diff --git a/.circleci/config.yml b/.circleci/config.yml
index f6768dd..c24608b 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -25,55 +25,6 @@ references:
 
 jobs:
 
-  build_and_test_35:
-    docker:
-      - image: circleci/python:3.5
-    steps:  
-      - *restore_repo
-      - checkout
-      - *save_repo
-      - restore_cache:
-          keys: 
-            - v1-dependencies35-{{ checksum "requirements.txt"}}
-            - v1-dependencies35        
-      - run: |
-            pip install virtualenv
-            virtualenv ~/venv35
-            . ~/venv35/bin/activate
-            pip install -r requirements.txt
-            pip install -r requirements-dev.txt
-            pip install .
-            cd test
-            pytest -v --cov satstac --cov-report term-missing
-      - save_cache:
-          key: v1-dependencies35-{{ checksum "requirements.txt"}}
-          paths:
-            - ~/venv35
-
-  build_and_test_36:
-    docker:
-      - image: circleci/python:3.6
-    steps:  
-      - *restore_repo
-      - checkout
-      - *save_repo
-      - restore_cache:
-          keys: 
-            - v1-dependencies36-{{ checksum "requirements.txt"}}
-            - v1-dependencies36        
-      - run: |
-            python3 -m venv ~/venv36
-            . ~/venv36/bin/activate
-            pip install -r requirements.txt
-            pip install -r requirements-dev.txt
-            pip install .
-            cd test
-            pytest -v --cov satstac --cov-report term-missing
-      - save_cache:
-          key: v1-dependencies36-{{ checksum "requirements.txt"}}
-          paths:
-            - ~/venv36
-
   build_and_test_37:
     docker:
       - image: circleci/python:3.7
@@ -101,17 +52,17 @@ jobs:
 
   deploy:
     docker:
-      - image: circleci/python:3.6
+      - image: circleci/python:3.7
     steps:
       - *restore_repo
       - restore_cache:
           keys: 
-            - v1-dependencies36-{{ checksum "requirements.txt"}}
-            - v1-dependencies36
+            - v1-dependencies37-{{ checksum "requirements.txt"}}
+            - v1-dependencies37
       - run:
           name: Deploy
           command: |
-            . ~/venv36/bin/activate
+            . ~/venv37/bin/activate
             mkdir -p ~/.ssh
             ssh-keyscan github.com >> ~/.ssh/known_hosts
             pip install twine
@@ -124,18 +75,12 @@ jobs:
 
 workflows:
   version: 2
-  build_test_35:
-    jobs:
-      - build_and_test_35
-  build_test_36:
+  build_test_37:
     jobs:
-      - build_and_test_36
+      - build_and_test_37
       - deploy:
           requires:
-            - build_and_test_36
+            - build_and_test_37
           filters:
             branches:
               only: master
-  build_test_37:
-    jobs:
-      - build_and_test_37
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 147c6c7..f7739e1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,11 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### Changed
+- Thing.publish() removed. Self links are not used at all (and not recommended for static catalogs)
+- Thing.root() and Thing.parent() functions now return `None` if no root or parent (rather than an empty list). If more than one root or parent then an error will now be thrown.
+- Internal JSON data now stored in variable called `_data` rather than `data`
+
 ## [v0.1.3] - 2019-05-04
 
 ### Added
diff --git a/README.md b/README.md
index 2da4ccb..08cd6d9 100644
--- a/README.md
+++ b/README.md
@@ -41,6 +41,7 @@ The table below shows the corresponding versions between sat-stac and STAC:
 | sat-stac | STAC  |
 | -------- | ----  |
 | 0.1.x    | 0.6.x |
+| 0.2.x    | 0.7.x |
 
 ## Tutorials
 
diff --git a/satstac/catalog.py b/satstac/catalog.py
index 011c474..cea1932 100644
--- a/satstac/catalog.py
+++ b/satstac/catalog.py
@@ -11,24 +11,25 @@ class Catalog(Thing):
     def __init__(self, data, root=None, **kwargs):
         """ Initialize a catalog with a catalog file """
         super(Catalog, self).__init__(data, **kwargs)
-        self._root = root
 
     @property
     def stac_version(self):
         """ Get the STAC version of this catalog """
-        return self.data['stac_version']
+        return self._data['stac_version']
 
     @property
     def description(self):
         """ Get catalog description """
-        return self.data.get('description', '')
+        return self._data.get('description', '')
 
