Generic Event Delivery Using HTTP Push
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RAI
WEBPUSHInternet-DraftHTTPHTTP2PushWebPush
A simple protocol for the delivery of real-time events to user agents is
described. This scheme uses HTTP/2 server push.
Many applications on mobile and embedded devices require continuous
access to network communications so that real-time events - such as
incoming calls or messages - can be delivered (or "pushed") in a timely
fashion. These devices typically have limited power reserves, so finding
more efficient ways to serve application requirements greatly benefits
the application ecosystem.
One significant contributor to power usage is the radio. Radio
communications consume a significant portion of the energy budget
on a wireless device.
Uncoordinated use of persistent connections or sessions from multiple
applications can contribute to unnecessary use of the device radio,
since each independent session can incur its own overhead. In
particular, keep alive traffic used to ensure that middleboxes do not
prematurely time out sessions, can result in significant waste.
Maintenance traffic tends to dominate over the long term, since events
are relatively rare.
Consolidating all real-time events into a single session ensures more
efficient use of network and radio resources. A single service
consolidates all events, distributing those events to applications as
they arrive. This requires just one session, avoiding duplicated
overhead costs.
The W3C Push API describes an API that
enables the use of a consolidated push service from web applications.
This document expands on that work by describing a protocol that can be used to:
request the delivery of a push message to a user agent,
create new push message delivery subscriptions, and
monitor for new push messages.
A standardized method of event delivery is particularly important for
the W3C Push API, where application servers might need to use multiple
push services. The subscription, management and monitoring functions
are currently fulfilled by proprietary protocols; these are adequate,
but do not offer any of the advantages that standardization affords.
This document intentionally does not describe how a push service is
discovered. Discovery of push services is left for future efforts, if
it turns out to be necessary at all. User agents are expected to be
configured with a URL for a push service.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in .
This document defines the following terms:
Both the sender and ultimate consumer of push messages. Many
applications have components that are run on a user agent and
other components that run on servers.
The component of an application that usually runs on a server and
requests the delivery of a push message.
A message delivery context that is established between the user
agent and the push service and shared with the application server.
All push messages are associated with a push message subscription.
A message delivery context that is established between the user
agent and the push service that collects multiple push message
subscriptions into a set.
A message sent from an application server to a user agent via a
push service.
A message delivery confirmation sent from the push service to the
application server.
A service that delivers push messages to user agents.
A device and software that is the recipient of push messages.
Examples in this document use the HTTP/1.1
message format. Many of the exchanges can be completed using
HTTP/1.1, where HTTP/2 is necessary, the more verbose frame format
from is used.
Examples do not include specific methods for push message encryption
or application server authentication because the protocol does not define
a mandatory system. The examples in Voluntary Application Server Identification
and Message Encryption for WebPush
demonstrate the approach adopted by the W3C Push API for
its requirements.
A general model for push services includes three basic actors: a user
agent, a push service, and an application (server).
At the very beginning of the process, a new message subscription is
created by the user agent and then distributed to its application
server. This subscription is the basis of all future interactions between
the actors. A subscription is used by the application server to send messages to
the push service for being delivered to the user agent. It is used by
the user agent to monitor the push service for any incoming message.
To offer more control for authorization, a message subscription is
modeled as two resources with different capabilities:
A subscription resource is used to receive messages from a
subscription and to delete a subscription. It is private to the user
agent.
A push resource is used to send messages to a subscription. It is
public and shared by the user agent with its application server.
It is expected that a unique subscription will be distributed to each
application; however, there are no inherent cardinality constraints in
the protocol. Multiple subscriptions might be created for the same
application, or multiple applications could use the same subscription.
Note however that sharing subscriptions has security and privacy
implications.
Subscriptions have a limited lifetime. They can also be terminated by
either the push service or user agent at any time. User agents and
application servers must be prepared to manage changes in subscription
state.
This protocol uses HTTP resources and
link relations. The following resources
are defined:
This resource is used to create push message subscriptions
(). A URL for the push
service is configured into user agents.
This resource provides read and delete access for a message
subscription. A user agent receives push
messages using a push message subscription. Every push
message subscription has exactly one push resource associated with
it.
