diff --git a/programs/bpf/tests/programs.rs b/programs/bpf/tests/programs.rs
index 4cfcbd5f9a..4fc15998f5 100644
--- a/programs/bpf/tests/programs.rs
+++ b/programs/bpf/tests/programs.rs
@@ -29,6 +29,7 @@ mod bpf {
         use super::*;
         use solana_sdk::bpf_loader;
         use solana_sdk::signature::KeypairUtil;
+        use solana_sdk::sync_client::SyncClient;
         use std::io::Read;
 
         #[test]
@@ -47,7 +48,7 @@ mod bpf {
             let program_id = load_program(&bank_client, &alice_keypair, &bpf_loader::id(), elf);
             let instruction = create_invoke_instruction(alice_keypair.pubkey(), program_id, &1u8);
             bank_client
-                .process_instruction(&alice_keypair, instruction)
+                .send_instruction(&alice_keypair, instruction)
                 .unwrap();
         }
 
@@ -86,7 +87,7 @@ mod bpf {
                 let instruction =
                     create_invoke_instruction(alice_keypair.pubkey(), program_id, &1u8);
                 bank_client
-                    .process_instruction(&alice_keypair, instruction)
+                    .send_instruction(&alice_keypair, instruction)
                     .unwrap();
             }
         }
@@ -100,6 +101,7 @@ mod bpf {
     mod bpf_rust {
         use super::*;
         use solana_sdk::signature::KeypairUtil;
+        use solana_sdk::sync_client::SyncClient;
         use std::io::Read;
 
         #[test]
@@ -130,7 +132,7 @@ mod bpf {
                 let instruction =
                     create_invoke_instruction(alice_keypair.pubkey(), program_id, &1u8);
                 bank_client
-                    .process_instruction(&alice_keypair, instruction)
+                    .send_instruction(&alice_keypair, instruction)
                     .unwrap();
             }
         }
diff --git a/programs/budget_api/src/budget_processor.rs b/programs/budget_api/src/budget_processor.rs
index 58c76aad41..6cc1df3577 100644
--- a/programs/budget_api/src/budget_processor.rs
+++ b/programs/budget_api/src/budget_processor.rs
@@ -151,6 +151,7 @@ mod tests {
     use solana_sdk::instruction::InstructionError;
     use solana_sdk::message::Message;
     use solana_sdk::signature::{Keypair, KeypairUtil};
+    use solana_sdk::sync_client::SyncClient;
     use solana_sdk::transaction::TransactionError;
 
     fn create_bank(lamports: u64) -> (Bank, Keypair) {
@@ -169,7 +170,7 @@ mod tests {
         let instructions = budget_instruction::payment(&alice_pubkey, &bob_pubkey, 100);
         let message = Message::new(instructions);
         bank_client
-            .process_message(&[&alice_keypair], message)
+            .send_message(&[&alice_keypair], message)
             .unwrap();
         assert_eq!(bank.get_balance(&bob_pubkey), 100);
     }
@@ -194,7 +195,7 @@ mod tests {
         );
         let message = Message::new(instructions);
         bank_client
-            .process_message(&[&alice_keypair], message)
+            .send_message(&[&alice_keypair], message)
             .unwrap();
 
         // Attack! Part 1: Sign a witness transaction with a random key.
@@ -213,7 +214,7 @@ mod tests {
 
         // Ensure the transaction fails because of the unsigned key.
         assert_eq!(
-            bank_client.process_message(&[&mallory_keypair], message),
+            bank_client.send_message(&[&mallory_keypair], message),
             Err(TransactionError::InstructionError(
                 0,
                 InstructionError::MissingRequiredSignature
@@ -242,7 +243,7 @@ mod tests {
         );
         let message = Message::new(instructions);
         bank_client
-            .process_message(&[&alice_keypair], message)
+            .send_message(&[&alice_keypair], message)
             .unwrap();
 
         // Attack! Part 1: Sign a timestamp transaction with a random key.
@@ -261,7 +262,7 @@ mod tests {
 
