cross platform mobile app

BRIEF Create a mobile and desktop personal calendar app. DESCRIPTION Allow events/appointments to be created within the app that also create a matching event/appointments at the business where the appointment is located. EXAMPLE Jane wants to make a hair appointment, she opens her calendar app and checks her availability. Jane has spare time on Wednesday at 1pm, she clicks on the date and time slot on her calendar and selects the type of appointment and which salon/business the appointment is with. In this case lets say its Joes Hair salon. Still within her calendar app, Jane finds out that Joes Hair salon is busy at that time but has a later time available. Jane selects the later time and is instantly notified by Joes Hair Salon that her appointment is with Lucy, will cost $50 and will take 2 hours. Because Jane's Calendar knows where she will be before her appointment the calendar books out travel time and sets a reminder to allow Jane to arrive on time. FUTURE Allow SMS and email connectivity to update appointment status when an appointment reminder from Joes Hair Salon is received by Jane to confirm. Repeat appointments and recurring appointment function Multiple/repeat alarms CONSIDERATIONS Might require multiple API development to "sync" with existing appointment scheduling software. Would this be better served by a HTML5 browser add on or stand alone solution or a hosted online cloud service?