diff --git a/Cargo.lock b/Cargo.lock
index 837f92161..581a9fe63 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -250,7 +250,7 @@ checksum = "8c3c1a368f70d6cf7302d78f8f7093da241fb8e8807c05cc9e51a125895a6d5b"
 
 [[package]]
 name = "benchmark-example-node"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "dora-node-api",
  "eyre",
@@ -263,7 +263,7 @@ dependencies = [
 
 [[package]]
 name = "benchmark-example-sink"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "dora-node-api",
  "eyre",
@@ -513,7 +513,7 @@ dependencies = [
 
 [[package]]
 name = "communication-layer-pub-sub"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "flume",
  "zenoh",
@@ -521,7 +521,7 @@ dependencies = [
 
 [[package]]
 name = "communication-layer-request-reply"
-version = "0.2.1"
+version = "0.2.2"
 
 [[package]]
 name = "concurrent-queue"
@@ -817,7 +817,7 @@ dependencies = [
 
 [[package]]
 name = "dora-cli"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "atty",
  "clap 4.0.3",
@@ -841,7 +841,7 @@ dependencies = [
 
 [[package]]
 name = "dora-coordinator"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "ctrlc",
  "dora-core",
@@ -864,7 +864,7 @@ dependencies = [
 
 [[package]]
 name = "dora-core"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "dora-message",
  "eyre",
@@ -880,7 +880,7 @@ dependencies = [
 
 [[package]]
 name = "dora-daemon"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "async-trait",
  "bincode",
@@ -906,7 +906,7 @@ dependencies = [
 
 [[package]]
 name = "dora-download"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "eyre",
  "reqwest",
@@ -931,7 +931,7 @@ dependencies = [
 
 [[package]]
 name = "dora-message"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "capnp",
  "capnpc",
@@ -941,7 +941,7 @@ dependencies = [
 
 [[package]]
 name = "dora-metrics"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "futures",
  "opentelemetry 0.17.0",
@@ -952,7 +952,7 @@ dependencies = [
 
 [[package]]
 name = "dora-node-api"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "bincode",
  "capnp",
@@ -974,7 +974,7 @@ dependencies = [
 
 [[package]]
 name = "dora-node-api-c"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "dora-node-api",
  "eyre",
@@ -984,7 +984,7 @@ dependencies = [
 
 [[package]]
 name = "dora-node-api-cxx"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "cxx",
  "cxx-build",
@@ -994,7 +994,7 @@ dependencies = [
 
 [[package]]
 name = "dora-node-api-python"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "dora-node-api",
  "dora-operator-api-python",
@@ -1007,7 +1007,7 @@ dependencies = [
 
 [[package]]
 name = "dora-operator-api"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "dora-operator-api-macros",
  "dora-operator-api-types",
@@ -1015,14 +1015,14 @@ dependencies = [
 
 [[package]]
 name = "dora-operator-api-c"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "dora-operator-api-types",
 ]
 
 [[package]]
 name = "dora-operator-api-cxx"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "cxx",
  "cxx-build",
@@ -1031,7 +1031,7 @@ dependencies = [
 
 [[package]]
 name = "dora-operator-api-macros"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1040,7 +1040,7 @@ dependencies = [
 
 [[package]]
 name = "dora-operator-api-python"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "dora-node-api",
  "eyre",
@@ -1051,14 +1051,14 @@ dependencies = [
 
 [[package]]
 name = "dora-operator-api-types"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "safer-ffi",
 ]
 
 [[package]]
 name = "dora-runtime"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "clap 4.0.3",
  "dora-core",
@@ -1086,7 +1086,7 @@ dependencies = [
 
 [[package]]
 name = "dora-tracing"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "eyre",
  "opentelemetry 0.18.0",
@@ -3097,7 +3097,7 @@ dependencies = [
 
 [[package]]
 name = "rust-dataflow-example-node"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "dora-node-api",
  "eyre",
@@ -3108,14 +3108,14 @@ dependencies = [
 
 [[package]]
 name = "rust-dataflow-example-operator"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "dora-operator-api",
 ]
 
 [[package]]
 name = "rust-dataflow-example-sink"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "dora-node-api",
  "eyre",
@@ -3400,7 +3400,7 @@ dependencies = [
 
 [[package]]
 name = "shared-memory-server"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "bincode",
  "eyre",
@@ -4804,7 +4804,7 @@ dependencies = [
 
 [[package]]
 name = "zenoh-logger"
-version = "0.2.1"
+version = "0.2.2"
 dependencies = [
  "zenoh",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index f5de7e860..ea907ef70 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -24,28 +24,28 @@ members = [
 
 [workspace.package]
 # Make sure to also bump `apis/node/python/__init__.py` version.
-version = "0.2.1"
+version = "0.2.2"
 description = "`dora` goal is to be a low latency, composable, and distributed data flow."
 documentation = "https://dora.carsmos.ai/dora/"
 license = "Apache-2.0"
 