     @classmethod
-    def create(cls, id='stac-catalog', description='A STAC Catalog', root=None, **kwargs):
+    def create(cls, id='stac-catalog', title='A STAC Catalog', 
+               description='A STAC Catalog', root=None, **kwargs):
         """ Create new catalog """
         kwargs.update({
             'id': id,
             'stac_version': STAC_VERSION,
+            'title': title,
             'description': description,
             'links': []
         })
@@ -45,78 +46,49 @@ def catalogs(self):
         for cat in self.children():
             for subcat in cat.children():
                 yield subcat
-                # Python 2
-                for x in subcat.catalogs():
-                    yield x
-                # Python 3.3+
-                # yield from subcat.catalogs()
+                yield from subcat.catalogs()
             yield cat
 
     def collections(self):
         """ Recursively get all collections within this Catalog """
         for cat in self.children():
-            if 'extent' in cat.data.keys():
+            if 'extent' in cat._data.keys():
                 yield Collection.open(cat.filename)
                 # TODO - keep going? if other Collections can appear below a Collection
             else:
-                # Python 2
-                for x in cat.collections():
-                    yield x
-                # Python 3.3+
-                # yield from cat.collections()
+                yield from cat.collections()
 
     def items(self):
         """ Recursively get all items within this Catalog """
         for item in self.links('item'):
             yield Item.open(item)
         for child in self.children():
-            # Python 2
-            for x in child.items():
-                yield x
-            # Python 3.3+
-            # yield from child.items()
+            yield from child.items()
 
-    def add_catalog(self, catalog):
+    def add_catalog(self, catalog, basename='catalog'):
         """ Add a catalog to this catalog """
         if self.filename is None:
             raise STACError('Save catalog before adding sub-catalogs')
         # add new catalog child link
-        child_link = '%s/catalog.json' % catalog.id
+        child_link = '%s/%s.json' % (catalog.id, basename)
         child_fname = os.path.join(self.path, child_link)
         child_path = os.path.dirname(child_fname)
-        root_link = self.links('root')[0]
+        root_links = self.links('root')
+        root_link = root_links[0] if len(root_links) > 0 else self.filename
         root_path = os.path.dirname(root_link)
         self.add_link('child', child_link)
         self.save()
         # strip self, parent, child links from catalog and add new links
         catalog.clean_hierarchy()
-        catalog.add_link('self', os.path.join(self.endpoint(), os.path.relpath(child_fname, root_path)))
         catalog.add_link('root', os.path.relpath(root_link, child_path))
         catalog.add_link('parent', os.path.relpath(self.filename, child_path))
         # create catalog file
-        catalog.save_as(child_fname)
+        catalog.save(filename=child_fname)
         return self
 
-    def endpoint(self):
-        """ Get endpoint URL to the root catalog """
-        return os.path.dirname(self.root().links('self')[0])
-
-    def publish(self, endpoint, root=None):
-        """ Update all self links throughout catalog to use new endpoint """
-        # we don't use the catalogs and items functions as we'd have to go 
-        # through the tree twice, once for catalogs and once for items
-        # update myself
-        if root is None:
-            root = self.filename
-        super(Catalog, self).publish(endpoint, root=root)
-        # update direct items
-        for link in self.links('item'):
-            item = Item.open(link)
-            item.publish(endpoint, root=root)
-        # follow children
-        for cat in self.children():
-            cat.publish(endpoint, root=root)
-
+    def add_collection(self, catalog, basename='collection'):
+        """ Add a collection to this catalog """
+        return self.add_catalog(catalog, basename=basename)
 
 
 # import and end of module prevents problems with circular dependencies.
diff --git a/satstac/cli.py b/satstac/cli.py
index 2b80441..91d58fc 100644
--- a/satstac/cli.py
+++ b/satstac/cli.py
@@ -28,17 +28,7 @@ def parse_args(args):
     parser.add_argument('id', help='ID of the new catalog')
     parser.add_argument('description', help='Description of new catalog')
     parser.add_argument('--filename', help='Filename of catalog', default='catalog.json')
-    group = parser.add_argument_group('root catalog options (mutually exclusive)')
-    group = group.add_mutually_exclusive_group(required=True)
-    group.add_argument('--root', help='Filename to existing root catalog', default=None)
-    group.add_argument('--endpoint', help='Endpoint for this new root catalog', default=None)
-
-    # command 2
-    h = 'Update entire catalog with a new endpoint (update self links)'
-    parser = subparsers.add_parser('publish', parents=[pparser], help=h, formatter_class=dhf)
-    parser.add_argument('root', help='Filename to existing root catalog')
-    parser.add_argument('endpoint', help='New endpoint')
-    # parser.add_argument()
+    parser.add_argument('--root', help='Filename to existing root catalog', default=None)
 
     # turn Namespace into dictinary
     parsed_args = vars(parser0.parse_args(args))
@@ -57,11 +47,8 @@ def cli():
             cat = Catalog.create(id=args['id'], description=args['description'])
             root.add_catalog(cat)
         else:
-            cat = Catalog.create(id=args['id'], description=args['description'], root=args['endpoint'])
-            cat.save_as(args['filename'])
-    elif cmd == 'publish':
-        cat = Catalog.open(args['root'])
-        cat.publish(args['endpoint'])
+            cat = Catalog.create(id=args['id'], description=args['description'])
+            cat.save(filename=args['filename'])
 
 
 if __name__ == "__main__":
diff --git a/satstac/collection.py b/satstac/collection.py
index 452c237..dd8c5e6 100644
--- a/satstac/collection.py
+++ b/satstac/collection.py
@@ -22,32 +22,32 @@ def __init__(self, *args, **kwargs):
 
