The Archive and Packaging Pointer (app) URI scheme
draft-soilandreyes-app-02
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
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|
|---|---|---|---|
| Authors | Stian Soiland-Reyes , Marcos Cáceres | ||
| Last updated | 2018-01-18 | ||
| Replaced by | draft-soilandreyes-arcp, draft-soilandreyes-arcp | ||
| RFC stream | (None) | ||
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| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
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| IESG | IESG state | I-D Exists | |
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draft-soilandreyes-app-02
Network Working Group S. Soiland-Reyes
Internet-Draft The University of Manchester
Intended status: Informational M. Caceres
Expires: July 23, 2018 Mozilla Corporation
January 19, 2018
The Archive and Packaging Pointer (app) URI scheme
draft-soilandreyes-app-02
Abstract
This Internet-Draft proposes the Archive and Packaging Pointer URI
scheme "app".
app URIs can be used to consume or reference hypermedia resources
bundled inside a file archive or a mobile application package, as
well as to resolve URIs for archive resources within a programmatic
framework.
This URI scheme provides mechanisms to generate a unique base URI to
represent the root of the archive, so that relative URI references in
a bundled resource can be resolved within the archive without having
to extract the archive content on the local file system.
An app URI can be used for purposes of isolation (e.g. when consuming
multiple archives), security constraints (avoiding "climb out" from
the archive), or for externally identiyfing sub-resources in other
hypermedia formats.
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 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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This Internet-Draft will expire on July 23, 2018.
Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Background . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Scheme syntax . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Authority . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Path . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Scheme semantics . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Resolution protocol . . . . . . . . . . . . . . . . . . . 6
3.2. Resolving from a .well-known endpoint . . . . . . . . . . 7
4. Encoding considerations . . . . . . . . . . . . . . . . . . . 8
5. Interoperability considerations . . . . . . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1. Normative References . . . . . . . . . . . . . . . . . . 10
8.2. Informative References . . . . . . . . . . . . . . . . . 11
8.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 12
A.1. Sandboxing . . . . . . . . . . . . . . . . . . . . . . . 12
A.2. Origin-based . . . . . . . . . . . . . . . . . . . . . . 13
A.3. Hash-based . . . . . . . . . . . . . . . . . . . . . . . 14
A.4. Archives that are not files . . . . . . . . . . . . . . . 14
A.5. Resolution of packaged resources . . . . . . . . . . . . 15
Appendix B. History . . . . . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Background
Applications that are accessing resources bundled inside a file
archive (e.g. zip or tar.gz) can struggle to consume hypermedia
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content types that use relative URI references [RFC3986], as it is
challenging to determine the base URI in a consistent fashion.
Frequently the archive must be unpacked locally to synthesize base
URIs like "file:///tmp/a1b27ae03865/" to represent the root of the
archive. Such URIs are fluctual, might not be globally unique, and
could be vulnerable to attacks such as "climbing out" of the root
directory.
Mobile and Web applications that are distributed as packages may
bundle resources such as stylesheets with relative URI references to
images and fonts.
An archive containing multiple HTML or Linked Data resources, such as
in a BagIt archive [I-D.draft-kunze-bagit-14], may be using relative
URIs to cross-reference constituent files.
Consumptions of archives might be performed in memory or through a
common framework, abstracting away any local file location.
Consumption of an archive with a consistent base URL should be
possible no matter from which location it was retrieved, or on which
device it is inspected.
When consuming multiple archives from untrusted sources it would be
beneficial to have a Same Origin policy [RFC6454] so that relative
hyperlinks can't escape the particular archive.
The "file:" URI scheme [RFC8089] can be ill-suited for purposes such
as above, where a location-independent URI scheme is more flexible,
secure and globally unique.
2. Scheme syntax
The "app" URI scheme follows the [RFC3986] syntax for hierarchical
URIs according to the following production:
appURI = "app://" app-authority [ path-absolute ]
[ "?" query ] [ "#" fragment ]
The "app-authority" component provides a unique identifier for the
opened archive. See Section 2.1 for details.
The "path-absolute" component provides the absolute path of a
resource (e.g. a file or directory) within the archive. See
Section 2.2 for details.
