WOPI discovery

WOPI discovery is the process where a WOPI host identifies Office for the web capabilities and how to set up Office for the web applications within a site. WOPI hosts use the discovery XML to determine how to interact with Office for the web. The WOPI host should cache the data in the discovery XML. Although this XML doesn't change often, we recommend that you issue a request for the XML periodically to ensure you always have the latest version. 12-24 hours is a good cadence to refresh, although in practice it's updated much less frequently.

A more dynamic option is to re-run discovery when proof key validation fails, or when it succeeds using the old key. That implies that the keys have been rotated, so discovery should definitely be re-run to get the new public key.

Lastly, another option is to run discovery whenever one of your machines restart. All these approaches, as well as combinations of them, have been used by hosts in the past. Whichever approach makes the most sense depends on your infrastructure.

WOPI discovery actions

The action element and its attributes in the discovery XML provides some important information about Office for the web.

The following example shows an action element in the Office for the web discovery XML:

<action name="edit" ext="docx" requires="locks,update"
        urlsrc="https://word-edit.officeapps.live.com/we/wordeditorframe.aspx?
        <ui=UI_LLCC&><rs=DC_LLCC&><showpagestats=PERFSTATS&>"/>

This example defines an action called edit that's supported for docx files. The edit action requires the locks and update capabilities. To invoke the edit action on a file, navigate to the URI included in the urlsrc attribute. You must parse the urlsrc value and add some parameters. For a full description of this process, see Action URLs.

WOPI actions

All WOPI actions require hosts to implement CheckFileInfo and GetFile.

view

An action that renders a non-editable view of a document.

edit

An action that lets users edit a document.

Requires: update, locks

editnew

An action that creates a new document using a blank file template appropriate to the file type, then opens that file for editing in Office for the web.

Requires: update, locks

convert

An action that converts a document in a binary format, such as doc, into a modern format, like docx, so that it can be edited in Office for the web. For more information about this action, see Editing binary document formats.

Requires: update, locks

getinfo

An action that returns a set of URLs for running automated test cases. This action is only used by the WOPI Validator and is meant to be used in an automated fashion.

interactivepreview

🔒 Not supported in the CSPP

An action that provides an interactive preview of the file type.

mobileView

An action that renders a non-editable view of a document that's optimized for viewing on mobile devices such as smartphones.

embedview

An action that renders a non-editable view of a document that's optimized for embedding in a web page.

imagepreview()

🔒 Not supported in the CSPP

An action that provides a static image preview of the file type.

formsubmit

An action that supports accepting changes to the file type via a form-style interface. For example, a user might be able to use this action to change the content of a workbook even if they didn't have permission to use the edit action.

formedit

An action that supports editing the file type in a mode better suited to working with files that have been used to collect form data via the formsubmit action.

rest

An action that supports interacting with the file type via additional URL parameters that are specific to the file type in question.

present

🔒 Not supported in the CSPP

An action that presents a broadcast of a document.

presentservice

🔒 Not supported in the CSPP

This action provides the location of a broadcast endpoint for broadcast presenters. Interaction with the endpoint is described in [MS-OBPRS].

attend

🔒 Not supported in the CSPP

An action that attends a broadcast of a document.

attendservice

🔒 Not supported in the CSPP

This action provides the location of a broadcast endpoint for broadcast attendees. Interaction with the endpoint is described in [MS-OBPAS].

preloadedit

An action to preload static content for Office for the web edit applications.

preloadview

An action to preload static content for Office for the web view applications.

syndicate

🔒 Not supported in the CSPP

legacywebservice

🔒 Not supported in the CSPP

rtc

🔒 Not supported in the CSPP

collab

🔒 Not supported in the CSPP

documentchat

🔒 Not supported in the CSPP

Action requirements

The WOPI protocol exposes a number of different REST endpoints and operations that you can perform via those endpoints. You don’t have to implement all of these for all actions. Actions define their requirements as part of the discovery XML. The requirements themselves are groups of WOPI operations that must be supported in order for the action to work.

update

Requires: PutFile, PutRelativeFile

locks

Requires: Lock, RefreshLock, Unlock, UnlockAndRelock

Action URLs

The URI values provided in the urlsrc attribute in the discovery XML aren't in a valid format. Simply navigating to them results in errors. A WOPI host must transform the URIs provided in order to make them valid action URLs that you can use to invoke actions on a file. To transform the urlsrc attribute into a proper action URL, the host must parse and replace Placeholder values with appropriate values or discard them completely.

After the URL is transformed, it's a valid URL. When the URL is opened, the action invokes against the file indicated by the WOPISrc.

Transforming the urlsrc parameter

Some WOPI actions expose parameters that hosts can use to customize the behavior of the Office for the web application. For example, most actions support optional query string parameters that tell Office for the web what language to render the application UI in.

