# CAR-Tourist: An Integrity-Preserved Collaborative Augmented Reality Framework-Tourism as a Use-Case
## 3 Methodology and Proposed Architecture
### Working of Blockchain-Registration of Tourists and Guides  
In the proposed architecture, the study outlined four participants which are tourists, guides, blockchain network and CAR module. The tourist and guide interact through the CAR application. The blockchain network is used to ensure trust between the users. All the transactions are captured in the blockchain network to make the interaction trustful. The important transactions of our CAR-Tourist module are formally defined below:  
**Definition 1**. : _(Tourist's request for a guide:) Tourists \(T\) can have a guide \(G\) request if \(T\) and \(G\) have a valid registration over Blockchain Network \(BN\), and \(T\) have a valid status and credit card. Similarly, \(G\) should have an eligible status._  
**Definition 2**. : _(Blockchain network \(BN\) should monitor \(T\)'s status to transfer \(Tn\) service charges): If \(Tn\) cannot be performed \(T\) should be disabled. On Low balance, LB, Warning \(W\) should be generated._  
**Definition 3**. : _(Dispute Resolution): Blockchain network \(BN\) should verify the Transaction \(Tr\) if the Dispute \(D\) occurs. \(D\) should be generated either from \(T\) or \(G\). Dispute \(D\) should explain \(T\)'s perspective if \(G\) did not provide the right service. Or \(G\) violates the privacy of \(T\) as per the defined rules. Similarly, \(G\) can have the dispute \(D\) if \(G\) didn't get the specified amount from \(T\)._  
**Definition 4**. : _(Miscellaneous additional Transaction over \(BN\)):_  
* \(T\) _can initiate a chat with_ \(G\) _without a contract_ \(C\)_. Blockchain network_ \(BN\) _will only record the request and response._
* \(T\) _and_ \(G\) _can have a voice call without_ \(C\)_._ \(BN\) _will only record transaction_ \(Tr\) _for record purposes which may be used for dispute resolution._
* \(T\) _and_ \(G\) _can share the_ \(T1\) _screen with multiple tourists_ \(Ti\) _if and only if_ \(T1\) _allows._
* \(G\) _has given the option by_ \(BN\) _to write on_ \(V\)_'s screen with CAR module to explain the landmark-specific spot asked by_ \(T\) _for the explanation._  
According to this study's use-case requirement, the proposed integrity-aware Collaborative AR (CAR) module will register tourists and individuals with knowledge (known as travel guides) within the Kingdom of Saudi Arabia (KSA). Upon successful registration on the smart contract, the travel guides and visitors will become trusted due to the consensus and underlying trusted network. Moreover, since the consensus and other related nodes on top of the smart contract will be distributed around the KSA, the decentralized peer nodes all over the country can efficiently work from anywhere within the country. The smart contract is used for the Tourists so they can observe the nearby available guides to get their services. The blockchain configured for this study is composed of essential nodes including the membership nodes, certification authority, orderer nodes, endorsement peers and consensus nodes. All of these nodes are set up on lightweight containers and placed in various locations in the country. After setting up the nodes, a consensus algorithm was opted for. As per present blockchain consensus technologies, the study has to opt among A,RAFT, PBFT, etc., consensus mechanisms. However, observing the effective usage results of the RAFT consensus algorithm and its voting-based approach, this study considered it more appropriate and efficient for the presented use case. Any registered traveller during visits to different sacred landmarks could have the opportunity to view registered available guides over the blockchain infrastructure and can initiate the CAR module. The proposed framework of the designed integrated blockchain and CAR module can make the guides available to a different blockchain network. This means two blockchain networks can communicate with each other, i.e., one AR-enabled blockchain and another without AR.