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The semantics of the "query" component is undefined by this Internet-
Draft. Implementations SHOULD NOT generate a query component for app
URIs.
The "fragment" component MAY be used by implementations according to
[RFC3986] and the implied media type [RFC2046] of the resource at the
path. This Internet-Draft does not specify how to determine the
media type.
2.1. Authority
The purpose of the "authority" component in an app URI is to build a
unique base URI for a particular archive. The authority is NOT
intended to be resolvable without former knowledge of the archive.
The authority of an app URI MUST be valid according to this
production:
app-authority = UUID | alg-val | authority
The "UUID" production match its definition in [RFC4122], e.g.
"2a47c495-ac70-4ed1-850b-8800a57618cf"
The "alg-val" production match its definition in [RFC6920], e.g.
"sha-256;JCS7yveugE3UaZiHCs1XpRVfSHaewxAKka0o5q2osg8"
The "authority" production match its definition in [RFC3986], e.g.
"example.com". As this production necessarily also match the "UUID"
and "alg-val" productions, consumers of app URIs should attempt to
match those first. While [RFC7320] section 2.2 says an extension may
not "define the structure or the semantics for URI authorities",
extensions of this Internet-Draft *are* permitted to do so, if using
a DNS domain name under their control. For instance, a vendor owning
"example.com" may specify that "{OID}" in "{OID}.oid.example.com" has
special semantics.
The choice of authority depends on the purpose of the app URI within
the implementation. Below are some recommendations:
1. _Sandboxing_, when independently interpreting resources in an
archive, the authority SHOULD be a UUID v4 [RFC4122] created with
a suitable random number generator [RFC4086]. This ensures with
high probablity that the app base URI is globally unique. An
application MAY choose to reuse a previously assigned UUID that
is associated with the archive.
2. _Location-based_, for referencing resources in an archive
accessed at a particular URL, the authority SHOULD be generated
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as a name-based UUID v5 [RFC4122]; that is based on the SHA1
concatination of the URL namespace "6ba7b811-9dad-
11d1-80b4-00c04fd430c8" (as UUID bytes) and the ASCII bytes of
the particular URL. It is NOT RECOMMENDED to use this approach
with a file URI [RFC8089] without a fully qualified "host" name.
3. _Hash-based_, for referencing resources in an archive as a
particular bytestream, independent of its location, the authority
SHOULD be a checksum of the archive bytes. The checksum MUST be
expressed according to [RFC6920]'s "alg-val" production, and
SHOULD use the "sha-256" algorithm. It is NOT RECOMMENDED to use
truncated hash methods.
The generic "authority" production MAY be used for extensions if the
above mechanisms are not suitable. Care should be taken so that the
custom "authority" do not match the "UUID" nor "alg-val" productions.
2.2. Path
The "path-absolute" component MUST match the production in [RFC3986]
and provide the absolute path of a resource (e.g. a file or
directory) within the archive.
Archive media types vary in constraints and flexibilities of how to
express paths. Here we assume an archive generally consists of a
single root directory, which can contain multiple directories and
files at arbitrary nesting levels.
Paths SHOULD be expressed using "/" as the directory separator. The
below productions are from [RFC3986]:
path-absolute = "/" [ segment-nz *( "/" segment ) ]
segment = *pchar
segment-nz = 1*pchar
In an app URI, each intermediate "segment" (or "segment-nz")
represent a directory name, while the last segment represent either a
directory or file name.
It is RECOMMENDED to include the trailing "/" if it is known the path
represents a directory.
3. Scheme semantics
This Internet-Draft does not constrain what particular format might
constitute an _archive_, and neither does it require that the archive
is retrievable as a single bytestream or file. Examples of archive
media types include "application/zip", "application/
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vnd.android.package-archive", "application/x-tar", "application/
x-gtar" and "application/x-7z-compressed".
The _authority_ component identifies the archive file.
The _path_ component of an app URI identify individual resources
within a particular archive, typically a _directory_ or _file_.
o If the _path_ is missing/empty - e.g. "app://833ebda2-f9a8-4462-
b74a-4fcdc1a02d22" - then the app URI represent the whole archive
file.
o If the _path_ is "/" - e.g. "app://833ebda2-f9a8-4462-b74a-
4fcdc1a02d22/" - then the app URI represent the root directory of
the archive.
o If the path ends with "/" then the path represents a directory in
the archive
The app URIs can be used for uniquely identifying the resources
independent of the location of the archive, such as within an
information system.
