Network Working Group J. Whitehead
Request for Comments: 4437 U.C. Santa Cruz
Category: Experimental G. Clemm
IBM
J. Reschke, Ed.
greenbytes
March 2006
Network Working Group J. Whitehead
Request for Comments: 4437 U.C. Santa Cruz
Category: Experimental G. Clemm
IBM
J. Reschke, Ed.
greenbytes
March 2006
Web Distributed Authoring and Versioning (WebDAV) Redirect Reference Resources
Web分布式创作和版本控制（WebDAV）重定向参考资源
Status of This Memo
关于下段备忘
This memo defines an Experimental Protocol for the Internet community. It does not specify an Internet standard of any kind. Discussion and suggestions for improvement are requested. Distribution of this memo is unlimited.
这份备忘录为互联网社区定义了一个实验性协议。它没有规定任何类型的互联网标准。要求进行讨论并提出改进建议。本备忘录的分发不受限制。
Copyright Notice
版权公告
Copyright (C) The Internet Society (2006).
版权所有（C）互联网协会（2006年）。
Abstract
摘要
This specification defines an extension to Web Distributed Authoring and Versioning (WebDAV) to allow clients to author HTTP redirect reference resources whose default response is an HTTP/1.1 3xx (Redirection) status code. A redirect reference makes it possible to access the target resourced indirectly through any URI mapped to the redirect reference resource. This specification does not address remapping of trees of resources or regular expression based redirections. There are no integrity guarantees associated with redirect reference resources. Other mechanisms can also be used to achieve the same functionality as this specification. This specification allows operators to experiment with this mechanism and develop experience on what is the best approach to the problem.
本规范定义了对Web分布式创作和版本控制（WebDAV）的扩展，以允许客户端编写HTTP重定向参考资源，其默认响应为HTTP/1.1 3xx（重定向）状态代码。重定向引用可以通过映射到重定向引用资源的任何URI间接访问目标资源。本规范不涉及资源树的重新映射或基于正则表达式的重定向。没有与重定向引用资源关联的完整性保证。其他机制也可用于实现与本规范相同的功能。本规范允许操作员试验这种机制，并就解决问题的最佳方法积累经验。
Table of Contents
目录
1. Introduction ....................................................3
2. Notational Conventions ..........................................4
3. Terminology .....................................................4
4. Overview of Redirect Reference Resources ........................5
5. Operations on Redirect Reference Resources ......................6
6. MKREDIRECTREF Method ............................................7
1. Introduction ....................................................3
2. Notational Conventions ..........................................4
3. Terminology .....................................................4
4. Overview of Redirect Reference Resources ........................5
5. Operations on Redirect Reference Resources ......................6
6. MKREDIRECTREF Method ............................................7
6.1. Example: Creating a Redirect Reference Resource
with MKREDIRECTREF .........................................8
7. UPDATEREDIRECTREF Method ........................................9
7.1. Example: Updating a Redirect Reference Resource with
UPDATEREDIRECTREF .........................................10
8. Operations on Collections That Contain Redirect
Reference Resources ............................................11
8.1. Example: PROPFIND on a Collection with Redirect
Reference .................................................11
8.2. Example: PROPFIND with Apply-To-Redirect-Ref on a
Collection with Redirect Reference Resources ..............13
9. Operations on Targets of Redirect Reference Resources ..........15
10. Relative References in DAV:reftarget ..........................15
10.1. Example: Resolving a Relative Reference in a
Multi-Status Response.....................................16
11. Redirect References to Collections ............................17
12. Headers .......................................................18
12.1. Redirect-Ref Response Header .............................18
12.2. Apply-To-Redirect-Ref Request Header .....................19
13. Redirect Reference Resource Properties ........................19
13.1. DAV:redirect-lifetime (protected) ........................19
13.2. DAV:reftarget (protected) ................................19
14. XML Elements ..................................................19
14.1. redirectref XML Element ..................................19
15. Extensions to the DAV:response XML Element for Multi-Status
Responses .....................................................20
16. Capability Discovery ..........................................20
16.1. Example: Discovery of Support for Redirect
Reference Resources ......................................20
17. Security Considerations .......................................21
17.1. Privacy Concerns .........................................21
17.2. Redirect Loops ...........................................21
17.3. Redirect Reference Resources and Denial of Service .......21
17.4. Revealing Private Locations ..............................22
18. Internationalization Considerations ...........................22
19. IANA Considerations ...........................................22
19.1. HTTP headers .............................................22
19.1.1. Redirect-Ref ......................................22
19.1.2. Apply-To-Redirect-Ref .............................23
20. Contributors ..................................................23
21. Acknowledgements ..............................................23
22. Normative References ..........................................23
6.1. Example: Creating a Redirect Reference Resource
with MKREDIRECTREF .........................................8
7. UPDATEREDIRECTREF Method ........................................9
7.1. Example: Updating a Redirect Reference Resource with
UPDATEREDIRECTREF .........................................10
8. Operations on Collections That Contain Redirect
Reference Resources ............................................11
8.1. Example: PROPFIND on a Collection with Redirect
Reference .................................................11
8.2. Example: PROPFIND with Apply-To-Redirect-Ref on a
Collection with Redirect Reference Resources ..............13
9. Operations on Targets of Redirect Reference Resources ..........15
10. Relative References in DAV:reftarget ..........................15
10.1. Example: Resolving a Relative Reference in a
Multi-Status Response.....................................16
11. Redirect References to Collections ............................17
12. Headers .......................................................18
12.1. Redirect-Ref Response Header .............................18
12.2. Apply-To-Redirect-Ref Request Header .....................19
13. Redirect Reference Resource Properties ........................19
13.1. DAV:redirect-lifetime (protected) ........................19
13.2. DAV:reftarget (protected) ................................19
14. XML Elements ..................................................19
14.1. redirectref XML Element ..................................19
15. Extensions to the DAV:response XML Element for Multi-Status
Responses .....................................................20
16. Capability Discovery ..........................................20
16.1. Example: Discovery of Support for Redirect
Reference Resources ......................................20
17. Security Considerations .......................................21
17.1. Privacy Concerns .........................................21
17.2. Redirect Loops ...........................................21
17.3. Redirect Reference Resources and Denial of Service .......21
17.4. Revealing Private Locations ..............................22
18. Internationalization Considerations ...........................22
19. IANA Considerations ...........................................22
19.1. HTTP headers .............................................22
19.1.1. Redirect-Ref ......................................22
19.1.2. Apply-To-Redirect-Ref .............................23
20. Contributors ..................................................23
21. Acknowledgements ..............................................23
22. Normative References ..........................................23
This specification extends the Web Distributed Authoring Protocol (WebDAV) to enable clients to create new access paths to existing resources. This capability is useful for several reasons.
此规范扩展了Web分布式创作协议（WebDAV），使客户端能够创建到现有资源的新访问路径。此功能之所以有用，有几个原因。
WebDAV makes it possible to organize HTTP resources into hierarchies, placing them into groupings, known as collections, that are more easily browsed and manipulated than a single flat collection. However, hierarchies require categorization decisions that locate resources at a single location in the hierarchy, a drawback when a resource has multiple valid categories. For example, in a hierarchy of vehicle descriptions containing collections for cars and boats, a description of a combination car/boat vehicle could belong in either collection. Ideally, the description should be accessible from both. Allowing clients to create new URIs that access the existing resource lets them put that resource into multiple collections.
WebDAV使将HTTP资源组织到层次结构中成为可能，将它们放入称为集合的分组中，这些分组比单个平面集合更容易浏览和操作。但是，层次结构要求分类决策将资源定位在层次结构中的单个位置，这是资源具有多个有效类别时的一个缺点。例如，在包含汽车和船只集合的车辆描述层次结构中，汽车/船只组合车辆的描述可以属于任一集合。理想情况下，描述应该可以从两者中访问。允许客户端创建访问现有资源的新URI，可以将该资源放入多个集合中。
Hierarchies also make resource sharing more difficult, since resources that have utility across many collections are still forced into a single collection. For example, the mathematics department at one university might create a collection of information on fractals that contains bindings to some local resources, but also provides access to some resources at other universities. For many reasons, it may be undesirable to make physical copies of the shared resources: to conserve disk space, to respect copyright constraints, or to make any changes in the shared resources visible automatically. Being able to create new access paths to existing resources in other collections or even on other unrelated systems is useful for this sort of case.