This resource provides read and delete access for a collection of push
message subscriptions. A user agent receives
push messages for all the push message subscriptions in the set. A
link relation of type "urn:ietf:params:push:set" identifies a push message
subscription set.
An application server requests the delivery of a
push message using a push resource. A link relation of type "urn:ietf:params:push"
identifies a push resource.
The push service creates a push message resource to identify push messages that
have been accepted for delivery. The push message
resource is also deleted by the user agent to
acknowledge receipt of a push message.
An application server receives
delivery confirmations for push messages using a receipt
subscription. A link relation of type "urn:ietf:params:push:receipt"
identifies a receipt subscription.
The push service shares the same default port number (443/TCP) with HTTPS, but MAY
also advertise the IANA allocated TCP System Port 1001 using HTTP alternative services
.
While the default port (443) offers broad reachability characteristics, it is most
often used for web browsing scenarios with a lower idle timeout than other ports
configured in middleboxes. For webpush scenarios, this would contribute to unnecessary
radio communications to maintain the connection on battery-powered devices.
Advertising the alternate port (1001) allows middleboxes to optimize idle timeouts
for connections specific to push scenarios with the expectation that data exchange will be
infrequent.
Middleboxes SHOULD comply with REQ-5 in which requires that
"the value of the 'established connection idle-timeout' MUST NOT be less than
2 hours 4 minutes".
A user agent sends a POST request to its configured push service
resource to create a new subscription.
A 201 (Created) response indicates that the a push subscription was
created. A URI for the push message subscription resource that was
created in response to the request MUST be returned in the Location
header field.
The push service MUST provide a URI for the push resource corresponding
to the push message subscription in a link relation of type
"urn:ietf:params:push".
An application-specific method is used to distribute the push URI to the
application server. Confidentiality protection and application server
authentication MUST be used to ensure that this URI is not disclosed
to unauthorized recipients ().
Collecting multiple push message subscriptions into a subscription set
can represent a significant efficiency improvement for push services
and user agents. The push service MAY provide a URI for a subscription
set resource in a link relation of type "urn:ietf:params:push:set".
When a subscription set is returned in a push message subscription
response, the user agent SHOULD include this subscription set in a link
relation of type "urn:ietf:params:push:set" in subsequent requests to
create new push message subscriptions.
A user agent MAY omit the subscription set if it is unable to receive
push messages in an aggregated way for the lifetime of the subscription.
This might be necessary if the user agent is monitoring subscriptions on
behalf of other push message receivers.
The push service SHOULD return the same subscription set in its response, although
it MAY return a new subscription set if it is unable to reuse the one provided
by the user agent.
A push service MUST return a 400 (Bad Request) status code for requests which
contain an invalid subscription set. A push service MAY return a 429
(Too Many Requests) status code to reject requests
which omit a subscription set.
How a push service detects that requests originate from the same user agent
is implementation-specific but could take ambient information into
consideration, such as the TLS connection, source IP address and port.
Implementers are reminded that some heuristics can produce false
positives and cause requests to be rejected incorrectly.
An application server requests the delivery of a push message by sending
a HTTP POST request to a push resource distributed to the application
server by a user agent. The content of the push message is included
in the body of the request.
An application server can include the Prefer header
field with the "respond-async" preference to request confirmation
from the push service when a push message is delivered and then acknowledged
by the user agent. The push service MUST support delivery confirmations.
For subsequent receipt requests to the same origin ,
the application server SHOULD include the returned receipt subscription in
a link relation of type "urn:ietf:params:push:receipt". This gives the push
service an option to aggregate the receipts. The push service SHOULD return
the same receipt subscription in its response, although it MAY return a new
receipt subscription if it is unable to reuse the one provided by the application
server.
An application server MAY omit the receipt subscription if it is
unable to receive receipts in an aggregated way for the lifetime of
the receipt subscription. This might be necessary if the application
server is monitoring receipt subscriptions on the behalf of other
push message senders.
A push service MUST return a 400 (Bad Request) status code for requests which contain
an invalid receipt subscription. If a push service wishes to limit the number of
receipt subscriptions that it maintains, it MAY return a 429 (Too Many Requests)
status code to reject receipt requests which omit a receipt
subscription.
A push service can improve the reliability of push message delivery
considerably by storing push messages for a period. User agents are
often only intermittently connected, and so benefit from having short
term message storage at the push service.
