diff --git a/.github/workflows/testing.yml b/.github/workflows/testing.yml
index e4fa55d..a4bfa2c 100644
--- a/.github/workflows/testing.yml
+++ b/.github/workflows/testing.yml
@@ -16,6 +16,8 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install -r requirements.txt -r requirements-dev.txt
-          pylint src --errors-only
+          pylint src tests  --errors-only
       - name: Build package
-        run: pytest --junitxml output/report.xml
+        run: |
+          pip install -e .
+          pytest --junitxml output/report.xml
diff --git a/.gitignore b/.gitignore
index c78c064..137644c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,5 +12,5 @@ output/
 venv/
 build/
 dist/
-.pypirc
+.env
 dmtgen.egg-info/
\ No newline at end of file
diff --git a/.pypirc b/.pypirc
new file mode 100644
index 0000000..f726079
--- /dev/null
+++ b/.pypirc
@@ -0,0 +1,8 @@
+[distutils]
+index-servers =
+    gitlab
+
+[gitlab]
+repository = https://gitlab.sintef.no/api/v4/projects/${env.CI_PROJECT_ID}/packages/pypi
+username = gitlab-ci-token
+password = ${env.CI_JOB_TOKEN}
diff --git a/publish.sh b/publish.sh
index c5679f9..73e9d30 100644
--- a/publish.sh
+++ b/publish.sh
@@ -1,6 +1,6 @@
 set -e
 
-python setup.py clean --all sdist bdist_wheel
+python -m build --wheel --sdist
 
 if $PUBLISH_LIB; then
     python -m twine upload dist/* --config-file .pypirc
diff --git a/requirements-dev.txt b/requirements-dev.txt
index b49a23e..086c32a 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -1,5 +1,4 @@
-setuptools==65.5.1
-wheel==0.38.1
-twine==3.2.0
+build
+twine
 pytest
 pylint
\ No newline at end of file
diff --git a/setup.py b/setup.py
index 2ddfad7..2957910 100644
--- a/setup.py
+++ b/setup.py
@@ -17,7 +17,7 @@
 
 setup(
     name='dmtgen',
-    version='0.5.0.dev1',
+    version='0.5.0',
     author="SINTEF Ocean",
     description="Python generator utilities for DMT",
     long_description=long_description,
diff --git a/src/dmtgen/base_generator.py b/src/dmtgen/base_generator.py
index 5c7bd8a..3ee84d9 100644
--- a/src/dmtgen/base_generator.py
+++ b/src/dmtgen/base_generator.py
@@ -27,7 +27,7 @@ def __init__(self, root_dir: Path, package_name: str,
         self.source_only = False
         self.root_package = root_package
 
-    # pylint: disable=unused-argument, no-self-use
+    # pylint: disable=unused-argument
     def get_template_generator(self, template: Path, config: Dict) -> TemplateBasedGenerator:
         """ Override in subclasses to control which template generator to use"""
         return BasicTemplateGenerator()
@@ -72,10 +72,10 @@ def __find_templates_and_generate(self, output_dir: Path, config: Dict):
     @staticmethod
     def __read_template(templatefile: Path):
         loader = jinja2.FileSystemLoader(templatefile.parents[0])
-        env_parameters = dict(
-            loader=loader,
-            undefined=jinja2.StrictUndefined
-        )
+        env_parameters = {
+            "loader": loader,
+            "undefined":jinja2.StrictUndefined
+        }
         environment = jinja2.Environment(**env_parameters)
         environment.filters["escape_string"] = escape_string
         return environment.get_template(templatefile.name)
diff --git a/src/dmtgen/common/blueprint.py b/src/dmtgen/common/blueprint.py
index d6fd738..885d5ed 100644
--- a/src/dmtgen/common/blueprint.py
+++ b/src/dmtgen/common/blueprint.py
@@ -9,28 +9,23 @@
 class Blueprint:
     """ " A basic SIMOS Blueprint"""
 