层次结构还使得资源共享更加困难，因为跨多个集合具有实用性的资源仍然被强制放在单个集合中。例如，一所大学的数学系可能会创建一个分形信息集合，其中包含对某些本地资源的绑定，但也提供对其他大学某些资源的访问。出于许多原因，可能不希望创建共享资源的物理副本：以节省磁盘空间、遵守版权限制或使共享资源中的任何更改自动可见。对于这种情况，能够创建到其他集合甚至其他无关系统中现有资源的新访问路径非常有用。
The redirect reference resources defined here provide a mechanism for creating alternative access paths to existing resources. A redirect reference resource is a resource in one collection whose purpose is to redirect requests to another resource (its target), possibly in a different collection. In this way, it allows clients to submit requests to the target resource from another collection. It redirects most requests to the target resource using an HTTP status code from the 3xx range (Redirection), thereby providing a form of mediated access to the target resource.
这里定义的重定向引用资源提供了一种机制，用于创建对现有资源的替代访问路径。重定向引用资源是一个集合中的资源，其目的是将请求重定向到另一个资源（其目标），可能位于不同的集合中。这样，它允许客户端从另一个集合向目标资源提交请求。它使用3xx范围内的HTTP状态代码（重定向）将大多数请求重定向到目标资源，从而提供对目标资源的中介访问形式。
A redirect reference is a resource with properties but with no body of its own. Properties of a redirect reference resource can contain information such as who created the reference, when, and why. Since redirect reference resources are implemented using HTTP 3xx responses, it generally takes two round trips to submit a request to the intended resource. Redirect references work equally well for local resources and for resources that reside on a different system from the reference.
重定向引用是一种具有属性但没有自身主体的资源。重定向引用资源的属性可以包含诸如谁创建引用、何时创建引用以及为什么创建引用等信息。由于重定向引用资源是使用HTTP 3xx响应实现的，因此通常需要两次往返才能将请求提交到预期的资源。重定向引用同样适用于本地资源和驻留在与引用不同的系统上的资源。
The remainder of this document is structured as follows: Section 3 defines terms that will be used throughout the specification. Section 4 provides an overview of redirect reference resources. Section 5 defines the semantics of existing methods when applied to redirect reference resources. Section 6 discusses how to create a redirect reference resource, and Section 7 discusses updating redirect references. Section 8 discusses their semantics when applied to collections that contain redirect reference resources. Sections 9 through 11 discuss several other issues raised by the existence of redirect reference resources. Sections 12 through 15 define the new headers, properties, and XML elements required to support redirect reference resources. Section 16 discusses capability discovery. Sections 17 through 19 present the security, internationalization, and IANA concerns raised by this specification. The remaining sections provide a variety of supporting information.
本文件其余部分的结构如下：第3节定义了本规范中将使用的术语。第4节概述了重定向参考资源。第5节定义了应用于重定向引用资源时现有方法的语义。第6节讨论如何创建重定向引用资源，第7节讨论更新重定向引用。第8节讨论了它们在应用于包含重定向引用资源的集合时的语义。第9节至第11节讨论了重定向参考资源的存在引起的其他几个问题。第12节到第15节定义了支持重定向引用资源所需的新标题、属性和XML元素。第16节讨论能力发现。第17至19节介绍了本规范提出的安全性、国际化和IANA问题。其余部分提供了各种支持信息。
Since this document describes a set of extensions to the WebDAV Distributed Authoring Protocol [RFC2518], itself an extension to the HTTP/1.1 protocol, the augmented BNF used here to describe protocol elements is exactly the same as described in Section 2.1 of [RFC2616]. Since this augmented BNF uses the basic production rules provided in Section 2.2 of [RFC2616], these rules apply to this document as well.
由于本文档描述了WebDAV分布式创作协议[RFC2518]的一组扩展，其本身就是HTTP/1.1协议的扩展，因此此处用于描述协议元素的扩展BNF与[RFC2616]第2.1节中描述的完全相同。由于此扩充BNF使用[RFC2616]第2.2节中提供的基本生产规则，因此这些规则也适用于本文件。
In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in [RFC2119].
本文件中的关键词“必须”、“不得”、“要求”、“应”、“不应”、“应”、“不应”、“建议”、“可”和“可选”应按照[RFC2119]中的说明进行解释。
The terminology used here follows and extends that in the WebDAV Distributed Authoring Protocol specification [RFC2518]. Definitions of the terms resource, Uniform Resource Identifier (URI), and Uniform Resource Locator (URL) are provided in [RFC3986].
这里使用的术语遵循并扩展了WebDAV分布式创作协议规范[RFC2518]中的术语。[RFC3986]中提供了术语资源、统一资源标识符（URI）和统一资源定位器（URL）的定义。
Redirect Reference Resource
重定向引用资源
A resource created to redirect all requests made to it, using an HTTP status code from the 3xx range, to a defined target resource.
创建的资源，使用3xx范围内的HTTP状态代码将向其发出的所有请求重定向到定义的目标资源。
Non-Reference Resource
非参考资源
A resource that is not a reference to another resource.
不是对其他资源的引用的资源。
Target Resource
目标资源
The resource to which requests are redirected by a redirect reference resource. A target resource can be anything that can be identified by an absolute URI (see [RFC3986], "absolute-URI").
重定向引用资源将请求重定向到的资源。目标资源可以是可以由绝对URI标识的任何内容（请参见[RFC3986]，“绝对URI”）。
This document uses the terms "precondition", "postcondition", and "protected property" as defined in [RFC3253]. Servers MUST report pre-/postcondition failures as described in Section 1.6 of this document.
本文件使用[RFC3253]中定义的术语“前提条件”、“后条件”和“受保护财产”。服务器必须报告本文档第1.6节所述的前置/后置条件故障。
For all operations submitted to a redirect reference resource, the default response is a 302 (Found), accompanied by the Redirect-Ref header (defined in Section 12.1, below) and the Location header ([RFC2616], Section 14.30) set to the URI of the target resource. With this information, the client can resubmit the request to the URI of the target resource.
对于提交给重定向引用资源的所有操作，默认响应为302（找到），并伴有重定向引用头（在下面第12.1节中定义）和设置为目标资源URI的位置头（[RFC2616]，第14.30节）。有了这些信息，客户端可以将请求重新提交到目标资源的URI。
A redirect reference resource never automatically forwards requests to its target resource. Redirect resources bring the same benefits as links in HTML documents. They can be created and maintained without the involvement or even knowledge of their target resource. This reduces the cost of linking between resources.
重定向引用资源从不自动将请求转发到其目标资源。重定向资源带来的好处与HTML文档中的链接相同。它们可以在不涉及甚至不知道目标资源的情况下创建和维护。这降低了资源之间链接的成本。
If the client is aware that it is operating on a redirect reference resource, it can resolve the reference by retrieving the reference resource's DAV:reftarget property (defined in Section 13.2, below), whose value contains the URI of the target resource. It can then submit requests to the target resource.
如果客户端知道它正在重定向引用资源上操作，它可以通过检索引用资源的DAV:reftarget属性（在下面的第13.2节中定义）来解析引用，该属性的值包含目标资源的URI。然后，它可以向目标资源提交请求。
A redirect reference resource is a new type of resource. To distinguish redirect reference resources from non-reference resources, a new value of the DAV:resourcetype property (defined in [RFC2518]), DAV:redirectref, is defined in Section 14.1, below.
重定向引用资源是一种新型资源。为了区分重定向引用资源和非引用资源，下面第14.1节定义了DAV:resourcetype属性（在[RFC2518]中定义）的新值DAV:redirectref。
Since a redirect reference resource is a resource, methods can be applied to the reference resource as well as to its target resource.
由于重定向引用资源是一种资源，因此可以将方法应用于引用资源及其目标资源。
The Apply-To-Redirect-Ref request header (defined in Section 12.2, below) is provided so that referencing-aware clients can control whether an operation is applied to the redirect reference resource or standard HTTP/WebDAV behaviour (redirection with a 3xx status code) should occur. The Apply-To-Redirect-Ref header can be used with most requests to redirect reference resources. This header is particularly useful with PROPFIND, to retrieve the reference resource's own properties.
提供Apply To Redirect Ref request标头（在下面的第12.2节中定义），以便支持引用的客户端可以控制是将操作应用于重定向引用资源还是应发生标准HTTP/WebDAV行为（使用3xx状态代码重定向）。Apply To Redirect Ref标头可用于大多数重定向引用资源的请求。此标头对于PROPFIND特别有用，用于检索引用资源自身的属性。
Implementation Note: Operations on the target of a redirect reference usually do not affect the redirect reference itself. However, clients should not rely on this behaviour (for instance, some servers may update redirect references as a result of namespace operations on the reference's target).