Delaying delivery might also be used to batch communication with the
user agent, thereby conserving radio resources.
Some push messages are not useful once a certain period of time
elapses. Delivery of messages after they have ceased to be relevant
is wasteful. For example, if the push message contains a call
notification, receiving a message after the caller has abandoned the
call is of no value; the application at the user agent is forced to
suppress the message so that it does not generate a useless alert.
An application server MUST include the TTL (Time-To-Live) header field in
its request for push message delivery. The TTL header field contains a value
in seconds that suggests how long a push message is retained by the push service.
A push service MUST return a 400 (Bad Request) status code in response to
requests that omit the TTL header field.
A push service MAY retain a push message for a shorter duration than requested.
It indicates this by returning a TTL header field in its response with the actual
TTL. This TTL value MUST be less than or equal to the value provided by the
application server.
Once the TTL period elapses, the push service MUST NOT attempt to deliver the push
message to the user agent. A push service might adjust the TTL value to account for
time accounting errors in processing. For instance, distributing a push message
within a server cluster might accrue errors due to clock skew or propagation delays.
A push service is not obligated to account for time spent by the
application server in sending a push message to the push service, or
delays incurred while sending a push message to the user agent. An
application server needs to account for transit delays in selecting a
TTL header field value.
A Push message with a zero TTL is immediately delivered if the user agent is
available to receive the message. After delivery, the push service is permitted
to immediately remove a push message with a zero TTL. This might occur before the
user agent acknowledges receipt of the message by performing a HTTP DELETE on the
push message resource. Consequently, an application server cannot rely on receiving
acknowledgement receipts for zero TTL push messages.
If the user agent is unavailable, a push message with a zero TTL expires and
is never delivered.
For a device that is battery-powered, it is often critical that it remains
dormant for extended periods. Radio communication in particular consumes
significant power and limits the length of time that the device can operate.
To avoid consuming resources to receive trivial messages, it is helpful
if an application server can communicate the urgency of a message and if the
user agent can request that the push server only forward messages of a specific
urgency.
An application server MAY include an Urgency header field in its
request for push message delivery. This header field indicates the
message urgency. The push service MUST not forward the Urgency header
field to the user agent. A push message without the Urgency header
field defaults to a value of "normal".
A user agent MAY include the Urgency header field when monitoring for
push messages to indicate the lowest urgency of push messages that it
is willing to receive. A push service MUST NOT deliver push messages
with lower urgency than the value indicated by the user agent in its
monitoring request. Push messages of any urgency are delivered to a
user agent that does not include an Urgency header field when
monitoring for messages.
In order of increasing urgency:
UrgencyDevice StateApplication Scenariovery-lowOn power and wifiAdvertisementslowOn either power or wifiTopic updatesnormalOn neither power nor wifiChat or Calendar MessagehighLow batteryIncoming phone call or time-sensitive alert
Multiple values for the Urgency header
field MUST NOT be included in requests; otherwise, the push service
MUST return a 400 (Bad Request) status code.
A push message that has been stored by the push service can be
replaced with new content. If the user agent is offline during the
time that the push messages are sent, updating a push message avoids
the situation where outdated or redundant messages are sent to the
user agent.
Only push messages that have been assigned a topic can be replaced. A
push message with a topic replaces any outstanding push message with
an identical topic.
A push message topic is a string carried in a Topic header field.
A topic is used to correlate push messages sent to the same subscription and
does not convey any other semantics.
The grammar for the Topic header field uses the token rule defined in .
For use with this protocol, the Topic header field MUST be restricted
to no more than 32 characters from the URL and filename safe Base 64
alphabet . A push service that receives a request
with a Topic header field that does not meet these constraints MUST return
a 400 (Bad Request) status code to the application server.
A push message replacement request creates a new push message resource
and simultaneously deletes any existing message resource that has a
matching topic. Delivery receipts for the deleted message SHOULD be
suppressed.
The replacement request also replaces the stored TTL, Urgency, and any
receipt subscription associated with the previous message in the
matching topic.
A push message with a topic that is not shared by an outstanding
message to the same subscription is stored or delivered as normal.
The value of the Topic header field MUST NOT be forwarded to user
agents. Its value is neither encrypted nor authenticated.
