tla+

rahasak-validate.tla

--------------------------- MODULE BlockchainTransactions ---------------------------
EXTENDS Integers, Sequences, TLC

(*-- Constants used in the specification --*)
CONSTANT Clients, KafkaNodes, SmartContracts, StorageNodes, CacheNodes, LokkaServices

(*-- The set of all possible transactions --*)
VARIABLE transactions, messageBroker, blockchainStorage, distributedCache, blocks

(* -- Define the initial state of the blockchain system --*)
Init ==
    /\ transactions = << >> \* Initially, no transactions are submitted
    /\ messageBroker = << >> \* Kafka starts with no messages
    /\ blockchainStorage = << >> \* No transactions executed and stored yet
    /\ distributedCache = {} \* Cache starts empty
    /\ blocks = << >> \* No blocks created yet

(*-- Clients submit transactions to the API --*)
SubmitTransaction(t) ==
    /\ t \notin transactions
    /\ transactions' = Append(transactions, t)
    /\ UNCHANGED <<messageBroker, blockchainStorage, distributedCache, blocks>>

(*-- API publishes transactions to Kafka --*)
PublishToKafka ==
    /\ transactions /= << >>
    /\ messageBroker' = transactions \* Kafka orders the transactions
    /\ transactions' = << >>
    /\ UNCHANGED <<blockchainStorage, distributedCache, blocks>>

(*-- Smart contracts stream and execute transactions --*)
ExecuteTransactions ==
    /\ messageBroker /= << >>
    /\ LET t == Head(messageBroker)
            sc == CHOOSE s \in SmartContracts: TRUE \* Choose any smart contract node
        IN
        /\ ~IsDoubleSpend(t)
        /\ blockchainStorage' = Append(blockchainStorage, t)
        /\ messageBroker' = Tail(messageBroker)
        /\ distributedCache' = distributedCache \union {t}
        /\ UNCHANGED blocks

(*-- Check if a transaction is a double spend --*)
IsDoubleSpend(t) ==
    t \in distributedCache

(*-- Cassandra replicates state updates to other blockchain nodes --*)
ReplicateState ==
    /\ blockchainStorage /= << >>
    /\ LET t == Head(blockchainStorage)
            sn == CHOOSE s \in StorageNodes: TRUE \* Choose any storage node
        IN
        /\ blockchainStorage' = Tail(blockchainStorage) \* State update replicated
        /\ UNCHANGED <<transactions, messageBroker, distributedCache, blocks>>

(*-- Lokka service creates blocks with transaction IDs in the cache --*)
CreateBlocks ==
    /\ distributedCache /= {}
    /\ LET t == CHOOSE x \in distributedCache: TRUE \* Choose any transaction in cache
            ls == CHOOSE l \in LokkaServices: TRUE \* Choose any Lokka service
        IN
        /\ blocks' = Append(blocks, t)
        /\ distributedCache' = distributedCache \ {t}
        /\ UNCHANGED <<transactions, messageBroker, blockchainStorage>>

(*-- Define the next state based on possible actions --*)
Next ==
    \/ \E t \in DOMAIN transactions: SubmitTransaction(t)
    \/ PublishToKafka
    \/ ExecuteTransactions
    \/ ReplicateState
    \/ CreateBlocks

(*-- Specify safety properties --*)
Consistency == \A t \in DOMAIN transactions: ~IsDoubleSpend(t)

(*-- Specification combines initial state and next state relation --*)
Spec == Init /\ [][Next]_<<transactions, messageBroker, blockchainStorage, distributedCache, blocks>>

(*-- What TLC should check --*)
INVARIANTS Consistency

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