 [workspace.dependencies]
-dora-node-api = { version = "0.2.1", path = "apis/rust/node", default-features = false }
-dora-operator-api = { version = "0.2.1", path = "apis/rust/operator", default-features = false }
-dora-operator-api-macros = { version = "0.2.1", path = "apis/rust/operator/macros" }
-dora-operator-api-types = { version = "0.2.1", path = "apis/rust/operator/types" }
-dora-operator-api-python = { version = "0.2.1", path = "apis/python/operator" }
-dora-operator-api-c = { version = "0.2.1", path = "apis/c/operator" }
-dora-node-api-c = { version = "0.2.1", path = "apis/c/node" }
-dora-core = { version = "0.2.1", path = "libraries/core" }
-dora-tracing = { version = "0.2.1", path = "libraries/extensions/telemetry/tracing" }
-dora-metrics = { version = "0.2.1", path = "libraries/extensions/telemetry/metrics" }
-dora-download = { version = "0.2.1", path = "libraries/extensions/download" }
-shared-memory-server = { version = "0.2.1", path = "libraries/shared-memory-server" }
-communication-layer-request-reply = { version = "0.2.1", path = "libraries/communication-layer/request-reply" }
-dora-message = { version = "0.2.1", path = "libraries/message" }
-dora-runtime = { version = "0.2.1", path = "binaries/runtime" }
-dora-daemon = { version = "0.2.1", path = "binaries/daemon" }
+dora-node-api = { version = "0.2.2", path = "apis/rust/node", default-features = false }
+dora-operator-api = { version = "0.2.2", path = "apis/rust/operator", default-features = false }
+dora-operator-api-macros = { version = "0.2.2", path = "apis/rust/operator/macros" }
+dora-operator-api-types = { version = "0.2.2", path = "apis/rust/operator/types" }
+dora-operator-api-python = { version = "0.2.2", path = "apis/python/operator" }
+dora-operator-api-c = { version = "0.2.2", path = "apis/c/operator" }
+dora-node-api-c = { version = "0.2.2", path = "apis/c/node" }
+dora-core = { version = "0.2.2", path = "libraries/core" }
+dora-tracing = { version = "0.2.2", path = "libraries/extensions/telemetry/tracing" }
+dora-metrics = { version = "0.2.2", path = "libraries/extensions/telemetry/metrics" }
+dora-download = { version = "0.2.2", path = "libraries/extensions/download" }
+shared-memory-server = { version = "0.2.2", path = "libraries/shared-memory-server" }
+communication-layer-request-reply = { version = "0.2.2", path = "libraries/communication-layer/request-reply" }
+dora-message = { version = "0.2.2", path = "libraries/message" }
+dora-runtime = { version = "0.2.2", path = "binaries/runtime" }
+dora-daemon = { version = "0.2.2", path = "binaries/daemon" }
 
 [package]
 name = "dora-examples"
diff --git a/Changelog.md b/Changelog.md
index 7cf78e8e2..d6f4f5511 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,5 +1,25 @@
 # Changelog
 
+## v0.2.2 (2023-04-01)
+
+### Features
+
+* Make queue length configurable through the dataflow file by @phil-opp in https://github.com/dora-rs/dora/pull/231
+* Hot reloading Python Operator  by @haixuanTao in https://github.com/dora-rs/dora/pull/239
+* Synchronize node and operator start by @phil-opp in https://github.com/dora-rs/dora/pull/236
+* Add opentelemetry capability at runtime instead of compile time by @haixuanTao in https://github.com/dora-rs/dora/pull/234
+
+### Others
+
+* Wait on events and messages simultaneously to prevent queue buildup by @phil-opp in https://github.com/dora-rs/dora/pull/235
+* Fix looping in daemon listener loop by @phil-opp in https://github.com/dora-rs/dora/pull/244
+* Validate shell command as source and url source by @haixuanTao in https://github.com/dora-rs/dora/pull/243
+* Push error into the `init_done` channel for debugging context by @haixuanTao in https://github.com/dora-rs/dora/pull/238
+* Option communication config by @haixuanTao in https://github.com/dora-rs/dora/pull/241
+* Validate yaml when reading by @haixuanTao in https://github.com/dora-rs/dora/pull/237
+
+**Full Changelog**: https://github.com/dora-rs/dora/compare/v0.2.1...v0.2.2
+
 ## v0.2.1 (2023-03-22)
 
 ### Features
diff --git a/apis/python/node/dora/__init__.py b/apis/python/node/dora/__init__.py
index 0674c0190..24b0da0ea 100644
--- a/apis/python/node/dora/__init__.py
+++ b/apis/python/node/dora/__init__.py
@@ -3,7 +3,7 @@
 from .dora import *
 
