diff --git a/contracts/v3/EnumerableSet.sol b/contracts/v3/EnumerableSet.sol
index f24ddd4..b7af691 100644
--- a/contracts/v3/EnumerableSet.sol
+++ b/contracts/v3/EnumerableSet.sol
@@ -80,14 +80,19 @@ library EnumerableSet {
      * Returns true if the value was added to the set, that is if it was not
      * already present.
      */
-    function _replace(Set storage set, uint256 index, bytes32 oldValue , bytes32 newValue) private returns (bool) {
-        if (set._values[index-1] != oldValue){
+    function _replace(
+        Set storage set,
+        uint256 index,
+        bytes32 oldValue,
+        bytes32 newValue
+    ) private returns (bool) {
+        if (set._values[index - 1] != oldValue) {
             return false;
         }
         set._indexes[oldValue] = 0;
         // 0 represents the value is empty
         set._indexes[newValue] = index;
-        set._values[index-1] = newValue;
+        set._values[index - 1] = newValue;
         return true;
     }
 
@@ -134,7 +139,10 @@ library EnumerableSet {
     /**
      * @dev Returns true if the value is in the set. O(1).
      */
-    function _contains(Set storage set, bytes32 value) private view returns (bool) {
+    function _contains(
+        Set storage set,
+        bytes32 value
+    ) private view returns (bool) {
         return set._indexes[value] != 0;
     }
 
@@ -155,7 +163,10 @@ library EnumerableSet {
      *
      * - `index` must be strictly less than {length}.
      */
-    function _at(Set storage set, uint256 index) private view returns (bytes32) {
+    function _at(
+        Set storage set,
+        uint256 index
+    ) private view returns (bytes32) {
         return set._values[index];
     }
 
@@ -183,7 +194,10 @@ library EnumerableSet {
      * Returns true if the value was added to the set, that is if it was not
      * already present.
      */
-    function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {
+    function add(
+        Bytes32Set storage set,
+        bytes32 value
+    ) internal returns (bool) {
         return _add(set._inner, value);
     }
 
@@ -193,14 +207,20 @@ library EnumerableSet {
      * Returns true if the value was removed from the set, that is if it was
      * present.
      */
-    function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {
+    function remove(
+        Bytes32Set storage set,
+        bytes32 value
+    ) internal returns (bool) {
         return _remove(set._inner, value);
     }
 
     /**
      * @dev Returns true if the value is in the set. O(1).
      */
-    function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {
+    function contains(
+        Bytes32Set storage set,
+        bytes32 value
+    ) internal view returns (bool) {
         return _contains(set._inner, value);
     }
 
@@ -221,7 +241,10 @@ library EnumerableSet {
      *
      * - `index` must be strictly less than {length}.
      */
-    function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {
+    function at(
+        Bytes32Set storage set,
+        uint256 index
+    ) internal view returns (bytes32) {
         return _at(set._inner, index);
     }
 
@@ -233,7 +256,9 @@ library EnumerableSet {
      * this function has an unbounded cost, and using it as part of a state-changing function may render the function
      * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
      */
-    function values(Bytes32Set storage set) internal view returns (bytes32[] memory) {
+    function values(
+        Bytes32Set storage set
+    ) internal view returns (bytes32[] memory) {
         bytes32[] memory store = _values(set._inner);
         bytes32[] memory result;
 
@@ -257,12 +282,26 @@ library EnumerableSet {
      * Returns true if the value was added to the set, that is if it was not
      * already present.
      */
-    function add(AddressSet storage set, address value) internal returns (bool) {
+    function add(
+        AddressSet storage set,
+        address value
+    ) internal returns (bool) {
         return _add(set._inner, bytes32(uint256(uint160(value))));
     }
 
