diff --git a/beacon_node/beacon_chain/src/beacon_chain.rs b/beacon_node/beacon_chain/src/beacon_chain.rs
index ad0627078b..33205e97c3 100644
--- a/beacon_node/beacon_chain/src/beacon_chain.rs
+++ b/beacon_node/beacon_chain/src/beacon_chain.rs
@@ -1,6 +1,7 @@
 use crate::checkpoint::CheckPoint;
 use crate::errors::{BeaconChainError as Error, BlockProductionError};
 use crate::eth1_chain::{Eth1Chain, Eth1ChainBackend};
+use crate::events::{EventHandler, EventKind};
 use crate::fork_choice::{Error as ForkChoiceError, ForkChoice};
 use crate::iter::{ReverseBlockRootIterator, ReverseStateRootIterator};
 use crate::metrics;
@@ -95,6 +96,7 @@ pub trait BeaconChainTypes: Send + Sync + 'static {
     type LmdGhost: LmdGhost<Self::Store, Self::EthSpec>;
     type Eth1Chain: Eth1ChainBackend<Self::EthSpec>;
     type EthSpec: types::EthSpec;
+    type EventHandler: EventHandler<Self::EthSpec>;
 }
 
 /// Represents the "Beacon Chain" component of Ethereum 2.0. Allows import of blocks and block
@@ -117,6 +119,8 @@ pub struct BeaconChain<T: BeaconChainTypes> {
     /// A state-machine that is updated with information from the network and chooses a canonical
     /// head block.
     pub fork_choice: ForkChoice<T>,
+    /// A handler for events generated by the beacon chain.
+    pub event_handler: T::EventHandler,
     /// Logging to CLI, etc.
     log: Logger,
 }
@@ -126,6 +130,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     pub fn from_genesis(
         store: Arc<T::Store>,
         eth1_backend: T::Eth1Chain,
+        event_handler: T::EventHandler,
         mut genesis_state: BeaconState<T::EthSpec>,
         mut genesis_block: BeaconBlock<T::EthSpec>,
         spec: ChainSpec,
@@ -174,6 +179,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             canonical_head,
             genesis_block_root,
             fork_choice: ForkChoice::new(store.clone(), &genesis_block, genesis_block_root),
+            event_handler,
             store,
             log,
         })
@@ -183,6 +189,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     pub fn from_store(
         store: Arc<T::Store>,
         eth1_backend: T::Eth1Chain,
+        event_handler: T::EventHandler,
         spec: ChainSpec,
         log: Logger,
     ) -> Result<Option<BeaconChain<T>>, Error> {
@@ -219,6 +226,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             slot_clock,
             fork_choice: ForkChoice::new(store.clone(), last_finalized_block, last_finalized_root),
             op_pool,
+            event_handler,
             eth1_chain: Eth1Chain::new(eth1_backend),
             canonical_head: RwLock::new(p.canonical_head),
             genesis_block_root: p.genesis_block_root,
@@ -629,6 +637,59 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     pub fn process_attestation(
         &self,
         attestation: Attestation<T::EthSpec>,
+    ) -> Result<AttestationProcessingOutcome, Error> {
+        let outcome = self.process_attestation_internal(attestation.clone());
+
+        match &outcome {
+            Ok(outcome) => match outcome {
+                AttestationProcessingOutcome::Processed => {
+                    trace!(
+                        self.log,
+                        "Beacon attestation imported";
+                        "shard" => attestation.data.crosslink.shard,
+                        "target_epoch" => attestation.data.target.epoch,
+                    );
+                    let _ = self
+                        .event_handler
+                        .register(EventKind::BeaconAttestationImported {
+                            attestation: Box::new(attestation),
+                        });
+                }
+                other => {
+                    warn!(
+                        self.log,
+                        "Beacon attestation rejected";
