diff --git a/rust/Cargo.lock b/rust/Cargo.lock
index 837436a..3f089b0 100644
--- a/rust/Cargo.lock
+++ b/rust/Cargo.lock
@@ -114,6 +114,7 @@ version = "0.1.0"
 dependencies = [
  "mammoth",
  "yellowstone",
+ "yunq",
 ]
 
 [[package]]
diff --git a/rust/lib/mammoth/src/bindings.rs b/rust/lib/mammoth/src/bindings.rs
index aaffeb5..16309b3 100644
--- a/rust/lib/mammoth/src/bindings.rs
+++ b/rust/lib/mammoth/src/bindings.rs
@@ -508,7 +508,7 @@ pub struct ZReplyPortSendReq {
     pub num_bytes: u64,
     pub data: *const ::core::ffi::c_void,
     pub num_caps: u64,
-    pub caps: *mut z_cap_t,
+    pub caps: *const z_cap_t,
 }
 #[repr(C)]
 #[derive(Debug, Copy, Clone)]
diff --git a/rust/lib/mammoth/src/syscall.rs b/rust/lib/mammoth/src/syscall.rs
index 0346e7f..86765af 100644
--- a/rust/lib/mammoth/src/syscall.rs
+++ b/rust/lib/mammoth/src/syscall.rs
@@ -122,6 +122,17 @@ pub fn port_poll(
     Ok((num_bytes, num_caps))
 }
 
+pub fn endpoint_create() -> Result<z_cap_t, ZError> {
+    let mut endpoint_cap: z_cap_t = 0;
+    syscall(
+        zion::kZionEndpointCreate,
+        &zion::ZEndpointCreateReq {
+            endpoint_cap: &mut endpoint_cap,
+        },
+    )?;
+    Ok(endpoint_cap)
+}
+
 pub fn endpoint_send(
     endpoint_cap: z_cap_t,
     bytes: &[u8],
@@ -134,7 +145,7 @@ pub fn endpoint_send(
         endpoint_cap,
         data: bytes.as_ptr() as *const c_void,
         num_bytes: bytes.len() as u64,
-        reply_port_cap: &mut reply_port_cap as *mut z_cap_t,
+        reply_port_cap: &mut reply_port_cap,
     };
 
     syscall(zion::kZionEndpointSend, &send_req)?;
@@ -142,6 +153,45 @@ pub fn endpoint_send(
     Ok(reply_port_cap)
 }
 
+pub fn endpoint_recv(
+    endpoint_cap: z_cap_t,
+    bytes: &mut [u8],
+    caps: &mut [z_cap_t],
+) -> Result<(u64, u64, z_cap_t), ZError> {
+    let mut num_bytes = bytes.len() as u64;
+    let mut num_caps = caps.len() as u64;
+    let mut reply_port_cap = 0;
+    let recv_req = zion::ZEndpointRecvReq {
+        endpoint_cap,
+        data: bytes.as_mut_ptr() as *mut c_void,
+        num_bytes: &mut num_bytes,
+        caps: caps.as_mut_ptr(),
+        num_caps: &mut num_caps,
+        reply_port_cap: &mut reply_port_cap,
+    };
+
+    syscall(zion::kZionEndpointRecv, &recv_req)?;
+
+    Ok((num_bytes, num_caps, reply_port_cap))
+}
+
+pub fn reply_port_send(
+    reply_port_cap: z_cap_t,
+    bytes: &[u8],
+    caps: &[z_cap_t],
+) -> Result<(), ZError> {
+    syscall(
+        zion::kZionReplyPortSend,
+        &zion::ZReplyPortSendReq {
+            reply_port_cap,
+            data: bytes.as_ptr() as *const c_void,
+            num_bytes: bytes.len() as u64,
+            caps: caps.as_ptr(),
+            num_caps: caps.len() as u64,
+        },
+    )
+}
+
 pub fn reply_port_recv(
     reply_port_cap: z_cap_t,
     bytes: &mut [u8],
@@ -152,9 +202,9 @@ pub fn reply_port_recv(
     let recv_req = zion::ZReplyPortRecvReq {
         reply_port_cap,
         caps: caps.as_mut_ptr(),
-        num_caps: &mut num_caps as *mut u64,
+        num_caps: &mut num_caps,
         data: bytes.as_mut_ptr() as *mut c_void,
-        num_bytes: &mut num_bytes as *mut u64,
+        num_bytes: &mut num_bytes,
     };
 
     syscall(zion::kZionReplyPortRecv, &recv_req)?;
diff --git a/rust/lib/mammoth/src/thread.rs b/rust/lib/mammoth/src/thread.rs
index 1ddc85d..92fd086 100644
--- a/rust/lib/mammoth/src/thread.rs
+++ b/rust/lib/mammoth/src/thread.rs
@@ -2,39 +2,40 @@ use crate::syscall;
 use crate::zion;
 use crate::zion::z_cap_t;
 
