diff --git a/authenticationsystem.capnp b/auth.capnp
similarity index 98%
rename from authenticationsystem.capnp
rename to auth.capnp
index e576ef0..1f7145a 100644
--- a/authenticationsystem.capnp
+++ b/auth.capnp
@@ -8,7 +8,7 @@ using CSharp = import "programming_language/csharp.capnp";
 $CSharp.namespace("FabAccessAPI.Schema");
 
 using L10NString = import "utils.capnp".L10NString;
-using Session = import "connection.capnp".Session;
+using Session = import "main.capnp".Session;
 
 struct Response {
     enum Error {
@@ -100,7 +100,7 @@ struct Response {
 }
 
 interface Authentication {
-    step @0 ( data: Data ) -> ( response: Response );
+    step @0 (data :Data) -> Response;
     # Respond to a challenge with more data. A client MUST NOT call this after having received an
     # "successful" response.
 
diff --git a/machine.capnp b/machine.capnp
deleted file mode 100644
index be0ac7e..0000000
--- a/machine.capnp
+++ /dev/null
@@ -1,98 +0,0 @@
-@0x8c2f829df1930cd5;
-
-using Rust = import "programming_language/rust.capnp";
-$Rust.parentModule("schema");
-
-using CSharp = import "programming_language/csharp.capnp";
-$CSharp.namespace("FabAccessAPI.Schema");
-
-using General = import "general.capnp";
-using User = import "user.capnp".User;
-using Space = import "space.capnp".Space;
-
-struct Machine {
-    enum MachineState {
-        free @0;
-        inUse @1;
-        toCheck @2;
-        blocked @3;
-        disabled @4;
-        reserved @5;
-    }
-    struct MachineInfoExtended {
-        currentUser @0 :User;
-        transferUser @1 :User;
-    }
-
-    struct Reservation {
-        user @0 :User;
-        start @1: UInt64;
-        end @2: UInt64;
-    }
-
-    id @0 :General.UUID;
-    space @1 :Space;
-    name @2 :Text;
-    description @3 :Text;
-    state @4 :MachineState;
-    manager @5:User;
-
-    info @6 :Info;
-    interface Info $CSharp.name("InfoInterface") {
-        getMachineInfoExtended @0 () -> ( machineInfoExtended :MachineInfoExtended, dummy :UInt8 = 0);
-
-        getPropertyList @1 () -> ( propertyList :List(General.KeyValuePair) );
-
-        getReservationList @2 () -> ( reservationList :List(Reservation) );
-    }
-
-    use @7 :Use;
-    interface Use $CSharp.name("UseInterface") {
-        use @0 ();
-
-        reserve @1 ();
-        reserveto @2 (start :UInt64, end :UInt64);
-    }
-
-    inuse @8 :InUse;
-    interface InUse $CSharp.name("InUseInterface") {
-        giveBack @0 ();
-        sendRawData @1 (data :Data);
-    }
-
-    transfer @9 :Transfer;
-    interface Transfer $CSharp.name("TransferInterface") {
-        accept @0 ();
-        reject @1 ();
-    }
-
-    check @10 :Check;
-    interface Check $CSharp.name("CheckInterface") {
-        check @0 ();
-        reject @1 ();
-    }
-
-    manage @11 :Manage;
-    interface Manage $CSharp.name("ManageInterface") {
-        setProperty @0 (property :General.KeyValuePair);
-        removeProperty @1 (property :General.KeyValuePair);
-
-        forceUse @2 ();
-        forceFree @3 ();
-
-        forceTransfer @4 (user :User);
-
-        block @5 ();
-        disabled @6 ();
-    }
-
-    admin @12 :Admin;
-    interface Admin $CSharp.name("AdminInterface") {
-        forceSetState @0 ( state :MachineState );
-        forceSetUser @1 ( user :User );
-
-        getAdminPropertyList @2 () -> (propertyList :List(General.KeyValuePair));
-        setAdminProperty @3 (property :General.KeyValuePair);
-        removeAdminProperty @4 (property :General.KeyValuePair);
-    }
-}
diff --git a/connection.capnp b/main.capnp
similarity index 56%
rename from connection.capnp
rename to main.capnp
index 667809c..7970447 100644
--- a/connection.capnp
+++ b/main.capnp
@@ -6,17 +6,16 @@ $Rust.parentModule("schema");
 using CSharp = import "programming_language/csharp.capnp";
 $CSharp.namespace("FabAccessAPI.Schema");
 