These parameters are exposed in the urlsrc attribute in the discovery XML. Each of these optional parameters are contained within angle brackets (< and >), and conform to the pattern <name=PLACEHOLDER_VALUE[&]>, where name is the name of the query string parameter and PLACEHOLDER_VALUE is a value that can be replaced by the host. By convention all placeholder values in Office for the web action URIs are capitalized.

The list of all placeholder values used by Office for the web and what values are valid replacements for each placeholder are listed in the Placeholder values section.

The placeholders are replaced as follows:

• If the PLACEHOLDER_VALUE is unknown to the host, the entire parameter, including the angle brackets, is removed.
• Similarly, if the PLACEHOLDER_VALUE is known but the host wishes to ignore it or use the default value for that parameter, you should remove the entire parameter, including the angle brackets.
• If the PLACEHOLDER_VALUE is known, the angle brackets are removed, the name value is left intact, and the PLACEHOLDER_VALUE string is replaced with an appropriate value. If present, you must keep the optional &.

The following section contains a list of all current placeholder values that Office for the web exposes in its discovery XML.

Placeholder values

The following are the placeholder values.

BUSINESS_USER

You can set this value to 1 to indicate that the current user is a business user. This placeholder value must be used by hosts that support the business user flow. For more information, see Supporting document editing for business users.

DC_LLCC

This value represents the language that Office for the web should use for the purposes of data calculation. For a list of currently supported languages, see What languages does Office for the web support?

In addition to the values provided in the Locale ID column, you can supply any language, provided it's in the format described in RFC 1766. Typically, this value is the same as the value provided for UI_LLCC, and defaults to that value if not provided.

DISABLE_ASYNC

You can set this value to true to prevent a broadcast attendee from navigating a file independently.

DISABLE_BROADCAST

You can set this value to true to load a view of a document that doesn't start or join a broadcast session. This view looks and behaves like a regular broadcast frame.

DISABLE_CHAT

You can set this value to 1 to disable in-document chat functionality.

EMBEDDED

You can set this value to true to indicate that the output of the action is embedded in a web page.

FULLSCREEN

You can set this value to true to load the file type in full-screen mode.

HOST_SESSION_ID

This value is passed by hosts to associate an Office for the web session with a host session identifier. This helps Office for the web engineers more quickly find logs for troubleshooting purposes based on a host-specific session identifier.

RECORDING

You can set this value to true to load the file type with a minimal user interface.

SESSION_CONTEXT

You can replace this placeholder by any string value. If provided, this value is passed back to the host in subsequent CheckFileInfo and CheckFolderInfo calls in the X-WOPI-SessionContext request header. There is no defined limit for the length of this string; however, since it's passed on the query string, it's subject to the overall Office for the web URL length limit of 2048 bytes.

New in version 2018.12.15: Prior to this version, session context was supported but hosts were required to add it to the action URL manually using the sc query parameter. This placeholder enables hosts to handle session context in the same way as other URL parameters.

THEME_ID

You can set this value to either 1 or 2 to designate a specific user interface appearance. 1 denotes a light-colored theme and 2 denotes a darker theme.

UI_LLCC

This value represents the language the Office for the web application UI should use. Office for the web doesn't support all languages, and might use a substitute language if the language requested isn't supported. For a list of currently supported languages, see What languages does Office for the web support?.

In addition to the values provided in the Locale ID column, you can supply any language, provided it's in the format described in RFC 1766. If you don't set a value for this placeholder, Office for the web tries to use the browser language setting (navigator.language). If no valid language can be determined, Office for the web defaults to en-US (US English).

VALIDATOR_TEST_CATEGORY

You can set this value to All, OfficeOnline or OfficeNativeClient to activate the tests specific to Office for the web and Microsoft 365 for mobile. If omitted, the default value is All.

All: activates all WOPI Validator tests.

OfficeOnline: activates all tests necessary for Office for the web integration.

OfficeNativeClient: activates all tests necessary for Microsoft 365 for mobile integration.

WOPI_SOURCE

This placeholder must be replaced by a WopiSrc value.

New in version 2018.12.15: Prior to this version, hosts were required to add the WopiSrc to the action URL for most (but not all) actions. This placeholder enables hosts to handle the WopiSrc in the same way as other URL parameters.

Additional notes

Depending on the specific scenario where action URLs are invoked, there are additional relevant components to action URLs. Since action URLs are typically invoked from the host page, these are covered in the Building a host page section.

Favicon URLs

The discovery XML includes a URL to an appropriate favicon for all Office for the web applications in the favIconUrl attribute of the app element. For example:

<app name="Excel"
     favIconUrl="https://excel.officeapps.live.com/x/_layouts/resources/FavIcon_Excel.ico"
     checkLicense="true">
    ...
</app>

Hosts should use this URL as the favicon for their host page, so that the appropriate application icon appears when Office for the web is used.