+use alloc::boxed::Box;
 use core::ffi::c_void;
 
 pub type ThreadEntry = fn(*const c_void) -> ();
 
 #[no_mangle]
-extern "C" fn internal_entry_point(entry_ptr: *const ThreadEntry, arg1: *const c_void) -> ! {
-    let entry = unsafe { *entry_ptr };
+extern "C" fn internal_entry_point(thread_ptr: *const Thread, arg1: *const c_void) -> ! {
+    let thread: &Thread = unsafe { thread_ptr.as_ref().expect("Failed to unwrap thread ref") };
 
-    entry(arg1);
+    (thread.entry)(arg1);
 
     syscall::thread_exit()
 }
 // TODO: Add a Drop implementation that kills this thread and drops its capability.
-pub struct Thread<'a> {
+pub struct Thread {
     cap: z_cap_t,
     // This field only exists to ensure that the entry reference will outlive the thread object
     // itself.
-    _entry: &'a ThreadEntry,
+    entry: ThreadEntry,
 }
 
-impl<'a> Thread<'a> {
-    pub fn spawn(entry: &'a ThreadEntry, arg1: *const c_void) -> Result<Self, zion::ZError> {
+impl Thread {
+    pub fn spawn(entry: ThreadEntry, arg1: *const c_void) -> Result<Box<Self>, zion::ZError> {
         let proc_cap = unsafe { crate::init::SELF_PROC_CAP };
         let cap = syscall::thread_create(proc_cap)?;
-
+        let thread = Box::new(Self { cap, entry });
         syscall::thread_start(
             cap,
             internal_entry_point as u64,
-            entry as *const ThreadEntry as u64,
+            thread.as_ref() as *const Thread as u64,
             arg1 as u64,
         )?;
 
-        Ok(Self { cap, _entry: entry })
+        Ok(thread)
     }
 
     pub fn join(&self) -> Result<(), zion::ZError> {
diff --git a/rust/lib/yunq/src/client.rs b/rust/lib/yunq/src/client.rs
index de8cada..ad3a761 100644
--- a/rust/lib/yunq/src/client.rs
+++ b/rust/lib/yunq/src/client.rs
@@ -28,5 +28,11 @@ pub fn call_endpoint<Req: YunqMessage, Resp: YunqMessage, const N: usize>(
         cap_buffer.as_mut_slice(),
     )?;
 
+    let resp_code: u64 = byte_buffer.at(8)?;
+
+    if resp_code != 0 {
+        return Err(ZError::from(resp_code));
+    }
+
     Ok(Resp::parse_from_request(&byte_buffer, &cap_buffer)?)
 }
diff --git a/rust/lib/yunq/src/lib.rs b/rust/lib/yunq/src/lib.rs
index 515760b..93166ac 100644
--- a/rust/lib/yunq/src/lib.rs
+++ b/rust/lib/yunq/src/lib.rs
@@ -6,6 +6,7 @@ extern crate alloc;
 mod buffer;
 pub mod client;
 pub mod message;
+pub mod server;
 
 pub use buffer::ByteBuffer;
 pub use message::YunqMessage;
diff --git a/rust/lib/yunq/src/message.rs b/rust/lib/yunq/src/message.rs
index 73b37e4..7b84b8d 100644
--- a/rust/lib/yunq/src/message.rs
+++ b/rust/lib/yunq/src/message.rs
@@ -4,13 +4,23 @@ use mammoth::zion::z_cap_t;
 use mammoth::zion::ZError;
 
 pub const MESSAGE_IDENT: u32 = 0x33441122;
-const SENTINEL: u32 = 0xBEEFDEAD;
 pub const MESSAGE_HEADER_SIZE: usize = 24; // 4x uint32, 1x uint64
+const SENTINEL: u32 = 0xBEEFDEAD;
+const SERIALIZE_HEADER_SIZE: u32 = 0x10;
 
 pub fn field_offset(offset: usize, field_index: usize) -> usize {
     offset + MESSAGE_HEADER_SIZE + (8 * field_index)
 }
 
