Algorithm 3 Creating a service request using the service broker.

Require:

B:   Global state of the blockchain.

P:   Service broker smart contract caller.

$I_{req}$:    UUID of the request.

$T_{req}$: Date and time when the request is created.

$N_{srv}$:   Name of the requested service.

$I_{dev}$:    ID of the device that provides the service.

$I_{org}$: ID of the organization to which the device belongs.

$M_{req}$:  Request method.

$A_{req}$:  Optional arguments of the request.

Ensure:

Service request information is saved in the blockchain.

1: if $WRITE\notin$ GetCallerPermissions $\left(P\right)$ then

2:  return error      ▹ Abort if caller is not allowed to update the blockchain

3: end if

4: if GetService $(I_{org},I_{dev},N_{srv})=\varnothing$ then

5:   return error          ▹ Abort if requested service is not registered

6: end if

7: if GetServiceRequest $\left(I_{req}\right)\ne \varnothing$ then

8:     return error              ▹ Abort if service request already exists

9: end if

10: $S_{req}\leftarrow$ Serialize $(I_{req},T_{req},N_{srv},I_{dev},I_{org},M_{req},A_{req})$

11: $B\left[I_{req}\right]\leftarrow S_{req}$

12: NotifyEvent $\left(S_{req}\right)$

13: return $S_{req}$