-    function replace(AddressSet storage set,uint256 index,  address oldValue, address newValue) internal returns (bool) {
-        return _replace(set._inner, index ,bytes32(uint256(uint160(oldValue))),  bytes32(uint256(uint160(newValue))));
+    function replace(
+        AddressSet storage set,
+        uint256 index,
+        address oldValue,
+        address newValue
+    ) internal returns (bool) {
+        return
+            _replace(
+                set._inner,
+                index,
+                bytes32(uint256(uint160(oldValue))),
+                bytes32(uint256(uint160(newValue)))
+            );
     }
 
     /**
@@ -271,14 +310,20 @@ library EnumerableSet {
      * Returns true if the value was removed from the set, that is if it was
      * present.
      */
-    function remove(AddressSet storage set, address value) internal returns (bool) {
+    function remove(
+        AddressSet storage set,
+        address value
+    ) internal returns (bool) {
         return _remove(set._inner, bytes32(uint256(uint160(value))));
     }
 
     /**
      * @dev Returns true if the value is in the set. O(1).
      */
-    function contains(AddressSet storage set, address value) internal view returns (bool) {
+    function contains(
+        AddressSet storage set,
+        address value
+    ) internal view returns (bool) {
         return _contains(set._inner, bytes32(uint256(uint160(value))));
     }
 
@@ -299,7 +344,10 @@ library EnumerableSet {
      *
      * - `index` must be strictly less than {length}.
      */
-    function at(AddressSet storage set, uint256 index) internal view returns (address) {
+    function at(
+        AddressSet storage set,
+        uint256 index
+    ) internal view returns (address) {
         return address(uint160(uint256(_at(set._inner, index))));
     }
 
@@ -311,7 +359,9 @@ library EnumerableSet {
      * this function has an unbounded cost, and using it as part of a state-changing function may render the function
      * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
      */
-    function values(AddressSet storage set) internal view returns (address[] memory) {
+    function values(
+        AddressSet storage set
+    ) internal view returns (address[] memory) {
         bytes32[] memory store = _values(set._inner);
         address[] memory result;
 
@@ -345,14 +395,20 @@ library EnumerableSet {
      * Returns true if the value was removed from the set, that is if it was
      * present.
      */
-    function remove(UintSet storage set, uint256 value) internal returns (bool) {
+    function remove(
+        UintSet storage set,
+        uint256 value
+    ) internal returns (bool) {
         return _remove(set._inner, bytes32(value));
     }
 
     /**
      * @dev Returns true if the value is in the set. O(1).
      */
-    function contains(UintSet storage set, uint256 value) internal view returns (bool) {
+    function contains(
+        UintSet storage set,
+        uint256 value
+    ) internal view returns (bool) {
         return _contains(set._inner, bytes32(value));
     }
 
@@ -373,7 +429,10 @@ library EnumerableSet {
      *
      * - `index` must be strictly less than {length}.
      */
-    function at(UintSet storage set, uint256 index) internal view returns (uint256) {
+    function at(
+        UintSet storage set,
+        uint256 index
+    ) internal view returns (uint256) {
         return uint256(_at(set._inner, index));
     }
 
@@ -385,7 +444,9 @@ library EnumerableSet {
      * this function has an unbounded cost, and using it as part of a state-changing function may render the function
      * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
      */
-    function values(UintSet storage set) internal view returns (uint256[] memory) {
+    function values(
+        UintSet storage set
+    ) internal view returns (uint256[] memory) {
         bytes32[] memory store = _values(set._inner);
         uint256[] memory result;
 