Assuming an appropriate resolution mechanism which have knowledge of
the corresponding archive, an app URI can also be used for
resolution.
3.1. Resolution protocol
This Internet-Draft do not specify directly the protocol to resolve
resources according to the app URI scheme. For instance, one
implementation might rewrite app URIs to localized "file:///" paths
in a temporary directory, while another implementation might use an
embedded HTTP server.
It is envisioned that an implementation will have extracted or opened
an archive in advance, and assigned it an appropriate authority
according to Section 2.1. Such an implementation can then resolve
app URIs programmatically, e.g. by using in-memory access or mapping
paths to the extracted archive on the local file system.
Implementations that support resolving app URIs SHOULD:
1. Fail with the equivalent of _Not Found_ if the authority is
unknown.
2. Fail with the equivalent of _Gone_ if the authority is known, but
the content of the archive is no longer available.
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3. Fail with the equivalent of _Not Found_ if the path does not map
to a file or directory within the archive.
4. Return the corresponding (potentially uncompressed) bytestream if
the path maps to a file within the archive.
5. Return an appropriate directory listing if the path maps to a
directory within the archive.
6. Return an appropriate directory listing of the archive's root
directory if the path is "/"
7. Return the archive file if the path component is missing/empty.
Not all archive formats or implementations will have the concept of a
directory listing, in which case the directory listing SHOULD fail
with the equivalent of "Not Implemented".
It is not specified in this Internet-Draft how an implementation can
determine the media type of a file within an archive. This may be
expressed in secondary resources (such as a manifest), be determined
by file extensions or magic bytes.
The media type "text/uri-list" [RFC2483] MAY be used to represent a
directory listing, in which case it SHOULD contain only URIs that
start with the app URI of the directory.
Some archive formats might support resources which are neither
directories nor regular files (e.g. device files, symbolic links).
This Internet-Draft does not specify the semantics of attempting to
resolve such resources.
This Internet-Draft does not specify how to change an archive or its
content using app URIs.
3.2. Resolving from a .well-known endpoint
If the "authority" component of an app URI matches the "alg-val"
production, an application MAY attempt to resolve the authority from
any ".well-known/ni/" endpoint [RFC5785] as specified in [RFC6920]
section 4, in order to retrieve the complete archive. Applications
SHOULD verify the checksum of the retrieved archive before resolving
the individual path.
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4. Encoding considerations
The production for "UUID" and "alg-val" are restricted to ASCII and
should not require any encoding considerations.
Care should be taken to %-encode the directory and file segments of
"path-absolute" according to [RFC3986] (for URIs) or [RFC3987] (for
IRIs).
When used as part an IRI, paths SHOULD be expressed using
international Unicode characters instead of %-encoding as ASCII.
Not all archive media types have an explicit character encoding
specified for their paths. If no such information is available for
the archive format, implementations MAY assume that the path
component is encoded with UTF-8 [RFC2279].
Some archive media types are case-insensitive, in which cases it is
RECOMMENDED to preserve the casing as expressed in the archive.
5. Interoperability considerations
As multiple authorities are possible (Section 2.1), there could be
interoperability challenges when exchanging app URIs between
implementations. Some considerations:
1. Two implementations describe the same archive (e.g. stored in the
same local file path), but using different v4 UUIDs. The
implementations may need to detect equality of the two UUIDs out
of band.
2. Two implementations describe an archive retrieved from the same
URL, with the same v5 UUIDs, but retrieved at different times.
The implementations might disagree about the content of the
archive.
3. Two implementations describe an archive retrieved from the same
URL, with the same v5 UUIDs, but retrieved using different
content negotiation resulting in different archive
representations. The implementations may disagree about path
encoding, file name casing or hierarchy.
4. Two implementations describe the same archive bytestream using
the "alg-val" production, but they have used two different hash
algorithms. The implementations may need to negotiate to a
common hash algorithm.
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5. An implementation describe an archive using the "alg-val"
production, but a second implementation concurrently modifies the
archive's content. The first implementation may need to detect
changes to the archive or verify the checksum at the end of its
operations.