+                        "reason" => format!("{:?}", other),
+                    );
+                    let _ = self
+                        .event_handler
+                        .register(EventKind::BeaconAttestationRejected {
+                            reason: format!("Invalid attestation: {:?}", other),
+                            attestation: Box::new(attestation),
+                        });
+                }
+            },
+            Err(e) => {
+                error!(
+                    self.log,
+                    "Beacon attestation processing error";
+                    "error" => format!("{:?}", e),
+                );
+                let _ = self
+                    .event_handler
+                    .register(EventKind::BeaconAttestationRejected {
+                        reason: format!("Internal error: {:?}", e),
+                        attestation: Box::new(attestation),
+                    });
+            }
+        }
+
+        outcome
+    }
+
+    pub fn process_attestation_internal(
+        &self,
+        attestation: Attestation<T::EthSpec>,
     ) -> Result<AttestationProcessingOutcome, Error> {
         metrics::inc_counter(&metrics::ATTESTATION_PROCESSING_REQUESTS);
         let timer = metrics::start_timer(&metrics::ATTESTATION_PROCESSING_TIMES);
@@ -932,6 +993,57 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     pub fn process_block(
         &self,
         block: BeaconBlock<T::EthSpec>,
+    ) -> Result<BlockProcessingOutcome, Error> {
+        let outcome = self.process_block_internal(block.clone());
+
+        match &outcome {
+            Ok(outcome) => match outcome {
+                BlockProcessingOutcome::Processed { block_root } => {
+                    trace!(
+                        self.log,
+                        "Beacon block imported";
+                        "block_root" => format!("{:?}", block_root),
+                        "block_slot" => format!("{:?}", block_root),
+                    );
+                    let _ = self.event_handler.register(EventKind::BeaconBlockImported {
+                        block_root: *block_root,
+                        block: Box::new(block),
+                    });
+                }
+                other => {
+                    warn!(
+                        self.log,
+                        "Beacon block rejected";
+                        "reason" => format!("{:?}", other),
+                    );
+                    let _ = self.event_handler.register(EventKind::BeaconBlockRejected {
+                        reason: format!("Invalid block: {:?}", other),
+                        block: Box::new(block),
+                    });
+                }
+            },
+            Err(e) => {
+                error!(
+                    self.log,
+                    "Beacon block processing error";
+                    "error" => format!("{:?}", e),
+                );
+                let _ = self.event_handler.register(EventKind::BeaconBlockRejected {
+                    reason: format!("Internal error: {:?}", e),
+                    block: Box::new(block),
+                });
+            }
+        }
+
+        outcome
+    }
+
+    /// Accept some block and attempt to add it to block DAG.
+    ///
+    /// Will accept blocks from prior slots, however it will reject any block from a future slot.
+    fn process_block_internal(
+        &self,
+        block: BeaconBlock<T::EthSpec>,
     ) -> Result<BlockProcessingOutcome, Error> {
         metrics::inc_counter(&metrics::BLOCK_PROCESSING_REQUESTS);
         let full_timer = metrics::start_timer(&metrics::BLOCK_PROCESSING_TIMES);
diff --git a/beacon_node/beacon_chain/src/beacon_chain_builder.rs b/beacon_node/beacon_chain/src/beacon_chain_builder.rs
index 2a3537020a..357644a2d5 100644
--- a/beacon_node/beacon_chain/src/beacon_chain_builder.rs