diff --git a/contracts/v3/Hub.sol b/contracts/v3/Hub.sol
deleted file mode 100644
index 29a7948..0000000
--- a/contracts/v3/Hub.sol
+++ /dev/null
@@ -1,166 +0,0 @@
-pragma solidity ^0.8.0;
-
-// import "hardhat/console.sol";
-// import "@openzeppelin/contracts/access/Ownable.sol";
-
-import "@openzeppelin/contracts-upgradeable/access/AccessControlUpgradeable.sol";
-import "@openzeppelin/contracts-upgradeable/access/AccessControlEnumerableUpgradeable.sol";
-import "./EnumerableSet.sol";
-import "./Repositorylib.sol";
-import "./database/database.sol";
-contract Hub is AccessControlEnumerableUpgradeable{
-
-    using EnumerableSet for EnumerableSet.AddressSet;
-    using RepositoryLib for RepositoryLib.BranchInfo;
-
-    // Hub Info
-    bytes32 public constant CREATOR = bytes32(uint256(0));
-    bytes32 public constant MANAGER =  bytes32(uint256(1));
-    bytes32 public constant CONTRIBUTOR =  bytes32(uint256(2));
-    bytes32[] public RoleList = [CREATOR,MANAGER,CONTRIBUTOR];
-    bool public permissionless;
-
-    // Repository Info
-    struct RepositoryInfo{
-        uint256 repoNameIndex;
-        address owner;
-        bool    exist;
-        EnumerableSet.AddressSet repoContributors;
-        RepositoryLib.BranchInfo branchs;
-    }
-
-    mapping(bytes=>RepositoryInfo) nameToRepository;
-    bytes[] public repoNames;
-
-    // DataBase Info 
-    database public db;
-
-
-    // ===== hub operator functions====== 
-    function openPermissonlessJoin(bool open) public {
-        require(hasRole(CREATOR, _msgSender()));
-        permissionless = open;
-    }
-
-    function memberShip() public view returns(bool){
-        if (hasRole(CREATOR, _msgSender())){
-            return true;
-        }else if (hasRole(MANAGER, _msgSender())){
-            return true;
-        }else if (hasRole(CONTRIBUTOR, _msgSender())){
-            return true;
-        }else{
-            return false;
-        }
-    }
-
-    //createRepository can be invoked by anyone within Hub 
-    function createRepository(bytes memory repoName) public{
-        require(memberShip());
-        require(
-            repoName.length > 0 && repoName.length <= 100,
-            "RepoName length must be 1-100"
-        );
-        for (uint i; i < repoName.length; i++) {
-            bytes1 char = repoName[i];
-            require(
-                (char >= 0x61 && char <= 0x7A) || //a-z
-                    (char >= 0x41 && char <= 0x5A) || //A-Z
-                    (char >= 0x30 && char <= 0x39) || //0-9
-                    (char == 0x2D || char == 0x2E || char == 0x5F), //-._
-                "RepoName must be alphanumeric or -._"
-            );
-        }
-
-        RepositoryInfo storage repo = nameToRepository[repoName];
-        require(
-            repo.exist == false ,
-            "RepoName already exist"
-        );
-        
-        repo.repoNameIndex = repoNames.length;
-        repo.owner = _msgSender();
-        repo.exist =  true;
-        repoNames.push(repoName);
-    }
-
-    function deleteRepository(bytes memory repoName) public returns(address){
-        require(hasRole(CREATOR, _msgSender()) || hasRole(MANAGER, _msgSender()));
-        require(nameToRepository[repoName].exist==true,"repoName do not exist");    
-        delete(nameToRepository[repoName]);
-    }
-
-    function addMember( bytes32 senderRole , bytes32 role,address member) public{
-        require(hasRole(senderRole, _msgSender()));
-        require(senderRole>role);
-        grantRole(role, member);
-    }
-
-
-    function deleteMember(bytes32 senderRole  ,bytes32 role,address member) public{
-        require(hasRole(senderRole, _msgSender()));
-        require(senderRole>role);
-        revokeRole(role, member);
-    }
-
-    // permissionlessJoin can be invoked by everyone who want to join this hub 