-    def __init__(self, bp_dict: Dict, parent: Package) -> None:
+    # pylint: disable=too-many-instance-attributes
+    def __init__(self, content: Dict, parent: Package) -> None:
         self.parent = parent
-        self.blueprint = bp_dict
-        self.name = self.blueprint["name"]
-        self.description = bp_dict.get("description","")
-        self.__abstract = bp_dict.get("abstract",False)
+        self.content = content
+        self.name: str = self.content["name"]
+        self.description: str = content.get("description",None)
         attributes = {}
-        for a_dict in bp_dict.get("attributes",[]):
+        for a_dict in content.get("attributes",[]):
             attribute = BlueprintAttribute(a_dict, self)
             attributes[attribute.name]=attribute
+        self.__abstract = content.get("abstract",False)
         self.__attributes = attributes
-        extends = bp_dict.get("extends",[])
-        self.__extends = extends
+        self.__extends = content.get("extends",[])
         # We will resolve this later
         self.__extensions = None
 
 
-    @property
-    def abstract(self) -> bool:
-        """If the blueprint represent an abstract type"""
-        return self.__abstract
-
     @property
     def attributes(self) -> Sequence[BlueprintAttribute]:
         """Attributes"""
@@ -53,17 +48,33 @@ def extensions(self) -> Sequence[Blueprint]:
         if self.__extensions is not None:
             return self.__extensions
 
-        self.__extensions =  [self.__resolve(extension) for extension in self.__extends]
+        self.__extensions =  [self.__resolve_extension(extension) for extension in self.__extends]
         return self.__extensions
 
-    def __resolve(self,extension: str):
+    def resolve(self):
+        """ Resolve all attributes"""
+        for attribute in self.__attributes.values():
+            attribute.resolve()
+
+
+    def __resolve_extension(self,extension: str):
         package: Package = self.parent
-        return package.get_blueprint(extension)
+        resolved = package.resolve_type(extension)
+        return package.get_blueprint(resolved)
+
+    def is_abstract(self) -> bool:
+        """If the blueprint represent an abstract type. 
+        In object oriented terms, this would be an interface or abstract class."""
+        return self.__abstract
 
     def get_path(self):
-        """ Get full path to blueprint """
+        """ Get full path to blueprint"""
         parent = self.parent
         if parent:
             return parent.get_path() + "/" + self.name
         # Then we are at root
-        return "/" + self.name
+        return self.name
+
+    def get_attribute(self, name:str) -> BlueprintAttribute:
+        """ Return the attribute if it exists, otherwise None"""
+        return self.all_attributes.get(name,None)
diff --git a/src/dmtgen/common/blueprint_attribute.py b/src/dmtgen/common/blueprint_attribute.py
index ee28170..d92a06d 100644
--- a/src/dmtgen/common/blueprint_attribute.py
+++ b/src/dmtgen/common/blueprint_attribute.py
@@ -8,7 +8,8 @@
 class BlueprintAttribute:
     """ " A basic SIMOS Attribute"""
 
-    def __init__(self, content: Dict, parent_blueprint: Blueprint) -> None:
+    # pylint: disable=too-many-instance-attributes
+    def __init__(self, content: Dict, parent: Blueprint) -> None:
         self.content = content
         name = content["name"]
         if len(name)==0:
@@ -24,48 +25,94 @@ def __init__(self, content: Dict, parent_blueprint: Blueprint) -> None:
             self.dimensions = []
 