实现说明：重定向引用目标上的操作通常不会影响重定向引用本身。但是，客户端不应该依赖这种行为（例如，某些服务器可能会由于对引用的目标进行命名空间操作而更新重定向引用）。
Although non-referencing-aware clients cannot create reference resources, they should be able to submit requests through the reference resources created by reference-aware WebDAV clients. They should be able to follow any references to their targets. To make this possible, a server that receives any request made via a redirect reference resource MUST return a 3xx range (Redirection) status code, unless the request includes an Apply-To-Redirect-Ref header specifying "T". The client and server MUST follow [RFC2616], Section 10.3, but with these additional rules:
尽管非参考感知客户端无法创建参考资源，但它们应该能够通过参考感知WebDAV客户端创建的参考资源提交请求。他们应该能够跟踪任何对其目标的引用。为了实现这一点，接收通过重定向引用资源发出的任何请求的服务器必须返回3xx范围（重定向）状态代码，除非该请求包含指定“T”的Apply To redirect Ref标头。客户机和服务器必须遵守[RFC2616]第10.3节的规定，但有以下附加规则：
o The Location response header MUST contain a URI (see [RFC3986], Section 3) that identifies the target of the reference resource.
o 位置响应标头必须包含标识引用资源目标的URI（请参阅[RFC3986]，第3节）。
o The response MUST include the Redirect-Ref header. This header allows reference-aware WebDAV clients to recognize the resource as a reference resource and to understand the reason for the redirection.
o 响应必须包括重定向引用标头。此标头允许支持引用的WebDAV客户端将资源识别为引用资源，并了解重定向的原因。
A reference-aware WebDAV client can, like a non-referencing client, resubmit the request to the URI in the Location header in order to operate on the target resource. Alternatively, it can resubmit the request to the URI of the redirect reference resource with the "Apply-To-Redirect-Ref: T" header in order to operate on the reference resource itself. In this case, the request MUST be applied to the reference resource itself, and a 3xx response MUST NOT be returned.
与非引用客户端一样，支持引用的WebDAV客户端可以将请求重新提交到位置头中的URI，以便对目标资源进行操作。或者，它可以使用“Apply to redirect Ref:T”头将请求重新提交到重定向引用资源的URI，以便对引用资源本身进行操作。在这种情况下，请求必须应用于引用资源本身，并且不得返回3xx响应。
As redirect references do not have bodies, GET and PUT requests with "Apply-To-Redirect-Ref: T" MUST fail with status 403 (forbidden).
由于重定向引用没有主体，带有“Apply To redirect Ref:T”的GET和PUT请求必须失败，状态为403（禁止）。
The MKREDIRECTREF method requests the creation of a redirect reference resource.
MKREDIRECTREF方法请求创建重定向引用资源。
If a MKREDIRECTREF request fails, the server state preceding the request MUST be restored.
如果MKREDIRECTREF请求失败，则必须恢复请求之前的服务器状态。
Responses from a MKREDIRECTREF request MUST NOT be cached, as MKREDIRECTREF has non-idempotent and non-safe semantics (see [RFC2616], Section 9.1).
不得缓存来自MKREDIRECTREF请求的响应，因为MKREDIRECTREF具有非幂等和非安全语义（请参见[RFC2616]，第9.1节）。
Marshalling
编组
The request body MUST be a DAV:mkredirectref XML element.
请求主体必须是DAV:mkredirectref XML元素。
<!ELEMENT mkredirectref (reftarget, redirect-lifetime?)>
<!ELEMENT reftarget (href)>
<!ELEMENT redirect-lifetime (permanent | temporary)>
<!ELEMENT permanent EMPTY>
<!ELEMENT temporary EMPTY>
<!ELEMENT mkredirectref (reftarget, redirect-lifetime?)>
<!ELEMENT reftarget (href)>
<!ELEMENT redirect-lifetime (permanent | temporary)>
<!ELEMENT permanent EMPTY>
<!ELEMENT temporary EMPTY>
The DAV:href element is defined in [RFC2518] (Section 12.3) and MUST contain either a URI or a relative-ref (see [RFC3986], Sections 3 and 4.2).
DAV:href元素在[RFC2518]（第12.3节）中定义，必须包含URI或相对引用（请参见[RFC3986]，第3节和第4.2节）。
If no DAV:redirect-lifetime element is specified, the server MUST behave as if a value of DAV:temporary was specified.
如果未指定DAV:redirect life元素，则服务器的行为必须与指定了DAV:temporary值一样。
If the request succeeds, the server MUST return 201 (Created) status.
如果请求成功，服务器必须返回201（已创建）状态。
If a response body for a successful request is included, it MUST be a DAV:mkredirectref-response XML element. Note that this document does not define any elements for the MKREDIRECTREF response body, but the DAV:mkredirectref-response element is defined to ensure interoperability between future extensions that do define elements for the response body.
如果包含成功请求的响应主体，则它必须是DAV:mkredirectref响应XML元素。请注意，本文档没有为MKREDIRECTREF响应体定义任何元素，但定义DAV:MKREDIRECTREF响应元素是为了确保将来定义响应体元素的扩展之间的互操作性。
<!ELEMENT mkredirectref-response ANY>
<!ELEMENT mkredirectref-response ANY>
Preconditions
前提条件
(DAV:resource-must-be-null): A resource MUST NOT exist at the Request-URI.
（DAV:resource必须为null）：请求URI中不能存在资源。
(DAV:parent-resource-must-be-non-null): The Request-URI minus the last past segment MUST identify a collection.
（DAV：父资源必须为非null）：请求URI减去最后一个过去的段必须标识集合。
(DAV:name-allowed): The last segment of the Request-URI is available for use as a resource name.
（DAV:name allowed）：请求URI的最后一段可用作资源名称。
(DAV:locked-update-allowed): If the collection identified by the Request-URI minus the last path segment is write-locked, then the appropriate token MUST be specified in an If request header.
（DAV：允许锁定更新）：如果由请求URI减去最后一个路径段标识的集合被写锁定，则必须在If请求头中指定适当的令牌。
(DAV:redirect-lifetime-supported): If the request body contains a DAV:redirect-lifetime element, the server MUST support the specified lifetime. Support for DAV:temporary is REQUIRED, while support for DAV:permanent is OPTIONAL.
（DAV:redirect lifetime supported）：如果请求正文包含DAV:redirect lifetime元素，则服务器必须支持指定的生存期。需要支持DAV:temporary，而支持DAV:permanent是可选的。
(DAV:legal-reftarget): The specified is a legal URI or relative-ref.
（DAV:legal-reftarget）：指定的是合法URI或相对引用。
Postconditions
后置条件
(DAV:new-redirectref): a new redirect reference resource is created whose DAV:reftarget property has the value specified in the request body.
（DAV:new redirectref）：创建一个新的重定向引用资源，其DAV:reftarget属性具有请求正文中指定的值。
>> Request:
>>请求：
MKREDIRECTREF /~whitehead/dav/spec08.ref HTTP/1.1
Host: www.example.com
Content-Type: text/xml; charset="utf-8"
Content-Length: xxx
MKREDIRECTREF /~whitehead/dav/spec08.ref HTTP/1.1
Host: www.example.com
Content-Type: text/xml; charset="utf-8"
Content-Length: xxx
<?xml version="1.0" encoding="utf-8" ?>
<D:mkredirectref xmlns:D="DAV:">
<D:reftarget>
<D:href>/i-d/draft-webdav-protocol-08.txt</D:href>
</D:reftarget>
</D:mkredirectref>
<?xml version="1.0" encoding="utf-8" ?>
<D:mkredirectref xmlns:D="DAV:">
<D:reftarget>
<D:href>/i-d/draft-webdav-protocol-08.txt</D:href>
</D:reftarget>
</D:mkredirectref>
>> Response:
>>答复：
HTTP/1.1 201 Created
HTTP/1.1201已创建
This request resulted in the creation of a new redirect reference resource at http://www.example.com/~whitehead/dav/spec08.ref, which points to the resource identified by the DAV:reftarget property. In this example, the target resource is identified by the URI http://www.example.com/i-d/draft-webdav-protocol-08.txt. The redirect reference resource's DAV:resourcetype property is set to DAV:redirectref, and its DAV:redirect-lifetime property has the value DAV:temporary.
