diff --git a/docs/commit-log.md b/docs/commit-log.md
new file mode 100644
index 00000000..5a656372
--- /dev/null
+++ b/docs/commit-log.md
@@ -0,0 +1,58 @@
+# Commit log analysis
+
+See here https://files.slack.com/files-pri/T03ACD12T-F04V4QC6E/2015-05-21_16.14.50.jpg for details.
+
+We have some data storage (to decide -- one global storage or separate storage for each resource?
+One global commit log or separate for each resource?) -- call it DB for simplicity.
+
+User modifies some data of some resources K1, K2, H. This data is not stored immediately in the DB,
+instead it is stored in some separate place and queued for execution (we call this 'Staged Log').
+
+The modified data for a resource is represented as a diff in its inputs. So if user adds new resource
+and assigns an IP to it, it is represented something like:
+
+```
+ip:
+  from: None
+  to: 10.20.0.2
+```
+
+User commands 'apply'. Orchestrator takes the modified resources and applies appropriate actions
+in appropriate order that it computes.
+
+We think that the 'appropriate action' can be inferred from the diff for each resource. So for example
+if resource is new and has added IP the action `run` can be inferred because previous state was
+`None` and current is something new. If on the other hand previous state was some value `A` and
+new state is some value `B` -- the orchestrator decides that the action to be run is `update`. And
+if previous state is some `A` and new state is `None` the action will be `remove`.
+
+The 'appropriate order' taken by orchestrator can be just like the data flow graph initially. We
+see possibility of optimizing the number of actions taken by orchestrator so that moving Keystone
+service to another node can be simplified from 4 actions (update HAProxy without removed Keystone,
+install Keystone on new node, update HAProxy with new Keystone, remove Keystone from old node)
+taken to 3 actions (add Keystone to new node, update HAProxy removing old Keystone and adding
+new one, remove Keystone from old node).
+
+After resource action is finished the new state is saved to the commit log and data is updated in
+the DB.
+
+We want to support rollbacks via commit log. Rollback is done by replaying the commit log backwards.
+
+In case of separate commit logs per resource we think rollback could be done like this: some resource
+`K` is rolled back by one commit log, the diff action is the same as reversed diff action of the
+commit we are rolling back. We can update other resources with this new data by analyzing the connections.
+So in other words -- we change the data in one resource according to what is in the commit to be rolled
+back and then we trigger changes in other connected resources. Then we run orchestrator actions like
+described above.
+
+In case of single commit log for all resources -- is it sufficient to just rollback a commit? Or
+do we need to trigger changes in connected resources too? In global commit log we have ordering
+of commits like they were run by orchestrator.
+
+From analysis of resource removal we think that we need to save connection data in each commit --
+otherwise when we rollback that resource removal we wouldn't know how to restore its connections
+to other resources.
+
+Single commits after every action finished on a resource causes many commits per one user 'apply'
+action. In order to allow user to revert the whole action and not just single commits we have some
+idea of 'tagging' group of commits by some action id.
diff --git a/example.py b/example.py
index 24a0a756..06903f4c 100644
--- a/example.py
+++ b/example.py
@@ -1,5 +1,6 @@
 import shutil
 import os
+import time
 
 from solar.core import resource
 from solar.core import signals
@@ -13,17 +14,16 @@ os.mkdir('rs')
 
 node1 = resource.create('node1', 'resources/ro_node/', 'rs/', {'ip':'10.0.0.3', 'ssh_key' : '/vagrant/tmp/keys/ssh_private', 'ssh_user':'vagrant'})
 node2 = resource.create('node2', 'resources/ro_node/', 'rs/', {'ip':'10.0.0.4', 'ssh_key' : '/vagrant/tmp/keys/ssh_private', 'ssh_user':'vagrant'})
-node3 = resource.create('node3', 'resources/ro_node/', 'rs/', {'ip':'10.0.0.5', 'ssh_key' : '/vagrant/tmp/keys/ssh_private', 'ssh_user':'vagrant'})
 