         // Ensure the transaction fails because of the unsigned key.
         assert_eq!(
-            bank_client.process_message(&[&mallory_keypair], message),
+            bank_client.send_message(&[&mallory_keypair], message),
             Err(TransactionError::InstructionError(
                 0,
                 InstructionError::MissingRequiredSignature
@@ -289,7 +290,7 @@ mod tests {
         );
         let message = Message::new(instructions);
         bank_client
-            .process_message(&[&alice_keypair], message)
+            .send_message(&[&alice_keypair], message)
             .unwrap();
         assert_eq!(bank.get_balance(&alice_pubkey), 1);
         assert_eq!(bank.get_balance(&budget_pubkey), 1);
@@ -303,7 +304,7 @@ mod tests {
             budget_instruction::apply_timestamp(&alice_pubkey, &budget_pubkey, &mallory_pubkey, dt);
         assert_eq!(
             bank_client
-                .process_instruction(&alice_keypair, instruction)
+                .send_instruction(&alice_keypair, instruction)
                 .unwrap_err(),
             TransactionError::InstructionError(
                 0,
@@ -323,7 +324,7 @@ mod tests {
         let instruction =
             budget_instruction::apply_timestamp(&alice_pubkey, &budget_pubkey, &bob_pubkey, dt);
         bank_client
-            .process_instruction(&alice_keypair, instruction)
+            .send_instruction(&alice_keypair, instruction)
             .unwrap();
         assert_eq!(bank.get_balance(&alice_pubkey), 1);
         assert_eq!(bank.get_balance(&budget_pubkey), 0);
@@ -351,7 +352,7 @@ mod tests {
         );
         let message = Message::new(instructions);
         bank_client
-            .process_message(&[&alice_keypair], message)
+            .send_message(&[&alice_keypair], message)
             .unwrap();
         assert_eq!(bank.get_balance(&alice_pubkey), 2);
         assert_eq!(bank.get_balance(&budget_pubkey), 1);
@@ -371,7 +372,7 @@ mod tests {
         let instruction =
             budget_instruction::apply_signature(&mallory_pubkey, &budget_pubkey, &bob_pubkey);
         bank_client
-            .process_instruction(&mallory_keypair, instruction)
+            .send_instruction(&mallory_keypair, instruction)
             .unwrap();
         // nothing should be changed because apply witness didn't finalize a payment
         assert_eq!(bank.get_balance(&alice_pubkey), 1);
@@ -382,7 +383,7 @@ mod tests {
         let instruction =
             budget_instruction::apply_signature(&alice_pubkey, &budget_pubkey, &alice_pubkey);
         bank_client
-            .process_instruction(&alice_keypair, instruction)
+            .send_instruction(&alice_keypair, instruction)
             .unwrap();
         assert_eq!(bank.get_balance(&alice_pubkey), 2);
         assert_eq!(bank.get_account(&budget_pubkey), None);
diff --git a/programs/config_api/src/config_processor.rs b/programs/config_api/src/config_processor.rs
index 58265846e1..0cf2582b16 100644
--- a/programs/config_api/src/config_processor.rs
+++ b/programs/config_api/src/config_processor.rs
@@ -36,6 +36,7 @@ mod tests {
     use solana_sdk::genesis_block::GenesisBlock;
     use solana_sdk::message::Message;
     use solana_sdk::signature::{Keypair, KeypairUtil};
+    use solana_sdk::sync_client::SyncClient;
     use solana_sdk::system_instruction;
 