     @property
     def title(self):
-        return self.data.get('title', '')
+        return self._data.get('title', '')
 
     @property
     def keywords(self):
-        return self.data.get('keywords', [])
+        return self._data.get('keywords', [])
 
     @property
     def version(self):
-        return self.data.get('version', '')
+        return self._data.get('version', '')
 
     @property
     def license(self):
-        return self.data.get('license')
+        return self._data.get('license')
 
     @property
     def providers(self):
-        return self.data.get('providers', [])
+        return self._data.get('providers', [])
 
     @property
     def extent(self):
-        return self.data.get('extent')
+        return self._data.get('extent')
 
     @property
     def properties(self):
         """ Get dictionary of properties """
-        return self.data.get('properties', {})
+        return self._data.get('properties', {})
 
     @functools.lru_cache()
     def parent_catalog(self, path):
@@ -63,7 +63,7 @@ def parent_catalog(self, path):
             except STACError as err:
                 # create a new sub-catalog
                 subcat = self.create(id=d, description='%s catalog' % var_names[i])
-                subcat.save_as(fname)
+                subcat.save(filename=fname)
                 # add the sub-catalog to this catalog
                 cat.add_catalog(subcat)
             cat = subcat
@@ -88,13 +88,12 @@ def add_item(self, item, path='', filename='${id}'):
 
         # create links from item
         item.clean_hierarchy()
-        item.add_link('self', os.path.join(self.endpoint(), os.path.relpath(item_fname, root_path)))
         item.add_link('root', os.path.relpath(root_link, item_path))
         item.add_link('parent', os.path.relpath(parent.filename, item_path))
         # this assumes the item has been added to a Collection, not a Catalog
         item.add_link('collection', os.path.relpath(self.filename, item_path))
 
         # save item
-        item.save_as(item_fname)
+        item.save(filename=item_fname)
         logger.debug('Added %s in %s seconds' % (item.filename, datetime.now()-start))
         return self
diff --git a/satstac/item.py b/satstac/item.py
index 96753dd..cbd7094 100644
--- a/satstac/item.py
+++ b/satstac/item.py
@@ -47,7 +47,7 @@ def eobands(self):
     @property
     def properties(self):
         """ Get dictionary of properties """
-        return self.data.get('properties', {})
+        return self._data.get('properties', {})
 
     def __getitem__(self, key):
         """ Get key from properties """
@@ -68,17 +68,17 @@ def datetime(self):
 
     @property
     def geometry(self):
-        return self.data['geometry']
+        return self._data['geometry']
 
     @property
     def bbox(self):
         """ Get bounding box of scene """
-        return self.data['bbox']
+        return self._data['bbox']
 
     @property
     def assets(self):
         """ Return dictionary of assets """
-        return self.data.get('assets', {})
+        return self._data.get('assets', {})
 
     @property
     def assets_by_common_name(self):
@@ -126,7 +126,7 @@ def substitute(self, string):
     def download_assets(self, keys=None, **kwargs):
         """ Download multiple assets """
         if keys is None:
-            keys = self.data['assets'].keys()
+            keys = self._data['assets'].keys()
         filenames = []
         for key in keys:
             filenames.append(self.download(key, **kwargs))
diff --git a/satstac/items.py b/satstac/items.py
index b0d4c1e..6ce1d0e 100644
--- a/satstac/items.py
+++ b/satstac/items.py
@@ -109,11 +109,11 @@ def save(self, filename):
 
     def geojson(self):
         """ Get Items as GeoJSON FeatureCollection """
-        features = [s.data for s in self._items]
+        features = [s._data for s in self._items]
         geoj = {
             'type': 'FeatureCollection',
             'features': features,
-            'collections': [c.data for c in self._collections],
+            'collections': [c._data for c in self._collections],
         }
         if self._search is not None:
             geoj['search'] = self._search
diff --git a/satstac/thing.py b/satstac/thing.py
index 1c9efa1..f4b4f73 100644
--- a/satstac/thing.py
+++ b/satstac/thing.py
@@ -2,16 +2,15 @@
 import os
 import requests
 
-try:
-    # Python 3
-    from urllib.parse import urljoin
-except ImportError:
-    # Python 2
-    from urlparse import urljoin
+from logging import getLogger
+from urllib.parse import urljoin
 from .version import __version__
 from .utils import mkdirp, get_s3_signed_url
 