 mariadb_service1 = resource.create('mariadb_service1', 'resources/mariadb_service', 'rs/', {'image':'mariadb', 'root_password' : 'mariadb', 'port' : '3306', 'ip': '', 'ssh_user': '', 'ssh_key': ''})
 keystone_db = resource.create('keystone_db', 'resources/mariadb_db/', 'rs/', {'db_name':'keystone_db', 'login_password':'', 'login_user':'root', 'login_port': '', 'ip':'', 'ssh_user':'', 'ssh_key':''})
 keystone_db_user = resource.create('keystone_db_user', 'resources/mariadb_user/', 'rs/', {'new_user_name' : 'keystone', 'new_user_password' : 'keystone', 'db_name':'', 'login_password':'', 'login_user':'root', 'login_port': '', 'ip':'', 'ssh_user':'', 'ssh_key':''})
 
 keystone_config1 = resource.create('keystone_config1', 'resources/keystone_config/', 'rs/', {'config_dir' : '/etc/solar/keystone', 'ip':'', 'ssh_user':'', 'ssh_key':'', 'admin_token':'admin', 'db_password':'', 'db_name':'', 'db_user':'', 'db_host':''})
-keystone_service1 = resource.create('keystone_service1', 'resources/keystone_service/', 'rs/', {'port':'5000', 'admin_port':'35357', 'ip':'', 'ssh_key':'', 'ssh_user':'', 'config_dir':'', 'config_dir':''})
+keystone_service1 = resource.create('keystone_service1', 'resources/keystone_service/', 'rs/', {'port':'5001', 'admin_port':'35357', 'ip':'', 'ssh_key':'', 'ssh_user':'', 'config_dir':'', 'config_dir':''})
 
 keystone_config2 = resource.create('keystone_config2', 'resources/keystone_config/', 'rs/', {'config_dir' : '/etc/solar/keystone', 'ip':'', 'ssh_user':'', 'ssh_key':'', 'admin_token':'admin', 'db_password':'', 'db_name':'', 'db_user':'', 'db_host':''})
-keystone_service2 = resource.create('keystone_service2', 'resources/keystone_service/', 'rs/', {'port':'5000', 'admin_port':'35357', 'ip':'', 'ssh_key':'', 'ssh_user':'', 'config_dir':'', 'config_dir':''})
+keystone_service2 = resource.create('keystone_service2', 'resources/keystone_service/', 'rs/', {'port':'5002', 'admin_port':'35357', 'ip':'', 'ssh_key':'', 'ssh_user':'', 'config_dir':'', 'config_dir':''})
 
 
 haproxy_keystone_config = resource.create('haproxy_keystone1_config', 'resources/haproxy_config/', 'rs/', {'name':'keystone_config', 'listen_port':'5000', 'servers':[], 'ports':[]})
@@ -62,11 +62,12 @@ signals.connect(node2, keystone_service2)
 signals.connect(keystone_config2, keystone_service2, {'config_dir': 'config_dir'})
 
 signals.connect(keystone_service1, haproxy_keystone_config, {'ip':'servers', 'port':'ports'})
+signals.connect(keystone_service2, haproxy_keystone_config, {'ip':'servers', 'port':'ports'})
 
-signals.connect(node1, haproxy_config)
+signals.connect(node2, haproxy_config)
 signals.connect(haproxy_keystone_config, haproxy_config, {'listen_port': 'listen_ports', 'name':'configs_names', 'ports' : 'configs_ports', 'servers':'configs'})
 
-signals.connect(node1, haproxy_service)
+signals.connect(node2, haproxy_service)
 signals.connect(haproxy_config, haproxy_service, {'listen_ports':'ports', 'config_dir':'host_binds'})
 
 
@@ -74,19 +75,21 @@ signals.connect(haproxy_config, haproxy_service, {'listen_ports':'ports', 'confi
 from solar.core import actions
 
 actions.resource_action(mariadb_service1, 'run')
+time.sleep(10)
 actions.resource_action(keystone_db, 'run')
 actions.resource_action(keystone_db_user, 'run')
 actions.resource_action(keystone_config1, 'run')
 actions.resource_action(keystone_service1, 'run')
+actions.resource_action(keystone_service2, 'run')
 actions.resource_action(haproxy_config, 'run')
 actions.resource_action(haproxy_service, 'run')
 