     #[derive(Serialize, Deserialize, Default, Debug, PartialEq)]
@@ -76,7 +77,7 @@ mod tests {
             .unwrap();
 
         bank_client
-            .process_instruction(
+            .send_instruction(
                 &mint_keypair,
                 config_instruction::create_account::<MyConfig>(
                     &mint_keypair.pubkey(),
@@ -114,7 +115,7 @@ mod tests {
             config_instruction::store(&from_keypair.pubkey(), &config_pubkey, &my_config);
         let message = Message::new(vec![instruction]);
         bank_client
-            .process_message(&[&from_keypair, &config_keypair], message)
+            .send_message(&[&from_keypair, &config_keypair], message)
             .unwrap();
 
         let config_account = bank.get_account(&config_pubkey).unwrap();
@@ -139,7 +140,7 @@ mod tests {
 
         let message = Message::new(vec![instruction]);
         bank_client
-            .process_message(&[&from_keypair, &config_keypair], message)
+            .send_message(&[&from_keypair, &config_keypair], message)
             .unwrap_err();
     }
 
@@ -162,7 +163,7 @@ mod tests {
         // Don't sign the transaction with `config_client`
         let message = Message::new(vec![move_instruction, store_instruction]);
         bank_client
-            .process_message(&[&system_keypair], message)
+            .send_message(&[&system_keypair], message)
             .unwrap_err();
     }
 }
diff --git a/programs/exchange_api/src/exchange_processor.rs b/programs/exchange_api/src/exchange_processor.rs
index 078cc4c1b1..2f80fd5c3f 100644
--- a/programs/exchange_api/src/exchange_processor.rs
+++ b/programs/exchange_api/src/exchange_processor.rs
@@ -453,6 +453,7 @@ mod test {
     use solana_runtime::bank_client::BankClient;
     use solana_sdk::genesis_block::GenesisBlock;
     use solana_sdk::signature::{Keypair, KeypairUtil};
+    use solana_sdk::sync_client::SyncClient;
     use solana_sdk::system_instruction;
     use std::mem;
 
@@ -572,7 +573,7 @@ mod test {
             &id(),
         );
         client
-            .process_instruction(&owner, instruction)
+            .send_instruction(&owner, instruction)
             .expect(&format!("{}:{}", line!(), file!()));
         new
     }
@@ -587,11 +588,11 @@ mod test {
             &id(),
         );
         client
-            .process_instruction(owner, instruction)
+            .send_instruction(owner, instruction)
             .expect(&format!("{}:{}", line!(), file!()));
         let instruction = exchange_instruction::account_request(&owner.pubkey(), &new);
         client
-            .process_instruction(owner, instruction)
+            .send_instruction(owner, instruction)
             .expect(&format!("{}:{}", line!(), file!()));
         new
     }
@@ -600,7 +601,7 @@ mod test {
         let instruction =
             exchange_instruction::transfer_request(&owner.pubkey(), to, &id(), token, tokens);
         client
-            .process_instruction(owner, instruction)
+            .send_instruction(owner, instruction)
             .expect(&format!("{}:{}", line!(), file!()));
     }
 
@@ -630,7 +631,7 @@ mod test {
             &dst,
         );
         client
-            .process_instruction(owner, instruction)
+            .send_instruction(owner, instruction)
             .expect(&format!("{}:{}", line!(), file!()));
         (trade, src, dst)
     }
@@ -672,7 +673,7 @@ mod test {
         let new = create_token_account(&client, &owner);
         let instruction = exchange_instruction::account_request(&owner.pubkey(), &new);
         client
-            .process_instruction(&owner, instruction)
+            .send_instruction(&owner, instruction)
             .expect_err(&format!("{}:{}", line!(), file!()));
     }
 
@@ -687,7 +688,7 @@ mod test {
         let instruction =
             exchange_instruction::transfer_request(&owner.pubkey(), &new, &id(), Token::A, 42);
         client
-            .process_instruction(&owner, instruction)
+            .send_instruction(&owner, instruction)
             .expect(&format!("{}:{}", line!(), file!()));
 
         let new_account = bank.get_account(&new).unwrap();
@@ -790,7 +791,7 @@ mod test {
             &profit,
         );
         client
-            .process_instruction(&owner, instruction)
+            .send_instruction(&owner, instruction)
             .expect(&format!("{}:{}", line!(), file!()));
 
         let to_trade_account = bank.get_account(&to_trade).unwrap();
diff --git a/programs/failure_program/tests/failure.rs b/programs/failure_program/tests/failure.rs
index e5958e8aee..3a0b61498b 100644
--- a/programs/failure_program/tests/failure.rs
+++ b/programs/failure_program/tests/failure.rs
@@ -5,6 +5,7 @@ use solana_sdk::genesis_block::GenesisBlock;
 use solana_sdk::instruction::InstructionError;
 use solana_sdk::native_loader;
 use solana_sdk::signature::KeypairUtil;
+use solana_sdk::sync_client::SyncClient;
 use solana_sdk::transaction::TransactionError;
 
