Online business

Hi, I would like to give you a outline of my business before we talk, For example consider below for the explinations Engineers as : Plumbers, Carpenters or Electricians Users : Customers or end users Business problem : As we know that, Now a days users are facing lots of problems in maintaining there house , these can be multiple areas like plumbing , electrical, carpenter etc. For example lets consider an user needs to fix the running tap problem . What he does is first checks the known plumber contact or get the contact information from the internet ( can be via just-dial or any other sources) and try to contact him over a phone . There are many instances where these engineers nerver truns up on time and they keep postpone the work . This makes a huge difficult for an user to fix the problem. Business Solution: We are providing mobile application based solution where the user can find the engineers or send a request to multiple engineer. upoun receiving the request, Engineer will communicate with the customer and fix the problem in time Note: Here Enginneer are not the employees of the company. They are registered online . Roll of the business is that we just bridge the gap between the engineers and users for getting the job done faster and smarter way Here are my querries : - Is it legal to start such kind of online business ? - If any thing wrong happens i.e if the engineer robs, misbehaves with the user who will be responsible .