-using Authentication = import "authenticationsystem.capnp".Authentication;
-using MachineSystem = import "machinesystem.capnp".MachineSystem;
-using UserSystem = import "usersystem.capnp".UserSystem;
-using PermissionSystem = import "permissionsystem.capnp".PermissionSystem;
+using Authentication = import "auth.capnp".Authentication;
+using Ressources = import "ressources.capnp".Ressources;
+using Users = import "users.capnp".Users;
 
 interface Bootstrap
 {
     mechanisms @0 () -> ( mechs: List(Text) );
     # Get a list of Mechanisms this server allows in this context.
 
-    createSession @1 ( mechanism :Text, initialData :Data ) -> ( authentication :Authentication);
+    createSession @1 ( mechanism :Text, initialData :Data ) -> ( authentication :Authentication );
     # Create a new session with the server that you wish to authenticate using `mechanism`.
     # If the mechanism is a client-first mechanism you MAY set `initialData` to contain the data you
     # want to send. If the mechanism is server-first or you do not wish to send initial data, make
@@ -24,7 +23,13 @@ interface Bootstrap
 }
 
 struct Session {
-    machineSystem @0 : MachineSystem;
-    userSystem @1 : UserSystem;
-    permissionSystem @2 : PermissionSystem;
+    # An API session with the server. The below capabilities are set to NULL if the authenticated
+    # user doesn't have permission to access the system in question.
+
+    ressources @0 : Ressources;
+    # Access to the ressources configured. 
+
+    users @1 : Users;
+    # User administration. This includes both modifying other users and self-modification, so this
+    # is allowed for most sessions
 }
diff --git a/permissionsystem.capnp b/permissionsystem.capnp
deleted file mode 100644
index fbca4be..0000000
--- a/permissionsystem.capnp
+++ /dev/null
@@ -1,22 +0,0 @@
-@0xd0568a21cf11488e;
-
-using Rust = import "programming_language/rust.capnp";
-$Rust.parentModule("schema");
-
-using CSharp = import "programming_language/csharp.capnp";
-$CSharp.namespace("FabAccessAPI.Schema");
-
-using Role = import "role.capnp".Role;
-
-interface PermissionSystem 
-{
-    info @0 () -> ( info : Info );
-    interface Info $CSharp.name("InfoInterface") {
-    	getRoleList @0 () -> ( role_list :List(Role) );
-	}
-
-	manage @1 () -> ( manage : Manage );
-    interface Manage $CSharp.name("ManageInterface") {
-    	
-	}
-}
\ No newline at end of file
diff --git a/resource.capnp b/resource.capnp
new file mode 100644
index 0000000..badf634
--- /dev/null
+++ b/resource.capnp
@@ -0,0 +1,173 @@
+@0x8c2f829df1930cd5;
+
+using Rust = import "programming_language/rust.capnp";
+$Rust.parentModule("schema");
+
+using CSharp = import "programming_language/csharp.capnp";
+$CSharp.namespace("FabAccessAPI.Schema");
+
+using Persistent = import "/capnp/persistent.capnp".Persistent;
+using Value = import "/capnp/schema.capnp".Value;
+
+using General = import "general.capnp";
+using User = import "user.capnp".User;
+using Space = import "space.capnp".Space;
+
+struct Node {
+    # A node in the state tree. If it's the root note this struct "contains" the whole tree.
+
+    # TODO: I'm not happy with this representation. While it's about as generic as we can get it's
+    # unhandly because all clients and servers have to always manually check every leaf of the
+    # state tree, relying on convention instead of static type checking. But I'm not sure how else
+    # to represent the state extensibly in a way that lets us evolve the protocol by stabilizing
+    # extensions. One option could be to use OID or UUID as "tag bits" and "stabilize" them by
+    # defining those as `const` values, but that wouldn't give us proper type checking either.
+
+    part @0 :Text;
+    # Name of the node, making up a path to this node (e.g. "set/colour/red")
+
+    union {
+        # Content of a node. A node has either children *or* a value, not both.
+
+        children @1 :List(Node);
+        # Node is not a leaf node ⇒ it has a list of children
+
+        value @2 :Value;
+        # Node is a leaf node ⇒ it contains a (typed) Cap'n Proto value.
+        # The type `Value` comes from the Cap'n Proto schema definition file (usually
+        # /usr/include/capnp/schema.capnp) and can be any basic capnp type, including lists and
+        # structs (as :AnyPointer which a client has to cast)
+    }
+}
+
+struct Applied {
+    # Encodes if a specific actor has applied/verified a state change
+
+    name @0 :Text;
+    # Name of the actor
+
+    state @1 :State;
