Merge pull request #5 from bwindels/bwindels/sending

Send text messages

doc/GOAL.md

@@ -3,3 +3,6 @@ goal:
 write client that works on lumia 950 phone, so I can use matrix on my phone.
 
 try approach offline to indexeddb. go low-memory, and test the performance of storing every event individually in indexeddb.
+
+try to use little bandwidth, mainly by being an offline application and storing all requested data in indexeddb.
+be as functional as possible while offline

doc/SENDING.md

@@ -1,3 +1,11 @@
+# Remaining stuffs
+ - don't swallow send errors, they should probably appear in the room error?
+    - not sure it makes sense to show them where the composer is,
+      because they might get sent a long time after you enter them in brawl,
+      so you don't neccessarily have the context of the composer anymore
+ - local echo
+
+
 takes care of rate limiting,
 and sending events from different rooms in parallel,
 NO: txnIds are created inside room. ~~making txnIds? ... it's rooms though that will receive the event in their sync response~~
@@ -76,8 +84,36 @@ steps of sending
     // sender is the thing that is shared across rooms to handle rate limiting.
     const sendQueue = new SendQueue({roomId, hsApi, sender, storage});
     await sendQueue.load();     //loads the queue?
-                                //might need to load members for e2e rooms
+                                //might need to load members for e2e rooms ...
+                                //events should be encrypted before storing them though ...
  
+
+    // terminology ...?
+    // task: to let us wait for it to be our turn
+    // given rate limiting
+    class Sender {
+        acquireSlot() {
+            return new SendSlot();
+        }
+    }
+    // terminology ...?
+    // task: after waiting for it to be our turn given rate-limiting,
+    // send the actual thing we want to send.
+    // this should be used for all rate-limited apis... ? 
+    class SendSlot {
+        sendContent(content) {
+
+        }
+
+        sendRedaction() {
+
+        }
+
+        uploadMedia() {
+
+        }
+    }
+
     class SendQueue {
         // when trying to send
         enqueueEvent(pendingEvent) {
@@ -93,11 +129,13 @@ steps of sending
             while (let pendingEvent = await findNextPendingEvent()) {
                 pendingEvent.status = QUEUED;
                 try {
-                    await this.sender.sendEvent(() => {
+                    const mediaSlot = await this.sender.acquireSlot();
-                        // callback gets called
+                    const mxcUrl = await mediaSlot.uploadMedia(pendingEvent.blob);
-                        pendingEvent.status = SENDING;
+                    pendingEvent.content.url = mxcUrl;
-                        return pendingEvent;
+                    const contentSlot = await this.sender.acquireSlot();
-                    });
+                    contentSlot.sendContent(pendingEvent.content);
+                    pendingEvent.status = SENDING;
+                    await slot.sendContent(...);
                 } catch (err) {
                     //offline
                 }

src/Platform.js

@@ -1,5 +1,5 @@
-// #ifdef PLATFORM_GNOME
+//#ifdef PLATFORM_GNOME
-// export {default} from "./ui/gnome/GnomePlatform.js";
+//##export {default} from "./ui/gnome/GnomePlatform.js";
-// #else
+//#else
 export {default} from "./ui/web/WebPlatform.js";
-// #endif
+//#endif

src/domain/session/SessionViewModel.js

@@ -45,7 +45,7 @@ export default class SessionViewModel extends EventEmitter {
         }
         this._currentRoomViewModel = new RoomViewModel({
             room,
-            ownUserId: this._session.userId,
+            ownUserId: this._session.user.id,
             closeCallback: () => this._closeCurrentRoom(),
         });
         this._currentRoomViewModel.load();

src/domain/session/room/RoomViewModel.js

@@ -63,4 +63,10 @@ export default class RoomViewModel extends EventEmitter {
     get avatarInitials() {
         return avatarInitials(this._room.name);
     }
+
+    sendMessage(message) {
+        if (message) {
+            this._room.sendEvent("m.room.message", {msgtype: "m.text", body: message});
+        }
+    }
 }

src/domain/session/room/timeline/tiles/MessageTile.js

@@ -4,8 +4,8 @@ export default class MessageTile extends SimpleTile {
 
     constructor(options) {
         super(options);
-        this._isOwn = this._entry.event.sender === options.ownUserId;
+        this._isOwn = this._entry.sender === options.ownUserId;
-        this._date = new Date(this._entry.event.origin_server_ts);
+        this._date = new Date(this._entry.timestamp);
         this._isContinuation = false;
     }
 
@@ -14,7 +14,7 @@ export default class MessageTile extends SimpleTile {
     }
 
     get sender() {
-        return this._entry.event.sender;
+        return this._entry.sender;
     }
 
     get date() {
@@ -34,8 +34,7 @@ export default class MessageTile extends SimpleTile {
     }
 
     _getContent() {
-        const event = this._entry.event;
+        return this._entry.content;
-        return event && event.content;
     }
 
     updatePreviousSibling(prev) {

src/domain/session/room/timeline/tiles/RoomMemberTile.js

@@ -7,21 +7,20 @@ export default class RoomNameTile extends SimpleTile {
     }
 
     get announcement() {
-        const event = this._entry.event;
+        const {sender, content, stateKey} = this._entry;
-        const content = event.content;
         switch (content.membership) {
-            case "invite": return `${event.state_key} was invited to the room by ${event.sender}`;
+            case "invite": return `${stateKey} was invited to the room by ${sender}`;
-            case "join": return `${event.state_key} joined the room`;
+            case "join": return `${stateKey} joined the room`;
             case "leave": {
-                if (event.state_key === event.sender) {
+                if (stateKey === sender) {
-                    return `${event.state_key} left the room`;
+                    return `${stateKey} left the room`;
                 } else {
                     const reason = content.reason;
-                    return `${event.state_key} was kicked from the room by ${event.sender}${reason ? `: ${reason}` : ""}`;
+                    return `${stateKey} was kicked from the room by ${sender}${reason ? `: ${reason}` : ""}`;
                 }
             }
-            case "ban": return `${event.state_key} was banned from the room by ${event.sender}`;
+            case "ban": return `${stateKey} was banned from the room by ${sender}`;
-            default: return `${event.sender} membership changed to ${content.membership}`;
+            default: return `${sender} membership changed to ${content.membership}`;
         }
     }
 }

src/domain/session/room/timeline/tiles/RoomNameTile.js

@@ -7,8 +7,7 @@ export default class RoomNameTile extends SimpleTile {
     }
 
     get announcement() {
-        const event = this._entry.event;
+        const content = this._entry.content;
-        const content = event.content;
+        return `${this._entry.sender} named the room "${content.name}"`
-        return `${event.sender} named the room "${content.name}"`
     }
 }

src/domain/session/room/timeline/tiles/SimpleTile.js

@@ -69,4 +69,8 @@ export default class SimpleTile {
     get internalId() {
         return this._entry.asEventKey().toString();
     }
+
+    get isPending() {
+        return this._entry.isPending;
+    }
 }