 
 #remove
-actions.resource_action(haproxy_service, 'remove')
-actions.resource_action(haproxy_config, 'remove')
-actions.resource_action(keystone_service1, 'remove')
-actions.resource_action(keystone_config1, 'remove')
-actions.resource_action(keystone_db_user, 'remove')
-actions.resource_action(keystone_db, 'remove')
-actions.resource_action(mariadb_service1, 'remove')
+#actions.resource_action(haproxy_service, 'remove')
+#actions.resource_action(haproxy_config, 'remove')
+#actions.resource_action(keystone_service1, 'remove')
+#actions.resource_action(keystone_config1, 'remove')
+#actions.resource_action(keystone_db_user, 'remove')
+#actions.resource_action(keystone_db, 'remove')
+#actions.resource_action(mariadb_service1, 'remove')
diff --git a/requirements.txt b/requirements.txt
index ca7d2def..9b690cee 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,3 +2,4 @@ click==4.0
 jinja2==2.7.3
 networkx==1.9.1
 PyYAML==3.11
+jsonschema==2.4.0
diff --git a/resources/data_container/meta.yaml b/resources/data_container/meta.yaml
index d4185a1a..9910b184 100644
--- a/resources/data_container/meta.yaml
+++ b/resources/data_container/meta.yaml
@@ -3,5 +3,11 @@ handler: ansible
 version: 1.0.0
 input:
     ip:
+      type: str!
+      value:
     image: 
-    export_volumes:    
+      type: str!
+      value:
+    export_volumes:
+      type: str!
+      value:
diff --git a/resources/docker_container/meta.yaml b/resources/docker_container/meta.yaml
index 182c872c..dd54506e 100644
--- a/resources/docker_container/meta.yaml
+++ b/resources/docker_container/meta.yaml
@@ -3,13 +3,23 @@ handler: ansible
 version: 1.0.0
 input:
     ip:
+      schema: str!
+      value:
     image:
+      schema: str!
+      value:
     ports:
+      schema: [int]
+      value: []
     host_binds:
+      schema: [int]
+      value: []
     volume_binds:
+      schema: [int]
+      value: []
     ssh_user:
+      schema: str!
+      value: []
     ssh_key:
-input-types:
-    ports:
-    host_binds: list
-    volume_binds: list
+      schema: str!
+      value: []
diff --git a/resources/file/meta.yaml b/resources/file/meta.yaml
index 14eb2e2c..19744ba2 100644
--- a/resources/file/meta.yaml
+++ b/resources/file/meta.yaml
@@ -2,4 +2,6 @@ id: file
 handler: shell
 version: 1.0.0
 input:
-    path: /tmp/test_file
+    path:
+      schema: str!
+      value: /tmp/test_file
diff --git a/resources/haproxy/meta.yaml b/resources/haproxy/meta.yaml
index 57f53a69..793f84d8 100644
--- a/resources/haproxy/meta.yaml
+++ b/resources/haproxy/meta.yaml
@@ -3,15 +3,26 @@ handler: ansible
 version: 1.0.0
 input:
     ip:
-    config_dir: {src: /etc/solar/haproxy, dst: /etc/haproxy}
+      schema: int!
+      value:
+    config_dir:
+      schema: {src: str!, dst: str!}
+      value: {src: /etc/solar/haproxy, dst: /etc/haproxy}
     listen_ports:
+      schema: [int]
+      value: []
     configs:
+      schema: [[str]]
+      value: []
     configs_names:
+      schema: [str]
+      value: []
     configs_ports:
+      schema: [[int]]
+      value: []
     ssh_user:
+      schema: str!
+      value:
     ssh_key:
-input-types:
-    listen_ports: list
-    configs: list
-    configs_names: list
-    configs_ports: list
+      schema: str!
+      value:
diff --git a/resources/haproxy_config/meta.yaml b/resources/haproxy_config/meta.yaml
index a7584600..307b5345 100644
--- a/resources/haproxy_config/meta.yaml
+++ b/resources/haproxy_config/meta.yaml
@@ -3,9 +3,14 @@ handler: none
 version: 1.0.0
 input:
     name:
+      schema: str!
+      value:
     listen_port:
+      schema: int!
+      value:
     ports:
+      schema: [int]
+      value:
     servers:
-input-types:
-    ports: list
-    servers: list
+      schema: [str]
+      value:
diff --git a/resources/keystone_config/meta.yaml b/resources/keystone_config/meta.yaml
index b4ea7ce6..5124d5dd 100644
--- a/resources/keystone_config/meta.yaml
+++ b/resources/keystone_config/meta.yaml
@@ -3,11 +3,29 @@ handler: ansible
 version: 1.0.0
 input:
     config_dir:
+      schema: str!
+      value:
     admin_token:
+      schema: str!
+      value:
     db_user:
+      schema: str!
+      value:
     db_password:
+      schema: str!
+      value:
     db_host:
+      schema: str!
+      value:
     db_name:
+      schema: str!
+      value:
     ip:
+      schema: str!
+      value:
     ssh_key:
+      schema: str!
+      value:
     ssh_user:
+      schema: str!
+      value:
diff --git a/resources/keystone_service/meta.yaml b/resources/keystone_service/meta.yaml
index 1e3add8d..e05179dc 100644
--- a/resources/keystone_service/meta.yaml
+++ b/resources/keystone_service/meta.yaml
@@ -2,10 +2,24 @@ id: keystone
 handler: ansible
 version: 1.0.0
 input:
-    image: kollaglue/centos-rdo-keystone
+    image:
+      schema: str!
+      value: kollaglue/centos-rdo-keystone
     config_dir:
+      schema: str!
+      value:
     port:
+      schema: int!
+      value:
     admin_port:
+      schema: int!
+      value:
     ip:
+      schema: str!
+      value:
     ssh_key:
+      schema: str!
+      value:
     ssh_user:
+      schema: str!
+      value:
diff --git a/resources/keystone_user/meta.yaml b/resources/keystone_user/meta.yaml
index 6293937c..0057019f 100644
--- a/resources/keystone_user/meta.yaml
+++ b/resources/keystone_user/meta.yaml
@@ -3,12 +3,32 @@ handler: ansible
 version: 1.0.0
 input:
     keystone_host:
+      schema: str!
+      value:
     keystone_port:
+      schema: int!
+      value:
     login_user:
+      schema: str!
+      value:
     login_token:
+      schema: str!
+      value:
     user_name:
+      schema: str!
+      value:
     user_password:
+      schema: str!
+      value:
     tenant_name:
+      schema: str!
+      value:
     ip:
+      schema: str!
+      value:
     ssh_key:
+      schema: str!
+      value:
     ssh_user:
+      schema: str!
+      value:
diff --git a/resources/mariadb_db/meta.yaml b/resources/mariadb_db/meta.yaml
index 609814ca..41b952e6 100644
--- a/resources/mariadb_db/meta.yaml
+++ b/resources/mariadb_db/meta.yaml
@@ -6,9 +6,23 @@ actions:
     remove: remove.yml
 input:
     db_name:
+      schema: str!
+      value:
     login_password:
+      schema: str!
+      value:
     login_port:
+      schema: int!
+      value:
     login_user:
-    ip: 
-    ssh_key: 
-    ssh_user: 
+      schema: str!
+      value:
+    ip:
+      schema: str!
+      value:
+    ssh_key:
+      schema: str!
+      value:
+    ssh_user:
+      schema: str!
+      value:
diff --git a/resources/mariadb_service/meta.yaml b/resources/mariadb_service/meta.yaml
index 6fa200d0..4295b7e1 100644
--- a/resources/mariadb_service/meta.yaml
+++ b/resources/mariadb_service/meta.yaml
@@ -3,8 +3,20 @@ handler: ansible
 version: 1.0.0
 input:
     image: 
-    root_password: 
-    port: 
-    ip: 
-    ssh_key: 
-    ssh_user: 
+      schema: str!
+      value:
+    root_password:
+      schema: str!
+      value:
+    port:
+      schema: str!
+      value:
+    ip:
+      schema: int!
+      value:
+    ssh_key:
+      schema: str!
+      value:
+    ssh_user:
+      schema: str!
+      value:
diff --git a/resources/mariadb_user/meta.yaml b/resources/mariadb_user/meta.yaml
index b45f8e47..b46d6e26 100644
--- a/resources/mariadb_user/meta.yaml
+++ b/resources/mariadb_user/meta.yaml
@@ -6,11 +6,29 @@ actions:
     remove: remove.yml
 input:
     new_user_password:
+      schema: str!
+      value:
     new_user_name:
+      schema: str!
+      value:
     db_name:
+      schema: str!
+      value:
     login_password:
+      schema: str!
+      value:
     login_port:
+      schema: int!
+      value:
     login_user:
-    ip: 
-    ssh_key: 
-    ssh_user: 
+      schema: str!
+      value:
+    ip:
+      schema: str!
+      value:
+    ssh_key:
+      schema: str!
+      value:
+    ssh_user:
+      schema: str!
+      value:
diff --git a/resources/nova/meta.yaml b/resources/nova/meta.yaml
index 0591a410..5c48b0b9 100644
--- a/resources/nova/meta.yaml
+++ b/resources/nova/meta.yaml
@@ -3,5 +3,11 @@ handler: ansible
 version: 1.0.0
 input:
     ip:
-    port: 8774
+      schema: str!
+      value:
+    port:
+      schema: int!
+      value: 8774
     image: # TODO
+      schema: str!
+      value:
diff --git a/resources/ro_node/meta.yaml b/resources/ro_node/meta.yaml
index 1ceaa0fc..c37fcb7f 100644
--- a/resources/ro_node/meta.yaml
+++ b/resources/ro_node/meta.yaml
@@ -4,5 +4,11 @@ version: 1.0.0
 actions:
 input:
     ip:
+      schema: str!
+      value:
     ssh_key:
+      schema: str!
+      value:
     ssh_user:
+      schema: str!
+      value:
diff --git a/run_tests.sh b/run_tests.sh
index 6dffeda3..6f3572f5 100755
--- a/run_tests.sh
+++ b/run_tests.sh
@@ -17,8 +17,9 @@ fi
 