此请求导致在上创建新的重定向引用资源http://www.example.com/~whitehead/dav/spec08.ref，它指向由dav:reftarget属性标识的资源。在本例中，目标资源由URI标识http://www.example.com/i-d/draft-webdav-protocol-08.txt. 重定向引用资源的DAV:resourcetype属性设置为DAV:redirectref，其DAV:redirect lifetime属性的值为DAV:temporary。
The UPDATEREDIRECTREF method requests the update of a redirect reference resource.
UPDATEREDIRECTREF方法请求更新重定向引用资源。
If a UPDATEREDIRECTREF request fails, the server state preceding the request MUST be restored.
如果UpdateDirectRef请求失败，则必须恢复该请求之前的服务器状态。
Responses from a UPDATEREDIRECTREF request MUST NOT be cached, as UPDATEREDIRECTREF has non-safe semantics (see [RFC2616], Section 9.1).
不得缓存来自UPDATEREDIRECTREF请求的响应，因为UPDATEREDIRECTREF具有非安全语义（请参阅[RFC2616]，第9.1节）。
Marshalling
编组
The request body MUST be a DAV:updateredirectref XML element.
请求正文必须是DAV:updateredirectref XML元素。
<!ELEMENT updateredirectref (reftarget?, redirect-lifetime?)>
<!ELEMENT updateredirectref (reftarget?, redirect-lifetime?)>
See Section 6 for a definition of DAV:reftarget and DAV:redirect-lifetime.
有关DAV:reftarget和DAV:redirect lifetime的定义，请参见第6节。
If no DAV:reftarget element is specified, the server MUST NOT change the target of the redirect reference.
如果未指定DAV:reftarget元素，则服务器不得更改重定向引用的目标。
If no DAV:redirect-lifetime element is specified, the server MUST NOT change the lifetime of the redirect reference.
如果未指定DAV:redirect lifetime元素，则服务器不得更改重定向引用的生存期。
If a response body for a successful request is included, it MUST be a DAV:updateredirectref-response XML element. Note that this document does not define any elements for the UPDATEREDIRECTREF response body, but the DAV:updateredirectref-response element is defined to ensure interoperability between future extensions that do define elements for the response body.
如果包含成功请求的响应主体，则它必须是DAV:updateredirectref响应XML元素。请注意，本文档没有为UPDATEREDIRECTREF响应主体定义任何元素，但定义了DAV:UPDATEREDIRECTREF响应元素以确保将来为响应主体定义元素的扩展之间的互操作性。
<!ELEMENT updateredirectref-response ANY>
<!ELEMENT updateredirectref-response ANY>
Preconditions
前提条件
(DAV:locked-update-allowed): if the resource is write-locked, then the appropriate token MUST be specified in an If request header.
（DAV：允许锁定更新）：如果资源被写锁定，则必须在if请求头中指定适当的令牌。
(DAV:must-be-redirectref): the resource identified by the Request-URI must be a redirect reference resource as defined by this specification.
（DAV:必须是redirectref）：请求URI标识的资源必须是本规范定义的重定向引用资源。
(DAV:redirect-lifetime-supported): see Section 6.
（DAV：支持重定向生存期）：参见第6节。
(DAV:redirect-lifetime-update-supported): servers MAY support changing the DAV:redirect-lifetime property; if they don't, this condition code can be used to signal failure.
（支持DAV:重定向生存期更新）：服务器可能支持更改DAV:重定向生存期属性；如果没有，此条件代码可用于表示故障。
(DAV:legal-reftarget): see Section 6.
（DAV：法律参考目标）：见第6节。
Postconditions
后置条件
(DAV:redirectref-updated): the DAV:reftarget and DAV:redirect-lifetime properties of the redirect reference have been updated accordingly.
（DAV:redirectref更新）：重定向引用的DAV:reftarget和DAV:redirect生存期属性已相应更新。
7.1. Example: Updating a Redirect Reference Resource with UPDATEREDIRECTREF
7.1. 示例：使用UPDATEREDIRECTREF更新重定向引用资源
>> Request:
>>请求：
UPDATEREDIRECTREF /~whitehead/dav/spec08.ref HTTP/1.1
Host: www.example.com
Apply-To-Redirect-Ref: T
Content-Type: text/xml; charset="utf-8"
Content-Length: xxx
UPDATEREDIRECTREF /~whitehead/dav/spec08.ref HTTP/1.1
Host: www.example.com
Apply-To-Redirect-Ref: T
Content-Type: text/xml; charset="utf-8"
Content-Length: xxx
<?xml version="1.0" encoding="utf-8" ?>
<D:updateredirectref xmlns:D="DAV:">
<D:reftarget>
<D:href>/i-d/draft-webdav-protocol-08b.txt</D:href>
</D:reftarget>
</D:updateredirectref>
<?xml version="1.0" encoding="utf-8" ?>
<D:updateredirectref xmlns:D="DAV:">
<D:reftarget>
<D:href>/i-d/draft-webdav-protocol-08b.txt</D:href>
</D:reftarget>
</D:updateredirectref>
>> Response:
>>答复：
HTTP/1.1 200 OK
HTTP/1.1200ok
This request has updated the redirect reference's DAV:reftarget property to "/i-d/draft-webdav-protocol-08b.txt" and has not changed the DAV:redirect-lifetime value. Note that the "Apply-To-Redirect-
此请求已将重定向引用的DAV:reftarget属性更新为“/i-d/draft-webdav-protocol-08b.txt”，并且未更改DAV:redirect生存期值。请注意，“应用于重定向”-
Ref" request header must be used; otherwise, the request would result in a redirect (3xx) response status.
必须使用Ref“请求头；否则，请求将导致重定向（3xx）响应状态。
According to [RFC2518], Section 9.2, methods that have defined interactions with the "Depth" request header should apply all other request headers to each resource in scope. However, applying this principle to the "Apply-To-Redirect-Ref" header uniformly would make it impractical to implement this specification on top of existing servers and also would result in unexpected server behaviour for clients that do not take the existence of redirect references into account. On the other hand, the definition of the "Depth" header allows alternate behaviours to be explicitly defined.
根据[RFC2518]第9.2节，定义了与“深度”请求头交互的方法应将所有其他请求头应用于范围内的每个资源。但是，将此原则统一应用于“Apply to Redirect Ref”头将使在现有服务器上实现此规范变得不切实际，并且还将导致不考虑重定向引用存在的客户端出现意外的服务器行为。另一方面，“深度”标题的定义允许明确定义替代行为。
For this reason, this specification defines the interaction between "Depth" and "Apply-To-Redirect-Ref" request headers on a case-by-case basis and also provides a default for methods not mentioned here that do not specify the behaviour themselves.
因此，本规范根据具体情况定义了“Depth”和“Apply To Redirect Ref”请求头之间的交互，并为此处未提及的、不指定行为本身的方法提供了默认值。
+-------------+-----------------+------------------+-----------+
| method name | defined in | supported depths | behaviour |
+-------------+-----------------+------------------+-----------+
| COPY | [RFC2518], 8.9 | 0, infinity | "T" |
| DELETE | [RFC2518], 8.7 | infinity | "T" |
| LOCK | [RFC2518], 8.11 | 0, infinity | "T" |
| MOVE | [RFC2518], 8.10 | 0, infinity | "T" |
| PROPFIND | [RFC2518], 8.2 | 0, 1, infinity | inherit |
| REPORT | [RFC3253], 3.6 | 0, 1, infinity | inherit |
| default | | | "T" |
+-------------+-----------------+------------------+-----------+
+-------------+-----------------+------------------+-----------+
| method name | defined in | supported depths | behaviour |
+-------------+-----------------+------------------+-----------+
| COPY | [RFC2518], 8.9 | 0, infinity | "T" |
| DELETE | [RFC2518], 8.7 | infinity | "T" |
| LOCK | [RFC2518], 8.11 | 0, infinity | "T" |
| MOVE | [RFC2518], 8.10 | 0, infinity | "T" |
| PROPFIND | [RFC2518], 8.2 | 0, 1, infinity | inherit |
| REPORT | [RFC3253], 3.6 | 0, 1, infinity | inherit |
| default | | | "T" |
+-------------+-----------------+------------------+-----------+
When the behaviour is defined to be "inherit", the method should follow RFC2518's default behaviour for "Depth" operations, which means applying the value given for "Apply-To-Redirect-Ref" to each resource in scope. On the other hand, when it is defined to be "T", the method should behave as if a "Apply-To-Redirect-Ref: T" header was specified for each operation on child resources. The latter ensures that "Depth: infinity" operations will not fail unexpectedly just because there was a redirect reference resource in scope.