src/domain/session/room/timeline/tiles/TextTile.js

@@ -4,9 +4,8 @@ export default class TextTile extends MessageTile {
     get text() {
         const content = this._getContent();
         const body = content && content.body;
-        const sender = this._entry.event.sender;
+        if (content.msgtype === "m.emote") {
-        if (this._entry.type === "m.emote") {
+            return `* ${this._entry.sender} ${body}`;
-            return `* ${sender} ${body}`;
         } else {
             return body;
         }

src/domain/session/room/timeline/tilesCreator.js

@@ -1,6 +1,5 @@
 import GapTile from "./tiles/GapTile.js";
 import TextTile from "./tiles/TextTile.js";
-import ImageTile from "./tiles/ImageTile.js";
 import LocationTile from "./tiles/LocationTile.js";
 import RoomNameTile from "./tiles/RoomNameTile.js";
 import RoomMemberTile from "./tiles/RoomMemberTile.js";
@@ -10,11 +9,10 @@ export default function ({timeline, ownUserId}) {
         const options = {entry, emitUpdate, ownUserId};
         if (entry.isGap) {
             return new GapTile(options, timeline);
-        } else if (entry.event) {
+        } else if (entry.eventType) {
-            const event = entry.event;
+            switch (entry.eventType) {
-            switch (event.type) {
                 case "m.room.message": {
-                    const content = event.content;
+                    const content = entry.content;
                     const msgtype = content && content.msgtype;
                     switch (msgtype) {
                         case "m.text":

src/main.js

@@ -5,7 +5,7 @@ import Sync from "./matrix/sync.js";
 import SessionView from "./ui/web/session/SessionView.js";
 import SessionViewModel from "./domain/session/SessionViewModel.js";
 
-const HOST = "192.168.2.108";
+const HOST = "127.0.0.1";
 const HOMESERVER = `http://${HOST}:8008`;
 const USERNAME = "bruno1";
 const USER_ID = `@${USERNAME}:localhost`;
@@ -76,6 +76,8 @@ export default async function main(container) {
         if (needsInitialSync) {
             showSession(container, session, sync);
         }
+        // this will start sending unsent messages
+        session.notifyNetworkAvailable();
     } catch(err) {
         console.error(`${err.message}:\n${err.stack}`);
     }

src/matrix/SendScheduler.js

@@ -0,0 +1,121 @@
+import Platform from "../Platform.js";
+import {HomeServerError, NetworkError} from "./error.js";
+
+export class RateLimitingBackoff {
+    constructor() {
+        this._remainingRateLimitedRequest = 0;
+    }
+
+    async waitAfterLimitExceeded(retryAfterMs) {
+        // this._remainingRateLimitedRequest = 5;
+        // if (typeof retryAfterMs !== "number") {
+        // } else {
+        // }
+        if (!retryAfterMs) {
+            retryAfterMs = 5000;
+        }
+        await Platform.delay(retryAfterMs);
+    }
+
+    // do we have to know about succeeding requests?
+    // we can just 
+
+    async waitForNextSend() {
+        // this._remainingRateLimitedRequest = Math.max(0, this._remainingRateLimitedRequest - 1);
+    }
+}
+
+/*
+this represents a slot to do one rate limited api call.
+because rate-limiting is handled here, it should only
+try to do one call, so the SendScheduler can safely
+retry if the call ends up being rate limited.
+This is also why we have this abstraction it hsApi is not
+passed straight to SendQueue when it is its turn to send.
+e.g. we wouldn't want to repeat the callback in SendQueue that could
+have other side-effects before the call to hsApi that we wouldn't want
+repeated (setting up progress handlers for file uploads,
+... a UI update to say it started sending?
+ ... updating storage would probably only happen once the call succeeded
+ ... doing multiple hsApi calls for e.g. a file upload before sending a image message (they should individually be retried)
+) maybe it is a bit overengineering, but lets stick with it for now.
+At least the above is a clear definition why we have this class
+*/
+//class SendSlot -- obsolete
+
+export class SendScheduler {
+    constructor({hsApi, backoff}) {
+        this._hsApi = hsApi;
+        this._sendRequests = [];
+        this._sendScheduled = false;
+        this._offline = false;
+        this._waitTime = 0;
+        this._backoff = backoff;
+        /* 
+        we should have some sort of flag here that we enable
+        after all the rooms have been notified that they can resume
+        sending, so that from session, we can say scheduler.enable();
+        this way, when we have better scheduling, it won't be first come,
+        first serve, when there are a lot of events in different rooms to send,
+        but we can apply some priorization of who should go first
+        */
+        // this._enabled;
+    }
+
+    // this should really be per roomId to avoid head-of-line blocking
+    // 
+    // takes a callback instead of returning a promise with the slot
+    // to make sure the scheduler doesn't get blocked by a slot that is not consumed
+    request(sendCallback) {
+        let request;
+        const promise = new Promise((resolve, reject) => request = {resolve, reject, sendCallback});
+        this._sendRequests.push(request);
+        if (!this._sendScheduled && !this._offline) {
+            this._sendLoop();
+        }
+        return promise;
+    }
+
+    async _sendLoop() {
+        while (this._sendRequests.length) {
+            const request = this._sendRequests.shift();
+            let result;
+            try {
+                // this can throw!
+                result = await this._doSend(request.sendCallback);
+            } catch (err) {
+                if (err instanceof NetworkError) {
+                    // we're offline, everybody will have
+                    // to re-request slots when we come back online
+                    this._offline = true;
+                    for (const r of this._sendRequests) {
+                        r.reject(err);
+                    }
+                    this._sendRequests = [];
+                }
+                console.error("error for request", request);
+                request.reject(err);
+                break;
+            }
+            request.resolve(result);
+        }
+        // do next here instead of in _doSend
+    }
+
+    async _doSend(sendCallback) {
+        this._sendScheduled = false;
+        await this._backoff.waitForNextSend();
+        // loop is left by return or throw
+        while (true) { // eslint-disable-line no-constant-condition
+            try {
+                return await sendCallback(this._hsApi);
+            } catch (err) {
+                if (err instanceof HomeServerError && err.errcode === "M_LIMIT_EXCEEDED") {
+                    await this._backoff.waitAfterLimitExceeded(err.retry_after_ms);
+                } else {
+                    throw err;
+                }
+            }
+        }
+    }
+}

src/matrix/User.js

@@ -0,0 +1,9 @@
+export default class User {
+    constructor(userId) {
+        this._userId = userId;
+    }
+
+    get id() {
+        return this._userId;
+    }
+}

src/matrix/error.js

@@ -2,6 +2,13 @@ export class HomeServerError extends Error {
     constructor(method, url, body) {
         super(`${body.error} on ${method} ${url}`);
         this.errcode = body.errcode;
+        this.retry_after_ms = body.retry_after_ms;
+    }
+
+    get isFatal() {
+        switch (this.errcode) {
+            
+        }
     }
 }
 

src/matrix/hs-api.js

@@ -32,6 +32,7 @@ class RequestWrapper {
     }
 }
 
+// todo: everywhere here, encode params in the url that could have slashes ... mainly event ids?
 export default class HomeServerApi {
     constructor(homeserver, accessToken) {
         // store these both in a closure somehow so it's harder to get at in case of XSS?
@@ -98,6 +99,10 @@ export default class HomeServerApi {
         return this._request("POST", csPath, queryParams, body);
     }
 