         atype = content["attributeType"]
-        self.parent = parent_blueprint
-        package = parent_blueprint.parent
-        self.type = package.resolve_type(atype)
-        self.is_primitive = atype in ['boolean', 'number', 'string', 'integer']
-        self.is_enum = self.content.get("enumType",None) is not None
-        self.is_blueprint = not (self.is_primitive or self.is_enum)
-        self.is_optional = self.content.get("optional",True)
-        self.is_array = len(self.dimensions)>0
-        self.is_contained = content.get("contained",True)
+        self.__parent = parent
+        self.__type = atype
+        self.__optional = self.content.get("optional",True)
+        self.__is_primitive = atype in ['boolean', 'number', 'string', 'integer']
+        self.enum_type = self.content.get("enumType",None)
+        self.__is_enum = self.enum_type is not None
+        self.__is_blueprint = not (self.__is_primitive or self.__is_enum)
+        self.__is_array = len(self.dimensions)>0
+        self.__is_string = self.type == "string"
+        self.__is_boolean = self.type == "boolean"
+        self.__is_integer = self.type == "integer"
+        self.__is_number = self.type == "number"
+        self.__is_contained = content.get("contained",True)
+
+    def resolve(self):
+        """ Resolve to correct type"""
+        package = self.parent.parent
+        self.__type = package.resolve_type(self.__type)
+        if self.enum_type:
+            self.enum_type = package.resolve_type(self.enum_type)
+
+    @property
+    def parent(self) -> Blueprint:
+        """The parent blueprint"""
+        return self.__parent
+
+    @property
+    def type(self) -> str:
+        """The type of the attribute"""
+        return self.__type
 
     @property
+    def optional(self) -> bool:
+        """Is this an optional attribute"""
+        return self.__optional
+
+    @property
+    def contained(self) -> bool:
+        """Is this a contained attribute"""
+        return self.__is_contained
+
+    def is_primitive(self) -> bool:
+        """Is this a primitive type"""
+        return self.__is_primitive
+
+    def is_enum(self) -> bool:
+        """Is this an enum type"""
+        return self.__is_enum
+
+    def is_blueprint(self) -> bool:
+        """Is this a blueprint type"""
+        return self.__is_blueprint
+
     def is_string(self) -> bool:
         """Is this a string"""
-        return self.type == "string"
+        return self.__is_string
 
-    @property
     def is_boolean(self) -> bool:
         """Is this a boolean"""
-        return self.type == "boolean"
+        return self.__is_boolean
 
-    @property
     def is_integer(self) -> bool:
         """Is this an integer"""
-        return self.type == "integer"
+        return self.__is_integer
 
-    @property
     def is_number(self) -> bool:
         """Is this a number"""
-        return self.type == "number"
+        return self.__is_number
+
+    def is_optional(self) -> bool:
+        """Is an optional relation"""
+        return self.__optional
 
-    @property
     def is_required(self) -> bool:
         """Is a required relation"""
-        return not self.is_optional
+        return not self.__optional
+
+    def is_array(self) -> bool:
+        """Is this an array"""
+        return self.__is_array
 
     def is_fixed_array(self) -> bool:
         """Is this a fixed array"""
-        return self.is_array and "*" not in self.dimensions
+        return self.__is_array and "*" not in self.dimensions
 
     def is_variable_array(self) -> bool:
         """Is this a variable array"""
-        return self.is_array and "*" in self.dimensions
+        return self.__is_array and "*" in self.dimensions
 
     def get(self, key, default=None):
         """Return the content value or an optional default"""
diff --git a/src/dmtgen/common/package.py b/src/dmtgen/common/package.py
index 2efb089..ee3f11f 100644
--- a/src/dmtgen/common/package.py
+++ b/src/dmtgen/common/package.py
@@ -7,7 +7,7 @@
 import os
 import re
 from pathlib import Path
-from typing import List, Sequence
+from typing import List, Sequence,Dict
 
 from .enum_description import EnumDescription
 from .blueprint import Blueprint
@@ -15,7 +15,8 @@
 class Package:
     """ " A basic SIMOS package"""
 