 
+logger = getLogger(__name__)
+
+
 class STACError(Exception):
     pass
 
@@ -21,10 +20,11 @@ class Thing(object):
     def __init__(self, data, filename=None):
         """ Initialize a new class with a dictionary """
         self.filename = filename
-        self.data = data
-        if 'links' not in self.data.keys():
-            self.data['links'] = []
-        self._root = None
+        self._data = data
+        if 'id' not in data:
+            raise STACError('ID is required')
+        if 'links' not in self._data.keys():
+            self._data['links'] = []
 
     def __repr__(self):
         return self.id
@@ -42,7 +42,7 @@ def open_remote(self, url, headers={}):
     @classmethod
     def open(cls, filename):
         """ Open an existing JSON data file """
-        # TODO - open remote URLs
+        logger.debug('Opening %s' % filename)
         if filename[0:5] == 'https':
             try:
                 dat = cls.open_remote(filename)
@@ -58,10 +58,15 @@ def open(cls, filename):
                 raise STACError('%s does not exist locally' % filename)
         return cls(dat, filename=filename)
 
+    def __getitem__(self, key):
+        """ Get key from properties """
+        props = self._data.get('properties', {})
+        return props.get(key, None)
+
     @property
     def id(self):
         """ Return id of this entity """
-        return self.data['id']
+        return self._data['id']
 
     @property
     def path(self):
@@ -70,7 +75,7 @@ def path(self):
 
     def links(self, rel=None):
         """ Get links for specific rel type """
-        links = self.data.get('links', [])
+        links = self._data.get('links', [])
         if rel is not None:
             links = [l for l in links if l.get('rel') == rel]
         links = [l['href'] for l in links]
@@ -79,7 +84,7 @@ def links(self, rel=None):
             for l in links:
                 if os.path.isabs(l) or l[0:4] == 'http':
                     # if absolute or https 
-                    link = l 
+                    link = l
                 else:
                     # relative path
                     if self.filename[0:4] == 'http':
@@ -93,17 +98,28 @@ def links(self, rel=None):
     def root(self):
         """ Get root link """
         links = self.links('root')
-        return self.open(links[0]) if len(links) == 1 else []
+        if len(links) == 1:
+            return self.open(links[0])
+        elif len(links) == 0:
+            # i'm the root of myself
+            return self
+        else:
+            raise STACError('More than one root provided')
 
     def parent(self):
         """ Get parent link """
         links = self.links('parent')
-        return self.open(links[0]) if len(links) == 1 else []
+        if len(links) == 1:
+            return self.open(links[0])
+        elif len(links) == 0:
+            return None
+        else:
+            raise STACError('More than one parent provided')
 
     def add_link(self, rel, link, type=None, title=None):
         """ Add a new link """
         # if this link already exists do not add it
-        for l in self.data['links']:
+        for l in self._data['links']:
             if l['rel'] == rel and l['href'] == link:
                 return
         l = {'rel': rel, 'href': link}
@@ -111,60 +127,36 @@ def add_link(self, rel, link, type=None, title=None):
             l['type'] = type
         if title is not None:
             l['title'] = title
-        self.data['links'].append(l)
+        self._data['links'].append(l)
+
 
     def clean_hierarchy(self):
         """ Clean links of self, parent, and child links (for moving and publishing) """
         rels = ['self', 'root', 'parent', 'child', 'collection', 'item']
         links = []
-        for l in self.data['links']:
+        for l in self._data['links']:
             if l['rel'] not in rels:
                 links.append(l)
-        self.data['links'] = links
-
-    def __getitem__(self, key):
-        """ Get key from properties """
-        props = self.data.get('properties', {})
-        return props.get(key, None)
+        self._data['links'] = links
 