+pub fn serialize_error<const N: usize>(buf: &mut ByteBuffer<N>, err: ZError) {
+    buf.write_at(0, SENTINEL)
+        .expect("Failed to serialize SENTINEL");
+    buf.write_at(4, SERIALIZE_HEADER_SIZE)
+        .expect("Failed to serialize size");
+    buf.write_at(8, err as u64)
+        .expect("Failed to serialize error");
+}
+
 pub trait YunqMessage {
     fn parse<const N: usize>(
         buf: &ByteBuffer<N>,
@@ -31,11 +41,6 @@ pub trait YunqMessage {
             return Err(ZError::INVALID_RESPONSE);
         }
 
-        let resp_code: u64 = buf.at(8)?;
-        if resp_code != 0 {
-            return Err(ZError::from(resp_code));
-        }
-
         Ok(Self::parse(&buf, 16, &caps)?)
     }
 
diff --git a/rust/lib/yunq/src/server.rs b/rust/lib/yunq/src/server.rs
new file mode 100644
index 0000000..c8c4f36
--- /dev/null
+++ b/rust/lib/yunq/src/server.rs
@@ -0,0 +1,46 @@
+use crate::buffer::ByteBuffer;
+use alloc::vec::Vec;
+use mammoth::syscall;
+use mammoth::zion::z_cap_t;
+use mammoth::zion::ZError;
+
+pub trait YunqServer {
+    fn server_loop(&self) {
+        loop {
+            let mut byte_buffer = ByteBuffer::<1024>::new();
+            let mut cap_buffer = vec![0; 10];
+            let (_, _, reply_port_cap) = syscall::endpoint_recv(
+                self.endpoint_cap(),
+                byte_buffer.mut_slice(),
+                &mut cap_buffer,
+            )
+            .expect("Failed to call endpoint recv");
+
+            let method = byte_buffer
+                .at::<u64>(8)
+                .expect("Failed to access request length.");
+            let resp = self.handle_request(method, &mut byte_buffer, &mut cap_buffer);
+            match resp {
+                Ok(resp_len) => syscall::reply_port_send(
+                    reply_port_cap,
+                    byte_buffer.slice(resp_len),
+                    &cap_buffer,
+                )
+                .expect("Failed to reply"),
+                Err(err) => {
+                    crate::message::serialize_error(&mut byte_buffer, err);
+                    syscall::reply_port_send(reply_port_cap, &byte_buffer.slice(0x10), &[])
+                        .expect("Failed to reply w/ error")
+                }
+            }
+        }
+    }
+
+    fn endpoint_cap(&self) -> z_cap_t;
+    fn handle_request(
+        &self,
+        method_number: u64,
+        byte_buffer: &mut ByteBuffer<1024>,
+        cap_buffer: &mut Vec<z_cap_t>,
+    ) -> Result<usize, ZError>;
+}
diff --git a/rust/usr/testbed/Cargo.toml b/rust/usr/testbed/Cargo.toml
index 66b00a9..7934e6c 100644
--- a/rust/usr/testbed/Cargo.toml
+++ b/rust/usr/testbed/Cargo.toml
@@ -6,3 +6,4 @@ edition = "2021"
 [dependencies]
 mammoth = { path = "../../lib/mammoth" }
 yellowstone = { path = "../../lib/yellowstone" }
+yunq = { path = "../../lib/yunq" }
diff --git a/rust/usr/testbed/src/main.rs b/rust/usr/testbed/src/main.rs
index 661c98b..1b27a05 100644
--- a/rust/usr/testbed/src/main.rs
+++ b/rust/usr/testbed/src/main.rs
@@ -8,11 +8,46 @@ use mammoth::debug;
 use mammoth::define_entry;
 use mammoth::thread;
 use mammoth::zion::z_err_t;
+use mammoth::zion::ZError;
 use yellowstone::GetEndpointRequest;
 use yellowstone::YellowstoneClient;
+use yellowstone::YellowstoneServer;
+use yunq::server::YunqServer;
 
 define_entry!();
 