A user agent requests the delivery of new push messages by making a GET
request to a push message subscription resource. The push service does
not respond to this request, it instead uses HTTP/2 server push to send the
contents of push messages as they are sent by application servers.
A user agent MAY include a Urgency header field in its request. The push service MUST
NOT deliver messages with lower urgency than the value of the header field
as defined in the .
Each push message is pushed as the response to a synthesized GET request
sent in a PUSH_PROMISE. This GET request is made to the push message resource
that was created by the push service when the application server requested
message delivery. The response headers SHOULD provide a URI for the push
resource corresponding to the push message subscription in a link relation
of type "urn:ietf:params:push". The response body is the entity body from
the most recent request sent to the push resource by the application server.
A user agent can also request the contents of the push message subscription
resource immediately by including a Prefer header
field with a "wait" preference set to "0". In response to this request,
the push service MUST generate a server push for all push messages that have not yet
been delivered.
A 204 (No Content) status code with no associated server pushes
indicates that no messages are presently available. This could be
because push messages have expired.
There are minor differences between receiving push messages for a subscription and
a subscription set. If a subscription set is available, the user agent SHOULD use the
subscription set to monitor for push messages rather than individual push message
subscriptions.
A user agent requests the delivery of new push messages for a collection of
push message subscriptions by making a GET request to a push message subscription
set resource. The push service does not respond to this request, it instead uses
HTTP/2 server push to send the contents of push
messages as they are sent by application servers.
A user agent MAY include a Urgency header field in its request. The push service MUST
NOT deliver messages with lower urgency than the value of the header field
as defined in the .
Each push message is pushed as the response to a synthesized GET request
sent in a PUSH_PROMISE. This GET request is made to the push message resource
that was created by the push service when the application server requested
message delivery. The synthetic request MUST provide a URI for the push resource
corresponding to the push message subscription in a link relation of type
"urn:ietf:params:push". This enables the user agent to differentiate the source
of the message. The response body is the entity body from the most recent request
sent to the push resource by an application server.
A user agent can request the contents of the push message subscription
set resource immediately by including a Prefer header
field with a "wait" preference set to "0". In response to this request,
the push service MUST generate a server push for all push messages that have not
yet been delivered.
A 204 (No Content) status code with no associated server pushes
indicates that no messages are presently available. This could be
because push messages have expired.
To ensure that a push message is properly delivered to the user agent
at least once, the user agent MUST acknowledge receipt of the message
by performing a HTTP DELETE on the push message resource.
If the push service receives the acknowledgement and the application
has requested a delivery receipt, the push service MUST return a 204 (No Content)
response to the application server monitoring the receipt subscription.
If the push service does not receive the acknowledgement within a
reasonable amount of time, then the message is considered to be not yet
delivered. The push service SHOULD continue to retry delivery of the message
until its advertised expiration.
The push service MAY cease to retry delivery of the message prior to its
advertised expiration due to scenarios such as an unresponsive user agent or
operational constraints. If the application has requested a delivery receipt,
then the push service MUST return a 410 (Gone) response to the application server
monitoring the receipt subscription.
The application server requests the delivery of receipts from the push
service by making a HTTP GET request to the receipt subscription
resource. The push service does not respond to this request, it
instead uses HTTP/2 server push to send push
receipts when messages are acknowledged ()
by the user agent.
Each receipt is pushed as the response to a synthesized GET request sent in a
PUSH_PROMISE. This GET request is made to the same push message resource that
was created by the push service when the application server requested message
delivery. The response includes a status code indicating the result of the message delivery and carries no data.
If the user agent fails to acknowledge the receipt of the push message and
the push service ceases to retry delivery of the message prior to its advertised
expiration, then the push service MUST push a failure response with a status code
of 410 (Gone).
A push service is likely to have to maintain a very large number of open
TCP connections. Effective management of those connections can depend
on being able to move connections between server instances.
A user agent MUST support the 307 (Temporary Redirect) status code
, which can be used by a push service to
redistribute load at the time that a new subscription is requested.
A server that wishes to redistribute load can do so using HTTP alternative
services . HTTP alternative
services allows for redistribution of load while maintaining the same
URIs for various resources. A user agent can ensure a graceful
transition by using the GOAWAY frame once it has established a
replacement connection.