-    function permissionlessJoin() public{
-        require(permissionless,"permissionless join no open");
-        grantRole(CONTRIBUTOR, _msgSender());
-    }
-
-    // ===== repository operator functions====== 
-
-    function isRepoContributor(bytes memory repoName , address member) internal view returns(bool){
-        RepositoryInfo storage repo = nameToRepository[repoName];
-        if (repo.owner == member) return true;
-        if (repo.repoContributors.contains(member)) {
-            return true;
-        }else {
-            return false;
-        }
-    }
-    
-    function listRepoBranchs( bytes memory repoName)external view {
-        nameToRepository[repoName].branchs.listBranchs();
-    }
-
-    function updateRepoBranch(
-        bytes memory repoName,
-        bytes memory branchPath,
-        bytes20 refHash
-    )external{
-        require(isRepoContributor(repoName, _msgSender()));
-        nameToRepository[repoName].branchs.updateBranch(repoName,branchPath,refHash);
-    }
-
-    function removeRepoBranch(
-        bytes memory repoName,
-        bytes memory branchPath
-    ) external{
-        require(isRepoContributor(repoName, _msgSender()));
-        nameToRepository[repoName].branchs.removeBranch(repoName,branchPath);
-    }
-
-    // ===== database operator functions======    
-    function newDataBase() external onlyRole(CREATOR) {
-        
-    }
-
-    function download(
-        bytes memory repoName,
-        bytes memory path
-    ) external view returns (bytes memory, bool) {
-        // call flat directory(FD)
-        return db.download(repoName, path);
-    }
-
-    function upload(
-        bytes memory repoName,
-        bytes memory path,
-        bytes calldata data
-    ) external payable {
-        return db.upload(repoName, path,data);
-    }
-
-}
diff --git a/contracts/v3/HubFactory.sol b/contracts/v3/HubFactory.sol
new file mode 100644
index 0000000..bdfc8dc
--- /dev/null
+++ b/contracts/v3/HubFactory.sol
@@ -0,0 +1,32 @@
+pragma solidity ^0.8.0;
+
+// import "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
+import "@openzeppelin/contracts/access/Ownable.sol";
+import "@openzeppelin/contracts/utils/Create2.sol";
+import "@openzeppelin/contracts/proxy/Clones.sol";
+import "./Hubv3.sol";
+
+contract HubFactory is Ownable {
+    event CreateHub(address indexed hub, address indexed creator);
+    address[] public hubs;
+    Hubv3 public hubImp;
+
+    // function initialize() initializer public {
+    //     __Ownable_init();
+    // }
+
+    function newHubImp() public onlyOwner {
+        hubImp = new Hubv3();
+    }
+
+    function setHubImp(address addr) public onlyOwner {
+        hubImp = Hubv3(addr);
+    }
+
+    function createHub(bool dbSelector) external {
+        address instance = Clones.clone(address(hubImp));
+        hubs.push(instance);
+        Hubv3(instance).initialize(dbSelector, _msgSender());
+        emit CreateHub(instance, _msgSender());
+    }
+}
diff --git a/contracts/v3/Hubv3.sol b/contracts/v3/Hubv3.sol
new file mode 100644
index 0000000..ddd3fb5
--- /dev/null
+++ b/contracts/v3/Hubv3.sol
@@ -0,0 +1,256 @@
+pragma solidity ^0.8.0;
+
+import "@openzeppelin/contracts/access/AccessControl.sol";
+import "@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";
+import "./EnumerableSet.sol";
+import "./Repolib.sol";
+import "./database/database.sol";
+import "./database/ethstorage.sol";
+import "./database/filecoin.sol";
+
+contract Hubv3 is AccessControl, Initializable {
+    using EnumerableSet for EnumerableSet.AddressSet;
+    using Repolib for Repolib.BranchInfo;
+
+    // Hub Info
+    // bytes32 public constant CREATOR = bytes32(uint256(1));
+    bytes32 public constant MANAGER = bytes32(uint256(1));
+    bytes32 public constant CONTRIBUTOR = bytes32(uint256(2));