+++ b/beacon_node/beacon_chain/src/beacon_chain_builder.rs
@@ -131,10 +131,11 @@ impl<T: BeaconChainTypes> BeaconChainBuilder<T> {
         self,
         store: Arc<T::Store>,
         eth1_backend: T::Eth1Chain,
+        event_handler: T::EventHandler,
     ) -> Result<BeaconChain<T>, String> {
         Ok(match self.build_strategy {
             BuildStrategy::LoadFromStore => {
-                BeaconChain::from_store(store, eth1_backend, self.spec, self.log)
+                BeaconChain::from_store(store, eth1_backend, event_handler, self.spec, self.log)
                     .map_err(|e| format!("Error loading BeaconChain from database: {:?}", e))?
                     .ok_or_else(|| format!("Unable to find exising BeaconChain in database."))?
             }
@@ -144,6 +145,7 @@ impl<T: BeaconChainTypes> BeaconChainBuilder<T> {
             } => BeaconChain::from_genesis(
                 store,
                 eth1_backend,
+                event_handler,
                 genesis_state.as_ref().clone(),
                 genesis_block.as_ref().clone(),
                 self.spec,
diff --git a/beacon_node/beacon_chain/src/events.rs b/beacon_node/beacon_chain/src/events.rs
new file mode 100644
index 0000000000..d690eabf18
--- /dev/null
+++ b/beacon_node/beacon_chain/src/events.rs
@@ -0,0 +1,51 @@
+use serde_derive::{Deserialize, Serialize};
+use std::marker::PhantomData;
+use types::{Attestation, BeaconBlock, EthSpec, Hash256};
+
+pub trait EventHandler<T: EthSpec>: Sized + Send + Sync {
+    fn register(&self, kind: EventKind<T>) -> Result<(), String>;
+}
+
+pub struct NullEventHandler<T: EthSpec>(PhantomData<T>);
+
+impl<T: EthSpec> EventHandler<T> for NullEventHandler<T> {
+    fn register(&self, _kind: EventKind<T>) -> Result<(), String> {
+        Ok(())
+    }
+}
+
+impl<T: EthSpec> Default for NullEventHandler<T> {
+    fn default() -> Self {
+        NullEventHandler(PhantomData)
+    }
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+#[serde(
+    bound = "T: EthSpec",
+    rename_all = "snake_case",
+    tag = "event",
+    content = "data"
+)]
+pub enum EventKind<T: EthSpec> {
+    BeaconHeadChanged {
+        reorg: bool,
+        current_head_beacon_block_root: Hash256,
+        previous_head_beacon_block_root: Hash256,
+    },
+    BeaconBlockImported {
+        block_root: Hash256,
+        block: Box<BeaconBlock<T>>,
+    },
+    BeaconBlockRejected {
+        reason: String,
+        block: Box<BeaconBlock<T>>,
+    },
+    BeaconAttestationImported {
+        attestation: Box<Attestation<T>>,
+    },
+    BeaconAttestationRejected {
+        reason: String,
+        attestation: Box<Attestation<T>>,
+    },
+}
diff --git a/beacon_node/beacon_chain/src/lib.rs b/beacon_node/beacon_chain/src/lib.rs
index 0361723489..7f7e4ec2b9 100644
--- a/beacon_node/beacon_chain/src/lib.rs
+++ b/beacon_node/beacon_chain/src/lib.rs
@@ -7,6 +7,7 @@ mod beacon_chain_builder;
 mod checkpoint;
 mod errors;
 mod eth1_chain;
+pub mod events;
 mod fork_choice;
 mod iter;
 mod metrics;
diff --git a/beacon_node/beacon_chain/src/test_utils.rs b/beacon_node/beacon_chain/src/test_utils.rs
index 7670ac74e4..97b802ddfe 100644
--- a/beacon_node/beacon_chain/src/test_utils.rs
+++ b/beacon_node/beacon_chain/src/test_utils.rs
@@ -1,6 +1,6 @@
 use crate::{
-    AttestationProcessingOutcome, BeaconChain, BeaconChainBuilder, BeaconChainTypes,
-    BlockProcessingOutcome, InteropEth1ChainBackend,
+    events::NullEventHandler, AttestationProcessingOutcome, BeaconChain, BeaconChainBuilder,
+    BeaconChainTypes, BlockProcessingOutcome, InteropEth1ChainBackend,
 };
 use lmd_ghost::LmdGhost;
 use rayon::prelude::*;
@@ -68,6 +68,7 @@ where
     type LmdGhost = L;
     type Eth1Chain = InteropEth1ChainBackend<E>;
     type EthSpec = E;
+    type EventHandler = NullEventHandler<E>;
 }
 