Storage of push messages based on the TTL header field comprises a
potentially significant amount of storage for a push service. A push
service is not obligated to store messages indefinitely. A push
service is able to indicate how long it intends to retain a message to
an application server using the TTL header field ().
A user agent that does not actively monitor for push messages will not
receive messages that expire during that interval.
Push messages that are stored and have not been delivered to a user agent are
delivered when the user agent recommences monitoring. Stored push
messages SHOULD include a Last-Modified header field (Section 2.2
of ) indicating when delivery was requested by
an application server.
A GET request to a push message subscription resource with only
expired messages results in a response as though no push message was
ever sent.
Push services might need to limit the size and number of stored push
messages to avoid overloading. To limit the size of messages, the
push service MAY return a 413 (Payload Too Large) status code
in response to requests that include an entity body that is too large.
Push services MUST NOT return a 413 status code in responses to an entity
body that is 4k (4096 bytes) or less in size.
To limit the number of stored push messages, the push service MAY either
expire messages prior to their advertised Time-To-Live or reduce their
advertised Time-To-Live.
In some cases, it may be necessary to terminate subscriptions so that
they can be refreshed. This applies to both push message
subscriptions and receipt subscriptions.
A push service MAY expire a subscription at any time. If there are outstanding
requests to an expired push message subscription resource ()
from a user agent or to an expired receipt subscription resource ()
from an application server, this MUST be signaled by returning a 404 (Not Found) status code.
A push service MUST return a 404 (Not Found) status code if an application server
attempts to send a push message to an expired push message subscription.
A user agent can remove its push message subscription by sending a DELETE request to
the corresponding URI. An application server can remove its receipt subscription by
sending a DELETE request to the corresponding URI.
A push service MAY expire a subscription set at any time and MUST also
expire all push message subscriptions in the set. If a user agent has an
outstanding request to a push subscription set ()
this MUST be signaled by returning a 404 (Not Found) status code.
A user agent can request that a subscription set be removed by sending a DELETE
request to the subscription set URI. This MUST also remove all push message
subscriptions in the set.
If a specific push message subscription that is a member of a subscription set is
expired or removed, then it MUST also be removed from its subscription set.
A push service that does not support reliable delivery over
intermittent network connections or failing applications on devices,
forces the device to acknowledge receipt directly to the application
server, incurring additional power drain in order to establish
(usually secure) connections to the individual application servers.
Push message reliability can be important if messages contain
information critical to the state of an application. Repairing state
can be expensive, particularly for devices with limited communications
capacity. Knowing that a push message has been correctly received
avoids retransmissions, polling, and state resynchronization.
The availability of push message delivery receipts ensures that the
application developer is not tempted to create alternative mechanisms
for message delivery in case the push service fails to deliver a
critical message. Setting up a polling mechanism or a backup messaging
channel in order to compensate for these shortcomings negates almost
all of the advantages a push service provides.
However, reliability might not be necessary for messages that are
transient (e.g. an incoming call) or messages that are quickly
superceded (e.g. the current number of unread emails).
If the push service requires that the user agent use push message subscription sets,
then it MAY limit the number of concurrently active streams with the
SETTINGS_MAX_CONCURRENT_STREAMS parameter within a HTTP/2 SETTINGS frame .
The user agent MAY be limited to one concurrent stream to manage push message
subscriptions and one concurrent stream for each subscription set returned by the push service.
This could force the user agent to serialize subscription requests to the push
service.
This protocol MUST use HTTP over TLS.
This includes any communications between user agent and push service,
plus communications between the application and the push service. All
URIs therefore use the "https" scheme. This provides confidentiality
and integrity protection for subscriptions and push messages from
external parties.
Applications using this protocol MUST use mechanisms that provide confidentiality,
integrity and data origin authentication. The application server sending the push
message and the application on the user agent that receives it are frequently just
different instances of the same application, so no standardized protocol is needed to
establish a proper security context. The distribution of subscription information
from the user agent to its application server also offers a convenient medium for
key agreement.
The protection afforded by TLS does not protect content from the push
service. Without additional safeguards, a push service can inspect
and modify the message content.
For its requirements, the W3C Push API has adopted
Message Encryption for WebPush
to secure the content of messages from the push service. Other scenarios can
be addressed by similar policies.
