This is C# demo with my blockchain implementation

• A distributed blockchain network to allow communicate 3 different types of users
  • Order makers: user publishes an order for execution. Sends to network a message about new order with Payment property.
  • Order executors: users that listen for new orders on network and peek up some of them for execution. Sends to network a message about intention to execute list of desired orders and Fee.
  • Network nodes that support this blockchain. Responsible to keep orders and order assignments in consistent state.
• Blockchain should support different kinds of orders – it should be pluggable.
• Demo contains plugin to support WalkDog orders that describe a walk dog task with properties like dog info, StartTime and Location.

• No persistency: there are only in-memory blockchain objects support
• No authentication: all members rely on client name (string)
• No encryption: to simplify transactions/blocks verification used only hashes without asymmetric encryption
• No smart blocks synchronization: all blockchain members initialized in one time and can see only current new blocks in network. There is only one server node that produce a new blocks.

• One or several users publish message OrderRequested with a new order to network
• Server listens to this new orders and add them to own ongoing block – it is next block candidate.
• At the same time server tries to sign ongoing block. When next block has a signature (hash value of ongoing block) that in less than configuration value HashFactor - then a new block will be added to blockchain. HashFactor responsible for probability that a new block will be included.
• Server publishes a new block to all members. Clients update their own copy of blockchain.
• Now another users can see in blockchain a new unassigned orders. They publish another type of messages (OrdersAssigned) to network with list of orders desired for execution. Also add a Fee parameter – what part of payment will take a server.
• Server keeps OrdersAssigned messages on the same ongoing block. A new message will be added to ongoing block only if it not break blockchain consistency. Consistency of OrderRequested messages depends from order type and as a result – from referenced plugin. Consistency of OrdersAssigned - can be only one executor of order. Because many executors can publish a message with same order – server will choose that which gives him the best prize – calculated as Fee*Payment. To simplify general consistency validation is used one limitation: each next block can contains only one message from one user.
• Who is real order executed calculated by next signed blocks: server should include a OrdersAssigned message to new block.
• When clients receive next block with their message inside – then they can publish new messages.