当行为定义为“继承”时，该方法应遵循RFC2518“深度”操作的默认行为，这意味着将为“Apply to Redirect Ref”给定的值应用于范围中的每个资源。另一方面，当它被定义为“T”时，该方法的行为应该像为子资源上的每个操作指定了“Apply to Redirect Ref:T”头一样。后者确保“Depth:infinity”操作不会因为作用域中存在重定向引用资源而意外失败。
8.1. Example: PROPFIND on a Collection with Redirect Reference Resources
8.1. 示例：对具有重定向引用资源的集合进行PROPFIND
Suppose a PROPFIND request with Depth: infinity is submitted to the following collection, with the members shown here:
假设一个具有Depth:infinity的PROPFIND请求提交到以下集合，其成员如下所示：
/MyCollection/ (non-reference resource) diary.html (redirect reference resource) nunavut
/MyCollection/（非参考资源）diary.html（重定向参考资源）nunavut
>> Request:
>>请求：
PROPFIND /MyCollection/ HTTP/1.1
Host: example.com
Depth: infinity
Apply-To-Redirect-Ref: F
Content-Type: text/xml
Content-Length: xxxx
PROPFIND /MyCollection/ HTTP/1.1
Host: example.com
Depth: infinity
Apply-To-Redirect-Ref: F
Content-Type: text/xml
Content-Length: xxxx
<?xml version="1.0" ?>
<D:propfind xmlns:D="DAV: ">
<D:prop xmlns:J="http://example.com/jsprops/">
<D:resourcetype/>
<J:keywords/>
</D:prop>
</D:propfind>
<?xml version="1.0" ?>
<D:propfind xmlns:D="DAV: ">
<D:prop xmlns:J="http://example.com/jsprops/">
<D:resourcetype/>
<J:keywords/>
</D:prop>
</D:propfind>
>> Response:
>>答复：
HTTP/1.1 207 Multi-Status
Content-Type: text/xml
Content-Length: xxxx
HTTP/1.1 207 Multi-Status
Content-Type: text/xml
Content-Length: xxxx
<?xml version="1.0" ?>
<D:multistatus xmlns:D="DAV:" xmlns:J="http://example.com/jsprops/">
<D:response>
<D:href>/MyCollection/</D:href>
<D:propstat>
<D:prop>
<D:resourcetype><D:collection/></D:resourcetype>
<J:keywords>diary, interests, hobbies</J:keywords>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>/MyCollection/diary.html</D:href>
<D:propstat>
<D:prop>
<D:resourcetype/>
<J:keywords>diary, travel, family, history</J:keywords>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<?xml version="1.0" ?>
<D:multistatus xmlns:D="DAV:" xmlns:J="http://example.com/jsprops/">
<D:response>
<D:href>/MyCollection/</D:href>
<D:propstat>
<D:prop>
<D:resourcetype><D:collection/></D:resourcetype>
<J:keywords>diary, interests, hobbies</J:keywords>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>/MyCollection/diary.html</D:href>
<D:propstat>
<D:prop>
<D:resourcetype/>
<J:keywords>diary, travel, family, history</J:keywords>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>/MyCollection/nunavut</D:href>
<D:status>HTTP/1.1 302 Found</D:status>
<D:location>
<D:href>http://example.ca/art/inuit/</D:href>
</D:location>
</D:response>
</D:multistatus>
</D:response>
<D:response>
<D:href>/MyCollection/nunavut</D:href>
<D:status>HTTP/1.1 302 Found</D:status>
<D:location>
<D:href>http://example.ca/art/inuit/</D:href>
</D:location>
</D:response>
</D:multistatus>
In this example, the Depth header is set to infinity, and the Apply-To-Redirect-Ref header is set to "F". The collection contains one URI that identifies a redirect reference resource. The response element for the redirect reference resource has a status of 302 (Found) and includes a DAV:location extension element to allow clients to retrieve the properties of its target resource. (The response element for the redirect reference resource does not include the requested properties. The client can submit another PROPFIND request to the URI in the DAV:location pseudo-property to retrieve those properties.)
在本例中，深度标题设置为无穷大，应用于重定向参考标题设置为“F”。集合包含一个标识重定向引用资源的URI。重定向引用资源的响应元素的状态为302（已找到），并包含一个DAV:location扩展元素，以允许客户端检索其目标资源的属性。（重定向引用资源的响应元素不包括请求的属性。客户端可以向DAV:location伪属性中的URI提交另一个PROPFIND请求以检索这些属性。）
8.2. Example: PROPFIND with Apply-To-Redirect-Ref on a Collection with Redirect Reference Resources
8.2. 示例：PROPFIND与Apply一起对具有重定向引用资源的集合重定向引用
Suppose a PROPFIND request with "Apply-To-Redirect-Ref: T" and Depth: infinity is submitted to the following collection, with the members shown here:
假设将带有“Apply To Redirect Ref:T”和Depth:infinity的PROPFIND请求提交到以下集合，其成员如下所示：
/MyCollection/ (non-reference resource) diary.html (redirect reference resource) nunavut
/MyCollection/（非参考资源）diary.html（重定向参考资源）nunavut
>> Request:
>>请求：
PROPFIND /MyCollection/ HTTP/1.1
Host: example.com
Depth: infinity
Apply-To-Redirect-Ref: T
Content-Type: text/xml
Content-Length: xxxx
PROPFIND /MyCollection/ HTTP/1.1
Host: example.com
Depth: infinity
Apply-To-Redirect-Ref: T
Content-Type: text/xml
Content-Length: xxxx
<?xml version="1.0" ?>
<D:propfind xmlns:D="DAV:">
<D:prop>
<D:resourcetype/>
<D:reftarget/>
<D:redirect-lifetime/>
</D:prop>
</D:propfind>
<?xml version="1.0" ?>
<D:propfind xmlns:D="DAV:">
<D:prop>
<D:resourcetype/>
<D:reftarget/>
<D:redirect-lifetime/>
</D:prop>
</D:propfind>
>> Response:
>>答复：
HTTP/1.1 207 Multi-Status
Content-Type: text/xml
Content-Length: xxxx
HTTP/1.1 207 Multi-Status
Content-Type: text/xml
Content-Length: xxxx
<?xml version="1.0" ?>
<D:multistatus xmlns:D="DAV:">
<D:response>
<D:href>/MyCollection/</D:href>
<D:propstat>
<D:prop>
<D:resourcetype><D:collection/></D:resourcetype>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<D:propstat>
<D:prop>
<D:reftarget/>
<D:redirect-lifetime/>
</D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>/MyCollection/diary.html</D:href>
<D:propstat>
<D:prop>
<D:resourcetype/>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<D:propstat>
<D:prop>
<D:reftarget/>
<D:redirect-lifetime/>
</D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
<?xml version="1.0" ?>
<D:multistatus xmlns:D="DAV:">
<D:response>
<D:href>/MyCollection/</D:href>
<D:propstat>
<D:prop>
<D:resourcetype><D:collection/></D:resourcetype>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<D:propstat>
<D:prop>
<D:reftarget/>
<D:redirect-lifetime/>
</D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>/MyCollection/diary.html</D:href>
<D:propstat>
<D:prop>
<D:resourcetype/>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<D:propstat>
<D:prop>
<D:reftarget/>
<D:redirect-lifetime/>
</D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>/MyCollection/nunavut</D:href>
<D:propstat>
<D:prop>
<D:resourcetype><D:redirectref/></D:resourcetype>
<D:reftarget>
<D:href>http://example.ca/art/inuit/</D:href>
</D:reftarget>
<D:redirect-lifetime><D:temporary/></D:redirect-lifetime>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
</D:multistatus>
</D:response>
<D:response>
<D:href>/MyCollection/nunavut</D:href>
<D:propstat>
<D:prop>
<D:resourcetype><D:redirectref/></D:resourcetype>
<D:reftarget>
<D:href>http://example.ca/art/inuit/</D:href>
</D:reftarget>
<D:redirect-lifetime><D:temporary/></D:redirect-lifetime>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
</D:multistatus>
Since the "Apply-To-Redirect-Ref: T" header is present, the response shows the properties of the redirect reference resource in the collection rather than reporting a 302 status.
由于存在“Apply To Redirect Ref:T”标头，因此响应将显示集合中重定向引用资源的属性，而不是报告302状态。
Operations on targets of redirect reference resources have no effect on the reference resource.
