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URI schemes

  • Článek

There are several URI (Uniform Resource Identifier) schemes that you can use to refer to files that come from your app's package, your app's data folders, or the cloud. You can also use a URI scheme to refer to strings loaded from your app's Resources Files (.resw). You can use these URI schemes in your code, in your XAML markup, in your app package manifest, or in your tile and toast notification templates.

Common features of the URI schemes

All of the schemes described in this topic follow typical URI scheme rules for normalization and resource retrieval. See RFC 3986 for the generic syntax of a URI.

All of the URI schemes define the hierarchical part per RFC 3986 as the authority and path components of the URI.

URI         = scheme ":" hier-part [ "?" query ] [ "#" fragment ]
hier-part   = "//" authority path-abempty
            / path-absolute
            / path-rootless
            / path-empty

What this means is that there are essentially three components to a URI. Immediately following the two forward slashes of the URI scheme is a component (which can be empty) called the authority. And immediately following that is the path. Taking the URI http://www.contoso.com/welcome.png as an example, the scheme is "http://", the authority is "www.contoso.com", and the path is "/welcome.png". Another example is the URI ms-appx:///logo.png, where the authority components is empty and takes a default value.

The fragment component is ignored by the scheme-specific processing of the URIs mentioned in this topic. During resource retrieval and comparison, the fragment component has no bearing. However, layers above specific implementation may interpret the fragment to retrieve a secondary resource.

Comparison occurs byte for byte after normalization of all IRI components.

Case-insensitivity and normalization

All the URI schemes described in this topic follow typical URI rules (RFC 3986) for normalization and resource retrieval for schemes. The normalized form of these URIs maintains case and percent-decodes RFC 3986 unreserved characters.

For all the URI schemes described in this topic, scheme, authority, and path are either case-insensitive by standard, or else are processed by the system in a case-insensitive way. Note The only exception to that rule is the authority of ms-resource, which is case-sensitive.

ms-appx and ms-appx-web

Use the ms-appx or the ms-appx-web URI scheme to refer to a file that comes from your app's package (see Packaging apps). Files in your app package are typically static images, data, code, and layout files. The ms-appx-web scheme accesses the same files as ms-appx, but in the web compartment. For examples and more info, see Reference an image or other asset from XAML markup and code.

Scheme name (ms-appx and ms-appx-web)

The URI scheme name is the string "ms-appx" or "ms-appx-web".

ms-appx://

ms-appx-web://

Authority (ms-appx and ms-appx-web)

The authority is the package identity name that is defined in the package manifest. It is therefore limited in both the URI and IRI (Internationalized resource identifier) form to the set of characters allowed in a package identity name. The package name must be the name of one of the packages in the current running app's package dependency graph.

ms-appx://Contoso.MyApp/
ms-appx-web://Contoso.MyApp/

If any other character appears in the authority, then retrieval and comparison fail. The default value for the authority is the currently running app's package.

ms-appx:///
ms-appx-web:///

User info and port (ms-appx and ms-appx-web)

The ms-appx scheme, unlike other popular schemes, does not define a user info or port component. Since "@" and ":" are not allowed as valid authority values, lookup will fail if they are included. Each of the following fails.

ms-appx://john@contoso.myapp/default.html
ms-appx://john:password@contoso.myapp/default.html
ms-appx://contoso.myapp:8080/default.html
ms-appx://john:password@contoso.myapp:8080/default.html

Path (ms-appx and ms-appx-web)

The path component matches the generic RFC 3986 syntax and supports non-ASCII characters in IRIs. The path component defines the logical or physical file path of a file. That file is in a folder associated with the installed location of the app package, for the app specified by the authority.

If the path refers to a physical path and file name then that physical file asset is retrieved. But if no such physical file is found then the actual resource returned during retrieval is determined by using content negotiation at runtime. This determination is based on app, OS, and user settings such as language, display scale factor, theme, high contrast, and other runtime contexts. For example, a combination of the app's languages, the system's display settings, and the user's high contrast settings may be taken into account when determining the actual resource value to be retrieved.

ms-appx:///images/logo.png

The URI above may actually retrieve a file within the current app's package with the following physical file name.

\Images\fr-FR\logo.scale-100_contrast-white.png

You could of course also retrieve that same physical file by referring to it directly by its full name.

<Image Source="ms-appx:///images/fr-FR/logo.scale-100_contrast-white.png"/>

The path component of ms-appx(-web) is, like generic URIs, case sensitive. However, when the underlying file system by which the resource is accessed is case insensitive, such as for NTFS, the retrieval of the resource is done case-insensitively.

The normalized form of the URI maintains case, and percent-decodes (a "%" symbol followed by the two-digit hexadecimal representation) RFC 3986 unreserved characters. The characters "?", "#", "/", "*", and '"' (the double-quote character) must be percent-encoded in a path to represent data such as file or folder names. All percent-encoded characters are decoded before retrieval. Thus, to retrieve a file named Hello#World.html, use this URI.

ms-appx:///Hello%23World.html

Query (ms-appx and ms-appx-web)

Query parameters are ignored during retrieval of resources. The normalized form of query parameters maintains case. Query parameters are not ignored during comparison.

ms-appdata

Use the ms-appdata URI scheme to refer to files that come from the app's local, roaming, and temporary data folders. For more info about these app data folders, see Store and retrieve settings and other app data.