+struct YellowstoneImpl {}
+
+impl yellowstone::YellowstoneServerHandler for YellowstoneImpl {
+    fn register_endpoint(&self, req: &yellowstone::RegisterEndpointRequest) -> Result<(), ZError> {
+        debug!("{}", req.endpoint_name);
+        Ok(())
+    }
+
+    fn get_endpoint(&self, req: &GetEndpointRequest) -> Result<yellowstone::Endpoint, ZError> {
+        debug!("{}", req.endpoint_name);
+        Ok(yellowstone::Endpoint {
+            endpoint: unsafe { mammoth::init::SELF_PROC_CAP },
+        })
+    }
+
+    fn get_ahci_info(&self) -> Result<yellowstone::AhciInfo, ZError> {
+        todo!()
+    }
+
+    fn get_xhci_info(&self) -> Result<yellowstone::XhciInfo, ZError> {
+        todo!()
+    }
+
+    fn get_framebuffer_info(&self) -> Result<yellowstone::FramebufferInfo, ZError> {
+        todo!()
+    }
+
+    fn get_denali(&self) -> Result<yellowstone::DenaliInfo, ZError> {
+        todo!()
+    }
+}
+
 #[no_mangle]
 pub extern "C" fn main() -> z_err_t {
     debug!("Testing!");
@@ -33,9 +68,25 @@ pub extern "C" fn main() -> z_err_t {
     let e: thread::ThreadEntry = |_| {
         debug!("Testing 1 2 3");
     };
-    let t = thread::Thread::spawn(&e, core::ptr::null()).expect("Failed to spawn thread");
+    let t = thread::Thread::spawn(e, core::ptr::null()).expect("Failed to spawn thread");
 
     t.join().expect("Failed to wait.");
 
+    let server = YellowstoneServer::new(YellowstoneImpl {}).expect("Failed to create server");
+
+    let mut yellowstone = YellowstoneClient::new(server.endpoint_cap());
+
+    let t = server.run_server().expect("Failed to start server");
+
+    let endpoint = yellowstone
+        .get_endpoint(&GetEndpointRequest {
+            endpoint_name: "test".to_string(),
+        })
+        .expect("Failed to get endpoint");
+
+    debug!("{:#x}", endpoint.endpoint);
+
+    t.join().expect("Failed to wait");
+
     0
 }
diff --git a/yunq/rust/src/codegen.rs b/yunq/rust/src/codegen.rs
index 1f4bc64..31f61e4 100644
--- a/yunq/rust/src/codegen.rs
+++ b/yunq/rust/src/codegen.rs
@@ -50,7 +50,7 @@ fn generate_method(method: &Method) -> TokenStream {
     }
 }
 
-fn generate_interface(interface: &Interface) -> TokenStream {
+fn generate_client(interface: &Interface) -> TokenStream {
     let client_name = interface.name.clone() + "Client";
     let name = ident(&client_name);
     let methods = interface.methods.iter().map(|m| generate_method(&m));
@@ -73,17 +73,144 @@ fn generate_interface(interface: &Interface) -> TokenStream {
     }
 }
 