 #[test]
@@ -19,7 +20,7 @@ fn test_program_native_failure() {
     // Call user program
     let instruction = create_invoke_instruction(alice_keypair.pubkey(), program_id, &1u8);
     assert_eq!(
-        bank_client.process_instruction(&alice_keypair, instruction),
+        bank_client.send_instruction(&alice_keypair, instruction),
         Err(TransactionError::InstructionError(
             0,
             InstructionError::GenericError
diff --git a/programs/noop_program/tests/noop.rs b/programs/noop_program/tests/noop.rs
index ed5dc7e222..63d1500c05 100644
--- a/programs/noop_program/tests/noop.rs
+++ b/programs/noop_program/tests/noop.rs
@@ -4,6 +4,7 @@ use solana_runtime::loader_utils::{create_invoke_instruction, load_program};
 use solana_sdk::genesis_block::GenesisBlock;
 use solana_sdk::native_loader;
 use solana_sdk::signature::KeypairUtil;
+use solana_sdk::sync_client::SyncClient;
 
 #[test]
 fn test_program_native_noop() {
@@ -19,6 +20,6 @@ fn test_program_native_noop() {
     // Call user program
     let instruction = create_invoke_instruction(alice_keypair.pubkey(), program_id, &1u8);
     bank_client
-        .process_instruction(&alice_keypair, instruction)
+        .send_instruction(&alice_keypair, instruction)
         .unwrap();
 }
diff --git a/programs/storage_api/src/storage_processor.rs b/programs/storage_api/src/storage_processor.rs
index cc8fcf8011..89982e2f72 100644
--- a/programs/storage_api/src/storage_processor.rs
+++ b/programs/storage_api/src/storage_processor.rs
@@ -334,6 +334,7 @@ mod tests {
     use solana_sdk::instruction::Instruction;
     use solana_sdk::pubkey::Pubkey;
     use solana_sdk::signature::{Keypair, KeypairUtil, Signature};
+    use solana_sdk::sync_client::SyncClient;
     use solana_sdk::system_instruction;
 
     fn test_instruction(
@@ -474,10 +475,10 @@ mod tests {
         let bank_client = BankClient::new(&bank);
 
         let ix = system_instruction::create_account(&mint_pubkey, &validator, 10, 4 * 1042, &id());
-        bank_client.process_instruction(&mint_keypair, ix).unwrap();
+        bank_client.send_instruction(&mint_keypair, ix).unwrap();
 
         let ix = system_instruction::create_account(&mint_pubkey, &replicator, 10, 4 * 1042, &id());
-        bank_client.process_instruction(&mint_keypair, ix).unwrap();
+        bank_client.send_instruction(&mint_keypair, ix).unwrap();
 
         let ix = storage_instruction::advertise_recent_blockhash(
             &validator,
@@ -486,7 +487,7 @@ mod tests {
         );
 
         bank_client
-            .process_instruction(&validator_keypair, ix)
+            .send_instruction(&validator_keypair, ix)
             .unwrap();
 
         let ix = storage_instruction::mining_proof(
@@ -496,7 +497,7 @@ mod tests {
             Signature::default(),
         );
         bank_client
-            .process_instruction(&replicator_keypair, ix)
+            .send_instruction(&replicator_keypair, ix)
             .unwrap();
 
