Adding features to XInput

[ravi-prakash-v]

Problem
Currently the XInput schema allows for limited functionality. However in real-world scenarios, there could be features like

1. Multi-step forms : Forms that span multiple steps. Sometimes the output of a form defines what the input of the next form will be.
2. Branching : Selection of a single field in a form leads to certain fields activating or deactivating
3. Multiple submissions : Some forms may allow multiple submissions by single user.
4. Editing and resubmitting a previous form : Some forms may allow for resubmitting a form for a arbitrary number of times.
5. Skipping a form : Some forms may be optional, allowing a user to skip filling it altogether.
6. Going back : Some multi-step forms may allow going back to a previous page and editing some details.
7. Validity : A form may expire after a specific time period
8. Non-repudiability : A form may change while keeping the URL same

Proposal
It would greatly improve the flexibility of the protocol if the XInput schema is updated with the above features for supporting use cases that rely heavily on forms.

Some examples that use extensive forms are

1. Application for a job : This requires filling up of an employment form.
2. Application for enrolment : This requires filling up an admissions form for admission into a course or university
3. Application for a visa : This requires multiple steps that can be saved and submitted later.
4. Availing financial services : This requires user to upload financial information, or provide consent for pulling records from a 3rd party

Alternatives considered
XForms 2.0 specification is the clear winner here.

It is an XML markup for a new generation of forms and form-like applications on the Web. XForms is not a free-standing document type, but is integrated into other markup languages, such as [XHTML], [ODF] or [SVG]. An XForms-based application gathers and processes data using an architecture that separates presentation, purpose and content. The underlying data of a form is organized into instances.

Thus, XForms accommodates form component reuse, fosters strong data type validation, eliminates unnecessary round-trips between the BAP and the BPP, offers device independence and accessibility, and reduces the need for scripting.

However, due to its fragmented adoption across the world, there needs to be an alternative solution that can be implemented quick and easily without much learning overhead.

Additional context
The core working group has had some discussions around this problem. Some solutions have been discussed.

Adding a header object to the XInput that contains

• number of steps in the form
• current state of the form (step number)
• headings of each form step
• skip functionality
• resubmit functionality
• redirect functionality

Final Schema is yet to be finalized