diff --git a/src/client.rs b/src/client.rs
new file mode 100644
index 000000000..76c2bac01
--- /dev/null
+++ b/src/client.rs
@@ -0,0 +1,215 @@
+use std::path::Path;
+use util::uint::U256;
+use util::hash::*;
+use util::sha3::*;
+use util::rlp::*;
+use util::bytes::Bytes;
+use blockchain::BlockChain;
+use views::BlockView;
+
+/// Status for a block in a queue.
+pub enum QueueStatus {
+	/// Part of the known chain.
+	Known,
+	/// Part of the unknown chain.
+	Unknown,
+}
+
+/// General block status
+pub enum BlockStatus {
+	/// Part of the blockchain.
+	InChain,
+	/// Queued for import.
+	Queued(QueueStatus),
+	/// Known as bad.
+	Bad,
+	/// Unknown.
+	Unknown,
+}
+
+/// Result of import block operation.
+pub enum ImportResult {
+	/// Added to import queue.
+	Queued(QueueStatus),
+	/// Already in the chain.
+	AlreadyInChain,
+	/// Already queued for import.
+	AlreadyQueued(QueueStatus),
+	/// Bad or already known as bad.
+	Bad,
+}
+
+/// Information about the blockchain gthered together.
+pub struct BlockChainInfo {
+	/// Blockchain difficulty.
+	pub total_difficulty: U256,
+	/// Block queue difficulty.
+	pub pending_total_difficulty: U256,
+	/// Genesis block hash.
+	pub genesis_hash: H256,
+	/// Best blockchain block hash.
+	pub best_block_hash: H256,
+	/// Best blockchain block number.
+	pub best_block_number: BlockNumber
+}
+
+/// Block queue status
+pub struct BlockQueueStatus {
+	pub full: bool,
+}
+
+pub type TreeRoute = ::blockchain::TreeRoute;
+
+pub type BlockNumber = u64;
+
+/// Blockchain database client. Owns and manages a blockchain and a block queue.
+pub trait BlockChainClient : Sync {
+	/// Get raw block header data by block header hash.
+	fn block_header(&self, hash: &H256) -> Option<Bytes>;
+
+	/// Get raw block body data by block header hash.
+	/// Block body is an RLP list of two items: uncles and transactions.
+	fn block_body(&self, hash: &H256) -> Option<Bytes>;
+
+	/// Get raw block data by block header hash.
+	fn block(&self, hash: &H256) -> Option<Bytes>;
+
+	/// Get block status by block header hash.
+	fn block_status(&self, hash: &H256) -> BlockStatus;
+
+	/// Get raw block header data by block number.
+	fn block_header_at(&self, n: BlockNumber) -> Option<Bytes>;
+
+	/// Get raw block body data by block number.
+	/// Block body is an RLP list of two items: uncles and transactions.
+	fn block_body_at(&self, n: BlockNumber) -> Option<Bytes>;
+
+	/// Get raw block data by block number.
+	fn block_at(&self, n: BlockNumber) -> Option<Bytes>;
+
+	/// Get block status by block number.
+	fn block_status_at(&self, n: BlockNumber) -> BlockStatus;
+
+	/// Get a tree route between `from` and `to`.
+	/// See `BlockChain::tree_route`.
+	fn tree_route(&self, from: &H256, to: &H256) -> TreeRoute;
+
+	/// Get latest state node
+	fn state_data(&self, hash: &H256) -> Option<Bytes>;
+
+	/// Get raw block receipts data by block header hash.
+	fn block_receipts(&self, hash: &H256) -> Option<Bytes>;
+
+	/// Import a block into the blockchain.
+	fn import_block(&mut self, byte: &[u8]) -> ImportResult;
+
+	/// Get block queue information.
+	fn queue_status(&self) -> BlockQueueStatus;
+
+	/// Clear block qeueu and abort all import activity.
+	fn clear_queue(&mut self);
+
+	/// Get blockchain information.
+	fn chain_info(&self) -> BlockChainInfo;
+}
+
+/// Blockchain database client backed by a persistent database. Owns and manages a blockchain and a block queue.
+pub struct Client {
+	chain: BlockChain
+}
+
+impl Client {
+	pub fn new(genesis: &[u8], path: &Path) -> Client {
+		Client {
+			chain: BlockChain::new(genesis, path)
+		}
+	}
+}
+
+impl BlockChainClient for Client {
+	fn block_header(&self, hash: &H256) -> Option<Bytes> {
+		self.chain.block(hash).map(|bytes| BlockView::new(&bytes).rlp().at(0).raw().to_vec())
+	}
+
+	fn block_body(&self, hash: &H256) -> Option<Bytes> {
+		self.chain.block(hash).map(|bytes| {
+			let rlp = Rlp::new(&bytes);
+			let mut body = RlpStream::new();
+			body.append_raw(rlp.at(1).raw(), 1);
+			body.append_raw(rlp.at(2).raw(), 1);
+			body.out()
+		})
+	}
+
+	fn block(&self, hash: &H256) -> Option<Bytes> {
+		self.chain.block(hash)
+	}
+
+	fn block_status(&self, hash: &H256) -> BlockStatus {
+		if self.chain.is_known(&hash) { BlockStatus::InChain } else { BlockStatus::Unknown }
+	}
+
+	fn block_header_at(&self, n: BlockNumber) -> Option<Bytes> {
+		self.chain.block_hash(&From::from(n)).and_then(|h| self.block_header(&h))
+	}
+
+	fn block_body_at(&self, n: BlockNumber) -> Option<Bytes> {
+		self.chain.block_hash(&From::from(n)).and_then(|h| self.block_body(&h))
+	}
+
+	fn block_at(&self, n: BlockNumber) -> Option<Bytes> {
+		self.chain.block_hash(&From::from(n)).and_then(|h| self.block(&h))
+	}
+
+	fn block_status_at(&self, n: BlockNumber) -> BlockStatus {
+		match self.chain.block_hash(&From::from(n)) {
+			Some(h) => self.block_status(&h),
+			None => BlockStatus::Unknown
+		}
+	}
+
+	fn tree_route(&self, from: &H256, to: &H256) -> TreeRoute {
+		self.chain.tree_route(from.clone(), to.clone())
+	}
+
+	fn state_data(&self, _hash: &H256) -> Option<Bytes> {
+		unimplemented!();
+	}
+
+	fn block_receipts(&self, _hash: &H256) -> Option<Bytes> {
+		unimplemented!();
+	}
+
+	fn import_block(&mut self, bytes: &[u8]) -> ImportResult {
+		//TODO: verify block
+		{
+			let block = BlockView::new(bytes);
+			let header = block.header_view();
+			let hash = header.sha3();
+			if self.chain.is_known(&hash) {
+				return ImportResult::Bad;
+			}
+		}
+		self.chain.insert_block(bytes);
+		ImportResult::Queued(QueueStatus::Known)
+	}
+
+	fn queue_status(&self) -> BlockQueueStatus {
+		BlockQueueStatus {
+			full: false
+		}
+	}
+
+	fn clear_queue(&mut self) {
+	}
+
+	fn chain_info(&self) -> BlockChainInfo {
+		BlockChainInfo {
+			total_difficulty: self.chain.best_block_total_difficulty(),
+			pending_total_difficulty: self.chain.best_block_total_difficulty(),
+			genesis_hash: self.chain.genesis_hash(),
+			best_block_hash: self.chain.best_block_hash(),
+			best_block_number: From::from(self.chain.best_block_number())
+		}
+	}
+}