 /// A testing harness which can instantiate a `BeaconChain` and populate it with blocks and
@@ -103,7 +104,11 @@ where
         let chain =
             BeaconChainBuilder::quick_start(HARNESS_GENESIS_TIME, &keypairs, spec.clone(), log)
                 .unwrap_or_else(|e| panic!("Failed to create beacon chain builder: {}", e))
-                .build(store.clone(), InteropEth1ChainBackend::default())
+                .build(
+                    store.clone(),
+                    InteropEth1ChainBackend::default(),
+                    NullEventHandler::default(),
+                )
                 .unwrap_or_else(|e| panic!("Failed to build beacon chain: {}", e));
 
         Self {
diff --git a/beacon_node/client/Cargo.toml b/beacon_node/client/Cargo.toml
index 383318b0d3..e557217938 100644
--- a/beacon_node/client/Cargo.toml
+++ b/beacon_node/client/Cargo.toml
@@ -6,6 +6,7 @@ edition = "2018"
 
 [dependencies]
 beacon_chain = { path = "../beacon_chain" }
+store = { path = "../store" }
 network = { path = "../network" }
 eth2-libp2p = { path = "../eth2-libp2p" }
 rpc = { path = "../rpc" }
diff --git a/beacon_node/client/src/lib.rs b/beacon_node/client/src/lib.rs
index 08674166d6..b4c7c9347a 100644
--- a/beacon_node/client/src/lib.rs
+++ b/beacon_node/client/src/lib.rs
@@ -20,18 +20,19 @@ use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
 use tokio::runtime::TaskExecutor;
 use tokio::timer::Interval;
 use types::EthSpec;
+use websocket_server::WebSocketSender;
 
 pub use beacon_chain::{BeaconChainTypes, Eth1ChainBackend, InteropEth1ChainBackend};
 pub use config::{BeaconChainStartMethod, Config as ClientConfig, Eth1BackendMethod};
 pub use eth2_config::Eth2Config;
 
 #[derive(Clone)]
-pub struct ClientType<S: Store, E: EthSpec> {
+pub struct RuntimeBeaconChainTypes<S: Store, E: EthSpec> {
     _phantom_s: PhantomData<S>,
     _phantom_e: PhantomData<E>,
 }
 
-impl<S, E> BeaconChainTypes for ClientType<S, E>
+impl<S, E> BeaconChainTypes for RuntimeBeaconChainTypes<S, E>
 where
     S: Store + 'static,
     E: EthSpec,
@@ -41,17 +42,22 @@ where
     type LmdGhost = ThreadSafeReducedTree<S, E>;
     type Eth1Chain = InteropEth1ChainBackend<E>;
     type EthSpec = E;
+    type EventHandler = WebSocketSender<E>;
 }
 
 /// Main beacon node client service. This provides the connection and initialisation of the clients
 /// sub-services in multiple threads.
-pub struct Client<T: BeaconChainTypes> {
+pub struct Client<S, E>
+where
+    S: Store + Clone + 'static,
+    E: EthSpec,
+{
     /// Configuration for the lighthouse client.
     _client_config: ClientConfig,
     /// The beacon chain for the running client.
-    beacon_chain: Arc<BeaconChain<T>>,
+    beacon_chain: Arc<BeaconChain<RuntimeBeaconChainTypes<S, E>>>,
     /// Reference to the network service.
-    pub network: Arc<NetworkService<T>>,
+    pub network: Arc<NetworkService<RuntimeBeaconChainTypes<S, E>>>,
     /// Signal to terminate the RPC server.
     pub rpc_exit_signal: Option<Signal>,
     /// Signal to terminate the slot timer.
@@ -60,19 +66,22 @@ pub struct Client<T: BeaconChainTypes> {
     pub api_exit_signal: Option<Signal>,
     /// The clients logger.
     log: slog::Logger,
+    /*
     /// Marker to pin the beacon chain generics.
-    phantom: PhantomData<T>,
+    phantom: PhantomData<BeaconChainTypes>,
+    */
 }
 
-impl<T> Client<T>
+impl<S, E> Client<S, E>
 where
-    T: BeaconChainTypes + Clone,
+    S: Store + Clone + 'static,
+    E: EthSpec,
 {
     /// Generate an instance of the client. Spawn and link all internal sub-processes.
     pub fn new(
         client_config: ClientConfig,
         eth2_config: Eth2Config,
-        store: T::Store,
+        store: S,
         log: slog::Logger,
         executor: &TaskExecutor,
     ) -> error::Result<Self> {
@@ -169,11 +178,19 @@ where
             }
         };
 
-        let eth1_backend = T::Eth1Chain::new(String::new()).map_err(|e| format!("{:?}", e))?;
+        let eth1_backend =
+            InteropEth1ChainBackend::new(String::new()).map_err(|e| format!("{:?}", e))?;
 
-        let beacon_chain: Arc<BeaconChain<T>> = Arc::new(
+        // Start the websocket server.
+        let websocket_sender: WebSocketSender<E> = if client_config.websocket_server.enabled {
+            websocket_server::start_server(&client_config.websocket_server, &log)?
+        } else {
+            WebSocketSender::dummy()
+        };
+
+        let beacon_chain: Arc<BeaconChain<RuntimeBeaconChainTypes<S, E>>> = Arc::new(
             beacon_chain_builder
-                .build(store, eth1_backend)
+                .build(store, eth1_backend, websocket_sender)
                 .map_err(error::Error::from)?,
         );
 