The Topic header field exposes information that allows more granular
correlation of push messages on the same subject. This might be used
to aid traffic analysis of push messages by the push service.
Push message confidentiality does not ensure that the identity of who
is communicating and when they are communicating is protected.
However, the amount of information that is exposed can be limited.
The URIs provided for push resources MUST NOT provide any basis to
correlate communications for a given user agent. It MUST NOT be
possible to correlate any two push resource URIs based solely on their
contents. This allows a user agent to control correlation across
different applications, or over time.
Similarly, the URIs provided by the push service to identify a push
message MUST NOT provide any information that allows for correlation
across subscriptions. Push message URIs for the same subscription MAY
contain information that would allow correlation with the associated
subscription or other push messages for that subscription.
User and device information MUST NOT be exposed through a push or push
message URI.
In addition, push URIs established by the same user agent or push
message URIs for the same subscription MUST NOT include any information
that allows them to be correlated with the user agent.
This need not be perfect as long as the resulting anonymity set
(, Section 6.1.1) is sufficiently
large. A push URI necessarily identifies a push service or a
single server instance. It is also possible that traffic analysis
could be used to correlate subscriptions.
A user agent MUST be able to create new subscriptions with new
identifiers at any time.
This protocol does not define how a push service establishes whether a
user agent is permitted to create a subscription, or whether push
messages can be delivered to the user agent. A push service MAY choose
to authorize requests based on any HTTP-compatible authorization method
available, of which there are numerous options. The authorization
process and any associated credentials are expected to be configured in
the user agent along with the URI for the push service.
Authorization is managed using capability URLs for the push message
subscription, push, and receipt subscription resources ().
A capability URL grants access to a resource based solely on knowledge of the URL.
Capability URLs are used for their "easy onward sharing" and "easy
client API" properties. These make it possible to avoid relying on
relationships between push services and application servers, with the
protocols necessary to build and support those relationships.
Capability URLs act as bearer tokens. Knowledge of a push message
subscription URI implies authorization to either receive push messages
or delete the subscription. Knowledge of a push URI implies
authorization to send push messages. Knowledge of a push message URI
allows for reading and acknowledging that specific message. Knowledge
of a receipt subscription URI implies authorization to receive push receipts.
Encoding a large amount of random entropy (at least 120 bits) in the
path component ensures that it is difficult to successfully guess a
valid capability URL.
A user agent can control where valid push messages originate by
limiting the distribution of push URIs to authorized application servers.
Ensuring that push URIs are hard to guess ensures that only application
servers that have received a push URI can use it.
Push messages that are not successfully authenticated by the user agent
will not be delivered, but this can present a denial of service risk. Even a
relatively small volume of push messages can cause battery-powered devices
to exhaust power reserves.
To address this case, the W3C Push API has adopted
Voluntary Application Server Identification,
which allows a user agent to restrict a subscription to a specific application
server. The push service can then identity and reject unwanted messages without
contacting the user agent.
A malicious application with a valid push URI could use the greater
resources of a push service to mount a denial of service attack on a
user agent. Push services SHOULD limit the rate at which push messages
are sent to individual user agents.
A push service MAY return a 429 (Too Many Requests) status code
when an application server has exceeded its rate limit for push message delivery to
a push resource. The push service SHOULD also include a Retry-After header
to indicate how long the application server
is requested to wait before it makes another request to the push resource.
A push service or user agent MAY also terminate subscriptions
that receive too many push messages.
A push service is also able to deny service to user agents.
Intentional failure to deliver messages is difficult to distinguish
from faults, which might occur due to transient network errors,
interruptions in user agent availability, or genuine service outages.
Server request logs can reveal subscription-related URIs or relationships
between subscription-related URIs for the same user agent.
Limitations on log retention and strong access control mechanisms can
ensure that URIs are not revealed to unauthorized entities.
This protocol defines new HTTP header fields in . New link relation types are identified
using the URNs defined in . Port registration is
defined in
HTTP header fields are registered within the "Message Headers"
registry maintained at .
This document defines the following HTTP header fields, so their
associated registry entries shall be added according to the permanent
registrations below ():
Header Field NameProtocolStatusReferenceTTLhttpstandardUrgencyhttpstandardTopichttpstandard
The change controller is: "IETF (iesg@ietf.org) - Internet
Engineering Task Force".