+    _put(csPath, queryParams, body) {
+        return this._request("PUT", csPath, queryParams, body);
+    }
+
     _get(csPath, queryParams, body) {
         return this._request("GET", csPath, queryParams, body);
     }
@@ -111,6 +116,10 @@ export default class HomeServerApi {
         return this._get(`/rooms/${roomId}/messages`, params);
     }
 
+    send(roomId, eventType, txnId, content) {
+        return this._put(`/rooms/${roomId}/send/${eventType}/${txnId}`, {}, content);
+    }
+
     passwordLogin(username, password) {
         return this._post("/login", undefined, {
           "type": "m.login.password",

src/matrix/room/room.js

@@ -3,9 +3,10 @@ import RoomSummary from "./summary.js";
 import SyncWriter from "./timeline/persistence/SyncWriter.js";
 import Timeline from "./timeline/Timeline.js";
 import FragmentIdComparer from "./timeline/FragmentIdComparer.js";
+import SendQueue from "./sending/SendQueue.js";
 
 export default class Room extends EventEmitter {
-	constructor({roomId, storage, hsApi, emitCollectionChange}) {
+	constructor({roomId, storage, hsApi, emitCollectionChange, sendScheduler, pendingEvents, user}) {
         super();
         this._roomId = roomId;
         this._storage = storage;
@@ -14,16 +15,22 @@ export default class Room extends EventEmitter {
         this._fragmentIdComparer = new FragmentIdComparer([]);
 		this._syncWriter = new SyncWriter({roomId, storage, fragmentIdComparer: this._fragmentIdComparer});
         this._emitCollectionChange = emitCollectionChange;
+        this._sendQueue = new SendQueue({roomId, storage, sendScheduler, pendingEvents});
         this._timeline = null;
+        this._user = user;
 	}
 
     async persistSync(roomResponse, membership, txn) {
 		const summaryChanged = this._summary.applySync(roomResponse, membership, txn);
 		const newTimelineEntries = await this._syncWriter.writeSync(roomResponse, txn);
-        return {summaryChanged, newTimelineEntries};
+        let removedPendingEvents;
+        if (roomResponse.timeline && roomResponse.timeline.events) {
+            removedPendingEvents = this._sendQueue.removeRemoteEchos(roomResponse.timeline.events, txn);
+        }
+        return {summaryChanged, newTimelineEntries, removedPendingEvents};
     }
 
-    emitSync({summaryChanged, newTimelineEntries}) {
+    emitSync({summaryChanged, newTimelineEntries, removedPendingEvents}) {
         if (summaryChanged) {
             this.emit("change");
             this._emitCollectionChange(this);
@@ -31,13 +38,24 @@ export default class Room extends EventEmitter {
         if (this._timeline) {
             this._timeline.appendLiveEntries(newTimelineEntries);
         }
+        if (removedPendingEvents) {
+            this._sendQueue.emitRemovals(removedPendingEvents);
+        }
 	}
 
+    resumeSending() {
+        this._sendQueue.resumeSending();
+    }
+
 	load(summary, txn) {
 		this._summary.load(summary);
 		return this._syncWriter.load(txn);
 	}
 
+    sendEvent(eventType, content) {
+        this._sendQueue.enqueueEvent(eventType, content);
+    }
+
     get name() {
         return this._summary.name;
     }
@@ -55,7 +73,9 @@ export default class Room extends EventEmitter {
             storage: this._storage,
             hsApi: this._hsApi,
             fragmentIdComparer: this._fragmentIdComparer,
+            pendingEvents: this._sendQueue.pendingEvents,
             closeCallback: () => this._timeline = null,
+            user: this._user,
         });
         await this._timeline.load();
         return this._timeline;

src/matrix/room/sending/PendingEvent.js

@@ -0,0 +1,14 @@
+export default class PendingEvent {
+    constructor(data) {
+        this._data = data;
+    }
+
+    get roomId() { return this._data.roomId; }
+    get queueIndex() { return this._data.queueIndex; }
+    get eventType() { return this._data.eventType; }
+    get txnId() { return this._data.txnId; }
+    get remoteId() { return this._data.remoteId; }
+    set remoteId(value) { this._data.remoteId = value; }
+    get content() { return this._data.content; }
+    get data() { return this._data; }
+}