6. Two implementations might have different views of the content of
the same archive if the format permits multiple entries with the
same path. Care should be taken to follow the convention and
specification of the particular archive format.
7. Two implementations that access the same archive which contain
file paths with Unicode characters, but they extract to two
different file systems. Limitations and conventions for file
names in the local file system (e.g. Unicode normalization, case
insensitivity, total path length) may result in the
implementations having inconsistent or inaccessible paths.
6. Security Considerations
As when handling any content, extra care should be taken when
consuming archives and app URIs from unknown sources.
An archive could contain compressed files that expand to fill all
available disk space.
A maliciously crafted archive could contain paths with characters
(e.g. backspace) which could make an app URI invalid or misleading if
used unescaped.
A maliciously crafted archive could contain paths (e.g. combined
Unicode sequences) that cause the app URI to be very long, causing
issues in information systems propagating said URI.
An archive might contain symbolic links that, if extracted to a local
file system, might address files outside the archive's directory
structure.
An maliciously crafted app URI might contain "../" segments, which if
naively converted to a "file:///" URI might address files outside the
archive's directory structure.
In particular for IRIs, an archive might contain multiple paths with
similar-looking characters or with different Unicode combine
sequences, which could be facilitated to mislead users.
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An URI hyperlink might use or guess an app URI authority to attempt
to climb into a different archive for malicious purposes.
Applications SHOULD employ Same Orgin policy [RFC6454] checks.
7. IANA Considerations
This Internet-Draft contains the Provisional IANA registration of the
app URI scheme according to [RFC7595].
Scheme name: app
Status: provisional
Applications/protocols that use this protocol: Hypermedia-consuming
application that handle archives or packages.
Contact: Stian Soiland-Reyes stain@apache.org [1]
Change controller: Stian Soiland-Reyes
8. References
8.1. Normative References
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046,
DOI 10.17487/RFC2046, November 1996,
<https://www.rfc-editor.org/info/rfc2046>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO
10646", RFC 2279, DOI 10.17487/RFC2279, January 1998,
<https://www.rfc-editor.org/info/rfc2279>.
[RFC2483] Mealling, M. and R. Daniel, "URI Resolution Services
Necessary for URN Resolution", RFC 2483,
DOI 10.17487/RFC2483, January 1999,
<https://www.rfc-editor.org/info/rfc2483>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
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[RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource
Identifiers (IRIs)", RFC 3987, DOI 10.17487/RFC3987,
January 2005, <https://www.rfc-editor.org/info/rfc3987>.
[RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker,
"Randomness Requirements for Security", BCP 106, RFC 4086,
DOI 10.17487/RFC4086, June 2005,
<https://www.rfc-editor.org/info/rfc4086>.
[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122,
DOI 10.17487/RFC4122, July 2005,
<https://www.rfc-editor.org/info/rfc4122>.
[RFC5785] Nottingham, M. and E. Hammer-Lahav, "Defining Well-Known
Uniform Resource Identifiers (URIs)", RFC 5785,
DOI 10.17487/RFC5785, April 2010,
<https://www.rfc-editor.org/info/rfc5785>.
[RFC6454] Barth, A., "The Web Origin Concept", RFC 6454,
DOI 10.17487/RFC6454, December 2011,
<https://www.rfc-editor.org/info/rfc6454>.
[RFC6920] Farrell, S., Kutscher, D., Dannewitz, C., Ohlman, B.,
Keranen, A., and P. Hallam-Baker, "Naming Things with
Hashes", RFC 6920, DOI 10.17487/RFC6920, April 2013,
<https://www.rfc-editor.org/info/rfc6920>.
[RFC7320] Nottingham, M., "URI Design and Ownership", BCP 190,
RFC 7320, DOI 10.17487/RFC7320, July 2014,
<https://www.rfc-editor.org/info/rfc7320>.
[RFC7595] Thaler, D., Ed., Hansen, T., and T. Hardie, "Guidelines
and Registration Procedures for URI Schemes", BCP 35,
RFC 7595, DOI 10.17487/RFC7595, June 2015,
<https://www.rfc-editor.org/info/rfc7595>.