-    def save(self):
+    def save(self, filename=None):
         """ Write a catalog file """
+        if filename is not None:
+            self.filename = filename
         if self.filename is None:
-            raise STACError('No filename, use save_as()')
+            raise STACError('No filename provided, specify with filename keyword')
+        logger.debug('Saving %s as %s' % (self.id, self.filename))
         fname = self.filename
         if self.filename[0:5] == 'https':
             # use signed URL
             signed_url, signed_headers = get_s3_signed_url(self.filename, rtype='PUT',
                                                            public=True, content_type='application/json')
-            resp = requests.put(signed_url, data=json.dumps(self.data), headers=signed_headers)
+            resp = requests.put(signed_url, data=json.dumps(self._data), headers=signed_headers)
             if resp.status_code != 200:
                 raise STACError('Unable to save file to %s: %s' % (self.filename, resp.text))
         else:
             # local file save
             mkdirp(os.path.dirname(fname))
             with open(fname, 'w') as f:
-                f.write(json.dumps(self.data))
-        return self
-
-    def save_as(self, filename):
-        """ Write a catalog file to a new file """
-        self.filename = filename
-        # TODO - if this is a root then add root link and self links to itself
-        if self._root is not None:
-            self.add_link('self', os.path.join(self._root, os.path.basename(filename)))
-            self.add_link('root', './%s' % os.path.basename(filename))
-        self.save()
-        return self
-
-    def publish(self, endpoint, root):
-        """ Update self link with endpoint """
-        if self.filename is None:
-            raise STACError('No filename, use save_as() before publishing')
-        # keep everything except self and root
-        links = [l for l in self.data['links'] if l['rel'] not in ['self', 'root']]
-        to_item = os.path.relpath(self.filename, os.path.dirname(root))
-        to_root = os.path.relpath(root, os.path.dirname(self.filename))
-        links.insert(0, {'rel': 'root', 'href': to_root})
-        links.insert(0, {'rel': 'self', 'href': os.path.join(endpoint, to_item)})
-        self.data['links'] = links
-        self.save()
+                f.write(json.dumps(self._data))
+        return self
\ No newline at end of file
diff --git a/satstac/version.py b/satstac/version.py
index 8ce9b36..7fd229a 100644
--- a/satstac/version.py
+++ b/satstac/version.py
@@ -1 +1 @@
-__version__ = '0.1.3'
+__version__ = '0.2.0'
diff --git a/test/catalog/eo/landsat-8-l1/item.json b/test/catalog/eo/landsat-8-l1/item.json
index 0b0d0be..9ea46dc 100644
--- a/test/catalog/eo/landsat-8-l1/item.json
+++ b/test/catalog/eo/landsat-8-l1/item.json
@@ -1,5 +1,6 @@
 {
     "id": "LC08_L1GT_120046_20181012_20181012_01_RT",
+    "collection": "landsat-8-l1",
     "bbox": [
         114.89853,
         19.54292,
@@ -34,7 +35,6 @@
         ]
     },
     "properties": {
-        "collection": "landsat-8-l1",
         "datetime": "2018-10-12T02:40:06.547Z",
         "eo:cloud_cover": 91,
         "eo:sun_azimuth": 141.68039757,
diff --git a/test/catalog/eo/sentinel-2-l1c/sentinel-2a/item.json b/test/catalog/eo/sentinel-2-l1c/sentinel-2a/item.json
index 50da45c..e6f0f6d 100644
--- a/test/catalog/eo/sentinel-2-l1c/sentinel-2a/item.json
+++ b/test/catalog/eo/sentinel-2-l1c/sentinel-2a/item.json
@@ -1,5 +1,6 @@
 {
     "id": "L1C_T53MNQ_A017245_20181011T011722",
+    "collection": "sentinel-2-l1c",
     "bbox": [
         135.6392640640852,
         -5.5163474919383235,
@@ -38,7 +39,6 @@
         ]
     },
     "properties": {
-        "collection": "sentinel-2-l1c",
         "datetime": "2018-10-11T01:17:22.460Z",
         "eo:platform": "Sentinel-2A",
         "eo:cloud_cover": 21,
diff --git a/test/test_catalog.py b/test/test_catalog.py
index 447d5f7..d6effa2 100644
--- a/test/test_catalog.py
+++ b/test/test_catalog.py
@@ -38,7 +38,7 @@ def test_init(self):
     def test_open(self):
         """ Initialize Catalog with a file """
         cat = self.get_catalog()
-        assert(len(cat.data.keys()) == 4)
+        assert(len(cat._data.keys()) == 4)
         assert(cat.id == 'stac')
         assert(len(cat.links())==3)
 
@@ -78,7 +78,7 @@ def test_get_items(self):
         assert(len(items) == 2)
 
     def test_add_catalog(self):
-        cat = Catalog.create(root='http://my.cat').save_as(os.path.join(self.path, 'catalog.json'))
+        cat = Catalog.create(root='http://my.cat').save(os.path.join(self.path, 'catalog.json'))
         col = Catalog.open(os.path.join(testpath, 'catalog/eo/landsat-8-l1/catalog.json'))
         cat.add_catalog(col)
         child = [c for c in cat.children()][0]
@@ -88,11 +88,3 @@ def test_add_catalog_without_saving(self):
         cat = Catalog.create()
         with self.assertRaises(STACError):
            cat.add_catalog({})
-
-    def test_publish(self):
-        path = os.path.join(self.path, 'test_publish')
-        shutil.copytree(os.path.join(testpath, 'catalog'), path)
-        cat = Catalog.open(os.path.join(path, 'catalog.json'))
-        cat.publish('https://my.cat')
-        item = Item.open(os.path.join(path, 'eo/landsat-8-l1/item.json'))
-        assert(item.links('self')[0] == 'https://my.cat/eo/landsat-8-l1/item.json')
\ No newline at end of file
diff --git a/test/test_cli.py b/test/test_cli.py
index e96d199..1fd5a24 100644
--- a/test/test_cli.py
+++ b/test/test_cli.py
@@ -21,14 +21,13 @@ def test_parse_no_args(self):
             parse_args(['-h'])
 