src/matrix/room/sending/SendQueue.js

@@ -0,0 +1,151 @@
+import SortedArray from "../../../observable/list/SortedArray.js";
+import {NetworkError} from "../../error.js";
+import PendingEvent from "./PendingEvent.js";
+
+function makeTxnId() {
+    const n = Math.floor(Math.random() * Number.MAX_SAFE_INTEGER);
+    const str = n.toString(16);
+    return "t" + "0".repeat(14 - str.length) + str;
+}
+
+export default class SendQueue {
+    constructor({roomId, storage, sendScheduler, pendingEvents}) {
+        pendingEvents = pendingEvents || [];
+        this._roomId = roomId;
+        this._storage = storage;
+        this._sendScheduler = sendScheduler;
+        this._pendingEvents = new SortedArray((a, b) => a.queueIndex - b.queueIndex);
+        if (pendingEvents.length) {
+            console.info(`SendQueue for room ${roomId} has ${pendingEvents.length} pending events`, pendingEvents);
+        }
+        this._pendingEvents.setManyUnsorted(pendingEvents.map(data => new PendingEvent(data)));
+        this._isSending = false;
+        this._offline = false;
+        this._amountSent = 0;
+    }
+
+    async _sendLoop() {
+        this._isSending = true;
+        try {
+            console.log("start sending", this._amountSent, "<", this._pendingEvents.length);
+            while (this._amountSent < this._pendingEvents.length) {
+                const pendingEvent = this._pendingEvents.get(this._amountSent);
+                console.log("trying to send", pendingEvent.content.body);
+                this._amountSent += 1;
+                if (pendingEvent.remoteId) {
+                    continue;
+                }
+                console.log("really sending now");
+                const response = await this._sendScheduler.request(hsApi => {
+                    console.log("got sendScheduler slot");
+                    return hsApi.send(
+                        pendingEvent.roomId,
+                        pendingEvent.eventType,
+                        pendingEvent.txnId,
+                        pendingEvent.content
+                    );
+                });
+                pendingEvent.remoteId = response.event_id;
+                // 
+                console.log("writing remoteId now");
+                await this._tryUpdateEvent(pendingEvent);
+                console.log("keep sending?", this._amountSent, "<", this._pendingEvents.length);
+            }
+        } catch(err) {
+            if (err instanceof NetworkError) {
+                this._offline = true;
+            }
+        } finally {
+            this._isSending = false;
+        }
+    }
+
+    removeRemoteEchos(events, txn) {
+        const removed = [];
+        for (const event of events) {
+            const txnId = event.unsigned && event.unsigned.transaction_id;
+            if (txnId) {
+                const idx = this._pendingEvents.array.findIndex(pe => pe.txnId === txnId);
+                if (idx !== -1) {
+                    const pendingEvent = this._pendingEvents.get(idx);
+                    txn.pendingEvents.remove(pendingEvent.roomId, pendingEvent.queueIndex);
+                    removed.push(pendingEvent);
+                }
+            }
+        }
+        return removed;
+    }
+
+    emitRemovals(pendingEvents) {
+        for (const pendingEvent of pendingEvents) {
+            const idx = this._pendingEvents.array.indexOf(pendingEvent);
+            if (idx !== -1) {
+                this._amountSent -= 1;
+                this._pendingEvents.remove(idx);
+            }
+        }
+    }
+
+    resumeSending() {
+        this._offline = false;
+        if (!this._isSending) {
+            this._sendLoop();
+        }
+    }
+
+    async enqueueEvent(eventType, content) {
+        const pendingEvent = await this._createAndStoreEvent(eventType, content);
+        this._pendingEvents.set(pendingEvent);
+        if (!this._isSending && !this._offline) {
+            this._sendLoop();
+        }
+    }
+
+    get pendingEvents() {
+        return this._pendingEvents;
+    }
+
+    async _tryUpdateEvent(pendingEvent) {
+        const txn = await this._storage.readWriteTxn([this._storage.storeNames.pendingEvents]);
+        console.log("_tryUpdateEvent: got txn");
+        try {
+            // pendingEvent might have been removed already here
+            // by a racing remote echo, so check first so we don't recreate it
+            console.log("_tryUpdateEvent: before exists");
+            if (await txn.pendingEvents.exists(pendingEvent.roomId, pendingEvent.queueIndex)) {
+                console.log("_tryUpdateEvent: inside if exists");
+                txn.pendingEvents.update(pendingEvent.data);
+            }
+            console.log("_tryUpdateEvent: after exists");
+        } catch (err) {
+            txn.abort();
+            console.log("_tryUpdateEvent: error", err);
+            throw err;
+        }
+        console.log("_tryUpdateEvent: try complete");
+        await txn.complete();
+    }
+
+    async _createAndStoreEvent(eventType, content) {
+        const txn = await this._storage.readWriteTxn([this._storage.storeNames.pendingEvents]);
+        let pendingEvent;
+        try {
+            const pendingEventsStore = txn.pendingEvents;
+            const maxQueueIndex = await pendingEventsStore.getMaxQueueIndex(this._roomId) || 0;
+            const queueIndex = maxQueueIndex + 1;
+            pendingEvent = new PendingEvent({
+                roomId: this._roomId,
+                queueIndex,
+                eventType,
+                content,
+                txnId: makeTxnId()
+            });
+            pendingEventsStore.add(pendingEvent.data);
+        } catch (err) {
+            txn.abort();
+            throw err;
+        }
+        await txn.complete();
+        return pendingEvent;
+    }
+}

src/matrix/room/timeline/Timeline.js

@@ -1,32 +1,39 @@
-import { SortedArray } from "../../../observable/index.js";
+import { SortedArray, MappedList, ConcatList } from "../../../observable/index.js";
 import Direction from "./Direction.js";
 import GapWriter from "./persistence/GapWriter.js";
 import TimelineReader from "./persistence/TimelineReader.js";
+import PendingEventEntry from "./entries/PendingEventEntry.js";
 
 export default class Timeline {
-    constructor({roomId, storage, closeCallback, fragmentIdComparer, hsApi}) {
+    constructor({roomId, storage, closeCallback, fragmentIdComparer, pendingEvents, user, hsApi}) {
         this._roomId = roomId;
         this._storage = storage;
         this._closeCallback = closeCallback;
         this._fragmentIdComparer = fragmentIdComparer;
         this._hsApi = hsApi;
-        this._entriesList = new SortedArray((a, b) => a.compare(b));
+        this._remoteEntries = new SortedArray((a, b) => a.compare(b));
         this._timelineReader = new TimelineReader({
             roomId: this._roomId,
             storage: this._storage,
             fragmentIdComparer: this._fragmentIdComparer
         });
+        const localEntries = new MappedList(pendingEvents, pe => {
+            return new PendingEventEntry({pendingEvent: pe, user});
+        }, (pee, params) => {
+            pee.notifyUpdate(params);
+        });
+        this._allEntries = new ConcatList(this._remoteEntries, localEntries);
     }
 
     /** @package */
     async load() {
         const entries = await this._timelineReader.readFromEnd(50);
-        this._entriesList.setManySorted(entries);
+        this._remoteEntries.setManySorted(entries);
     }
 
     /** @package */
     appendLiveEntries(newEntries) {
-        this._entriesList.setManySorted(newEntries);
+        this._remoteEntries.setManySorted(newEntries);
     }
 
     /** @public */
@@ -42,12 +49,12 @@ export default class Timeline {
             fragmentIdComparer: this._fragmentIdComparer
         });
         const newEntries = await gapWriter.writeFragmentFill(fragmentEntry, response);
-        this._entriesList.setManySorted(newEntries);
+        this._remoteEntries.setManySorted(newEntries);
     }
 
     // tries to prepend `amount` entries to the `entries` list.
     async loadAtTop(amount) {
-        const firstEventEntry = this._entriesList.array.find(e => !!e.event);
+        const firstEventEntry = this._remoteEntries.array.find(e => !!e.eventType);
         if (!firstEventEntry) {
             return;
         }
@@ -56,12 +63,12 @@ export default class Timeline {
             Direction.Backward,
             amount
         );
-        this._entriesList.setManySorted(entries);
+        this._remoteEntries.setManySorted(entries);
     }
 
     /** @public */
     get entries() {
-        return this._entriesList;
+        return this._allEntries;
     }
 
     /** @public */

src/matrix/room/timeline/entries/BaseEntry.js

@@ -1,5 +1,6 @@
 //entries can be sorted, first by fragment, then by entry index.
 import EventKey from "../EventKey.js";
+export const PENDING_FRAGMENT_ID = Number.MAX_SAFE_INTEGER;
 
 export default class BaseEntry {
     constructor(fragmentIdComparer) {
@@ -17,6 +18,10 @@ export default class BaseEntry {
     compare(otherEntry) {
         if (this.fragmentId === otherEntry.fragmentId) {
             return this.entryIndex - otherEntry.entryIndex;
+        } else if (this.fragmentId === PENDING_FRAGMENT_ID) {
+            return 1;
+        } else if (otherEntry.fragmentId === PENDING_FRAGMENT_ID) {
+            return -1;
         } else {
             // This might throw if the relation of two fragments is unknown.
             return this._fragmentIdComparer.compare(this.fragmentId, otherEntry.fragmentId);

src/matrix/room/timeline/entries/EventEntry.js

@@ -18,12 +18,20 @@ export default class EventEntry extends BaseEntry {
         return this._eventEntry.event.content;
     }
 