重定向引用资源目标上的操作对引用资源没有影响。
The URI in the href in a DAV:reftarget property MAY be a relative reference. In this case, the base URI to be used for resolving it to absolute form is the URI used in the HTTP message to identify the redirect reference resource to which the DAV:reftarget property belongs.
DAV:reftarget属性中href中的URI可能是相对引用。在本例中，用于将其解析为绝对形式的基本URI是HTTP消息中用于标识DAV:reftarget属性所属的重定向引用资源的URI。
When DAV:reftarget appears in the context of a Multi-Status response, it is in a DAV:response element that contains a single DAV:href element. The value of this DAV:href element serves as the base URI for resolving a relative reference in DAV:reftarget. The value of DAV:href may itself be relative, in which case it must be resolved first in order to serve as the base URI for the relative reference in DAV:reftarget. If the DAV:href element is relative, its base URI is constructed from the scheme component "http", the value of the Host header in the request, and the Request-URI.
当DAV:reftarget出现在多状态响应的上下文中时，它位于包含单个DAV:href元素的DAV:response元素中。此DAV:href元素的值用作在DAV:reftarget中解析相对引用的基本URI。DAV:href的值本身可能是相对的，在这种情况下，必须首先解析该值，才能作为DAV:reftarget中相对引用的基本URI。如果DAV:href元素是相对的，则其基本URI由方案组件“http”、请求中主机头的值和请求URI构成。
10.1. Example: Resolving a Relative Reference in a Multi-Status Response
10.1. 示例：解析多状态响应中的相对引用
>> Request:
>>请求：
PROPFIND /geog/ HTTP/1.1
Host: example.com
Apply-To-Redirect-Ref: T
Depth: 1
Content-Type: text/xml
Content-Length: nnn
PROPFIND /geog/ HTTP/1.1
Host: example.com
Apply-To-Redirect-Ref: T
Depth: 1
Content-Type: text/xml
Content-Length: nnn
<?xml version="1.0" ?>
<D:propfind xmlns:D="DAV:">
<D:prop>
<D:resourcetype/>
<D:reftarget/>
</D:prop>
</D:propfind>
<?xml version="1.0" ?>
<D:propfind xmlns:D="DAV:">
<D:prop>
<D:resourcetype/>
<D:reftarget/>
</D:prop>
</D:propfind>
>> Response:
>>答复：
HTTP/1.1 207 Multi-Status
Content-Type: text/xml
Content-Length: nnn
HTTP/1.1 207 Multi-Status
Content-Type: text/xml
Content-Length: nnn
<?xml version="1/0" ?>
<D:multistatus xmlns:D="DAV:">
<D:response>
<D:href>/geog/</D:href>
<D:propstat>
<D:prop>
<D:resourcetype><D:collection/></D:resourcetype>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<D:propstat>
<D:prop><D:reftarget/></D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>/geog/stats.html</D:href>
<D:propstat>
<D:prop>
<D:resourcetype><D:redirectref/></D:resourcetype>
<D:reftarget>
<D:href>statistics/population/1997.html</D:href>
<?xml version="1/0" ?>
<D:multistatus xmlns:D="DAV:">
<D:response>
<D:href>/geog/</D:href>
<D:propstat>
<D:prop>
<D:resourcetype><D:collection/></D:resourcetype>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<D:propstat>
<D:prop><D:reftarget/></D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>/geog/stats.html</D:href>
<D:propstat>
<D:prop>
<D:resourcetype><D:redirectref/></D:resourcetype>
<D:reftarget>
<D:href>statistics/population/1997.html</D:href>
</D:reftarget>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
</D:multistatus>
</D:reftarget>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
</D:multistatus>
In this example, the relative reference "statistics/population/1997.html" is returned as the value of the DAV:reftarget property for the reference resource identified by href /geog/stats.html. The href is itself a relative reference, which resolves to http://example.com/geog/stats.html. This is the base URI for resolving the relative reference in reftarget. The absolute URI of reftarget is http://example.com/geog/statistics/population/1997.html.
在本例中，相对引用“statistics/population/1997.html”作为href/geog/stats.html标识的引用资源的DAV:reftarget属性值返回。href本身是一个相对引用，解析为http://example.com/geog/stats.html. 这是用于解析reftarget中的相对引用的基本URI。reftarget的绝对URI为http://example.com/geog/statistics/population/1997.html.
In a Request-URI /segment1/segment2/segment3, any of the three segments may identify a redirect reference resource. (See [RFC3986], Section 3.3, for definitions of "path" and "segment".) If any segment in a Request-URI identifies a redirect reference resource, the response SHOULD be a 3xx. The value of the Location header in the response is as follows:
在请求URI/segment1/segment2/segment3中，三个段中的任何一个都可以标识重定向引用资源。（有关“路径”和“段”的定义，请参见[RFC3986]第3.3节）。如果请求URI中的任何段标识重定向引用资源，则响应应为3xx。响应中位置标头的值如下所示：
The leftmost path segment of the Request-URI that identifies a redirect reference resource, together with all path segments and separators to the left of it, is replaced by the value of the redirect reference resource's DAV:reftarget property (resolved to an absolute URI). The remainder of the Request-URI is concatenated to this path.
标识重定向引用资源的请求URI的最左侧路径段及其左侧的所有路径段和分隔符将替换为重定向引用资源的DAV:reftarget属性（解析为绝对URI）的值。请求URI的其余部分连接到此路径。
Note: If the DAV:reftarget property ends with a "/" and the remainder of the Request-URI is non-empty (and therefore must begin with a "/"), the final "/" in the DAV:reftarget property is dropped before the remainder of the Request-URI is appended.
注意：如果DAV:reftarget属性以“/”结尾，并且请求URI的其余部分非空（因此必须以“/”开头），则在追加请求URI的其余部分之前，会删除DAV:reftarget属性中的最后一个“/”。
Consider Request-URI /x/y/z.html. Suppose that /x/ is a redirect reference resource, whose target resource is collection /a/, which contains redirect reference resource y whose target resource is collection /b/, which contains redirect reference resource z.html, whose target resource is /c/d.html.
考虑请求URI/X/Y/Z.HTML。假设/x/是重定向引用资源，其目标资源为collection/a/，其中包含重定向引用资源y，其目标资源为collection/b/，其中包含重定向引用资源z.html，其目标资源为/c/d.html。
/x/y/z.html
|
| /x -> /a
|
v
/a/y/z.html
|
| /a/y -> /b
|
v
/b/z.html
|
| /b/z.html -> /c/d.html
|
v
/c/d.html
/x/y/z.html
|
| /x -> /a
|
v
/a/y/z.html
|
| /a/y -> /b
|
v
/b/z.html
|
| /b/z.html -> /c/d.html
|
v
/c/d.html
In this case, the client must follow up three separate 3xx responses before finally reaching the target resource. The server responds to the initial request with a 3xx with Location: /a/y/z.html, and the client resubmits the request to /a/y/z.html. The server responds to this request with a 3xx with Location: /b/z.html, and the client resubmits the request to /b/z.html. The server responds to this request with a 3xx with Location: /c/d.html, and the client resubmits the request to /c/d.html. This final request succeeds.
在这种情况下，客户端必须在最终到达目标资源之前跟踪三个单独的3xx响应。服务器使用3xx（带位置：/a/y/z.html）响应初始请求，客户端将请求重新提交到/a/y/z.html。服务器使用3xx（带位置：/b/z.html）响应此请求，客户端将请求重新提交到/b/z.html。服务器用3xx响应此请求，位置为：/c/d.html，客户端将请求重新提交到/c/d.html。此最终请求成功。
Note: The behaviour described above may have a very serious impact on the efficiency of mapping Request-URIs to resources in HTTP request processing. Therefore, servers MAY respond with a 404 status code if the cost of checking all leading path segments for redirect references seems prohibitive.
注意：上述行为可能会对HTTP请求处理中将请求URI映射到资源的效率产生非常严重的影响。因此，如果检查重定向引用的所有前导路径段的成本似乎过高，服务器可能会响应404状态代码。
Redirect-Ref = "Redirect-Ref:" (URI | relative-ref)
; URI: see [RFC3986], Section 3
; relative-ref: see [RFC3986], Section 4.2
Redirect-Ref = "Redirect-Ref:" (URI | relative-ref)
; URI: see [RFC3986], Section 3
; relative-ref: see [RFC3986], Section 4.2
The Redirect-Ref header is used in all 3xx responses from redirect reference resources. The value is the link target as specified during redirect reference resource creation.