[RFC8089] Kerwin, M., "The "file" URI Scheme", RFC 8089,
DOI 10.17487/RFC8089, February 2017,
<https://www.rfc-editor.org/info/rfc8089>.
8.2. Informative References
[CWLViewer]
Robinson, M., Soiland-Reyes, S., and M. Crusoe, "Common-
Workflow-Language/CWLviewer: CWL Viewer", Zenodo Software,
DOI 10.5281/zenodo.823534, August 2017,
<https://view.commonwl.org/>.
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[I-D.draft-kunze-bagit-14]
Kunze, J., Littman, J., Madden, L., Summers, E., Boyko,
A., and B. Vargas, "The BagIt File Packaging Format
(V0.97)", draft-kunze-bagit-14 (work in progress), October
2016.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<https://www.rfc-editor.org/info/rfc4648>.
[ROBundle]
Soiland-Reyes, S., Gamble, M., and R. Haines, "Research
Object Bundle 1.0", Zenodo report,
DOI 10.5281/zenodo.12586, November 2014,
<https://w3id.org/bundle/>.
[W3C.NOTE-app-uri-20150723]
Caceres, M., "The app: URL Scheme", World Wide Web
Consortium NOTE NOTE-app-uri-20150723, July 2015,
<http://www.w3.org/TR/2015/NOTE-app-uri-20150723>.
[W3C.NOTE-widgets-uri-20120313]
Caceres, M., "Widget URI scheme", World Wide Web
Consortium NOTE NOTE-widgets-uri-20120313, March 2012,
<http://www.w3.org/TR/2012/NOTE-widgets-uri-20120313>.
8.3. URIs
[1] mailto:stain@apache.org
Appendix A. Examples
A.1. Sandboxing
An document store application has received a file "document.tar.gz"
which content will be checked for consistency.
For sandboxing purposes it generates a UUID v4 "32a423d6-52ab-47e3-
a9cd-54f418a48571" using a pseudo-random generator. The app base URI
is thus "app://32a423d6-52ab-47e3-a9cd-54f418a48571/"
The archive contains the files:
o "./doc.html" which links to "css/base.css"
o "./css/base.css" which links to "../fonts/Coolie.woff"
o "./fonts/Coolie.woff"
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The application generates the corresponding app URIs and uses those
for URI resolutions to find hyperlinks:
app://32a423d6-52ab-47e3-a9cd-54f418a48571/doc.html
-> app://32a423d6-52ab-47e3-a9cd-54f418a48571/css/base.css
app://32a423d6-52ab-47e3-a9cd-54f418a48571/css/base.css
-> app://32a423d6-52ab-47e3-a9cd-54f418a48571/fonts/Coolie.woff
app://32a423d6-52ab-47e3-a9cd-54f418a48571/fonts/Coolie.woff
The application is now confident that all hyperlinked files are
indeed present in the archive. In its database it notes which ZIP
file corresponds to UUID "32a423d6-52ab-47e3-a9cd-54f418a48571".
If the application had encountered a malicious hyperlink
"../../../outside.txt" it would first resolve it to the absolute URI
"app://32a423d6-52ab-47e3-a9cd-54f418a48571/outside.txt" and conclude
from the "Not Found" error that the path "/outside.txt" was not
present in the archive.
A.2. Origin-based
A web crawler is about to index the content of the URL
"http://example.com/data.zip" and need to generate absolute URIs as
it continues crawling inside the individual resources of the archive.
The application generates a UUID v5 based on the URL namespace
"6ba7b811-9dad-11d1-80b4-00c04fd430c8" and the URL to the zip file:
>>> uuid.uuid5(uuid.NAMESPACE_URL, "http://example.com/data.zip")
UUID('b7749d0b-0e47-5fc4-999d-f154abe68065')
Thus the base app URI for indexing the ZIP content is
app://b7749d0b-0e47-5fc4-999d-f154abe68065/
Listing all directories and files in the ZIP, the crawler finds the
URIs:
app://b7749d0b-0e47-5fc4-999d-f154abe68065/
app://b7749d0b-0e47-5fc4-999d-f154abe68065/pics/
app://b7749d0b-0e47-5fc4-999d-f154abe68065/pics/flower.jpeg
When the application encounters "http://example.com/data.zip" some
time later it can recalculate the same base app URI. This time the
ZIP file has been modified upstream and the crawler finds
additionally:
app://b7749d0b-0e47-5fc4-999d-f154abe68065/pics/cloud.jpeg
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If files had been removed from the updated ZIP file the crawler can
simply remove those from its database, as it used the same app base
URI as in last crawl.