-    get event() {
+    get eventType() {
-        return this._eventEntry.event;
+        return this._eventEntry.event.type;
     }
 
-    get type() {
+    get stateKey() {
-        return this._eventEntry.event.type;
+        return this._eventEntry.event.state_key;
+    }
+
+    get sender() {
+        return this._eventEntry.event.sender;
+    }
+
+    get timestamp() {
+        return this._eventEntry.event.origin_server_ts;
     }
 
     get id() {

src/matrix/room/timeline/entries/PendingEventEntry.js

@@ -0,0 +1,53 @@
+import BaseEntry, {PENDING_FRAGMENT_ID} from "./BaseEntry.js";
+
+export default class PendingEventEntry extends BaseEntry {
+    constructor({pendingEvent, user}) {
+        super(null);
+        this._pendingEvent = pendingEvent;
+        this._user = user;
+    }
+
+    get fragmentId() {
+        return PENDING_FRAGMENT_ID;
+    }
+
+    get entryIndex() {
+        return this._pendingEvent.queueIndex;
+    }
+
+    get content() {
+        return this._pendingEvent.content;
+    }
+
+    get event() {
+        return null;
+    }
+
+    get eventType() {
+        return this._pendingEvent.eventType;
+    }
+
+    get stateKey() {
+        return null;
+    }
+
+    get sender() {
+        return this._user.id;
+    }
+
+    get timestamp() {
+        return null;
+    }
+
+    get isPending() {
+        return true;
+    }
+
+    get id() {
+        return this._pendingEvent.txnId;
+    }
+
+    notifyUpdate() {
+        
+    }
+}

src/matrix/session.js

@@ -1,5 +1,7 @@
 import Room from "./room/room.js";
 import { ObservableMap } from "../observable/index.js";
+import { SendScheduler, RateLimitingBackoff } from "./SendScheduler.js";
+import User from "./User.js";
 
 export default class Session {
     // sessionInfo contains deviceId, userId and homeServer
@@ -9,7 +11,9 @@ export default class Session {
         this._session = null;
         this._sessionInfo = sessionInfo;
         this._rooms = new ObservableMap();
+        this._sendScheduler = new SendScheduler({hsApi, backoff: new RateLimitingBackoff()});
         this._roomUpdateCallback = (room, params) => this._rooms.update(room.id, params);
+        this._user = new User(sessionInfo.userId);
     }
 
     async load() {
@@ -19,6 +23,7 @@ export default class Session {
             this._storage.storeNames.roomState,
             this._storage.storeNames.timelineEvents,
             this._storage.storeNames.timelineFragments,
+            this._storage.storeNames.pendingEvents,
         ]);
         // restore session object
         this._session = await txn.session.get();
@@ -26,24 +31,47 @@ export default class Session {
             this._session = {};
             return;
         }
+        const pendingEventsByRoomId = await this._getPendingEventsByRoom(txn);
         // load rooms
         const rooms = await txn.roomSummary.getAll();
         await Promise.all(rooms.map(summary => {
-            const room = this.createRoom(summary.roomId);
+            const room = this.createRoom(summary.roomId, pendingEventsByRoomId.get(summary.roomId));
             return room.load(summary, txn);
         }));
     }
 
+    notifyNetworkAvailable() {
+        for (const [, room] of this._rooms) {
+            room.resumeSending();
+        }
+    }
+
+    async _getPendingEventsByRoom(txn) {
+        const pendingEvents = await txn.pendingEvents.getAll();
+        return pendingEvents.reduce((groups, pe) => {
+            const group = groups.get(pe.roomId);
+            if (group) {
+                group.push(pe);
+            } else {
+                groups.set(pe.roomId, [pe]);
+            }
+            return groups;
+        }, new Map());
+    }
+
     get rooms() {
         return this._rooms;
     }
 
-    createRoom(roomId) {
+    createRoom(roomId, pendingEvents) {
         const room = new Room({
             roomId,
             storage: this._storage,
             emitCollectionChange: this._roomUpdateCallback,
             hsApi: this._hsApi,
+            sendScheduler: this._sendScheduler,
+            pendingEvents,
+            user: this._user,
         });
         this._rooms.add(roomId, room);
         return room;
@@ -60,7 +88,7 @@ export default class Session {
         return this._session.syncToken;
     }
 
-    get userId() {
+    get user() {
-        return this._sessionInfo.userId;
+        return this._user;
     }
 }

src/matrix/storage/common.js

@@ -1,4 +1,11 @@
-export const STORE_NAMES = Object.freeze(["session", "roomState", "roomSummary", "timelineEvents", "timelineFragments"]);
+export const STORE_NAMES = Object.freeze([
+    "session",
+    "roomState",
+    "roomSummary",
+    "timelineEvents",
+    "timelineFragments",
+    "pendingEvents",
+]);
 
 export const STORE_MAP = Object.freeze(STORE_NAMES.reduce((nameMap, name) => {
     nameMap[name] = name;
@@ -16,5 +23,8 @@ export class StorageError extends Error {
             fullMessage += cause.message;
         }
         super(fullMessage);
+        if (cause) {
+            this.errcode = cause.name;
+        }
     }
 }

src/matrix/storage/idb/create.js

@@ -20,6 +20,7 @@ function createStores(db) {
     timelineEvents.createIndex("byEventId", "eventIdKey", {unique: true});
     //key = room_id | event.type | event.state_key,
     db.createObjectStore("roomState", {keyPath: "key"});
+    db.createObjectStore("pendingEvents", {keyPath: "key"});
     
     // const roomMembers = db.createObjectStore("roomMembers", {keyPath: [
     //  "event.room_id",

src/matrix/storage/idb/query-target.js

@@ -21,6 +21,10 @@ export default class QueryTarget {
         return reqAsPromise(this._target.get(key));
     }
 
+    getKey(key) {
+        return reqAsPromise(this._target.getKey(key));
+    }
+
     reduce(range, reducer, initialValue) {
         return this._reduce(range, reducer, initialValue, "next");
     }
@@ -71,6 +75,16 @@ export default class QueryTarget {
         return this._find(range, predicate, "prev");
     }
 
+    async findMaxKey(range) {
+        const cursor = this._target.openKeyCursor(range, "prev");
+        let maxKey;
+        await iterateCursor(cursor, (_, key) => {
+            maxKey = key;
+            return {done: true};
+        });
+        return maxKey;
+    }
+
     /**
      * Checks if a given set of keys exist.
      * Calls `callback(key, found)` for each key in `keys`, in key sorting order (or reversed if backwards=true).