+    # State of the state change in the actor
+    enum State {
+        unapplied @0;
+        applied @1;
+        verified @2;
+    }
+}
+
+interface Access {
+    # Allow syncronous read access to a resource's state. You're not given this capability directly
+    # but instead Notify, Interest and Claim all extend it, allowing you to call these methods from
+    # any of those.
+
+    readState @0 Node;
+    readApplied @1 Applied;
+
+    # TODO: There should probably be a more efficient approach for reading state than "read *all*
+    # state".
+}
+
+interface Notify extends(Access) {
+    # The Notify interface allows clients to be informed about state changes asyncronously.
+    # It is mainly designed around the `register` function which allows a client to register a
+    # Callback on the client that is called every time state changes happen to the resource in
+    # question.
+    # Notify are ephermal. If the connection to the server is lost all `Notify` are unregistered
+
+    register @0 ( cb: Callback );
+    # Register a given callback to be called on every state update. If this client already has a
+    # callback registered for this resource the old callback is replaced.
+    # The two fields `state` and `applied` indicate interest for `state` and `applied`. If they are
+    # unset the respective method on the callback will not be called.
+
+    unregister @1 ();
+    # Unregister the current callback, if any.
+
+    interface Callback {
+        # This callback interface is implemented on the client
+
+        newState @0 Node;
+        # A server will call newState() with the updated set state tree if `state` was set to `true`
+        # in `register`, however unless the last call to newState() didn't complete yet, as to not
+        # overload a client.
+
+        # TODO: There should probably be a more efficient approach here too, something along the
+        # lines of server-side filtering.
+
+        # TODO: Add newApplied?
+    }
+}
+
+interface Interestable {
+    interest @0 () -> ( interest: Interest );
+}
+
+interface Interest extends(Access) {
+    register @0 ( cb: Callback );
+    unregister @1 ();
+
+    blocking @2 ();
+    # As an alternative to the `register`/`Callback` system you can also call `blocking` which will
+    # — as the name suggests — block until the last claim was dropped.
+
+    interface Callback {
+        drop @0 ();
+        # The last claim on the resource this Interest is registered on was dropped, invalidating
+        # the Interest.
+    }
+}
+
+interface Claimable {
+    # Having this capability set (i.e. not be a `nullptr`) means the user has at least writeable
+    # access to a resource and the resource is claimable (n > 0).
+
+    claim @0 () -> ClaimResponse;
+    # Assert a claim on a resource.
+}
+
+interface Lockable {
+    # Having this capability set means the user has managerial access to a resource.
+
+    lock @0 () -> ( lock: Claim );
+}
+
+struct ClaimResponse {
+    enum Error {
+        # Error describing why a claim failed.
+
+        exhausted @0;
+        # There are no more free Claim slots
+
+        locked @1;
+        # The resource was locked
+    }
+
+    union {
+        error @0 :Error;
+        success @1 :Claim;
+    }
+}
+
+interface Claim extends(Access) {
+    # TODO: extend Persistance. Claims and Interests need to be able to survive a connection loss,
+    # which is exactly what `SturdyRef`/Persistance are designed to provide. The Persistance
+    # interface only provides one method, `save`, returning a `SturdyRef`. A SturdyRef is a generic
+    # and generally speaking opaque type that can be restored to a live capability using some sort
+    # of `Restorer` service.
+    # In this case the `Restorer` service could be `Claimable` / `Interestable` providing a 
+    # `restore( ref: SturdyRef )` method.
+
+    update @0 Node;
+    # Update the State of the claimed resource with the given one
+}
+
+struct Resource {
+    name @0 :Text;
+    description @1 :Text;
+    typeid @2 :Text;
+
+    notify @3 :Notify;
+    interest @4 :Interest;
+    claimable @5 :Claimable;
+    lockable @6 :Lockable;
+}
diff --git a/machinesystem.capnp b/resources.capnp
similarity index 54%
rename from machinesystem.capnp
rename to resources.capnp
index 2697d3f..04118d5 100644
--- a/machinesystem.capnp
+++ b/resources.capnp
@@ -9,12 +9,8 @@ $CSharp.namespace("FabAccessAPI.Schema");
 using General = import "general.capnp";
 using Machine = import "machine.capnp".Machine;
 