The ms-appdata URI scheme does not perform the runtime content negotiation that ms-appx and ms-appx-web do. But you can respond to the contents of ResourceContext.QualifierValues and load the appropriate assets from app data using their full physical file name in the URI.

Scheme name (ms-appdata)

The URI scheme name is the string "ms-appdata".

ms-appdata://

Authority (ms-appdata)

The authority is the package identity name that is defined in the package manifest. It is therefore limited in both the URI and IRI (Internationalized resource identifier) form to the set of characters allowed in a package identity name. The package name must be the name of the current running app's package.

ms-appdata://Contoso.MyApp/

If any other character appears in the authority, then retrieval and comparison fail. The default value for the authority is the currently running app's package.

ms-appdata:///

User info and port (ms-appdata)

The ms-appdata scheme, unlike other popular schemes, does not define a user info or port component. Since "@" and ":" are not allowed as valid authority values, lookup will fail if they are included. Each of the following fails.

ms-appdata://john@contoso.myapp/local/data.xml
ms-appdata://john:password@contoso.myapp/local/data.xml
ms-appdata://contoso.myapp:8080/local/data.xml
ms-appdata://john:password@contoso.myapp:8080/local/data.xml

Path (ms-appdata)

The path component matches the generic RFC 3986 syntax and supports non-ASCII characters in IRIs. Within the Windows.Storage.ApplicationData location are three reserved folders for local, roaming, and temporary state storage. The ms-appdata scheme allows access to files and folders in those locations. The first segment of the path component must specify the particular folder in the following fashion. Thus the "path-empty" form of "hier-part" is not legal.

Local folder.

ms-appdata:///local/

Temporary folder.

ms-appdata:///temp/

Roaming folder.

ms-appdata:///roaming/

The path component of ms-appdata is, like generic URIs, case sensitive. However, when the underlying file system by which the resource is accessed is case insensitive, such as for NTFS, the retrieval of the resource is done case-insensitively.

The normalized form of the URI maintains case, and percent-decodes (a "%" symbol followed by the two-digit hexadecimal representation) RFC 3986 unreserved characters. The characters "?", "#", "/", "*", and '"' (the double-quote character) must be percent-encoded in a path to represent data such as file or folder names. All percent-encoded characters are decoded before retrieval. Thus, to retrieve a local file named Hello#World.html, use this URI.

ms-appdata:///local/Hello%23World.html

Retrieval of the resource, and identification of the top level path segment, are handled after normalization of dots (".././b/c"). Therefore, URIs cannot dot themselves out of one of the reserved folders. Thus, the following URI is not allowed.

ms-appdata:///local/../hello/logo.png

But this URI is allowed (albeit redundant).

ms-appdata:///local/../roaming/logo.png

Query (ms-appdata)

Query parameters are ignored during retrieval of resources. The normalized form of query parameters maintains case. Query parameters are not ignored during comparison.

ms-resource

Use the ms-resource URI scheme to refer to strings loaded from your app's Resources Files (.resw). For examples and more info about Resources Files, see Localize strings in your UI and app package manifest.

Scheme name (ms-resource)

The URI scheme name is the string "ms-resource".

ms-resource://

Authority (ms-resource)

The authority is the top-level resource map defined in the Package Resource Index (PRI), which typically corresponds to the package identity name that is defined in the package manifest. See Packaging apps). It is therefore limited in both the URI and IRI (Internationalized resource identifier) form to the set of characters allowed in a package identity name. The package name must be the name of one of the packages in the current running app's package dependency graph.

ms-resource://Contoso.MyApp/
ms-resource://Microsoft.WinJS.1.0/

If any other character appears in the authority, then retrieval and comparison fail. The default value for the authority is the case-sensitive package name of the currently running app.

ms-resource:///

The authority is case sensitive, and the normalized form maintains its case. Lookup of a resource, however, happens case-insensitively.

User info and port (ms-resource)

The ms-resource scheme, unlike other popular schemes, does not define a user info or port component. Since "@" and ":" are not allowed as valid authority values, lookup will fail if they are included. Each of the following fails.

ms-resource://john@contoso.myapp/Resources/String1
ms-resource://john:password@contoso.myapp/Resources/String1
ms-resource://contoso.myapp:8080/Resources/String1
ms-resource://john:password@contoso.myapp:8080/Resources/String1

Path (ms-resource)

The path identifies the hierarchical location of the ResourceMap subtree (see Resource Management System) and the NamedResource within it. Typically, this corresponds to the filename (excluding extension) of a Resources Files (.resw) and the identifier of a string resource within it.

For examples and more info, see Localize strings in your UI and app package manifest and Tile and toast notification support for language, scale, and high contrast.

The path component of ms-resource is, like generic URIs, case sensitive. However, the underlying retrieval does a CompareStringOrdinal with ignoreCase set to true.

The normalized form of the URI maintains case, and percent-decodes (a "%" symbol followed by the two-digit hexadecimal representation) RFC 3986 unreserved characters. The characters "?", "#", "/", "*", and '"' (the double-quote character) must be percent-encoded in a path to represent data such as file or folder names. All percent-encoded characters are decoded before retrieval. Thus, to retrieve a string resource from a Resources File named Hello#World.resw, use this URI.

ms-resource:///Hello%23World/String1

Query (ms-resource)

Query parameters are ignored during retrieval of resources. The normalized form of query parameters maintains case. Query parameters are not ignored during comparison. Query parameters are compared case-sensitively.

Developers of particular components layered above this URI parsing may choose to use the query parameters as they see fit.