重定向引用头用于重定向引用资源的所有3xx响应。该值是重定向引用资源创建期间指定的链接目标。
Apply-To-Redirect-Ref = "Apply-To-Redirect-Ref" ":" ("T" | "F")
Apply-To-Redirect-Ref = "Apply-To-Redirect-Ref" ":" ("T" | "F")
The optional Apply-To-Redirect-Ref header can be used on any request to a redirect reference resource. When it is present and set to "T", the request MUST be applied to the reference resource itself, and a 3xx response MUST NOT be returned.
可选的Apply To Redirect Ref标头可用于重定向引用资源的任何请求。当它存在并设置为“T”时，请求必须应用于引用资源本身，并且不得返回3xx响应。
If the Apply-To-Redirect-Ref header is used on a request to any other sort of resource besides a redirect reference resource, the server MUST ignore it.
如果在对重定向引用资源之外的任何其他类型资源的请求上使用Apply To Redirect Ref头，服务器必须忽略它。
The properties defined below are REQUIRED on redirect reference resources. A PROPFIND/allprop request SHOULD NOT return any of the properties defined in this document.
重定向引用资源需要以下定义的属性。PROPFIND/allprop请求不应返回此文档中定义的任何属性。
This property provides information about the lifetime of a redirect. It can be either DAV:permanent (HTTP status 301) or DAV:temporary (HTTP status 302). Future protocols may define additional values.
此属性提供有关重定向生存期的信息。它可以是DAV:永久（HTTP状态301）或DAV:临时（HTTP状态302）。未来的协议可能会定义附加值。
<!ELEMENT redirect-lifetime (permanent | temporary)>
<!ELEMENT permanent EMPTY>
<!ELEMENT temporary EMPTY>
<!ELEMENT redirect-lifetime (permanent | temporary)>
<!ELEMENT permanent EMPTY>
<!ELEMENT temporary EMPTY>
This property provides an efficient way for clients to discover the URI of the target resource. This is a read-only property after its initial creation. Its value can only be set in a MKREDIRECTREF request. The value is a DAV:href element containing the URI of the target resource.
此属性为目标客户端的资源发现提供了一种有效的方法。这是初始创建后的只读属性。只能在MKREDIRECTREF请求中设置其值。该值是一个DAV:href元素，包含目标资源的URI。
<!ELEMENT reftarget href >
<!ELEMENT reftarget href >
Name: redirectref
姓名：redirectref
Namespace: DAV:
名称空间：DAV:
Purpose: Used as the value of the DAV:resourcetype property to specify that the resource type is a redirect reference resource.
用途：用作DAV:resourcetype属性的值，以指定资源类型是重定向引用资源。
<!ELEMENT redirectref EMPTY >
<!ELEMENT redirectref EMPTY >
15. Extensions to the DAV:response XML Element for Multi-Status Responses
15. 用于多状态响应的DAV:response XML元素的扩展
As described in Section 8, the DAV:location element may be returned in the DAV:response element of a 207 Multi-Status response, to allow clients to resubmit their requests to the target resource of a redirect reference resource.
如第8节所述，可以在207多状态响应的DAV:response元素中返回DAV:location元素，以允许客户端将其请求重新提交到重定向引用资源的目标资源。
Consequently, the definition of the DAV:response XML element changes to the following:
因此，DAV:response XML元素的定义更改为：
<!ELEMENT response (href, ((href*, status)|(propstat+)),
responsedescription?, location?) >
<!ELEMENT location (href) >
<!ELEMENT response (href, ((href*, status)|(propstat+)),
responsedescription?, location?) >
<!ELEMENT location (href) >
Sections 9.1 and 15 of [RFC2518] describe the use of compliance classes with the DAV header in responses to OPTIONS, to indicate which parts of the WebDAV Distributed Authoring protocols the resource supports. This specification defines an OPTIONAL extension to [RFC2518]. It defines a new compliance class, called redirectrefs, for use with the DAV header in responses to OPTIONS requests. If a resource does support redirect references, its response to an OPTIONS request may indicate that it does, by listing the new redirectrefs compliance class in the DAV header and by listing the MKREDIRECTREF method as one it supports.
[RFC2518]第9.1节和第15节描述了在响应选项时使用符合性类和DAV头，以指示资源支持WebDAV分布式创作协议的哪些部分。本规范定义了[RFC2518]的可选扩展。它定义了一个新的符合性类，称为redirectrefs，用于在响应选项请求时与DAV头一起使用。如果资源确实支持重定向引用，则它对选项请求的响应可能表明它支持重定向引用，方法是在DAV标头中列出新的redirectrefs compliance类，并将MKREDIRECTREF方法列为它支持的方法。
When responding to an OPTIONS request, any type of resource can include redirectrefs in the value of the DAV header. Doing so indicates that the server permits a redirect reference resource at the Request-URI.
响应选项请求时，任何类型的资源都可以在DAV头的值中包含重定向引用。这样做表示服务器允许在请求URI处重定向引用资源。
>> Request:
>>请求：
OPTIONS /somecollection/someresource HTTP/1.1
Host: example.org
OPTIONS /somecollection/someresource HTTP/1.1
Host: example.org
>> Response:
>>答复：
HTTP/1.1 200 OK Allow: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE Allow: MKCOL, PROPFIND, PROPPATCH, LOCK, UNLOCK, MKREDIRECTREF DAV: 1, 2, redirectrefs
HTTP/1.1 200确定允许：选项、获取、头、发布、放置、删除、跟踪、复制、移动允许：MKCOL、PROPFIND、PROPPATCH、锁定、解锁、MKREDIRECTREF DAV:1、2、redirectrefs
The DAV header in the response indicates that the resource /somecollection/someresource is level 1 and level 2 compliant, as defined in [RFC2518]. In addition, /somecollection/someresource supports redirect reference resources. The Allow header indicates that MKREDIRECTREF requests can be submitted to /somecollection/someresource.
响应中的DAV头表示资源/somecollection/someresource符合[RFC2518]中定义的级别1和级别2。此外，/somecollection/someresource支持重定向引用资源。Allow标头表示可以将MKREDIRECTREF请求提交到/somecollection/someresource。
This section is provided to make applications that implement this protocol aware of the security implications of this protocol.
本节旨在使实现此协议的应用程序了解此协议的安全含义。
All of the security considerations of HTTP/1.1 and the WebDAV Distributed Authoring Protocol specification also apply to this protocol specification. In addition, redirect reference resources introduce several new security concerns and increase the risk of some existing threats. These issues are detailed below.
HTTP/1.1和WebDAV分布式创作协议规范的所有安全注意事项也适用于本协议规范。此外，重定向参考资源引入了几个新的安全问题，并增加了一些现有威胁的风险。这些问题详述如下。
By creating redirect reference resources on a trusted server, it is possible for a hostile agent to induce users to send private information to a target on an unrelated system. This risk is mitigated somewhat, since clients are required to notify the user of the redirection for any request other than GET or HEAD. (See [RFC2616], Section 10.3.3, 302 Found.)
通过在受信任的服务器上创建重定向引用资源，恶意代理可以诱导用户向无关系统上的目标发送私人信息。这种风险在某种程度上得到了缓解，因为除了GET或HEAD之外，客户机需要通知用户任何请求的重定向。（见[RFC2616]，第10.3.3节，第302页。）
Although redirect loops were already possible in HTTP 1.1, the introduction of the MKREDIRECTREF method creates a new avenue for clients to create loops accidentally or maliciously. If the reference resource and its target are on the same server, the server may be able to detect MKREDIRECTREF requests that would create loops. See also [RFC2616], Section 10.3, "Redirection 3xx."
虽然HTTP 1.1中已经可以使用重定向循环，但MKREDIRECTREF方法的引入为客户端意外或恶意创建循环创造了一条新途径。如果引用资源及其目标位于同一台服务器上，则服务器可能能够检测到将创建循环的MKREDIRECTREF请求。另见[RFC2616]，第10.3节，“重定向3xx”
Denial of service attacks were already possible by posting URLs that were intended for limited use at heavily used Web sites. The introduction of MKREDIRECTREF creates a new avenue for similar denial
通过在大量使用的网站上发布旨在限制使用的URL，已经可以进行拒绝服务攻击。MKREDIRECTREF的引入为类似的拒绝创造了新的途径
of service attacks. Clients can now create redirect reference resources at heavily used sites to target locations that were not designed for heavy usage.