 pip install -r requirements.txt --download-cache=/tmp/$JOB_NAME
 
-pushd x
+pushd solar/solar
 
-PYTHONPATH=$WORKSPACE CONFIG_FILE=$CONFIG_FILE python test/test_signals.py
+PYTHONPATH=$WORKSPACE/solar CONFIG_FILE=$CONFIG_FILE python test/test_signals.py
+PYTHONPATH=$WORKSPACE/solar CONFIG_FILE=$CONFIG_FILE python test/test_validation.py
 
 popd
diff --git a/solar/solar/core/resource.py b/solar/solar/core/resource.py
index fbfe007e..4f28651a 100644
--- a/solar/solar/core/resource.py
+++ b/solar/solar/core/resource.py
@@ -13,6 +13,7 @@ from solar.core import db
 from solar.core import observer
 from solar.core import signals
 from solar.core import utils
+from solar.core import validation
 
 
 class Resource(object):
@@ -21,14 +22,12 @@ class Resource(object):
         self.base_dir = base_dir
         self.metadata = metadata
         self.actions = metadata['actions'].keys() if metadata['actions'] else None
-        self.requires = metadata['input'].keys()
-        self._validate_args(args, metadata['input'])
         self.args = {}
         for arg_name, arg_value in args.items():
-            type_ = metadata.get('input-types', {}).get(arg_name) or 'simple'
+            metadata_arg = self.metadata['input'][arg_name]
+            type_ = validation.schema_input_type(metadata_arg.get('schema', 'str'))
+
             self.args[arg_name] = observer.create(type_, self, arg_name, arg_value)
-        self.metadata['input'] = args
-        self.input_types = metadata.get('input-types', {})
         self.changed = []
         self.tags = tags or []
 
@@ -95,22 +94,13 @@ class Resource(object):
         else:
             raise Exception('Uuups, action is not available')
 
-    def _validate_args(self, args, inputs):
-        for req in self.requires:
-            if req not in args:
-                # If metadata input is filled with a value, use it as default
-                # and don't report an error
-                if inputs.get(req):
-                    args[req] = inputs[req]
-                else:
-                    raise Exception('Requirement `{0}` is missing in args'.format(req))
-
     # TODO: versioning
     def save(self):
         metadata = copy.deepcopy(self.metadata)
 
         metadata['tags'] = self.tags
-        metadata['input'] = self.args_dict()
+        for k, v in self.args_dict().items():
+            metadata['input'][k]['value'] = v
 