src/matrix/storage/idb/store.js

@@ -46,6 +46,22 @@ class QueryTargetWrapper {
             throw new StorageError("get failed", err);
         }
     }
+    
+    getKey(...params) {
+        try {
+            return this._qt.getKey(...params);
+        } catch(err) {
+            throw new StorageError("getKey failed", err);
+        }
+    }
+
+    delete(...params) {
+        try {
+            return this._qt.delete(...params);
+        } catch(err) {
+            throw new StorageError("delete failed", err);
+        }
+    }
 
     index(...params) {
         try {
@@ -76,4 +92,8 @@ export default class Store extends QueryTarget {
     add(value) {
         return reqAsPromise(this._idbStore.add(value));
     }
+
+    delete(keyOrKeyRange) {
+        return reqAsPromise(this._idbStore.delete(keyOrKeyRange));
+    }
 }

src/matrix/storage/idb/stores/PendingEventStore.js

@@ -0,0 +1,55 @@
+import { encodeUint32, decodeUint32 } from "../utils.js";
+import Platform from "../../../../Platform.js";
+
+function encodeKey(roomId, queueIndex) {
+    return `${roomId}|${encodeUint32(queueIndex)}`;
+}
+
+function decodeKey(key) {
+    const [roomId, encodedQueueIndex] = key.split("|");
+    const queueIndex = decodeUint32(encodedQueueIndex);
+    return {roomId, queueIndex};
+}
+
+export default class PendingEventStore {
+    constructor(eventStore) {
+        this._eventStore = eventStore;
+    }
+
+    async getMaxQueueIndex(roomId) {
+        const range = IDBKeyRange.bound(
+            encodeKey(roomId, Platform.minStorageKey),
+            encodeKey(roomId, Platform.maxStorageKey),
+            false,
+            false,
+        );
+        const maxKey = await this._eventStore.findMaxKey(range);
+        if (maxKey) {
+            return decodeKey(maxKey).queueIndex;
+        }
+    }
+
+    remove(roomId, queueIndex) {
+        const keyRange = IDBKeyRange.only(encodeKey(roomId, queueIndex));
+        this._eventStore.delete(keyRange);
+    }
+
+    async exists(roomId, queueIndex) {
+        const keyRange = IDBKeyRange.only(encodeKey(roomId, queueIndex));
+        const key = await this._eventStore.getKey(keyRange);
+        return !!key;
+    }
+    
+    add(pendingEvent) {
+        pendingEvent.key = encodeKey(pendingEvent.roomId, pendingEvent.queueIndex);
+        return this._eventStore.add(pendingEvent);
+    }
+
+    update(pendingEvent) {
+        return this._eventStore.put(pendingEvent);
+    }
+
+    getAll() {
+        return this._eventStore.selectAll();
+    }
+}

src/matrix/storage/idb/stores/TimelineEventStore.js

@@ -1,13 +1,8 @@
 import EventKey from "../../../room/timeline/EventKey.js";
 import { StorageError } from "../../common.js";
+import { encodeUint32 } from "../utils.js";
 import Platform from "../../../../Platform.js";
 
-// storage keys are defined to be unsigned 32bit numbers in WebPlatform.js, which is assumed by idb
-function encodeUint32(n) {
-    const hex = n.toString(16);
-    return "0".repeat(8 - hex.length) + hex;
-}
-
 function encodeKey(roomId, fragmentId, eventIndex) {
     return `${roomId}|${encodeUint32(fragmentId)}|${encodeUint32(eventIndex)}`;
 }

src/matrix/storage/idb/stores/TimelineFragmentStore.js

@@ -1,10 +1,9 @@
 import { StorageError } from "../../common.js";
 import Platform from "../../../../Platform.js";
+import { encodeUint32 } from "../utils.js";
 
 function encodeKey(roomId, fragmentId) {
-    let fragmentIdHex = fragmentId.toString(16);
+    return `${roomId}|${encodeUint32(fragmentId)}`;
-    fragmentIdHex = "0".repeat(8 - fragmentIdHex.length) + fragmentIdHex;
-    return `${roomId}|${fragmentIdHex}`;
 }
 
 export default class RoomFragmentStore {

src/matrix/storage/idb/transaction.js

@@ -6,6 +6,7 @@ import RoomSummaryStore from "./stores/RoomSummaryStore.js";
 import TimelineEventStore from "./stores/TimelineEventStore.js";
 import RoomStateStore from "./stores/RoomStateStore.js";
 import TimelineFragmentStore from "./stores/TimelineFragmentStore.js";
+import PendingEventStore from "./stores/PendingEventStore.js";
 
 export default class Transaction {
     constructor(txn, allowedStoreNames) {
@@ -55,6 +56,10 @@ export default class Transaction {
         return this._store("roomState", idbStore => new RoomStateStore(idbStore));
     }
 
+    get pendingEvents() {
+        return this._store("pendingEvents", idbStore => new PendingEventStore(idbStore));
+    }
+
     complete() {
         return txnAsPromise(this._txn);
     }

src/matrix/storage/idb/utils.js

@@ -1,5 +1,16 @@
 import { StorageError } from "../common.js";
 
+
+// storage keys are defined to be unsigned 32bit numbers in WebPlatform.js, which is assumed by idb
+export function encodeUint32(n) {
+    const hex = n.toString(16);
+    return "0".repeat(8 - hex.length) + hex;
+}
+
+export function decodeUint32(str) {
+    return parseInt(str, 16);
+}
+
 export function openDatabase(name, createObjectStore, version) {
     const req = window.indexedDB.open(name, version);
     req.onupgradeneeded = (ev) => {

src/matrix/sync.js

@@ -77,6 +77,7 @@ export default class Sync extends EventEmitter {
             storeNames.roomState,
             storeNames.timelineEvents,
             storeNames.timelineFragments,
+            storeNames.pendingEvents,
         ]);
         const roomChanges = [];
         try {

src/observable/BaseObservableCollection.js

@@ -18,7 +18,7 @@ export default class BaseObservableCollection {
         }
         return () => {
             if (handler) {
-                this._handlers.delete(this._handler);
+                this._handlers.delete(handler);
                 if (this._handlers.size === 0) {
                     this.onUnsubscribeLast();
                 }
@@ -30,3 +30,25 @@ export default class BaseObservableCollection {
 
     // Add iterator over handlers here
 }
+
+export function tests() {
+    class Collection extends BaseObservableCollection {
+        constructor() {
+            super();
+            this.firstSubscribeCalls = 0;
+            this.firstUnsubscribeCalls = 0;
+        }
+        onSubscribeFirst() {  this.firstSubscribeCalls += 1; }
+        onUnsubscribeLast() { this.firstUnsubscribeCalls += 1; }
+    }
+
+    return {
+        test_unsubscribe(assert) {
+            const c = new Collection();
+            const unsubscribe = c.subscribe({});
+            unsubscribe();
+            assert.equal(c.firstSubscribeCalls, 1);
+            assert.equal(c.firstUnsubscribeCalls, 1);
+        }
+    }
+}

src/observable/index.js

@@ -5,6 +5,8 @@ import BaseObservableMap from "./map/BaseObservableMap.js";
 // re-export "root" (of chain) collections
 export { default as ObservableArray } from "./list/ObservableArray.js";
 export { default as SortedArray } from "./list/SortedArray.js";
+export { default as MappedList } from "./list/MappedList.js";
+export { default as ConcatList } from "./list/ConcatList.js";
 export { default as ObservableMap } from "./map/ObservableMap.js";
 