-    def __init__(self, pkg_dir: Path, parent: Package) -> None:
+    # pylint: disable=too-many-instance-attributes
+    def __init__(self, pkg_dir: Path, parent: Package, config: Dict=None) -> None:
         self.package_dir = pkg_dir
         self.version = 0
         self.name = pkg_dir.name
@@ -24,7 +25,23 @@ def __init__(self, pkg_dir: Path, parent: Package) -> None:
         self.__blueprints = {}
         self.__enums = {}
         self.__packages = {}
+        self.__dependencies = {}
+        if parent is None and config is not None:
+            # This is a root package and we might have dependencies
+            dependencies: dict = config.get('dependencies', {})
+            for alias,location in dependencies.items():
+                self.__dependencies[alias] = Package(Path(location),None)
+
         self.__read_package(pkg_dir)
+        if parent is None:
+            self.resolve()
+
+    def resolve(self):
+        """ Resolve all references in package and subpackages"""
+        for blueprint in self.blueprints:
+            blueprint.resolve()
+        for package in self.packages:
+            package.resolve()
 
     def __read_package(self, pkg_dir: Path):
         blueprints = {}
@@ -36,6 +53,7 @@ def __read_package(self, pkg_dir: Path):
         pkg_filename = "package.json"
         package_file = pkg_dir / pkg_filename
         if package_file.exists():
+            # Use with to ensure file is closed
             with open(package_file, encoding="utf-8") as file:
                 package = json.load(file)
                 self.__read_package_info(package)
@@ -43,19 +61,23 @@ def __read_package(self, pkg_dir: Path):
         for file in pkg_dir.glob("*.json"):
             if file.name == pkg_filename:
                 continue
-            with open(file, encoding="utf-8") as file:
-                entity = json.load(file)
-                etype = self.resolve_type(entity["type"])
-                if etype == "system/SIMOS/Blueprint":
-                    blueprint = Blueprint(entity, self)
-                    name = blueprint.name
-                    blueprints[name] = blueprint
-                elif etype == "system/SIMOS/Enum":
-                    enum = EnumDescription(entity, self)
-                    name = enum.name
-                    enums[name] = enum
-                else:
-                    raise ValueError("Unhandled entity type: " + etype)
+
+            if file.name == "__versions__.json":
+                self.__read_version(entity)
+            else:
+                with open(file, encoding="utf-8") as file:
+                    entity = json.load(file)
+                    etype = self.resolve_type(entity["type"])
+                    if etype == "system/SIMOS/Blueprint":
+                        blueprint = Blueprint(entity, self)
+                        name = blueprint.name
+                        blueprints[name] = blueprint
+                    elif etype == "system/SIMOS/Enum":
+                        enum = EnumDescription(entity, self)
+                        name = enum.name
+                        enums[name] = enum
+                    else:
+                        raise ValueError("Unhandled entity type: " + etype)
 
         for folder in pkg_dir.glob("*/"):
             if folder.is_dir():
@@ -87,9 +109,7 @@ def resolve_type(self, etype:str) -> str:
         idx=etype.find(":")
         if idx > 0:
             alias = etype[:idx].lower()
-            adress = self.aliases.get(alias,None)
-            if not adress:
-                raise ValueError(f"Alias not found \"{alias}\" in {self.name}")
+            adress = self.aliases.get(alias,alias)
             return adress + "/" + etype[idx+1:]
         return etype
 
@@ -153,7 +173,7 @@ def get_parent(self) -> Package:
         """Get parent package"""
         return self.parent
 
-    def get_root(self):
+    def get_root(self) -> Package:
         """Get root package"""
         parent: Package = self.parent
         if parent:
@@ -164,13 +184,6 @@ def get_root(self):
 
     def get_blueprint(self, path:str) -> Blueprint:
         """Get Blueprint from path"""
-        path = self.resolve_type(path)
-        idx=path.find(":")
-        if idx > 0:
-            alias = path[:idx].lower()
-            adress = self.aliases[alias]
-            path = adress + "/" + path[idx+1:]
-
         parts = re.split("/",path)
         bp_name = parts.pop()
         package = self.__get_package(parts)
@@ -178,7 +191,6 @@ def get_blueprint(self, path:str) -> Blueprint:
 