         meta_file = os.path.join(self.base_dir, 'meta.yaml')
         with open(meta_file, 'w') as f:
diff --git a/solar/solar/core/signals.py b/solar/solar/core/signals.py
index 05ca425a..9bcc0b3d 100644
--- a/solar/solar/core/signals.py
+++ b/solar/solar/core/signals.py
@@ -83,8 +83,8 @@ def guess_mapping(emitter, receiver):
     :return:
     """
     guessed = {}
-    for key in emitter.requires:
-        if key in receiver.requires:
+    for key in emitter.args:
+        if key in receiver.args:
             guessed[key] = key
 
     return guessed
diff --git a/solar/solar/core/validation.py b/solar/solar/core/validation.py
new file mode 100644
index 00000000..01045f8a
--- /dev/null
+++ b/solar/solar/core/validation.py
@@ -0,0 +1,115 @@
+from jsonschema import validate, ValidationError, SchemaError
+
+
+def schema_input_type(schema):
+    """Input type from schema
+
+    :param schema:
+    :return: simple/list
+    """
+    if isinstance(schema, list):
+        return 'list'
+
+    return 'simple'
+
+
+def _construct_jsonschema(schema, definition_base=''):
+    """Construct jsonschema from our metadata input schema.
+
+    :param schema:
+    :return:
+    """
+    if schema == 'str':
+        return {'type': 'string'}, {}
+
+    if schema == 'str!':
+        return {'type': 'string', 'minLength': 1}, {}
+
+    if schema == 'int' or schema == 'int!':
+        return {'type': 'number'}, {}
+
+    if isinstance(schema, list):
+        items, definitions = _construct_jsonschema(schema[0], definition_base=definition_base)
+
+        return {
+            'type': 'array',
+            'items': items,
+        }, definitions
+
+    if isinstance(schema, dict):
+        properties = {}
+        definitions = {}
+
+        for k, v in schema.items():
+            if isinstance(v, dict) or isinstance(v, list):
+                key = '{}_{}'.format(definition_base, k)
+                properties[k] = {'$ref': '#/definitions/{}'.format(key)}
+                definitions[key], new_definitions = _construct_jsonschema(v, definition_base=key)
+            else:
+                properties[k], new_definitions = _construct_jsonschema(v, definition_base=definition_base)
+
+            definitions.update(new_definitions)
+
+        required = [k for k, v in schema.items() if
+                    isinstance(v, basestring) and v.endswith('!')]
+
+        ret = {
+            'type': 'object',
+            'properties': properties,
+        }
+
+        if required:
+            ret['required'] = required
+
+        return ret, definitions
+
+
+def construct_jsonschema(schema):
+    jsonschema, definitions = _construct_jsonschema(schema)
+
+    jsonschema['definitions'] = definitions
+
+    return jsonschema
+
+
+def validate_input(value, jsonschema=None, schema=None):
+    """Validate single input according to schema.
+
+    :param value: Value to be validated
+    :param schema: Dict in jsonschema format
+    :param schema: Our custom, simplified schema
+    :return: list with errors
+    """
+    if jsonschema is None:
+        jsonschema = construct_jsonschema(schema)
+    try:
+        validate(value, jsonschema)
+    except ValidationError as e:
+        return [e.message]
+    except:
+        print 'jsonschema', jsonschema
+        print 'value', value
+        raise
+
+
+def validate_resource(r):
+    """Check if resource inputs correspond to schema.
+
+    :param r: Resource instance
+    :return: dict, keys are input names, value is array with error.
+    """
+    ret = {}
+
+    input_schemas = r.metadata['input']
+    args = r.args_dict()
+
+    for input_name, input_definition in input_schemas.items():
+        errors = validate_input(
+            args.get(input_name),
+            jsonschema=input_definition.get('jsonschema'),
+            schema=input_definition.get('schema')
+        )
+        if errors:
+            ret[input_name] = errors
+
+    return ret
diff --git a/solar/solar/test/base.py b/solar/solar/test/base.py
index f58e727b..7dfcd82c 100644
--- a/solar/solar/test/base.py
+++ b/solar/solar/test/base.py
@@ -4,9 +4,9 @@ import tempfile
 import unittest
 import yaml
 