 // avoid circular dependency between these classes

src/observable/list/BaseObservableList.js

@@ -3,26 +3,26 @@ import BaseObservableCollection from "../BaseObservableCollection.js";
 export default class BaseObservableList extends BaseObservableCollection {
     emitReset() {
         for(let h of this._handlers) {
-            h.onReset();
+            h.onReset(this);
         }
     }
     // we need batch events, mostly on index based collection though?
     // maybe we should get started without?
     emitAdd(index, value) {
         for(let h of this._handlers) {
-            h.onAdd(index, value);
+            h.onAdd(index, value, this);
         }
     }
 
     emitUpdate(index, value, params) {
         for(let h of this._handlers) {
-            h.onUpdate(index, value, params);
+            h.onUpdate(index, value, params, this);
         }
     }
 
     emitRemove(index, value) {
         for(let h of this._handlers) {
-            h.onRemove(index, value);
+            h.onRemove(index, value, this);
         }
     }
 
@@ -30,7 +30,7 @@ export default class BaseObservableList extends BaseObservableCollection {
     // been removed from its fromIdx
     emitMove(fromIdx, toIdx, value) {
         for(let h of this._handlers) {
-            h.onMove(fromIdx, toIdx, value);
+            h.onMove(fromIdx, toIdx, value, this);
         }
     }
 

src/observable/list/ConcatList.js

@@ -0,0 +1,144 @@
+import BaseObservableList from "./BaseObservableList.js";
+
+export default class ConcatList extends BaseObservableList {
+    constructor(...sourceLists) {
+        super();
+        this._sourceLists = sourceLists;
+        this._sourceUnsubscribes = null;
+    }
+
+    _offsetForSource(sourceList) {
+        const listIdx = this._sourceLists.indexOf(sourceList);
+        let offset = 0;
+        for (let i = 0; i < listIdx; ++i) {
+            offset += this._sourceLists[i].length;
+        }
+        return offset;
+    }
+
+    onSubscribeFirst() {
+        this._sourceUnsubscribes = [];
+        for (const sourceList of this._sourceLists) {
+            this._sourceUnsubscribes.push(sourceList.subscribe(this));
+        }
+    }
+
+    onUnsubscribeLast() {
+        for (const sourceUnsubscribe of this._sourceUnsubscribes) {
+            sourceUnsubscribe();
+        }
+    }
+
+    onReset() {
+        // TODO: not ideal if other source lists are large
+        // but working impl for now
+        // reset, and 
+        this.emitReset();
+        let idx = 0;
+        for(const item of this) {
+            this.emitAdd(idx, item);
+            idx += 1;
+        }
+    }
+
+    onAdd(index, value, sourceList) {
+        this.emitAdd(this._offsetForSource(sourceList) + index, value);
+    }
+
+    onUpdate(index, value, params, sourceList) {
+        this.emitUpdate(this._offsetForSource(sourceList) + index, value, params);
+    }
+
+    onRemove(index, value, sourceList) {
+        this.emitRemove(this._offsetForSource(sourceList) + index, value);
+    }
+
+    onMove(fromIdx, toIdx, value, sourceList) {
+        const offset = this._offsetForSource(sourceList);
+        this.emitMove(offset + fromIdx, offset + toIdx, value);
+    }
+
+    get length() {
+        let len = 0;
+        for (let i = 0; i < this._sourceLists.length; ++i) {
+            len += this._sourceLists[i].length;
+        }
+        return len;
+    }
+
+    [Symbol.iterator]() {
+        let sourceListIdx = 0;
+        let it = this._sourceLists[0][Symbol.iterator]();
+        return {
+            next: () => {
+                let result = it.next();
+                while (result.done) {
+                    sourceListIdx += 1;
+                    if (sourceListIdx >= this._sourceLists.length) {
+                        return result;  //done
+                    }
+                    it = this._sourceLists[sourceListIdx][Symbol.iterator]();
+                    result = it.next();
+                }
+                return result;
+            }
+        }
+    }
+}
+
+import ObservableArray from "./ObservableArray.js";
+export async function tests() {
+    return {
+        test_length(assert) {
+            const all = new ConcatList(
+                new ObservableArray([1, 2, 3]),
+                new ObservableArray([11, 12, 13])
+            );
+            assert.equal(all.length, 6);
+        },
+        test_iterator(assert) {
+            const all = new ConcatList(
+                new ObservableArray([1, 2, 3]),
+                new ObservableArray([11, 12, 13])
+            );
+            const it = all[Symbol.iterator]();
+            assert.equal(it.next().value, 1);
+            assert.equal(it.next().value, 2);
+            assert.equal(it.next().value, 3);
+            assert.equal(it.next().value, 11);
+            assert.equal(it.next().value, 12);
+            assert.equal(it.next().value, 13);
+            assert(it.next().done);
+        },
+        test_add(assert) {
+            const list1 = new ObservableArray([1, 2, 3]);
+            const list2 = new ObservableArray([11, 12, 13]);
+            const all = new ConcatList(list1, list2);
+            let fired = false;
+            all.subscribe({
+                onAdd(index, value) {
+                    fired = true;
+                    assert.equal(index, 4);
+                    assert.equal(value, 11.5);
+                }
+            });
+            list2.insert(1, 11.5);
+            assert(fired);
+        },
+        test_update(assert) {
+            const list1 = new ObservableArray([1, 2, 3]);
+            const list2 = new ObservableArray([11, 12, 13]);
+            const all = new ConcatList(list1, list2);
+            let fired = false;
+            all.subscribe({
+                onUpdate(index, value) {
+                    fired = true;
+                    assert.equal(index, 4);
+                    assert.equal(value, 10);
+                }
+            });
+            list2.emitUpdate(1, 10);
+            assert(fired);
+        },
+    };
+}

