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This specification defines an unified interface to store and retrieve performance metric data. This specification does not cover individual performance metric interfaces.
This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.
W3C publishes a Candidate Recommendation to indicate that the document is believed to be stable and to encourage implementation by the developer community.
The entrance criteria for this document to enter the Proposed Recommendation stage is to have a minimum of two independent and interoperable user agents that implementation all the features of this specification, which will be determined by passing the user agent tests defined in the test suite developed by the Working Group.
The Working Group does not expect to advance to Proposed Recommendation prior to . A preliminary implementation report is available and will be updated during the Candidate Recommendation period. This is a work in progress and may change without any notices.
The Working Group intends to gain implementation experience before recommending that implementations remove their vendor prefixes.
Please send comments to public-web-perf@w3.org (archived) with [PerformanceTimeline] at the start of the subject line by .
A diff document with the previous draft is available.
This document is produced by the Web Performance Working Group. The Web Performance Working Group is part of the Rich Web Clients Activity in the W3C Interaction Domain.
You can find the latest Editor's Draft of this document in the W3C's Mercurial repository, which is updated on a regular basis.
Publication as a Candidate Recommendation does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.
This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.
This section is non-normative.
Accurately measuring performance characteristics of web applications is an important aspect of making web applications faster. [Navigation Timing], [Resource Timing], and [User Timing] are examples of specifications that define timing information related to the navigation of the document, resources on the page, and developer scripts, respectively.
Together these interfaces, and potentially others created in the future, define performance metrics that describe the performance timeline of a web application. This specification provides an unifying interface to access and retrieve these various performance metrics from the performance timeline of a web application.
The following script shows how a developer can use the PerformanceEntry
interface
to obtain timing data related to the navigation of the document, resources on the page and developer scripts.
<!doctype html> <html> <head> </head> <body onload="init()"> <img id="image0" src="http://w3c-test.org/webperf/image0.png" /> <script> function init() { performance.mark("startWork"); // see [User Timing] doWork(); // Some developer code performance.mark("endWork"); measurePerf(); } function measurePerf() { var perfEntries = performance.getEntries(); for (var i = 0; i < perfEntries.length; i++) { if (window.console) console.log("Name: " + perfEntries[i].name + " Entry Type: " + perfEntries[i].entryType + " Start Time: " + perfEntries[i].startTime + " Duration: " + perfEntries[i].duration + "\n"); } } </script> </body> </html>
All diagrams, examples, and notes in this specification are non-normative, as are all sections explicitly marked non-normative. Everything else in this specification is normative.
The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in the normative parts of this document are to be interpreted as described in RFC 2119. For readability, these words do not appear in all uppercase letters in this specification.
Requirements phrased in the imperative as part of algorithms (such as "strip any leading space characters" or "return false and abort these steps") are to be interpreted with the meaning of the key word ("must", "should", "may", etc) used in introducing the algorithm.
Some conformance requirements are phrased as requirements on attributes, methods or objects. Such requirements are to be interpreted as requirements on user agents.
Conformance requirements phrased as algorithms or specific steps may be implemented in any manner, so long as the end result is equivalent. (In particular, the algorithms defined in this specification are intended to be easy to follow, and not intended to be performant.)
The IDL fragments in this specification must be interpreted as required for conforming IDL fragments, as described in the Web IDL specification. [Web IDL]
The construction "a Foo
object", where Foo
is actually an interface, is sometimes used instead of
the more accurate "an object implementing the interface Foo
".
All interfaces that participate in the Performance Timeline, such as the
PerformanceResourceTiming
[Resource Timing],
PerformanceMark
, and
PerformanceMeasure
[User Timing] interfaces,
must adhere to the following rules:
PerformanceEntry
interfacegetEntries
,
getEntriesByType
, and
getEntriesByName
methods
PerformanceEntry
interfaceinterface PerformanceEntry { readonly attribute DOMString name; readonly attribute DOMString entryType; readonly attribute DOMHighResTimeStamp startTime; readonly attribute DOMHighResTimeStamp duration; };
name
attribute
The name
attribute must return the identifier for this PerformanceEntry
object. This
identifier does not have to be unique.
entryType
attribute
The entryType
attribute must return a DOMString
that describes the type of the interface represented by this PerformanceEntry
object.
startTime
attribute
The startTime
attribute must return a DOMHighResTimeStamp
that contains the time value of the first recorded timestamp of this performance metric.
duration
attribute
The duration
attribute must return a DOMHighResTimeStamp
that contains the time value of the duration of the entire event being recorded by this PerformanceEntry
. Typically, this would be the
time difference between the last recorded timestamp and the first recorded timestamp of this PerformanceEntry
. A performance metric may choose
to return a duration
of 0, if the duration concept doesn't apply.
Performance
interfacepartial interface Performance { PerformanceEntryList getEntries(); PerformanceEntryList getEntriesByType(DOMString entryType); PerformanceEntryList getEntriesByName(DOMString name, optional DOMString entryType); }; typedef sequence <PerformanceEntry> PerformanceEntryList;
The window.performance
attribute provides a hosting area for performance measurement related attributes and methods using the Performance
interface [Navigation Timing].
getEntries
methodThe getEntries
method returns a
PerformanceEntryList
object that contains a copy of all PerformanceEntry
objects in chronological order with respect to startTime.
getEntriesByType
methodThe getEntriesByType
method returns a
PerformanceEntryList
object that contains a copy of all PerformanceEntry
objects, in chronological order with respect to startTime,
that have the same value for the entryType
attribute of PerformanceEntry
as the entryType
parameter.
Parameter
DOMString
entryType
A PerformanceEntryList
object that contains a copy of PerformanceEntry
objects
that have the same value for the entryType
attribute of PerformanceEntry
as the entryType
parameter.
If no such PerformanceEntry
objects exist, the PerformanceEntryList
must be empty.
Return value
APerformanceEntryList
object.
No exceptions
getEntriesByName
method
The getEntriesByName
method returns a
PerformanceEntryList
object that contains a copy of PerformanceEntry
objects, in chronological order with respect to startTime,
that have the same value for the name
attribute of PerformanceEntry
as the name
parameter
and, if specified, have the same value for the entryType
attribute of PerformanceEntry
as the entryType
parameter.
Parameter
DOMString
name
The PerformanceEntryList
object that contains a copy of PerformanceEntry
objects
that have the same value for the name
attribute of PerformanceEntry
as the name
parameter.
If no such PerformanceEntry
objects exist, the PerformanceEntryList
must be empty.
DOMString
entryType
The PerformanceEntryList
object that only contains a copy of PerformanceEntry
objects
that have the same value for the entryType
attribute of PerformanceEntry
as the entryType
parameter
and have the same value for the name
attribute of PerformanceEntry
as the name
parameter.
If no such PerformanceEntry
objects exist, the PerformanceEntryList
must be empty.
Return value
APerformanceEntryList
object.
No exceptions
We would like to offer our sincere thanks to all the people that we have been in touch with regarding this draft for their reviews and feedback.