-from x import db
-from x import resource as xr
-from x import signals as xs
+from solar.core import db
+from solar.core import resource as xr
+from solar.core import signals as xs
 
 
 class BaseResourceTest(unittest.TestCase):
diff --git a/solar/solar/test/test_signals.py b/solar/solar/test/test_signals.py
index 59887add..8b80e708 100644
--- a/solar/solar/test/test_signals.py
+++ b/solar/solar/test/test_signals.py
@@ -2,7 +2,7 @@ import unittest
 
 import base
 
-from x import signals as xs
+from solar.core import signals as xs
 
 
 class TestBaseInput(base.BaseResourceTest):
@@ -12,7 +12,9 @@ id: sample
 handler: ansible
 version: 1.0.0
 input:
-  values: {}
+  values:
+    schema: {a: int, b: int}
+    value: {}
         """)
 
         sample1 = self.create_resource(
@@ -63,7 +65,11 @@ handler: ansible
 version: 1.0.0
 input:
   ip:
+    schema: string
+    value:
   port:
+    schema: int
+    value:
         """)
         sample_ip_meta_dir = self.make_resource_meta("""
 id: sample-ip
@@ -71,6 +77,8 @@ handler: ansible
 version: 1.0.0
 input:
   ip:
+    schema: string
+    value:
         """)
         sample_port_meta_dir = self.make_resource_meta("""
 id: sample-port
@@ -78,6 +86,8 @@ handler: ansible
 version: 1.0.0
 input:
   port:
+    schema: int
+    value:
         """)
 
         sample = self.create_resource(
@@ -109,6 +119,8 @@ handler: ansible
 version: 1.0.0
 input:
   ip:
+    schema: string
+    value:
         """)
 
         sample = self.create_resource(
@@ -149,6 +161,8 @@ handler: ansible
 version: 1.0.0
 input:
   ip:
+    schema: str
+    value:
         """)
 
         sample1 = self.create_resource(
@@ -171,6 +185,8 @@ handler: ansible
 version: 1.0.0
 input:
   ip:
+    schema: str
+    value:
         """)
         list_input_single_meta_dir = self.make_resource_meta("""
 id: list-input-single
@@ -178,8 +194,8 @@ handler: ansible
 version: 1.0.0
 input:
   ips:
-input-types:
-  ips: list
+    schema: [str]
+    value: []
         """)
 
         sample1 = self.create_resource(
@@ -248,7 +264,11 @@ handler: ansible
 version: 1.0.0
 input:
   ip:
+    schema: str
+    value:
   port:
+    schema: int
+    value:
         """)
         list_input_multi_meta_dir = self.make_resource_meta("""
 id: list-input-multi
@@ -256,10 +276,11 @@ handler: ansible
 version: 1.0.0
 input:
   ips:
+    schema: [str]
+    value:
   ports:
-input-types:
-  ips: list
-  ports: list
+    schema: [int]
+    value:
         """)
 