     def test_parse_args(self):
-        input = "create testid 'this is a description' --endpoint 'https://my.cat'"
+        input = "create testid 'this is a description'"
         args = parse_args(split(input))
-        assert(len(args) == 7)
-        assert(args['endpoint'] == 'https://my.cat')
+        assert(len(args) == 6)
         assert(args['id'] == 'testid')
 
     def test_cli_create(self):
-        input = "sat-stac create cat 'this is a description' --endpoint 'https://my.cat'"
+        input = "sat-stac create cat 'this is a description'"
         sys.argv = split(input)
         cli()
         assert(os.path.exists('catalog.json'))
@@ -38,12 +37,3 @@ def test_cli_create(self):
         assert(os.path.exists('subcat/catalog.json'))
         rmtree('subcat')
         os.remove('catalog.json')
-
-    def test_cli_publish(self):
-        cat = Catalog.create(root='https://my.cat').save_as('catalog.json')
-        input = "sat-stac publish catalog.json https://my.kitten"
-        sys.argv = split(input)
-        cli()
-        cat = Catalog.open('catalog.json')
-        assert(cat.links('self')[0] == 'https://my.kitten/catalog.json')
-        os.remove('catalog.json')
\ No newline at end of file
diff --git a/test/test_collection.py b/test/test_collection.py
index d87ea0a..62874b5 100644
--- a/test/test_collection.py
+++ b/test/test_collection.py
@@ -44,7 +44,7 @@ def test_title(self):
         assert(len(cat.properties))
 
     def test_add_item(self):
-        cat = Catalog.create(root='http://my.cat').save_as(os.path.join(self.path, 'catalog.json'))
+        cat = Catalog.create(root='http://my.cat').save(os.path.join(self.path, 'catalog.json'))
         col = Collection.open(os.path.join(testpath, 'catalog/eo/landsat-8-l1/catalog.json'))
         cat.add_catalog(col)
         item = Item.open(os.path.join(testpath, 'catalog/eo/landsat-8-l1/item.json'))
@@ -58,7 +58,7 @@ def test_add_item_without_saving(self):
             col.add_item(item)
 
     def test_add_item_with_subcatalogs(self):
-        cat = Catalog.create(root='http://my.cat').save_as(os.path.join(self.path, 'test_subcatalogs.json'))
+        cat = Catalog.create(root='http://my.cat').save(os.path.join(self.path, 'test_subcatalogs.json'))
         col = Collection.open(os.path.join(testpath, 'catalog/eo/landsat-8-l1/catalog.json'))
         cat.add_catalog(col)
         item = Item.open(os.path.join(testpath, 'catalog/eo/landsat-8-l1/item.json'))
diff --git a/test/test_item.py b/test/test_item.py
index c032d0b..9a303c6 100644
--- a/test/test_item.py
+++ b/test/test_item.py
@@ -45,9 +45,9 @@ def test_open(self):
         item = Item.open(self.filename)
         dt, tm = item.properties['datetime'].split('T')
         assert(str(item.date) == dt)
-        assert(item.id == item.data['id'])
-        assert(item.geometry == item.data['geometry'])
-        assert(str(item) == item.data['id'])
+        assert(item.id == item._data['id'])
+        assert(item.geometry == item._data['geometry'])
+        assert(str(item) == item._data['id'])
         assert(len(item.bbox) == 4)
         #assert(list(item.keys()) == ['id', 'collection', 'datetime', 'eo:platform'])
 
@@ -60,13 +60,13 @@ def test_open_with_collection(self):
     def test_class_properties(self):
         """ Test the property functions of the Item class """
         item = Item.open(self.filename)
-        l = os.path.join(os.path.dirname(item.filename), item.data['links'][0]['href'])
+        l = os.path.join(os.path.dirname(item.filename), item._data['links'][0]['href'])
         assert(os.path.abspath(item.links()[0]) == os.path.abspath(l))
 
     def test_assets(self):
         """ Get assets for download """
         item = Item.open(self.filename)
-        href = item.data['assets']['B1']['href']
+        href = item._data['assets']['B1']['href']
         assert(item.assets['B1']['href'] == href)
         assert(item.asset('B1')['href'] == href)
         assert(item.asset('coastal')['href'] == href)
diff --git a/test/test_thing.py b/test/test_thing.py
index 1a3a5d6..655c33d 100644
--- a/test/test_thing.py
+++ b/test/test_thing.py
@@ -21,22 +21,24 @@ def tearDownClass(cls):
 
     def get_thing(self):
         """ Configure testing class """
-        with open(self.fname) as f:
-            data = json.loads(f.read())
-        return Thing(data)
+        return Thing.open(self.fname)
+
+    def test_init_error(self):
+        with self.assertRaises(STACError):
+            Thing({})
 
     def test_init(self):
         thing1 = self.get_thing()
         assert(thing1.id == 'stac')
         assert(len(thing1.links()) == 3)
         assert(len(thing1.links('self')) == 1)
-        data = thing1.data
+        data = thing1._data
         del data['links']
         thing2 = Thing(data)
         assert(thing2.links() == [])
         with self.assertRaises(STACError):
             thing2.save()
-        print(thing1)
+        assert(thing2.id == str(thing2))
 