A.3. Hash-based
An application where users can upload software distributions for
virus checking needs to avoid duplication as users tend to upload
"foo-1.2.tar" multiple times.
The application calculates the "sha-256" checksum of the uploaded
file to be in hexadecimal:
17edf80f84d478e7c6d2c7a5cfb4442910e8e1778f91ec0f79062d8cbdef42cd
The "base64url" encoding [RFC4648] of the binary version of the
checksum is:
F-34D4TUeOfG0selz7REKRDo4XePkewPeQYtjL3vQs0
The corresponding "alg-val" authority is thus:
sha-256;F-34D4TUeOfG0selz7REKRDo4XePkewPeQYtjL3vQs0
From this the base app URL is:
app://sha-256;F-34D4TUeOfG0selz7REKRDo4XePkewPeQYtjL3vQs0/
The crawler finds that it's virus database already contain entries
for:
app://sha-256;F-34D4TUeOfG0selz7REKRDo4XePkewPeQYtjL3vQs0/bin/evil
and flags the upload as malicious without having to scan it again.
A.4. Archives that are not files
An application is relating BagIt archives [I-D.draft-kunze-bagit-14]
on a shared file system, using structured folders and manifests
rather than individual archive files.
The BagIt payload manifest "/gfs/bags/scan15/manifest-md5.txt" lists
the files:
49afbd86a1ca9f34b677a3f09655eae9 data/27613-h/images/q172.png
408ad21d50cef31da4df6d9ed81b01a7 data/27613-h/images/q172.txt
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The application generates a random UUID v4 "ff2d5a82-7142-4d3f-b8cc-
3e662d6de756" which it adds to the bag metadata file
"/gfs/bags/scan15/bag-info.txt"
External-Identifier: ff2d5a82-7142-4d3f-b8cc-3e662d6de756
It then generates app URIs for the files listed in the manifest:
app://ff2d5a82-7142-4d3f-b8cc-3e662d6de756/data/27613-h/images/q172.png
app://ff2d5a82-7142-4d3f-b8cc-3e662d6de756/data/27613-h/images/q172.txt
A.5. Resolution of packaged resources
A virtual file system driver on a mobile operating system has mounted
several packaged application for resolving common resources. An
application requests the rendering framework to resolve a picture
from "app://eb1edec9-d2eb-4736-a875-eb97b37c690e/img/logo.png" to
show it within a user interface.
The framework first checks that the authority "eb1edec9-d2eb-
4736-a875-eb97b37c690e" is valid to access according to the Same
Origin policies or permissions of the running application. It then
matches the authority to the corresponding application package.
The framework then resolves "/img/logo.png" from within that package,
and returns an image buffer it already had cached in memory.
Appendix B. History
This Internet-Draft proposes the URI scheme "app", which was
originally proposed by [W3C.NOTE-app-uri-20150723] but never
registered with IANA. That W3C Note evolved from
[W3C.NOTE-widgets-uri-20120313] which proposed the URI scheme
"widget".
Neither W3C Notes did progress further as Recommendation track
documents.
While the focus of those W3C Notes was to specify how to resolve
resources from within a packaged application, this Internet-Draft
generalize the "app" URI scheme to support referencing and
identifying resources within any archive, and de-emphasize the
retrieval mechanism.
For compatibility with existing adaptations of the "app" URI scheme,
e.g. [ROBundle] and [CWLViewer], this Internet-Draft reuse the same
scheme name and remains compatible with the intentions of
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[W3C.NOTE-app-uri-20150723], but renames "app" to mean "Archive and
Packaging Pointer" instead of "Application".
Authors' Addresses
Stian Soiland-Reyes
The University of Manchester
Oxford Road
Manchester
United Kingdom
Email: stain@apache.org
Marcos Caceres
Mozilla Corporation
Email: marcos@marcosc.com
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