         sample1 = self.create_resource(
diff --git a/solar/solar/test/test_validation.py b/solar/solar/test/test_validation.py
new file mode 100644
index 00000000..da0da6d0
--- /dev/null
+++ b/solar/solar/test/test_validation.py
@@ -0,0 +1,174 @@
+import unittest
+
+from solar.test import base
+
+from solar.core import validation as sv
+
+
+class TestInputValidation(base.BaseResourceTest):
+    def test_input_str_type(self):
+        sample_meta_dir = self.make_resource_meta("""
+id: sample
+handler: ansible
+version: 1.0.0
+input:
+  value:
+    schema: str
+    value:
+  value-required:
+    schema: str!
+    value:
+        """)
+
+        r = self.create_resource(
+            'r1', sample_meta_dir, {'value': 'x', 'value-required': 'y'}
+        )
+        errors = sv.validate_resource(r)
+        self.assertEqual(errors, {})
+
+        r = self.create_resource(
+            'r2', sample_meta_dir, {'value': 1, 'value-required': 'y'}
+        )
+        errors = sv.validate_resource(r)
+        self.assertListEqual(errors.keys(), ['value'])
+
+        r = self.create_resource(
+            'r3', sample_meta_dir, {'value': ''}
+        )
+        errors = sv.validate_resource(r)
+        self.assertListEqual(errors.keys(), ['value-required'])
+
+
+    def test_input_int_type(self):
+        sample_meta_dir = self.make_resource_meta("""
+id: sample
+handler: ansible
+version: 1.0.0
+input:
+  value:
+    schema: int
+    value:
+  value-required:
+    schema: int!
+    value:
+        """)
+
+        r = self.create_resource(
+            'r1', sample_meta_dir, {'value': 1, 'value-required': 2}
+        )
+        errors = sv.validate_resource(r)
+        self.assertEqual(errors, {})
+
+        r = self.create_resource(
+            'r2', sample_meta_dir, {'value': 'x', 'value-required': 2}
+        )
+        errors = sv.validate_resource(r)
+        self.assertListEqual(errors.keys(), ['value'])
+
+        r = self.create_resource(
+            'r3', sample_meta_dir, {'value': 1}
+        )
+        errors = sv.validate_resource(r)
+        self.assertListEqual(errors.keys(), ['value-required'])
+
+    def test_input_dict_type(self):
+        sample_meta_dir = self.make_resource_meta("""
+id: sample
+handler: ansible
+version: 1.0.0
+input:
+  values:
+    schema: {a: int!, b: int}
+    value: {}
+        """)
+
+        r = self.create_resource(
+            'r', sample_meta_dir, {'values': {'a': 1, 'b': 2}}
+        )
+        errors = sv.validate_resource(r)
+        self.assertEqual(errors, {})
+
+        r.update({'values': None})
+        errors = sv.validate_resource(r)
+        self.assertListEqual(errors.keys(), ['values'])
+
+        r.update({'values': {'a': 1, 'c': 3}})
+        errors = sv.validate_resource(r)
+        self.assertEqual(errors, {})
+
+        r = self.create_resource(
+            'r1', sample_meta_dir, {'values': {'b': 2}}
+        )
+        errors = sv.validate_resource(r)
+        self.assertListEqual(errors.keys(), ['values'])
+
+    def test_complex_input(self):
+        sample_meta_dir = self.make_resource_meta("""
+id: sample
+handler: ansible
+version: 1.0.0
+input:
+  values:
+    schema: {l: [{a: int}]}
+    value: {l: [{a: 1}]}
+        """)
+
+        r = self.create_resource(
+            'r', sample_meta_dir, {
+                'values': {
+                    'l': [{'a': 1}],
+                }
+            }
+        )
+        errors = sv.validate_resource(r)
+        self.assertEqual(errors, {})
+
+        r.update({
+            'values': {
+                'l': [{'a': 'x'}],
+            }
+        })
+        errors = sv.validate_resource(r)
+        self.assertListEqual(errors.keys(), ['values'])
+
+        r.update({'values': {'l': [{'a': 1, 'c': 3}]}})
+        errors = sv.validate_resource(r)
+        self.assertEqual(errors, {})
+
+    def test_more_complex_input(self):
+        sample_meta_dir = self.make_resource_meta("""
+id: sample
+handler: ansible
+version: 1.0.0
+input:
+  values:
+    schema: {l: [{a: int}], d: {x: [int]}}
+    value: {l: [{a: 1}], d: {x: [1, 2]}}
+        """)
+
+        r = self.create_resource(
+            'r', sample_meta_dir, {
+                'values': {
+                    'l': [{'a': 1}],
+                    'd': {'x': [1, 2]}
+                }
+            }
+        )
+        errors = sv.validate_resource(r)
+        self.assertEqual(errors, {})
+
+        r.update({
+            'values': {
+                'l': [{'a': 1}],
+                'd': []
+            }
+        })
+        errors = sv.validate_resource(r)
+        self.assertListEqual(errors.keys(), ['values'])
+
+        r.update({'values': {'a': 1, 'c': 3}})
+        errors = sv.validate_resource(r)
+        self.assertEqual(errors, {})
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/x-TODO.md b/x-TODO.md
index f52e48a1..0263054f 100644
--- a/x-TODO.md
+++ b/x-TODO.md
@@ -1,5 +1,7 @@
 # TODO
 
+- grammar connections fuzzy matching algorithm (for example: type 'login' joins to type 'login' irrespective of names of both inputs)
+- resource connections JS frontend (?)
 - store all resource configurations somewhere globally (this is required to
   correctly perform an update on one resource and bubble down to all others)
 - config templates
@@ -9,6 +11,7 @@
   when some image is unused to conserve space
 
 # DONE
+- CI
 - Deploy HAProxy, Keystone and MariaDB
 - ansible handler (loles)
 - tags are kept in resource mata file (pkaminski)