服务攻击类型。客户机现在可以在频繁使用的站点上创建重定向引用资源，将其重定向到不适合频繁使用的目标位置。
There are several ways that redirect reference resources may reveal information about collection structures. First, the DAV:reftarget property of every redirect reference resource contains the URI of the target resource. Anyone who has access to the reference resource can discover the collection path that leads to the target resource. The owner of the target resource may have wanted to limit knowledge of this collection structure.
有几种重定向引用资源的方法可以显示有关集合结构的信息。首先，每个重定向引用资源的DAV:reftarget属性都包含目标资源的URI。任何有权访问引用资源的人都可以发现指向目标资源的收集路径。目标资源的所有者可能希望限制对此集合结构的了解。
Sufficiently powerful access control mechanisms can control this risk to some extent. Property-level access control could prevent users from examining the DAV:reftarget property. (The Location header returned in responses to requests on redirect reference resources reveals the same information, however.)
足够强大的访问控制机制可以在一定程度上控制这种风险。属性级访问控制可能会阻止用户检查DAV:reftarget属性。（但是，在响应重定向引用资源上的请求时返回的位置标头显示了相同的信息。）
This risk is no greater than the similar risk posed by HTML links.
这种风险并不比HTML链接带来的类似风险大。
All internationalization considerations mentioned in [RFC2518] also apply to this document.
[RFC2518]中提到的所有国际化注意事项也适用于本文件。
All IANA considerations mentioned in [RFC2518] also apply to this document.
[RFC2518]中提到的所有IANA注意事项也适用于本文件。
This document specifies the two new HTTP headers listed below.
本文档指定了下面列出的两个新HTTP头。
Header field name: Redirect-Ref
标题字段名称：重定向引用
Applicable protocol: http
适用协议：http
Status: standard
状态：标准
Author/Change controller: IETF
作者/变更控制员：IETF
Specification document: this specification (Section 12.1)
规范文件：本规范（第12.1节）
Header field name: Apply-To-Redirect-Ref
标题字段名称：应用于重定向引用
Applicable protocol: http
适用协议：http
Status: standard
状态：标准
Author/Change controller: IETF
作者/变更控制员：IETF
Specification document: this specification (Section 12.2)
规范文件：本规范（第12.2节）
Many thanks to Jason Crawford, Jim Davis, Chuck Fay, and Judith Slein, who can take credit for big parts of the original design of this specification.
非常感谢Jason Crawford、Jim Davis、Chuck Fay和Judith Slein，他们为本规范的大部分原始设计赢得了赞誉。
This document has benefited from thoughtful discussion by Jim Amsden, Peter Carlson, Steve Carter, Tyson Chihaya, Ken Coar, Ellis Cohen, Bruce Cragun, Spencer Dawkins, Mark Day, Rajiv Dulepet, David Durand, Lisa Dusseault, Stefan Eissing, Roy Fielding, Yaron Goland, Fred Hitt, Alex Hopmann, James Hunt, Marcus Jager, Chris Kaler, Manoj Kasichainula, Rohit Khare, Daniel LaLiberte, Steve Martin, Larry Masinter, Jeff McAffer, Joe Orton, Surendra Koduru Reddy, Juergen Reuter, Max Rible, Sam Ruby, Bradley Sergeant, Nick Shelness, John Stracke, John Tigue, John Turner, Kevin Wiggen, and others.
本文件得益于吉姆·阿姆斯登、彼得·卡尔森、史蒂夫·卡特、泰森·齐哈亚、肯·科尔、埃利斯·科恩、布鲁斯·克拉根、斯宾塞·道金斯、马克·戴、拉吉夫·杜莱佩、大卫·杜兰德、丽莎·杜肖特、斯特凡·艾辛、罗伊·菲尔丁、雅伦·戈兰、弗雷德·希特、亚历克斯·霍普曼、詹姆斯·亨特、马库斯·贾格尔、克里斯·卡勒、马诺伊·卡西切努拉、，罗希特·哈雷、丹尼尔·拉利伯特、史蒂夫·马丁、拉里·马辛特、杰夫·麦道夫、乔·奥尔顿、苏伦德拉·科杜鲁·雷迪、尤尔根·路透社、马克斯·里布尔、萨姆·鲁比、布拉德利中士、尼克·谢尔内斯、约翰·斯特拉克、约翰·蒂格、约翰·特纳、凯文·维根和其他人。
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2119]Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，1997年3月。
[RFC2518] Goland, Y., Whitehead, E., Faizi, A., Carter, S., and D. Jensen, "HTTP Extensions for Distributed Authoring -- WEBDAV", RFC 2518, February 1999.
[RFC2518]Goland，Y.，Whitehead，E.，Faizi，A.，Carter，S.，和D.Jensen，“分布式创作的HTTP扩展——WEBDAV”，RFC25181999年2月。
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC2616]菲尔丁，R.，盖蒂斯，J.，莫卧儿，J.，弗莱斯蒂克，H.，马斯特，L.，利奇，P.，和T.伯纳斯李，“超文本传输协议——HTTP/1.1”，RFC 2616，1999年6月。
[RFC3253] Clemm, G., Amsden, J., Ellison, T., Kaler, C., and J. Whitehead, "Versioning Extensions to WebDAV (Web Distributed Authoring and Versioning)", RFC 3253, March 2002.
[RFC3253]Clemm，G.，Amsden，J.，Ellison，T.，Kaler，C.，和J.Whitehead，“WebDAV的版本控制扩展（Web分布式创作和版本控制）”，RFC 3253，2002年3月。
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005.
[RFC3986]Berners Lee，T.，Fielding，R.，和L.Masinter，“统一资源标识符（URI）：通用语法”，STD 66，RFC 3986，2005年1月。
Authors' Addresses
作者地址
Jim Whitehead UC Santa Cruz, Dept. of Computer Science 1156 High Street Santa Cruz, CA 95064 US
吉姆·怀特黑德加州大学圣克鲁斯分校，计算机科学系，美国加利福尼亚州圣克鲁斯高街1156号，邮编95064
EMail: ejw@cse.ucsc.edu
EMail: ejw@cse.ucsc.edu
Geoff Clemm IBM 20 Maguire Road Lexington, MA 02421 US
美国马萨诸塞州列克星敦马圭尔路20号Geoff Clemm IBM 02421
EMail: geoffrey.clemm@us.ibm.com
EMail: geoffrey.clemm@us.ibm.com
Julian F. Reschke (editor) greenbytes GmbH Hafenweg 16 Muenster, NW 48155 Germany
Julian F.Reschke（编辑）greenbytes GmbH Hafenweg 16 Muenster，西北48155德国
Phone: +49 251 2807760
Fax: +49 251 2807761
EMail: julian.reschke@greenbytes.de
URI: http://greenbytes.de/tech/webdav/
Phone: +49 251 2807760
Fax: +49 251 2807761
EMail: julian.reschke@greenbytes.de
URI: http://greenbytes.de/tech/webdav/
Full Copyright Statement
完整版权声明
Copyright (C) The Internet Society (2006).
版权所有（C）互联网协会（2006年）。
This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights.
本文件受BCP 78中包含的权利、许可和限制的约束，除其中规定外，作者保留其所有权利。
This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
本文件及其包含的信息是按“原样”提供的，贡献者、他/她所代表或赞助的组织（如有）、互联网协会和互联网工程任务组不承担任何明示或暗示的担保，包括但不限于任何保证，即使用本文中的信息不会侵犯任何权利，或对适销性或特定用途适用性的任何默示保证。
Intellectual Property
知识产权
The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79.
IETF对可能声称与本文件所述技术的实施或使用有关的任何知识产权或其他权利的有效性或范围，或此类权利下的任何许可可能或可能不可用的程度，不采取任何立场；它也不表示它已作出任何独立努力来确定任何此类权利。有关RFC文件中权利的程序信息，请参见BCP 78和BCP 79。
Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr.
向IETF秘书处披露的知识产权副本和任何许可证保证，或本规范实施者或用户试图获得使用此类专有权利的一般许可证或许可的结果，可从IETF在线知识产权存储库获取，网址为http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org.
IETF邀请任何相关方提请其注意任何版权、专利或专利申请，或其他可能涵盖实施本标准所需技术的专有权利。请将信息发送至IETF的IETF-ipr@ietf.org.
Acknowledgement
确认
Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA).
RFC编辑器功能的资金由IETF行政支持活动（IASA）提供。