+    bytes32 public constant NOTFOUND = bytes32(uint256(10000));
+    bytes32[] public RoleList = [DEFAULT_ADMIN_ROLE, MANAGER, CONTRIBUTOR];
+    bool public permissionless;
+
+    // Repository Info
+    struct RepositoryInfo {
+        uint256 repoNameIndex;
+        address owner;
+        bool exist;
+        EnumerableSet.AddressSet repoContributors;
+        Repolib.BranchInfo branchs;
+    }
+
+    mapping(bytes => RepositoryInfo) nameToRepository;
+    bytes[] public repoNames;
+
+    // DataBase Info
+    database public db;
+
+    constructor() {
+        _setupRole(AccessControl.DEFAULT_ADMIN_ROLE, _msgSender());
+        _setupRole(MANAGER, _msgSender());
+        _setRoleAdmin(CONTRIBUTOR, MANAGER);
+    }
+
+    function initialize(bool dbSelector, address user) public initializer {
+        _setupRole(AccessControl.DEFAULT_ADMIN_ROLE, user);
+        _setupRole(MANAGER, user);
+        _setRoleAdmin(CONTRIBUTOR, MANAGER);
+        _newDataBase(dbSelector);
+    }
+
+    // ===== hub operator functions======
+    function openPermissonlessJoin(bool open) public {
+        require(hasRole(DEFAULT_ADMIN_ROLE, _msgSender()));
+        permissionless = open;
+    }
+
+    function memberRole(
+        address member
+    ) public view returns (bool IsAdmin, bool IsManager, bool IsContributor) {
+        if (hasRole(DEFAULT_ADMIN_ROLE, member)) {
+            IsAdmin = true;
+        }
+        if (hasRole(MANAGER, member)) {
+            IsManager = true;
+        }
+        if (hasRole(CONTRIBUTOR, member)) {
+            IsContributor = true;
+        }
+
+        return (IsAdmin, IsManager, IsContributor);
+    }
+
+    function membership(address member) public view returns (bool) {
+        if (hasRole(DEFAULT_ADMIN_ROLE, member)) {
+            return true;
+        }
+        if (hasRole(MANAGER, member)) {
+            return true;
+        }
+        if (hasRole(CONTRIBUTOR, member)) {
+            return true;
+        }
+        return false;
+    }
+
+    function addManager(address member) public {
+        grantRole(MANAGER, member);
+    }
+
+    function addContributor(address member) public {
+        grantRole(CONTRIBUTOR, member);
+    }
+
+    function removeManager(address member) public {
+        revokeRole(MANAGER, member);
+    }
+
+    function removeContributor(address member) public {
+        revokeRole(CONTRIBUTOR, member);
+    }
+
+    // permissionlessJoin can be invoked by everyone who want to join this hub
+    function permissionlessJoin() public {
+        require(permissionless, "permissionless join no open");
+        grantRole(CONTRIBUTOR, _msgSender());
+    }
+
+    // ===== repository operator functions======
+    //createRepository can be invoked by anyone within Hub
+    function createRepo(bytes memory repoName) public {
+        require(membership(_msgSender()));
+        require(
+            repoName.length > 0 && repoName.length <= 100,
+            "RepoName length must be 1-100"
+        );
+        for (uint i; i < repoName.length; i++) {
+            bytes1 char = repoName[i];
+            require(
+                (char >= 0x61 && char <= 0x7A) || //a-z
+                    (char >= 0x41 && char <= 0x5A) || //A-Z
+                    (char >= 0x30 && char <= 0x39) || //0-9
+                    (char == 0x2D || char == 0x2E || char == 0x5F), //-._
+                "RepoName must be alphanumeric or -._"
+            );
+        }
+
+        RepositoryInfo storage repo = nameToRepository[repoName];
+        require(repo.exist == false, "RepoName already exist");
+
+        repo.repoNameIndex = repoNames.length;
+        repo.owner = _msgSender();
+        repo.exist = true;
+        repoNames.push(repoName);
+    }
+
+    function deleteRepo(bytes memory repoName) public {
+        require(