     def test_open(self):
         thing1 = self.get_thing()
@@ -46,11 +48,16 @@ def test_open(self):
             os.path.basename(thing1.links()[0]) 
             == os.path.basename(thing2.links()[0])
         )
+        assert(thing2.path == os.path.dirname(self.fname))
+
+    def test_open_missing(self):
+        with self.assertRaises(STACError):
+            thing = Thing.open('nosuchfile.json')        
 
     def test_open_remote(self):
         thing = Thing.open('https://landsat-stac.s3.amazonaws.com/catalog.json')
         assert(thing.id == 'landsat-stac')
-        assert(len(thing.data['links']) == 3)
+        assert(len(thing._data['links']) == 3)
 
     def test_open_missing_remote(self):
         with self.assertRaises(STACError):
@@ -58,10 +65,10 @@ def test_open_missing_remote(self):
 
     def test_thing(self):
         thing = self.get_thing()
-        assert('id' in thing.data.keys())
-        assert('links' in thing.data.keys())
-        del thing.data['links']
-        assert('links' not in thing.data.keys())
+        assert('id' in thing._data.keys())
+        assert('links' in thing._data.keys())
+        del thing._data['links']
+        assert('links' not in thing._data.keys())
         assert(thing.links() == [])
 
     def test_get_links(self):
@@ -71,10 +78,38 @@ def test_get_links(self):
 
     def test_add_link(self):
         thing = self.get_thing()
+        thing.clean_hierarchy()
+        thing.filename = None
         thing.add_link('testlink', 'bobloblaw', type='text/plain', title='BobLoblaw')
-        assert(len(thing.links()) == 4)
+        assert(len(thing.links()) == 1)
+        # try adding it again, should not add it if rel and href the same
+        thing.add_link('testlink', 'bobloblaw', type='text/plain', title='BobLoblaw')
+        assert(len(thing.links()) == 1)
+        assert(len(thing.links('testlink')) == 1)
         assert(thing.links('testlink')[0] == 'bobloblaw')
 
+    def test_get_root(self):
+        thing = self.get_thing()
+        root = thing.root()
+        assert(root.filename == os.path.join(testpath, 'catalog/catalog.json'))
+        thing.add_link('root', 'root', title='root2')
+        with self.assertRaises(STACError):
+            thing.root()
+        thing.clean_hierarchy()
+        root = thing.root()
+        assert(root == thing)
+
+    def test_get_parent(self):
+        thing = Thing.open(os.path.join(testpath, 'catalog/eo/catalog.json'))
+        parent = thing.parent()
+        assert(parent.filename == os.path.join(testpath, 'catalog/catalog.json'))
+        thing.add_link('parent', 'catalog.json', title='parent2')
+        with self.assertRaises(STACError):
+            thing.parent()
+        thing.clean_hierarchy()
+        parent = thing.parent()
+        assert(parent is None)
+
     def test_clean_hierarchy(self):
         thing = self.get_thing()
         thing.add_link('testlink', 'bobloblaw')
@@ -90,30 +125,18 @@ def test_save(self):
         thing = Thing.open(self.fname)
         thing.save()
         fout = os.path.join(self.path, 'test-save.json')
-        thing.save_as(fout)
+        thing.save(fout)
         assert(os.path.exists(fout))
 
     def test_save_remote_with_signed_url(self):
         thing = Thing.open(self.fname)
-        thing.save_as('https://landsat-stac.s3.amazonaws.com/test/thing.json')
+        thing.save('https://landsat-stac.s3.amazonaws.com/test/thing.json')
 
