this ChannelId is a template, and the given target ChannelId is non-wild and non-template, and the two have the same depth(), then binds the variable(s) defined in this template with the values of the segments defined by the target ChannelId.
int	depth()
boolean	equals(Object obj)
List<String>	getAllIds()
String	getId()	Returns the normalized channel id string.
List<String>	getParameters()
String	getParent()
String	getRegularPart()	Returns the regular part of this ChannelId: the part of the channel id from the beginning until the first occurrence of a parameter or a wild character.
String	getSegment(int i)
List<String>	getWildIds()	Returns the list of wild channels that match this channel.
List<String>	getWilds()	Deprecated. use getWildIds() instead
int	hashCode()
boolean	isAncestorOf(ChannelId id)
boolean	isBroadcast()
static boolean	isBroadcast(String channelId)	Helper method to test if the string form of a ChannelId represents a broadcast ChannelId.
boolean	isDeepWild()	Deep wild ChannelIds end with a double wild character "**" and match non wild channels with the same or greater depth.
boolean	isMeta()	A ChannelId is a meta ChannelId if it starts with "/meta/".
static boolean	isMeta(String channelId)	Helper method to test if the string form of a ChannelId represents a meta ChannelId.
boolean	isParentOf(ChannelId id)
boolean	isService()	A ChannelId is a service ChannelId if it starts with "/service/".
static boolean	isService(String channelId)	Helper method to test if the string form of a ChannelId represents a service ChannelId.
boolean	isShallowWild()	Shallow wild ChannelIds end with a single wild character "*" and match non wild channels with the same depth.
boolean	isTemplate()
boolean	isWild()
boolean	matches(ChannelId channelId)	Tests whether this ChannelId matches the given ChannelId.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Details

WILD

public static final String WILD

See Also:

• Constant Field Values

DEEPWILD

public static final String DEEPWILD

See Also:

• Constant Field Values

Constructor Details

ChannelId

public ChannelId(String id)

Constructs a new ChannelId with the given id

Parameters:

id - the channel id in string form

Method Details

getId

public String getId()

Returns the normalized channel id string.

Normalization involves trimming white spaces and removing trailing slashes.

Returns:

the normalized channel id string

isWild

public boolean isWild()

Returns:

whether this ChannelId is either shallow wild or deep wild

isShallowWild

public boolean isShallowWild()

Shallow wild ChannelIds end with a single wild character "*" and match non wild channels with the same depth.

Example: /foo/* matches /foo/bar, but not /foo/bar/baz.

Returns:

whether this ChannelId is a shallow wild channel id

isDeepWild

public boolean isDeepWild()

Deep wild ChannelIds end with a double wild character "**" and match non wild channels with the same or greater depth.

Example: /foo/** matches /foo/bar and /foo/bar/baz.

Returns:

whether this ChannelId is a deep wild channel id

isMeta

public boolean isMeta()

A ChannelId is a meta ChannelId if it starts with "/meta/".

Returns:

whether the first segment is "meta"

isService

public boolean isService()

A ChannelId is a service ChannelId if it starts with "/service/".

Returns:

whether the first segment is "service"

isBroadcast

public boolean isBroadcast()

Returns:

whether this ChannelId is neither meta nor service

isTemplate

public boolean isTemplate()

Returns:

whether this ChannelId is a template, that is it contains segments that identify a variable name between braces, such as /foo/{var_name}.

See Also:

• bind(ChannelId)
• getParameters()

getParameters

public List<String> getParameters()

Returns:

the list of variable names if this ChannelId is a template, otherwise an empty list.

See Also:

• isTemplate()

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

matches

public boolean matches(ChannelId channelId)

Tests whether this ChannelId matches the given ChannelId.

If the given ChannelId is wild, then it matches only if it is equal to this ChannelId.

If this ChannelId is non-wild, then it matches only if it is equal to the given ChannelId.

Otherwise, this ChannelId is either shallow or deep wild, and matches ChannelIds with the same number of equal segments (if it is shallow wild), or ChannelIds with the same or a greater number of equal segments (if it is deep wild).

