Update API a bit

auth.capnp

@@ -6,6 +6,11 @@ $CSharp.namespace("FabAccessAPI.Schema");
 using import "utils.capnp".L10NString;
 using import "main.capnp".Session;
 
+struct Mechanism {
+    name @0 :Text;
+    additionalInfo @1 :AnyPointer;
+}
+
 struct Response {
     enum Reason {
         aborted @0;

cache.capnp

@@ -0,0 +1,17 @@
+@0xf6520578f143b471;
+
+using import "utils.capnp".UUID;
+
+struct Cache(Value) {
+    id @0 :UUID;
+    key @1 :Data;
+    value @2 :Cacheable(Value);
+}
+
+interface Cacheable(Value) {
+    get @0 () -> (key :Data, value :Value);
+    # Access the cached value. This returns both the value and the associated
+    # key. A consumer MUST use the Key returned here instead of the one stored
+    # in `Cache`, as it might have changed between being sent the `Cache`
+    # struct and calling `get`.
+}

claim.capnp

@@ -27,14 +27,16 @@ interface Lockable {
     # Restore a previously saved SturdyRef pointing to a Lock
 
     lock @1 () -> ( lock :Lock );
-    # Take exclusive access to a resource, disowning all other claims on this resource.
+    # Take exclusive access to a resource, disowning all other claims on this
+    # resource.
     #
-    # On resources that do not allow concurrent claims to exist this method behaves similar to
-    # `claim`, however it will also succeed if a resource is already claimed, disowning the previous
-    # claim.  On resources that do allow concurrent claims this method will disown all current claims on a
-    # resource and prevent new claims from being granted until the returned Lock capability is
-    # dropped.  A call to `lock` on a resource that is already locked will succeed, invalidating the former
-    # lock.
+    # On resources that do not allow concurrent claims to exist this method
+    # behaves similar to `claim`, however it will also succeed if a resource is
+    # already claimed, disowning the previous claim.  On resources that do
+    # allow concurrent claims this method will disown all current claims on a
+    # resource and prevent new claims from being granted until the returned
+    # Lock capability is dropped.  A call to `lock` on a resource that is
+    # already locked will succeed, invalidating the former lock.
 }
 
 interface Claim extends (Notifiable) {

main.capnp

@@ -4,15 +4,18 @@ using CSharp = import "programming_language/csharp.capnp";
 $CSharp.namespace("FabAccessAPI.Schema");
 
 using import "auth.capnp".Authentication;
+using import "auth.capnp".Mechanism;
 using import "resources.capnp".Resources;
 using import "users.capnp".Users;
 using import "user.capnp".User;
 using import "permissions.capnp".Permissions;
 
+const currentVersion :Version = (major = 1, minor = 0);
+
 struct Version
 {
-    major @0 :Int32 = 0;
-    minor @1 :Int32 = 4;
+    major @0 :Int32;
+    minor @1 :Int32;
 }
 
 interface Bootstrap
@@ -24,7 +27,7 @@ interface Bootstrap
     # debugging output so should be informative over machine-readable.
     # Example: ("bffhd", "0.3.1-f397e1e [rustc 1.57.0 (f1edd0429 2021-11-29)]")
 
-    mechanisms @2 () -> ( mechs :List(Text) );
+    mechanisms @2 () -> ( mechs :List(Mechanism) );
     # Get a list of Mechanisms this server allows in this context.
 
     createSession @3 ( mechanism :Text ) -> ( authentication :Authentication );

notify.capnp

@@ -6,13 +6,10 @@ $CSharp.namespace("FabAccessAPI.Schema");
 using import "resource.capnp".Resource;
 using import "utils.capnp".OID;
 using import "utils.capnp".Map;
+using import "state.capnp".Update;
 
 interface Notifiable {
-    traits @0 () -> Map(OID, AnyPointer);
-}
-
-interface Notify(State, Update) {
-    state @0 () -> ( state :State );
+    state @0 () -> ( state :Map(OID, AnyPointer) );
     # Returns the current state of a resource.
 
     subscribe @1 ( subscriber :Subscriber(Update) ) -> ( subscription :Subscription );
@@ -21,7 +18,7 @@ interface Notify(State, Update) {
 }
 
 interface Subscriber(Update) {
-    update @0 ( update :Update ) -> ();
+    update @0 ( update :Update ) -> UpdateResult;
     # Called by a server when a new state was produced for this resource.  This method MAY not be
     # called when a resource was updated but did not change its state.  A server will only ever have
     # one running update call per client session, so a client can limit the rate of updates by not
@@ -30,4 +27,8 @@ interface Subscriber(Update) {
     # resource.
 }
 
-interface Subscription { }
+struct UpdateResult { } # Empty struct to make `update` apply backpressure.
+
+interface Subscription { 
+    cancel @0 (); # Cancel this subscription, making the server not send anymore updates.
+}

resource.capnp

@@ -13,12 +13,16 @@ using import "utils.capnp".OID;
 using import "utils.capnp".L10NString;
 using import "utils.capnp".Map;
 
+using import "cache.capnp".Cache;
+
 struct Resource {
     # BFFH's smallest unit of a physical or abstract "thing".  A resource can be as simple and
     # physical as a table, as complex as a PCB production line or as abstract as "people with
     # specific know-how are present".
 
-    description @0 :Describable;
+    description @0 :Cache(Description);
+    # Return information about this resource.  This information is usually
+    # static and thus put behind a Cache.
 
     notify @1 :Notifiable;
     # NULL if the user does not have permission to read this resource, or if this resource is not
@@ -37,12 +41,6 @@ struct Resource {
     # does not support claiming or locking.
 }
 
-interface Describable {
-    description @0 () -> Description;
-    # Return information about this resource.  This information is usually static and does not
-    # change between calls.
-}
-
 struct Description {
     identifier @0 :Text;
     # The unique identifier for this resource
@@ -65,11 +63,28 @@ struct Description {
     # A category this resource belongs to. If a resource was not assigned a category this is empty,
     # see the definition of [`Category`](struct::Category) for details.
 
-    metadata @5 :Map(Text, Text);
+    metadata @5 :Map(Text, Metadata);
     # Metadata associated with this resource.  This can be things like links to wikis or similar.
     # Common keys are pre-defined as constants in this file.
 }
 
+struct Metadata {
+    # Metadata associated with a specific resource description.
+
+    union {
+        inline :group {
+            mediaType @0 :Text;  # Media type of the value sent (as per https://www.iana.org/assignments/media-types/media-types.xhtml )
+            value @1 :Data;     # The value as BLOB
+        }
+
+        remoteInline @2 :Text;
+        # URL pointing to the value. A client should fetch it and show it inline
+
+        remoteUrl @3 :Text;
+        # An URL that *is* the value. A client should display this as a clickable link.
+    }
+}
+
 struct Category {
     # A category this resource belongs to.