 __author__ = "Dora-rs Authors"
-__version__ = "0.2.1"
+__version__ = "0.2.2"
 
 
 class DoraStatus(Enum):
diff --git a/binaries/daemon/src/spawn.rs b/binaries/daemon/src/spawn.rs
index 271b74a5d..b079783d0 100644
--- a/binaries/daemon/src/spawn.rs
+++ b/binaries/daemon/src/spawn.rs
@@ -5,15 +5,13 @@ use crate::{
 use dora_core::{
     config::NodeRunConfig,
     daemon_messages::{DaemonCommunicationConfig, DataflowId, NodeConfig, RuntimeConfig},
-    descriptor::{resolve_path, source_is_url, OperatorSource, ResolvedNode},
+    descriptor::{resolve_path, source_is_url, OperatorSource, ResolvedNode, SHELL_SOURCE},
 };
 use dora_download::download_file;
 use eyre::WrapErr;
 use std::{env::consts::EXE_EXTENSION, path::Path, process::Stdio};
 use tokio::sync::mpsc;
 
-const SHELL_SOURCE: &str = "shell";
-
 pub async fn spawn_node(
     dataflow_id: DataflowId,
     working_dir: &Path,
diff --git a/libraries/core/src/descriptor/mod.rs b/libraries/core/src/descriptor/mod.rs
index cd5b52459..3f506aeb9 100644
--- a/libraries/core/src/descriptor/mod.rs
+++ b/libraries/core/src/descriptor/mod.rs
@@ -15,11 +15,13 @@ pub use visualize::collect_dora_timers;
 
 mod validate;
 mod visualize;
+pub const SHELL_SOURCE: &str = "shell";
 
 #[derive(Debug, Serialize, Deserialize)]
 #[serde(deny_unknown_fields)]
 pub struct Descriptor {
     // see https://github.com/dtolnay/serde-yaml/issues/298
+    #[serde(default)]
     #[serde(with = "serde_yaml::with::singleton_map")]
     pub communication: Option<CommunicationConfig>,
     pub nodes: Vec<Node>,
diff --git a/libraries/core/src/descriptor/validate.rs b/libraries/core/src/descriptor/validate.rs
index 8ce90e995..8105d3bac 100644
--- a/libraries/core/src/descriptor/validate.rs
+++ b/libraries/core/src/descriptor/validate.rs
@@ -10,8 +10,9 @@ use std::{
     path::{Path, PathBuf},
     process::Command,
 };
+use tracing::info;
 
-use super::Descriptor;
+use super::{Descriptor, SHELL_SOURCE};
 const VERSION: &str = env!("CARGO_PKG_VERSION");
 
 pub fn check_dataflow(
@@ -27,28 +28,31 @@ pub fn check_dataflow(
     // check that nodes and operators exist
     for node in &nodes {
         match &node.kind {
-            descriptor::CoreNodeKind::Custom(node) => {
-                let path = if source_is_url(&node.source) {
-                    todo!("check URL");
-                } else {
-                    let raw = Path::new(&node.source);
-                    if raw.extension().is_none() {
-                        raw.with_extension(EXE_EXTENSION)
+            descriptor::CoreNodeKind::Custom(node) => match node.source.as_str() {
+                SHELL_SOURCE => (),
+                source => {
+                    if source_is_url(source) {
+                        info!("{source} is a URL."); // TODO: Implement url check.
                     } else {
-                        raw.to_owned()
-                    }
-                };
-                base.join(&path)
-                    .canonicalize()
-                    .wrap_err_with(|| format!("no node exists at `{}`", path.display()))?;
-            }
+                        let raw = Path::new(source);
+                        let path = if raw.extension().is_none() {
+                            raw.with_extension(EXE_EXTENSION)
+                        } else {
+                            raw.to_owned()
+                        };
+                        base.join(&path)
+                            .canonicalize()
+                            .wrap_err_with(|| format!("no node exists at `{}`", path.display()))?;
+                    };
+                }
+            },
             descriptor::CoreNodeKind::Runtime(node) => {
                 for operator_definition in &node.operators {
                     match &operator_definition.config.source {
                         OperatorSource::SharedLibrary(path) => {
                             has_shared_lib_operator = true;
                             if source_is_url(path) {
-                                todo!("check URL");
+                                info!("{path} is a URL."); // TODO: Implement url check.
                             } else {
                                 let path = adjust_shared_library_path(Path::new(&path))?;
                                 if !base.join(&path).exists() {
@@ -59,14 +63,14 @@ pub fn check_dataflow(
                         OperatorSource::Python(path) => {
                             has_python_operator = true;
                             if source_is_url(path) {
-                                todo!("check URL");
+                                info!("{path} is a URL."); // TODO: Implement url check.
                             } else if !base.join(path).exists() {
                                 bail!("no Python library at `{path}`");
                             }
                         }
                         OperatorSource::Wasm(path) => {
                             if source_is_url(path) {
-                                todo!("check URL");
+                                info!("{path} is a URL."); // TODO: Implement url check.
                             } else if !base.join(path).exists() {
                                 bail!("no WASM library at `{path}`");
                             }