     def get_enum(self, path:str) -> EnumDescription:
         """Get enum from path"""
-        path = self.resolve_type(path)
         parts = re.split("/",path)
         enum_name = parts.pop()
         package = self.__get_package(parts)
@@ -190,15 +202,20 @@ def __get_package(self, parts: Sequence[str]) -> Package:
             if part == '.':
                 raise ValueError("Relative path not allowed. Should have been resolved by now.")
             if part == '':
-                package = self.get_root()
-            elif part == 'system':
+                continue
+            if part == 'system':
                 # pylint: disable=import-outside-toplevel
                 from .system_package import system_package
                 package =  system_package
             elif package is None:
-                package = self.get_root()
-                if part != package.name:
-                    raise ValueError(f"expected root {package.name} but got {part}")
+                # Use the root package to resolve
+                root_package: Package = self.get_root()
+                if part == root_package.name:
+                    package = root_package
+                else:
+                    package = root_package.__dependencies.get(part,None)
+                    if not package:
+                        raise ValueError(f"Package not found \"{part}\" in {root_package.name} or dependencies.")
             else:
                 package = package.package(part)
         return package
diff --git a/src/dmtgen/data/system/SIMOS/entity.json b/src/dmtgen/data/system/SIMOS/entity.json
index 43c7935..808a97d 100644
--- a/src/dmtgen/data/system/SIMOS/entity.json
+++ b/src/dmtgen/data/system/SIMOS/entity.json
@@ -12,7 +12,5 @@
             "default": "",
             "optional": true
         }
-    ],
-    "storageRecipes": [],
-    "uiRecipes": []
+    ]
 }
\ No newline at end of file
diff --git a/src/dmtgen/data/system/SIMOS/named_enity.json b/src/dmtgen/data/system/SIMOS/named_enity.json
index 3ae2cf2..77cf70a 100644
--- a/src/dmtgen/data/system/SIMOS/named_enity.json
+++ b/src/dmtgen/data/system/SIMOS/named_enity.json
@@ -2,7 +2,7 @@
     "name": "NamedEntity",
     "type": "system/SIMOS/Blueprint",
     "abstract" : true,
-    "extends" : ["system/SIMOS/Entity"],
+    "extends" : ["./Entity"],
     "description": "Describes the required attributes (name, type, description). All other blueprints should extend this one, or implement the attributes itself",
     "attributes": [
         {
@@ -12,7 +12,5 @@
             "label": "Name",
             "optional": true
         }
-    ],
-    "storageRecipes": [],
-    "uiRecipes": []
+    ]
 }
\ No newline at end of file
diff --git a/src/tests/__init__.py b/tests/__init__.py
similarity index 100%
rename from src/tests/__init__.py
rename to tests/__init__.py
diff --git a/src/tests/test_data/apps/EmployeeApp/Employee.blueprint.json b/tests/test_data/apps/EmployeeApp/Employee.blueprint.json
similarity index 100%
rename from src/tests/test_data/apps/EmployeeApp/Employee.blueprint.json
rename to tests/test_data/apps/EmployeeApp/Employee.blueprint.json
diff --git a/src/tests/test_data/apps/EmployeeApp/EmployeeApp.blueprint.json b/tests/test_data/apps/EmployeeApp/EmployeeApp.blueprint.json
similarity index 100%
rename from src/tests/test_data/apps/EmployeeApp/EmployeeApp.blueprint.json
rename to tests/test_data/apps/EmployeeApp/EmployeeApp.blueprint.json
diff --git a/src/tests/test_data/apps/package.json b/tests/test_data/apps/package.json
similarity index 100%
rename from src/tests/test_data/apps/package.json
rename to tests/test_data/apps/package.json
diff --git a/src/tests/test_relative_paths.py b/tests/test_relative_paths.py
similarity index 100%
rename from src/tests/test_relative_paths.py
rename to tests/test_relative_paths.py