     def test_save_remote_with_bad_signed_url(self):
         envs = dict(os.environ)
         thing = Thing.open(self.fname)
         os.environ['AWS_BUCKET_REGION'] = 'us-east-1'
         with self.assertRaises(STACError):
-            thing.save_as('https://landsat-stac.s3.amazonaws.com/test/thing.json')
+            thing.save('https://landsat-stac.s3.amazonaws.com/test/thing.json')
         os.environ.clear()
         os.environ.update(envs)
-
-    def test_publish(self):
-        thing = self.get_thing()
-        fout = os.path.join(self.path, 'test-save.json')
-        thing.save_as(fout)
-        thing.publish('https://my.cat', root=fout)
-        assert(thing.links('self')[0] == 'https://my.cat/test-save.json')
-
-    def test_publish_without_saving(self):
-        thing = self.get_thing()
-        with self.assertRaises(STACError):
-            thing.publish('https://my.cat', root=None)
\ No newline at end of file
diff --git a/tutorial-1.ipynb b/tutorial-1.ipynb
index 1b88d6c..4088be4 100644
--- a/tutorial-1.ipynb
+++ b/tutorial-1.ipynb
@@ -16,7 +16,6 @@
     "    - Adding collections to catalogs\n",
     "    - Adding items to collections\n",
     "- Views (sub-catalogs)\n",
-    "- Publishing catalogs\n",
     "\n",
     "\n",
     "The examples here use the [test catalog in the sat-stac repo](https://github.com/developmentseed/sat-stac/tree/master/test/catalog). The directory structure of the test catalog looks like the following, where the catalog.json files under the landsat-8-l1 and sentinel-2-l1c are `Collection`s, the rest of the catalog.json files are simple `Catalog`s, and the item.json files are `Item`s.\n",
@@ -51,7 +50,9 @@
   {
    "cell_type": "code",
    "execution_count": 1,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "from satstac import Catalog\n",
@@ -81,7 +82,9 @@
   {
    "cell_type": "code",
    "execution_count": 2,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -121,7 +124,9 @@
   {
    "cell_type": "code",
    "execution_count": 3,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -153,7 +158,9 @@
   {
    "cell_type": "code",
    "execution_count": 4,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -205,7 +212,9 @@
   {
    "cell_type": "code",
    "execution_count": 5,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -242,7 +251,9 @@
   {
    "cell_type": "code",
    "execution_count": 6,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -276,7 +287,9 @@
   {
    "cell_type": "code",
    "execution_count": 7,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -315,7 +328,9 @@
   {
    "cell_type": "code",
    "execution_count": 8,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -359,7 +374,9 @@
   {
    "cell_type": "code",
    "execution_count": 9,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -424,7 +441,9 @@
   {
    "cell_type": "code",
    "execution_count": 10,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -474,26 +493,6 @@
     "        ├── catalog.json\n",
     "```"
    ]
-  },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
-    "## Publishing a catalog<a name='publish' />\n",
-    "\n",
-    "The STAC spec allows for all of the hierarchical links to be stored as relative paths, except for self which must be an absolute path. However, when creating a Catalog that is going to be moved elsewhere, absolute paths do not yet make sense, so sat-stac keeps self links as relative.\n",
-    "\n",
-    "The Catalog can be published with a new endpoint by calling publish with the new root link. This is the absolute link to the root catalog. The publish() function will traverse the tree and update all of the self links in every Catalog, Collection, and Item to be an absolute path using the provided root link."
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": 11,
-   "metadata": {},
-   "outputs": [],
-   "source": [
-    "mycat.publish('https://my.other.cat')"
-   ]
   }
  ],
  "metadata": {
diff --git a/tutorial-2.ipynb b/tutorial-2.ipynb
index a3db153..ffb37c6 100644
--- a/tutorial-2.ipynb
+++ b/tutorial-2.ipynb
@@ -34,7 +34,9 @@
   {
    "cell_type": "code",
    "execution_count": 1,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -71,7 +73,9 @@
   {
    "cell_type": "code",
    "execution_count": 2,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -100,7 +104,9 @@
   {
    "cell_type": "code",
    "execution_count": 3,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -134,7 +140,9 @@
   {
    "cell_type": "code",
    "execution_count": 4,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -166,7 +174,9 @@
   {
    "cell_type": "code",
    "execution_count": 5,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -194,7 +204,9 @@
   {
    "cell_type": "code",
    "execution_count": 6,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -222,7 +234,9 @@
   {
    "cell_type": "code",
    "execution_count": 7,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -257,7 +271,9 @@
   {
    "cell_type": "code",
    "execution_count": 8,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -283,7 +299,9 @@
   {
    "cell_type": "code",
    "execution_count": 9,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -310,7 +328,9 @@
   {
    "cell_type": "code",
    "execution_count": 10,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -336,7 +356,9 @@
   {
    "cell_type": "code",
    "execution_count": 11,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -369,7 +391,9 @@
   {
    "cell_type": "code",
    "execution_count": 12,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -397,7 +421,9 @@
   {
    "cell_type": "code",
    "execution_count": 13,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -415,7 +441,9 @@
   {
    "cell_type": "code",
    "execution_count": 14,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -471,7 +499,9 @@
   {
    "cell_type": "code",
    "execution_count": 15,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -510,7 +540,9 @@
   {
    "cell_type": "code",
    "execution_count": 16,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -531,7 +563,9 @@
   {
    "cell_type": "code",
    "execution_count": 17,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -562,7 +596,9 @@
   {
    "cell_type": "code",
    "execution_count": 18,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -589,7 +625,9 @@
   {
    "cell_type": "code",
    "execution_count": 19,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -626,7 +664,9 @@
   {
    "cell_type": "code",
    "execution_count": 20,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",
@@ -644,7 +684,9 @@
   {
    "cell_type": "code",
    "execution_count": 21,
-   "metadata": {},
+   "metadata": {
+    "collapsed": false
+   },
    "outputs": [
     {
      "name": "stdout",