This document registers URNs for use in identifying link relation
types. These are added to a new "Web Push Identifiers" registry
according to the procedures in Section 4 of ;
the corresponding "push" sub-namespace is entered in the "IETF URN
Sub-namespace for Registered Protocol Parameter Identifiers"
registry.
The "Web Push Identifiers" registry operates under the IETF Review policy.
Web Push Identifiersurn:ietf:params:push(this document)[Editor/IANA note: please include a link
to the final registry location.]Values in this registry are URNs or URN
prefixes that start with the prefix urn:ietf:params:push. Each is registered
independently.
New registrations in the "Web Push Identifiers" are encouraged to
include the following information:
A complete URN or URN prefix.A summary description.A reference to a specification
describing the semantics of the URN or URN prefix.Email for the person or group making the
registration.As described in ,
URN prefixes that are registered include a description of how the
URN is constructed. This is not applicable for specific URNs.
These values are entered as the initial content of the "Web Push
Identifiers" registry.
urn:ietf:params:pushThis link relation type is used to
identify a resource for sending push messages.(this document)The Web Push WG (webpush@ietf.org)urn:ietf:params:push:set
This link relation type is used to identify a collection of push
message subscriptions.
(this document)The Web Push WG (webpush@ietf.org)urn:ietf:params:push:receipt
This link relation type is used to identify a resource for
receiving delivery confirmations for push messages.
(this document)The Web Push WG (webpush@ietf.org)
Service names and port numbers are registered within the "Service Name and
Transport Protocol Port Number Registry" maintained at .
IANA is requested to assign the System Port number 1001 and the service name
"webpush" in accordance with .
webpush
tcp
IESG (iesg@ietf.org)
The Web Push WG (webpush@ietf.org)
HTTP Web Push
[RFCthis]
1001
Significant technical input to this document has been provided by Ben
Bangert, Peter Beverloo, Kit Cambridge, JR Conlin, Matthew Kaufman,
Costin Manolache, Mark Nottingham, Idel Pivnitskiy, Robert Sparks,
Darshak Thakore and many others.
Key words for use in RFCs to Indicate Requirement Levels
Harvard Universitysob@harvard.edu
HTTP Over TLS
An IETF URN Sub-namespace for Registered Protocol ParametersRegistration Procedures for Message Header FieldsThe Base16, Base32, and Base64 Data EncodingsGuidelines for Writing an IANA Considerations Section in RFCsNAT Behavioral Requirements for TCPWeb Linking
Internet Assigned Numbers Authority (IANA) Procedures for the Management of the Service Name and Transport Protocol Port Number Registry
The Web Origin ConceptAdditional HTTP Status CodesHypertext Transfer Protocol (HTTP/1.1): Message Syntax and RoutingHypertext Transfer Protocol (HTTP/1.1): Semantics and ContentHypertext Transfer Protocol (HTTP/1.1): Conditional RequestsPrefer Header for HTTPHypertext Transfer Protocol Version 2HTTP Alternative ServicesGood Practices for Capability URLsMessage Encryption for Web PushVoluntary Application Server Identification for Web PushW3C Push APIPrivacy Considerations for Internet Protocols[[The RFC Editor is requested to remove this section at publication.]]
Editorial changes for Push Message Time-To-Live
Editorial changes for Push Acknowledgements
Removed subscription expiration based on HTTP cache headers
Added Subscription Sets
Added System Port as an alternate service with guidance for idle timeouts
Finalized status codes for acknowledgements
Editorial changes for Rate Limits
Added explicit correlation for Subscription Sets
Added Push Message Updates (message collapsing)
Renamed the push:receipt link relation to push:receipts and transitioned the
Push-Receipt header field to the push:receipt link relation type
An application server MUST include the TTL (Time-To-Live) header field in
its request for push message delivery.
Added Push Message Urgency header field
Simplified design for Push Receipts and eliminated the urn:ietf:params:push:receipts link
relation
Clarified Security Considerations section and added informative references to
Message Encryption and Voluntary Application Server Identification
Addressed feedback from Working Group Last Call
Updated informative references to W3C Push API, Message Encryption, and Voluntary
Application Server Identification