+            hasRole(DEFAULT_ADMIN_ROLE, _msgSender()) ||
+                hasRole(MANAGER, _msgSender())
+        );
+        require(
+            nameToRepository[repoName].exist == true,
+            "repoName do not exist"
+        );
+        delete (nameToRepository[repoName]);
+    }
+
+    function repoOwner(bytes memory repoName) public view returns (address) {
+        RepositoryInfo storage repo = nameToRepository[repoName];
+        return repo.owner;
+    }
+
+    function repoContributors(
+        bytes memory repoName
+    ) public view returns (address[] memory) {
+        RepositoryInfo storage repo = nameToRepository[repoName];
+        return repo.repoContributors.values();
+    }
+
+    function isRepoMembership(
+        bytes memory repoName,
+        address member
+    ) internal view returns (bool) {
+        RepositoryInfo storage repo = nameToRepository[repoName];
+        if (repo.owner == member) return true;
+        if (repo.repoContributors.contains(member)) {
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    function addRepoContributor(
+        bytes memory repoName,
+        address con
+    ) public returns (bool) {
+        RepositoryInfo storage repo = nameToRepository[repoName];
+        require(_msgSender() == repo.owner, "only repo owner");
+        return nameToRepository[repoName].repoContributors.add(con);
+    }
+
+    function removeRepoContributor(
+        bytes memory repoName,
+        address con
+    ) public returns (bool) {
+        RepositoryInfo storage repo = nameToRepository[repoName];
+        require(_msgSender() == repo.owner, "only repo owner");
+        return nameToRepository[repoName].repoContributors.remove(con);
+    }
+
+    // listRef
+    function listRepoRefs(
+        bytes memory repoName
+    ) external view returns (Repolib.refData[] memory list) {
+        return nameToRepository[repoName].branchs.listBranchs();
+    }
+
+    // setRef
+    function setRepoRef(
+        bytes memory repoName,
+        bytes memory branchPath,
+        bytes20 refHash
+    ) external {
+        require(isRepoMembership(repoName, _msgSender()));
+        nameToRepository[repoName].branchs.updateBranch(
+            repoName,
+            branchPath,
+            refHash
+        );
+    }
+
+    function getRepoRef(
+        bytes memory repoName,
+        bytes memory branchPath
+    ) external view returns (bytes20) {
+        return
+            nameToRepository[repoName].branchs.getBranch(repoName, branchPath);
+    }
+
+    function delRepoRef(
+        bytes memory repoName,
+        bytes memory branchPath
+    ) external {
+        require(isRepoMembership(repoName, _msgSender()));
+        nameToRepository[repoName].branchs.removeBranch(repoName, branchPath);
+    }
+
+    // ===== database operator functions======
+    function newDataBase(bool flag) public onlyRole(DEFAULT_ADMIN_ROLE) {
+        _newDataBase(flag);
+    }
+
+    function _newDataBase(bool flag) internal {
+        if (flag) {
+            db = new ethstorage();
+        } else {
+            db = new filecoin();
+        }
+    }
+
+    function download(
+        bytes memory repoName,
+        bytes memory path
+    ) external view returns (bytes memory, bool) {
+        // call flat directory(FD)
+        return db.download(repoName, path);
+    }
+
+    function upload(
+        bytes memory repoName,
+        bytes memory path,
+        bytes calldata data
+    ) external payable {
+        return db.upload(repoName, path, data);
+    }
+}
diff --git a/contracts/v3/Repositorylib.sol b/contracts/v3/Repolib.sol
similarity index 59%
rename from contracts/v3/Repositorylib.sol
rename to contracts/v3/Repolib.sol
index 0f7c9ad..0ec13fb 100644
--- a/contracts/v3/Repositorylib.sol
+++ b/contracts/v3/Repolib.sol
@@ -1,7 +1,6 @@
 pragma solidity ^0.8.0;
 
