diff --git a/services/backup/blob_client/src/put_client.rs b/services/backup/blob_client/src/put_client.rs
--- a/services/backup/blob_client/src/put_client.rs
+++ b/services/backup/blob_client/src/put_client.rs
@@ -2,9 +2,17 @@
   tonic::include_proto!("blob");
 }
 
+use proto::blob_service_client::BlobServiceClient;
+use proto::put_request;
+use proto::put_request::Data::*;
+use proto::PutRequest;
+use proto::PutResponse;
+
+use crate::constants::{BLOB_ADDRESS, MPSC_CHANNEL_BUFFER_CAPACITY};
 use lazy_static::lazy_static;
 use libc;
 use libc::c_char;
+use std::ffi::CStr;
 use std::sync::{Arc, Mutex};
 use tokio::runtime::Runtime;
 use tokio::sync::mpsc;
@@ -62,7 +70,114 @@
 }
 
 pub fn put_client_initialize_cxx() -> Result<(), String> {
-  unimplemented!();
+  if is_initialized() {
+    put_client_terminate_cxx()?;
+  }
+  assert!(!is_initialized(), "client cannot be initialized twice");
+  // grpc
+  if let Ok(mut grpc_client) =
+    RUNTIME.block_on(async { BlobServiceClient::connect(BLOB_ADDRESS).await })
+  {
+    let (request_thread_tx, mut request_thread_rx): (
+      mpsc::Sender<PutRequestData>,
+      mpsc::Receiver<PutRequestData>,
+    ) = mpsc::channel(MPSC_CHANNEL_BUFFER_CAPACITY);
+
+    let outbound = async_stream::stream! {
+      while let Some(data) = request_thread_rx.recv().await {
+        let request_data: Option<put_request::Data> = match data.field_index {
+          1 => {
+            match String::from_utf8(data.data) {
+              Ok(utf8_data) => Some(Holder(utf8_data)),
+              _ => {
+                report_error("invalid utf-8".to_string());
+                None
+              },
+            }
+          }
+          2 => {
+            match String::from_utf8(data.data).ok() {
+              Some(utf8_data) => Some(BlobHash(utf8_data)),
+              None => {
+                report_error("invalid utf-8".to_string());
+                None
+              },
+            }
+          }
+          3 => {
+            Some(DataChunk(data.data))
+          }
+          _ => {
+            report_error(format!("invalid field index value {}", data.field_index));
+            None
+          }
+        };
+        if let Some (unpacked_data) = request_data {
+          let request = PutRequest {
+            data: Some(unpacked_data),
+          };
+          yield request;
+        } else {
+          report_error("an error occured, aborting connection".to_string());
+          break;
+        }
+      }
+    };
+
+    // spawn receiver thread
+    let (response_thread_tx, response_thread_rx): (
+      mpsc::Sender<String>,
+      mpsc::Receiver<String>,
+    ) = mpsc::channel(MPSC_CHANNEL_BUFFER_CAPACITY);
+    let rx_handle = RUNTIME.spawn(async move {
+      match grpc_client.put(tonic::Request::new(outbound)).await {
+        Ok(response) => {
+          let mut inner_response = response.into_inner();
+          loop {
+            match inner_response.message().await {
+              Ok(maybe_response_message) => {
+                let mut result = false;
+                if let Some(response_message) = maybe_response_message {
+                  // warning: this will produce an error if there's more unread responses than
+                  // MPSC_CHANNEL_BUFFER_CAPACITY
+                  // you should then use put_client_blocking_read_cxx in order to dequeue
+                  // the responses in c++ and make room for more
+                  if let Ok(_) = response_thread_tx
+                    .try_send((response_message.data_exists as i32).to_string())
+                  {
+                    result = true;
+                  } else {
+                    report_error("response queue full".to_string());
+                  }
+                }
+                if !result {
+                  break;
+                }
+              }
+              Err(err) => {
+                report_error(err.to_string());
+                break;
+              }
+            };
+          }
+        },
+        Err(err) => {
+          report_error(err.to_string());
+        }
+      };
+    });
+
+    if let Ok(mut client) = CLIENT.lock() {
+      *client = Some(BidiClient {
+        tx: request_thread_tx,
+        rx: response_thread_rx,
+        rx_handle,
+      });
+      return Ok(());
+    }
+    return Err("could not access client".to_string());
+  }
+  Err("could not successfully connect to the blob server".to_string())
 }
 
 pub fn put_client_blocking_read_cxx() -> Result<String, String> {
@@ -71,9 +186,9 @@
 
 /**
  * field index:
- * 0 - holder (utf8 string)
- * 1 - blob hash (utf8 string)
- * 2 - data chunk (bytes)
+ * 1 - holder (utf8 string)
+ * 2 - blob hash (utf8 string)
+ * 3 - data chunk (bytes)
  */
 pub fn put_client_write_cxx(
   field_index: usize,