@@ -229,11 +246,6 @@ where
             None
         };
 
-        // Start the websocket server
-        let _websocket_sender = if client_config.websocket_server.enabled {
-            websocket_server::start_server::<T::EthSpec>(&client_config.websocket_server, &log)?;
-        };
-
         let (slot_timer_exit_signal, exit) = exit_future::signal();
         if let Some(duration_to_next_slot) = beacon_chain.slot_clock.duration_to_next_slot() {
             // set up the validator work interval - start at next slot and proceed every slot
@@ -268,12 +280,11 @@ where
             api_exit_signal,
             log,
             network,
-            phantom: PhantomData,
         })
     }
 }
 
-impl<T: BeaconChainTypes> Drop for Client<T> {
+impl<S: Store + Clone, E: EthSpec> Drop for Client<S, E> {
     fn drop(&mut self) {
         // Save the beacon chain to it's store before dropping.
         let _result = self.beacon_chain.persist();
diff --git a/beacon_node/client/src/notifier.rs b/beacon_node/client/src/notifier.rs
index 343918d4d5..20da963ec3 100644
--- a/beacon_node/client/src/notifier.rs
+++ b/beacon_node/client/src/notifier.rs
@@ -1,11 +1,12 @@
 use crate::Client;
-use beacon_chain::BeaconChainTypes;
 use exit_future::Exit;
 use futures::{Future, Stream};
 use slog::{debug, o, warn};
 use std::time::{Duration, Instant};
+use store::Store;
 use tokio::runtime::TaskExecutor;
 use tokio::timer::Interval;
+use types::EthSpec;
 
 /// The interval between heartbeat events.
 pub const HEARTBEAT_INTERVAL_SECONDS: u64 = 15;
@@ -17,7 +18,11 @@ pub const WARN_PEER_COUNT: usize = 1;
 /// durations.
 ///
 /// Presently unused, but remains for future use.
-pub fn run<T: BeaconChainTypes>(client: &Client<T>, executor: TaskExecutor, exit: Exit) {
+pub fn run<S, E>(client: &Client<S, E>, executor: TaskExecutor, exit: Exit)
+where
+    S: Store + Clone + 'static,
+    E: EthSpec,
+{
     // notification heartbeat
     let interval = Interval::new(
         Instant::now(),
diff --git a/beacon_node/src/run.rs b/beacon_node/src/run.rs
index d036ef0c40..3d6607552c 100644
--- a/beacon_node/src/run.rs
+++ b/beacon_node/src/run.rs
@@ -1,19 +1,17 @@
-use client::{
-    error, notifier, BeaconChainTypes, Client, ClientConfig, ClientType, Eth1BackendMethod,
-    Eth2Config,
-};
+use client::{error, notifier, Client, ClientConfig, Eth1BackendMethod, Eth2Config};
 use futures::sync::oneshot;
 use futures::Future;
 use slog::{error, info};
 use std::cell::RefCell;
 use std::path::Path;
 use std::path::PathBuf;
+use store::Store;
 use store::{DiskStore, MemoryStore};
 use tokio::runtime::Builder;
 use tokio::runtime::Runtime;
 use tokio::runtime::TaskExecutor;
 use tokio_timer::clock::Clock;
-use types::{InteropEthSpec, MainnetEthSpec, MinimalEthSpec};
+use types::{EthSpec, InteropEthSpec, MainnetEthSpec, MinimalEthSpec};
 
 /// Reads the configuration and initializes a `BeaconChain` with the required types and parameters.
 ///
@@ -52,14 +50,7 @@ pub fn run_beacon_node(
 
     macro_rules! run_client {
         ($store: ty, $eth_spec: ty) => {
-            run::<ClientType<$store, $eth_spec>>(
-                &db_path,
-                client_config,
-                eth2_config,
-                executor,
-                runtime,
-                log,
-            )
+            run::<$store, $eth_spec>(&db_path, client_config, eth2_config, executor, runtime, log)
         };
     }
 