-library RepositoryLib {
-
+library Repolib {
     struct refInfo {
         bytes20 hash;
         uint96 index;
@@ -12,13 +11,20 @@ library RepositoryLib {
         bytes name;
     }
 
-    struct BranchInfo{
+    struct BranchInfo {
         mapping(bytes => refInfo) branchToRefInfo; // dev => {hash: 0x1234..., index: 1 }
-        bytes[] branchs; // 有几条branch,就有几个reference
-    } 
+        bytes[] branchs; //
+    }
 
+    function branchNum(
+        BranchInfo storage info
+    ) internal view returns (uint256) {
+        return info.branchs.length;
+    }
 
-    function listBranchs(BranchInfo storage info) external view returns (refData[] memory list) {
+    function listBranchs(
+        BranchInfo storage info
+    ) internal view returns (refData[] memory list) {
         list = new refData[](info.branchs.length);
         for (uint index = 0; index < info.branchs.length; index++) {
             list[index] = _convertToRefData(
@@ -33,32 +39,40 @@ library RepositoryLib {
         bytes memory repositoryName,
         bytes memory branch,
         bytes20 refHash
-    ) external {
-        bytes memory fullname = bytes.concat(repositoryName,"/",branch);
-        require(refHash!=bytes20(0),"reference hash don't allow to set 0x0" );
-        if (info.branchToRefInfo[fullname].hash==bytes20(0)) {
+    ) internal {
+        bytes memory fullname = bytes.concat(repositoryName, "/", branch);
+        require(refHash != bytes20(0), "reference hash don't allow to set 0x0");
+        if (info.branchToRefInfo[fullname].hash == bytes20(0)) {
             info.branchToRefInfo[fullname].hash = refHash;
             info.branchToRefInfo[fullname].index = uint96(info.branchs.length);
             info.branchs.push(fullname);
-        }else {
+        } else {
             info.branchToRefInfo[fullname].hash = refHash;
         }
-    
+    }
+
+    function getBranch(
+        BranchInfo storage info,
+        bytes memory repositoryName,
+        bytes memory branch
+    ) internal view returns (bytes20) {
+        bytes memory fullname = bytes.concat(repositoryName, "/", branch);
+        return info.branchToRefInfo[fullname].hash;
     }
 
     function removeBranch(
         BranchInfo storage info,
         bytes memory repositoryName,
         bytes memory branch
-    ) external {
-        bytes memory fullname = bytes.concat(repositoryName,"/",branch);
-        refInfo memory refI =  info.branchToRefInfo[fullname];
+    ) internal {
+        bytes memory fullname = bytes.concat(repositoryName, "/", branch);
+        refInfo memory refI = info.branchToRefInfo[fullname];
         require(
             refI.hash != bytes20(0),
             "Reference of this name does not exist"
         );
-        uint256 lastIndex = info.branchs.length -1 ;
-        if (refI.index < lastIndex){
+        uint256 lastIndex = info.branchs.length - 1;
+        if (refI.index < lastIndex) {
             info.branchToRefInfo[info.branchs[lastIndex]].index = refI.index;
             info.branchs[refI.index] = info.branchs[lastIndex];
         }
@@ -73,5 +87,4 @@ library RepositoryLib {
         res.hash = rInfo.hash;
         res.name = info.branchs[rInfo.index];
     }
-
-}
\ No newline at end of file
+}
diff --git a/contracts/v3/database/database.sol b/contracts/v3/database/database.sol
index 497d3b0..b51ad6f 100644
--- a/contracts/v3/database/database.sol
+++ b/contracts/v3/database/database.sol
@@ -1,16 +1,14 @@
 pragma solidity ^0.8.0;
 
 interface database {
-
     function download(
         bytes memory repoName,
         bytes memory path
-    ) external view returns (bytes memory, bool) ;
+    ) external view returns (bytes memory, bool);
 