src/observable/list/MappedList.js

@@ -0,0 +1,115 @@
+import BaseObservableList from "./BaseObservableList.js";
+
+export default class MappedList extends BaseObservableList {
+    constructor(sourceList, mapper, updater) {
+        super();
+        this._sourceList = sourceList;
+        this._mapper = mapper;
+        this._updater = updater;
+        this._sourceUnsubscribe = null;
+        this._mappedValues = null;
+    }
+
+    onSubscribeFirst() {
+        this._sourceUnsubscribe = this._sourceList.subscribe(this);
+        this._mappedValues = [];
+        for (const item of this._sourceList) {
+            this._mappedValues.push(this._mapper(item));
+        }
+    }
+
+    onReset() {
+        this._mappedValues = [];
+        this.emitReset();
+    }
+
+    onAdd(index, value) {
+        const mappedValue = this._mapper(value);
+        this._mappedValues.splice(index, 0, mappedValue);
+        this.emitAdd(index, mappedValue);
+    }
+
+    onUpdate(index, value, params) {
+        const mappedValue = this._mappedValues[index];
+        if (this._updater) {
+            this._updater(mappedValue, params, value);
+        }
+        this.emitUpdate(index, mappedValue, params);
+    }
+
+    onRemove(index) {
+        const mappedValue = this._mappedValues[index];
+        this._mappedValues.splice(index, 1);
+        this.emitRemove(index, mappedValue);
+    }
+
+    onMove(fromIdx, toIdx) {
+        const mappedValue = this._mappedValues[fromIdx];
+        this._mappedValues.splice(fromIdx, 1);
+        this._mappedValues.splice(toIdx, 0, mappedValue);
+        this.emitMove(fromIdx, toIdx, mappedValue);
+    }
+
+    onUnsubscribeLast() {
+        this._sourceUnsubscribe();
+    }
+
+    get length() {
+        return this._mappedValues.length;
+    }
+
+    [Symbol.iterator]() {
+        return this._mappedValues.values();
+    }
+}
+
+export async function tests() {
+    class MockList extends BaseObservableList {
+        get length() {
+            return 0;
+        }
+        [Symbol.iterator]() {
+            return [].values();
+        }
+    }
+
+    return {
+        test_add(assert) {
+            const source = new MockList();
+            const mapped = new MappedList(source, n => {return {n: n*n};});
+            let fired = false;
+            const unsubscribe = mapped.subscribe({
+                onAdd(idx, value) {
+                    fired = true;
+                    assert.equal(idx, 0);
+                    assert.equal(value.n, 36);
+                }
+            });
+            source.emitAdd(0, 6);
+            assert(fired);
+            unsubscribe();
+        },
+        test_update(assert) {
+            const source = new MockList();
+            const mapped = new MappedList(
+                source,
+                n => {return {n: n*n};},
+                (o, p, n) => o.m = n*n
+            );
+            let fired = false;
+            const unsubscribe = mapped.subscribe({
+                onAdd() {},
+                onUpdate(idx, value) {
+                    fired = true;
+                    assert.equal(idx, 0);
+                    assert.equal(value.n, 36);
+                    assert.equal(value.m, 49);
+                }
+            });
+            source.emitAdd(0, 6);
+            source.emitUpdate(0, 7);
+            assert(fired);
+            unsubscribe();
+        }
+    };
+}

src/observable/list/ObservableArray.js

@@ -1,9 +1,9 @@
 import BaseObservableList from "./BaseObservableList.js";
 
 export default class ObservableArray extends BaseObservableList {
-    constructor() {
+    constructor(initialValues = []) {
         super();
-        this._items = [];
+        this._items = initialValues;
     }
 
     append(item) {

src/observable/list/SortedArray.js

@@ -8,6 +8,10 @@ export default class SortedArray extends BaseObservableList {
         this._items = [];
     }
 
+    setManyUnsorted(items) {
+        this.setManySorted(items);
+    }
+
     setManySorted(items) {
         // TODO: we can make this way faster by only looking up the first and last key,
         // and merging whatever is inbetween with items
@@ -32,8 +36,14 @@ export default class SortedArray extends BaseObservableList {
         }
     }
 
-    remove(item) {
+    get(idx) {
-        throw new Error("unimplemented");
+        return this._items[idx];
+    }
+
+    remove(idx) {
+        const item = this._items[idx];
+        this._items.splice(idx, 1);
+        this.emitRemove(idx, item);
     }
 
     get array() {

src/ui/web/WebPlatform.js

@@ -13,4 +13,8 @@ export default {
         // for indexeddb, we use unsigned 32 bit integers as keys
         return 0xFFFFFFFF;
     },
+
+    delay(ms) {
+        return new Promise(resolve => setTimeout(resolve, ms));
+    }
 }

src/ui/web/css/layout.css

@@ -50,6 +50,11 @@ body {
     min-height: 0;
     display: flex;
     flex-direction: column;
+    height: 100%;
+}
+
+.TimelinePanel ul {
+    flex: 1 0 0;
 }
 
 .RoomHeader {

src/ui/web/css/room.css

@@ -69,3 +69,11 @@
 .RoomView_error {
     color: red;
 }
+
+.MessageComposer > input {
+    display: block;
+    width: 100%;
+    box-sizing: border-box;
+    padding: 0.8em;
+    border: none;
+}

src/ui/web/css/timeline.css

@@ -1,6 +1,5 @@
 
 .TimelinePanel ul {
-    flex: 1;
     overflow-y: auto;
     list-style: none;
     padding: 0;
@@ -54,6 +53,10 @@
     background-color: darkgreen;
 }
 
+.TextMessageView.pending .message-container {
+    background-color: #333;
+}
+
 .message-container p {
     margin: 5px 0;
 }

src/ui/web/general/html.js

@@ -70,7 +70,7 @@ export function text(str) {
 export const TAG_NAMES = [
     "ol", "ul", "li", "div", "h1", "h2", "h3", "h4", "h5", "h6",
     "p", "strong", "em", "span", "img", "section", "main", "article", "aside",
-    "pre", "button", "time"];
+    "pre", "button", "time", "input", "textarea"];
 
 export const tag = {};
 

src/ui/web/session/room/MessageComposer.js

@@ -0,0 +1,23 @@
+import TemplateView from "../../general/TemplateView.js";
+
+export default class MessageComposer extends TemplateView {
+    constructor(viewModel) {
+        super(viewModel);
+        this._input = null;
+    }
+
+    render(t) {
+        this._input = t.input({
+            placeholder: "Send a message ...",
+            onKeydown: e => this._onKeyDown(e)
+        });
+        return t.div({className: "MessageComposer"}, [this._input]);
+    }
+
+    _onKeyDown(event) {
+        if (event.key === "Enter") {
+            this.viewModel.sendMessage(this._input.value);
+            this._input.value = "";
+        }
+    }
+}

src/ui/web/session/room/RoomView.js

@@ -1,5 +1,6 @@
 import TemplateView from "../../general/TemplateView.js";
 import TimelineList from "./TimelineList.js";
+import MessageComposer from "./MessageComposer.js";
 
 export default class RoomView extends TemplateView {
     constructor(viewModel) {
@@ -18,17 +19,20 @@ export default class RoomView extends TemplateView {
                     ]),
                 ]),
                 t.div({className: "RoomView_error"}, vm => vm.error),
-                this._timelineList.mount()
+                this._timelineList.mount(),
+                this._composer.mount(),
             ])
         ]);
     }
 
     mount() {
+        this._composer = new MessageComposer(this.viewModel);
         this._timelineList = new TimelineList();
         return super.mount();
     }
 
     unmount() {
+        this._composer.unmount();
         this._timelineList.unmount();
         super.unmount();
     }

src/ui/web/session/room/timeline/TextMessageView.js

@@ -4,7 +4,7 @@ export default class TextMessageView extends TemplateView {
     render(t, vm) {
         // no bindings ... should this be a template view?
         return t.li(
-            {className: {"TextMessageView": true, own: vm.isOwn}},
+            {className: {"TextMessageView": true, own: vm.isOwn, pending: vm.isPending}},
             t.div({className: "message-container"}, [
                 t.div({className: "sender"}, vm => vm.isContinuation ? "" : vm.sender),
                 t.p([vm.text, t.time(vm.date + " " + vm.time)]),