-interface MachineSystem 
+interface Ressources
 {
-	info @0 () -> ( info : Info );
-    interface Info $CSharp.name("InfoInterface") {
-    	getMachineList @0 () -> ( machine_list :List(Machine) );
-
-    	getMachine @1 ( name :Text ) -> ( machine :Machine, dummy :UInt8 = 0 );
-	}
+    listAll @0 () -> ( machine_list :List(Machine) );
+    get @1 ( name :Text ) -> Machine;
 }
diff --git a/users.capnp b/users.capnp
new file mode 100644
index 0000000..96e3793
--- /dev/null
+++ b/users.capnp
@@ -0,0 +1,24 @@
+@0x9a05e95f65f2edda;
+
+using Rust = import "programming_language/rust.capnp";
+$Rust.parentModule("schema");
+
+using CSharp = import "programming_language/csharp.capnp";
+$CSharp.namespace("FabAccessAPI.Schema");
+
+using General = import "general.capnp";
+using User = import "user.capnp".User;
+
+interface Users 
+{
+    whoami @0 () -> User;
+
+    manage @1 () -> ( manage :Manage );
+    interface Manage $CSharp.name("ManageInterface") {
+        list @0 () -> ( users :List(User) );
+
+        addUser @1 ( username: Text, password: Text ) -> User;
+
+        removeUser @2 User;
+    }
+}
diff --git a/usersystem.capnp b/usersystem.capnp
deleted file mode 100644
index 955514b..0000000
--- a/usersystem.capnp
+++ /dev/null
@@ -1,26 +0,0 @@
-@0x9a05e95f65f2edda;
-
-using Rust = import "programming_language/rust.capnp";
-$Rust.parentModule("schema");
-
-using CSharp = import "programming_language/csharp.capnp";
-$CSharp.namespace("FabAccessAPI.Schema");
-
-using General = import "general.capnp";
-using User = import "user.capnp".User;
-
-interface UserSystem 
-{
-	info @0 () -> ( info : Info );
-    interface Info $CSharp.name("InfoInterface") {
-    	getUserSelf @0 ( ) -> ( user :User, dummy :UInt8 = 0 );
-	}
-
-	manage @1 () -> ( manage : Manage );
-    interface Manage $CSharp.name("ManageInterface") {
-    	getUserList @0 () -> ( user_list :List(User) );
-
-    	addUser @1 (username :Text, password: Text) -> ( user :User );
-    	removeUser @2 (user :User, dummy :UInt8 = 0);
-	}
-}
\ No newline at end of file