     function upload(
         bytes memory repoName,
         bytes memory path,
         bytes calldata data
     ) external payable;
-
-}
\ No newline at end of file
+}
diff --git a/contracts/v3/database/ethstorage.sol b/contracts/v3/database/ethstorage.sol
index a1ecea4..706a323 100644
--- a/contracts/v3/database/ethstorage.sol
+++ b/contracts/v3/database/ethstorage.sol
@@ -1,6 +1,8 @@
 pragma solidity ^0.8.0;
 import "./EthStorage/LargeStorageManagerV2.sol";
-contract EthStorage is LargeStorageManagerV2{
+import "./database.sol";
+
+contract ethstorage is LargeStorageManagerV2, database {
     function stakeTokens(
         bytes memory repoName,
         bytes memory path
@@ -31,7 +33,7 @@ contract EthStorage is LargeStorageManagerV2{
     function download(
         bytes memory repoName,
         bytes memory path
-    ) external view returns (bytes memory, bool) {
+    ) external view override returns (bytes memory, bool) {
         // call flat directory(FD)
         return _get(keccak256(bytes.concat(repoName, "/", path)));
     }
@@ -40,7 +42,7 @@ contract EthStorage is LargeStorageManagerV2{
         bytes memory repoName,
         bytes memory path,
         bytes calldata data
-    ) external payable {
+    ) external payable override {
         _putChunkFromCalldata(
             keccak256(bytes.concat(repoName, "/", path)),
             0,
@@ -54,7 +56,7 @@ contract EthStorage is LargeStorageManagerV2{
         bytes memory path,
         uint256 chunkId,
         bytes calldata data
-    ) external payable{
+    ) external payable {
         _putChunkFromCalldata(
             keccak256(bytes.concat(repoName, "/", path)),
             chunkId,
@@ -63,10 +65,7 @@ contract EthStorage is LargeStorageManagerV2{
         );
     }
 
-    function remove(
-        bytes memory repoName,
-        bytes memory path
-    ) external  {
+    function remove(bytes memory repoName, bytes memory path) external {
         // The actually process of remove will remove all the chunks
         _remove(keccak256(bytes.concat(repoName, "/", path)), 0);
     }
@@ -75,7 +74,7 @@ contract EthStorage is LargeStorageManagerV2{
         bytes memory repoName,
         bytes memory path,
         uint256 chunkId
-    ) external  {
+    ) external {
         _removeChunk(keccak256(bytes.concat(repoName, "/", path)), chunkId);
     }
 
@@ -92,4 +91,4 @@ contract EthStorage is LargeStorageManagerV2{
     ) external view returns (uint256) {
         return _countChunks(keccak256(bytes.concat(repoName, "/", name)));
     }
-}
\ No newline at end of file
+}
diff --git a/contracts/v3/database/filecoin.sol b/contracts/v3/database/filecoin.sol
index 74d1608..cf8ce72 100644
--- a/contracts/v3/database/filecoin.sol
+++ b/contracts/v3/database/filecoin.sol
@@ -1,27 +1,25 @@
 pragma solidity ^0.8.0;
 
-contract filecoin{
+import "./database.sol";
 
+contract filecoin is database {
     mapping(bytes32 => bytes) public pathToHash;
 
-     function download(
+    function download(
         bytes memory repoName,
         bytes memory path
-    ) external view returns (bytes memory, bool) {
-
-        bytes32  fullName = keccak256(bytes.concat(repoName, "/", path));
+    ) external view override returns (bytes memory, bool) {
+        bytes32 fullName = keccak256(bytes.concat(repoName, "/", path));
         // call flat directory(FD)
-        return (pathToHash[fullName],true);
+        return (pathToHash[fullName], true);
     }
 
     function upload(
         bytes memory repoName,
         bytes memory path,
         bytes calldata data
-    ) external payable {
-        bytes32  fullName = keccak256(bytes.concat(repoName, "/", path));
+    ) external payable override {
+        bytes32 fullName = keccak256(bytes.concat(repoName, "/", path));
         pathToHash[fullName] = data;
-            
     }
-
-}
\ No newline at end of file
+}