+fn generate_server_case(method: &Method) -> TokenStream {
+    let id = proc_macro2::Literal::u64_suffixed(method.number);
+    let name = ident(&method.name.to_case(Case::Snake));
+    let maybe_req = method.request.clone().map(|r| ident(&r));
+    let maybe_resp = method.response.clone().map(|r| ident(&r));
+    match (maybe_req, maybe_resp) {
+        (Some(req), Some(_)) => quote! {
+            #id => {
+                let req = #req::parse_from_request(byte_buffer, cap_buffer)?;
+                let resp = self.handler.#name(&req)?;
+                cap_buffer.resize(0, 0);
+                let resp_len = resp.serialize_as_request(0, byte_buffer, cap_buffer)?;
+                Ok(resp_len)
+            },
+        },
+        (Some(req), None) => quote! {
+            #id => {
+                let req = #req::parse_from_request(byte_buffer, cap_buffer)?;
+                self.handler.#name(&req)?;
+                cap_buffer.resize(0, 0);
+                // TODO: Implement serialization for EmptyMessage so this is less hacky.
+                yunq::message::serialize_error(byte_buffer, ZError::from(0));
+                Ok(0x10)
+            },
+        },
+        (None, Some(_)) => quote! {
+            #id => {
+                let resp = self.handler.#name()?;
+                cap_buffer.resize(0, 0);
+                let resp_len = resp.serialize_as_request(0, byte_buffer, cap_buffer)?;
+                Ok(resp_len)
+            },
+        },
+        _ => unreachable!(),
+    }
+}
+
+fn generate_server_method(method: &Method) -> TokenStream {
+    let name = ident(&method.name.to_case(Case::Snake));
+    let maybe_req = method.request.clone().map(|r| ident(&r));
+    let maybe_resp = method.response.clone().map(|r| ident(&r));
+    match (maybe_req, maybe_resp) {
+        (Some(req), Some(resp)) => quote! {
+            fn #name (&self, req: & #req) -> Result<#resp, ZError>;
+        },
+        (Some(req), None) => quote! {
+            fn #name (&self, req: & #req) -> Result<(), ZError>;
+        },
+        (None, Some(resp)) => quote! {
+            fn #name (&self) -> Result<#resp, ZError>;
+        },
+        _ => unreachable!(),
+    }
+}
+
+fn generate_server(interface: &Interface) -> TokenStream {
+    let server_name = ident(&(interface.name.clone() + "Server"));
+    let server_trait = ident(&(interface.name.clone() + "ServerHandler"));
+    let server_trait_methods = interface.methods.iter().map(|m| generate_server_method(&m));
+    let server_match_cases = interface.methods.iter().map(|m| generate_server_case(&m));
+    quote! {
+        pub trait #server_trait {
+            #(#server_trait_methods)*
+        }
+
+        pub struct #server_name<T: #server_trait> {
+            endpoint_cap: z_cap_t,
+            handler: T
+        }
+
+        impl<T: #server_trait> #server_name<T> {
+            pub fn new(handler: T) -> Result<Self, ZError> {
+                Ok(Self {
+                    endpoint_cap: syscall::endpoint_create()?,
+                    handler,
+                })
+            }
+
+            pub fn run_server(&self) -> Result<Box<thread::Thread>, ZError> {
+                let thread_entry = |server_ptr: *const c_void| {
+                    let server = unsafe { (server_ptr as *const #server_name<T>).as_ref().expect("Failed to convert to server") };
+                    server.server_loop();
+                };
+                thread::Thread::spawn(
+                    thread_entry,
+                    self as *const Self as *const core::ffi::c_void,
+                )
+            }
+        }
+
+        impl<T: #server_trait> yunq::server::YunqServer for #server_name<T> {
+            fn endpoint_cap(&self) -> z_cap_t {
+                self.endpoint_cap
+            }
+
+            fn handle_request(
+                &self,
+                method_number: u64,
+                byte_buffer: &mut ByteBuffer<1024>,
+                cap_buffer: &mut Vec<z_cap_t>,
+                ) -> Result<usize, ZError> {
+                match method_number {
+                    #(#server_match_cases)*
+
+                    _ => Err(ZError::UNIMPLEMENTED)
+                }
+            }
+        }
+    }
+}
+
+fn generate_interface(interface: &Interface) -> TokenStream {
+    let client = generate_client(interface);
+    let server = generate_server(interface);
+    quote! {
+        #client
+
+        #server
+    }
+}
+
 pub fn generate_code(ast: &Vec<Decl>) -> String {
     let prelude = quote! {
 
     extern crate alloc;
 
+    use alloc::boxed::Box;
     use alloc::string::String;
     use alloc::string::ToString;
+    use alloc::vec::Vec;
+    use core::ffi::c_void;
+    use mammoth::syscall;
+    use mammoth::thread;
     use mammoth::zion::z_cap_t;
     use mammoth::zion::ZError;
     use yunq::ByteBuffer;
     use yunq::YunqMessage;
+    use yunq::server::YunqServer;
     use yunq_derive::YunqMessage;
     };
 
diff --git a/zion/include/zcall.h b/zion/include/zcall.h
index c5f9ca6..31e45df 100644
--- a/zion/include/zcall.h
+++ b/zion/include/zcall.h
@@ -56,7 +56,7 @@ SYS6(EndpointSend, z_cap_t, endpoint_cap, uint64_t, num_bytes, const void*,
 SYS6(EndpointRecv, z_cap_t, endpoint_cap, uint64_t*, num_bytes, void*, data,
      uint64_t*, num_caps, z_cap_t*, caps, z_cap_t*, reply_port_cap);
 SYS5(ReplyPortSend, z_cap_t, reply_port_cap, uint64_t, num_bytes, const void*,
-     data, uint64_t, num_caps, z_cap_t*, caps);
+     data, uint64_t, num_caps, const z_cap_t*, caps);
 SYS5(ReplyPortRecv, z_cap_t, reply_port_cap, uint64_t*, num_bytes, void*, data,
      uint64_t*, num_caps, z_cap_t*, caps);