@@ -82,7 +73,7 @@ pub fn run_beacon_node(
 }
 
 /// Performs the type-generic parts of launching a `BeaconChain`.
-fn run<T>(
+fn run<S, E>(
     db_path: &Path,
     client_config: ClientConfig,
     eth2_config: Eth2Config,
@@ -91,12 +82,13 @@ fn run<T>(
     log: &slog::Logger,
 ) -> error::Result<()>
 where
-    T: BeaconChainTypes + Clone,
-    T::Store: OpenDatabase,
+    S: Store + Clone + 'static + OpenDatabase,
+    E: EthSpec,
 {
-    let store = T::Store::open_database(&db_path)?;
+    let store = S::open_database(&db_path)?;
 
-    let client: Client<T> = Client::new(client_config, eth2_config, store, log.clone(), &executor)?;
+    let client: Client<S, E> =
+        Client::new(client_config, eth2_config, store, log.clone(), &executor)?;
 
     // run service until ctrl-c
     let (ctrlc_send, ctrlc_oneshot) = oneshot::channel();
diff --git a/beacon_node/websocket_server/Cargo.toml b/beacon_node/websocket_server/Cargo.toml
index f846f62b7c..a7bf85b12d 100644
--- a/beacon_node/websocket_server/Cargo.toml
+++ b/beacon_node/websocket_server/Cargo.toml
@@ -7,10 +7,12 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+beacon_chain = { path = "../beacon_chain" }
 exit-future = "0.1.3"
 futures = "0.1.25"
 serde = "1.0"
 serde_derive = "1.0"
+serde_json = "^1.0"
 slog = "^2.2.3"
 tokio = "0.1.16"
 types = { path = "../../eth2/types" }
diff --git a/beacon_node/websocket_server/src/lib.rs b/beacon_node/websocket_server/src/lib.rs
index eb28b10bea..1c7d9ddb9b 100644
--- a/beacon_node/websocket_server/src/lib.rs
+++ b/beacon_node/websocket_server/src/lib.rs
@@ -1,5 +1,7 @@
-use serde_derive::{Deserialize, Serialize};
+use beacon_chain::events::{EventHandler, EventKind};
+use serde::{Deserialize, Serialize};
 use slog::{error, info, Logger};
+use std::marker::PhantomData;
 use std::net::Ipv4Addr;
 use std::thread;
 use types::EthSpec;
@@ -25,19 +27,44 @@ impl Default for Config {
     }
 }
 
-pub struct WebSocketSender {
-    sender: Sender,
+pub struct WebSocketSender<T: EthSpec> {
+    sender: Option<Sender>,
+    _phantom: PhantomData<T>,
 }
 
-impl WebSocketSender {
+impl<T: EthSpec> WebSocketSender<T> {
+    /// Creates a dummy websocket server that never starts and where all future calls are no-ops.
+    pub fn dummy() -> Self {
+        Self {
+            sender: None,
+            _phantom: PhantomData,
+        }
+    }
+
     pub fn send_string(&self, string: String) -> Result<(), String> {
-        self.sender
-            .send(string)
-            .map_err(|e| format!("Unable to broadcast to websocket clients: {:?}", e))
+        if let Some(sender) = &self.sender {
+            sender
+                .send(string)
+                .map_err(|e| format!("Unable to broadcast to websocket clients: {:?}", e))
+        } else {
+            Ok(())
+        }
     }
 }
 
-pub fn start_server<T: EthSpec>(config: &Config, log: &Logger) -> Result<WebSocketSender, String> {
+impl<T: EthSpec> EventHandler<T> for WebSocketSender<T> {
+    fn register(&self, kind: EventKind<T>) -> Result<(), String> {
+        self.send_string(
+            serde_json::to_string(&kind)
+                .map_err(|e| format!("Unable to serialize event: {:?}", e))?,
+        )
+    }
+}
+
+pub fn start_server<T: EthSpec>(
+    config: &Config,
+    log: &Logger,
+) -> Result<WebSocketSender<T>, String> {
     let server_string = format!("{}:{}", config.listen_address, config.port);
 
     info!(
@@ -70,6 +97,7 @@ pub fn start_server<T: EthSpec>(config: &Config, log: &Logger) -> Result<WebSock
     });
 
     Ok(WebSocketSender {
-        sender: broadcaster,
+        sender: Some(broadcaster),
+        _phantom: PhantomData,
     })
 }