Parameters:

channelId - the channelId to match

Returns:

true if this ChannelId matches the given ChannelId

bind

public Map<String,String> bind(ChannelId target)

If this ChannelId is a template, and the given target ChannelId is non-wild and non-template, and the two have the same depth(), then binds the variable(s) defined in this template with the values of the segments defined by the target ChannelId.

For example:

 // template and target match.
 Map<String, String> bindings = new ChannelId("/a/{var1}/c/{var2}").bind(new ChannelId("/a/foo/c/bar"));
 bindings: {"var1": "foo", "var2": "bar"}

 // template has 2 segments, target has only 1 segment.
 bindings = new ChannelId("/a/{var1}").bind(new ChannelId("/a"))
 bindings = {}

 // template has 2 segments, target too many segments.
 bindings = new ChannelId("/a/{var1}").bind(new ChannelId("/a/b/c"))
 bindings = {}

 // same number of segments, but no match on non-variable segments.
 bindings = new ChannelId("/a/{var1}").bind(new ChannelId("/b/c"))
 bindings = {}
 

The returned map may not preserve the order of variables present in the template ChannelId.

Parameters:

target - the non-wild, non-template ChannelId to bind

Returns:

a map withe the bindings, or an empty map if no binding was possible

See Also:

• isTemplate()

toString

public String toString()

Overrides:

toString in class Object

depth

public int depth()

Returns:

how many segments this ChannelId is made of

See Also:

• getSegment(int)

isAncestorOf

public boolean isAncestorOf(ChannelId id)

Parameters:

id - the channel to test

Returns:

whether this ChannelId is an ancestor of the given ChannelId

See Also:

• isParentOf(ChannelId)

isParentOf

public boolean isParentOf(ChannelId id)

Parameters:

id - the channel to test

Returns:

whether this ChannelId is the parent of the given ChannelId

See Also:

• isAncestorOf(ChannelId)

getParent

public String getParent()

Returns:

the channel string parent of this ChannelId, or null if this ChannelId has only one segment

See Also:

• isParentOf(ChannelId)

getSegment

public String getSegment(int i)

Parameters:

i - the segment index

Returns:

the i-nth segment of this channel, or null if no such segment exist

See Also:

• depth()

getWilds

@Deprecated
public List<String> getWilds()

Deprecated.

use getWildIds() instead

Returns:

The list of wilds channels that match this channel, or the empty list if this channel is already wild.

getWildIds

public List<String> getWildIds()

Returns the list of wild channels that match this channel.

For channel /foo/bar/baz, returns [/foo/bar/*, /foo/bar/**, /foo/**, /**].

For channel /foo/bar/*, returns [/foo/bar/**, /foo/**, /**].

For channel /foo/bar/**, returns [/foo/**, /**].

For channel /*, returns [/**].

For channel /**, returns [], an empty list.

Returns:

The list of wilds channels that match this channel.

getAllIds

public List<String> getAllIds()

Returns:

a list with this channel id and its wild channel ids.

See Also:

• getId()
• getWildIds()

getRegularPart

public String getRegularPart()

Returns the regular part of this ChannelId: the part of the channel id from the beginning until the first occurrence of a parameter or a wild character.

Examples:

ChannelId.regularPart Examples

Channel	Regular Part
/foo	/foo
/foo/*	/foo
/foo/bar/**	/foo/bar
/foo/{p}	/foo
/foo/bar/{p}	/foo/bar
/*	null
/**	null
/{p}	null

Returns:

the regular part of this channel

isMeta

public static boolean isMeta(String channelId)

Helper method to test if the string form of a ChannelId represents a meta ChannelId.

Parameters:

channelId - the channel id to test

Returns:

whether the given channel id is a meta channel id

isService

public static boolean isService(String channelId)

Helper method to test if the string form of a ChannelId represents a service ChannelId.

Parameters:

channelId - the channel id to test

Returns:

whether the given channel id is a service channel id

isBroadcast

public static boolean isBroadcast(String channelId)

Helper method to test if the string form of a ChannelId represents a broadcast ChannelId.

Parameters:

channelId - the channel id to test

Returns:

whether the given channel id is a broadcast channel id