         let ix = storage_instruction::advertise_recent_blockhash(
@@ -505,7 +506,7 @@ mod tests {
             ENTRIES_PER_SEGMENT * 2,
         );
         bank_client
-            .process_instruction(&validator_keypair, ix)
+            .send_instruction(&validator_keypair, ix)
             .unwrap();
 
         let ix = storage_instruction::proof_validation(
@@ -521,7 +522,7 @@ mod tests {
             }],
         );
         bank_client
-            .process_instruction(&validator_keypair, ix)
+            .send_instruction(&validator_keypair, ix)
             .unwrap();
 
         let ix = storage_instruction::advertise_recent_blockhash(
@@ -530,12 +531,12 @@ mod tests {
             ENTRIES_PER_SEGMENT * 3,
         );
         bank_client
-            .process_instruction(&validator_keypair, ix)
+            .send_instruction(&validator_keypair, ix)
             .unwrap();
 
         let ix = storage_instruction::reward_claim(&validator, entry_height);
         bank_client
-            .process_instruction(&validator_keypair, ix)
+            .send_instruction(&validator_keypair, ix)
             .unwrap();
 
         // TODO enable when rewards are working
@@ -548,7 +549,7 @@ mod tests {
 
         let ix = storage_instruction::reward_claim(&replicator, entry_height);
         bank_client
-            .process_instruction(&replicator_keypair, ix)
+            .send_instruction(&replicator_keypair, ix)
             .unwrap();
 
         // TODO enable when rewards are working
@@ -622,12 +623,12 @@ mod tests {
             &id(),
         );
 
-        bank_client.process_instruction(&mint_keypair, ix).unwrap();
+        bank_client.send_instruction(&mint_keypair, ix).unwrap();
 
         let ix =
             system_instruction::create_account(&mint_pubkey, &validator_pubkey, 1, 4 * 1024, &id());
 
-        bank_client.process_instruction(&mint_keypair, ix).unwrap();
+        bank_client.send_instruction(&mint_keypair, ix).unwrap();
 
         let ix = storage_instruction::advertise_recent_blockhash(
             &validator_pubkey,
@@ -636,7 +637,7 @@ mod tests {
         );
 
         bank_client
-            .process_instruction(&validator_keypair, ix)
+            .send_instruction(&validator_keypair, ix)
             .unwrap();
 
         let entry_height = 0;
@@ -647,7 +648,7 @@ mod tests {
             Signature::default(),
         );
         let _result = bank_client
-            .process_instruction(&replicator_keypair, ix)
+            .send_instruction(&replicator_keypair, ix)
             .unwrap();
 
         assert_eq!(
diff --git a/programs/vote_api/src/vote_processor.rs b/programs/vote_api/src/vote_processor.rs
index bd8935ef28..d4cafa6d5f 100644
--- a/programs/vote_api/src/vote_processor.rs
+++ b/programs/vote_api/src/vote_processor.rs
@@ -54,6 +54,7 @@ mod tests {
     use solana_sdk::message::Message;
     use solana_sdk::pubkey::Pubkey;
     use solana_sdk::signature::{Keypair, KeypairUtil};
+    use solana_sdk::sync_client::SyncClient;
     use solana_sdk::system_instruction;
     use solana_sdk::transaction::TransactionError;
 
@@ -72,7 +73,7 @@ mod tests {
     ) -> Result<()> {
         let ixs = vote_instruction::create_account(&from_keypair.pubkey(), vote_id, lamports);
         let message = Message::new(ixs);
-        bank_client.process_message(&[from_keypair], message)
+        bank_client.send_message(&[from_keypair], message)
     }
 
     fn create_vote_account_with_delegate(
@@ -87,7 +88,7 @@ mod tests {
         let delegate_ix = vote_instruction::delegate_stake(&vote_id, delegate_id);
         ixs.push(delegate_ix);
         let message = Message::new(ixs);
-        bank_client.process_message(&[&from_keypair, vote_keypair], message)
+        bank_client.send_message(&[&from_keypair, vote_keypair], message)
     }
 
     fn submit_vote(
@@ -96,7 +97,7 @@ mod tests {
         tick_height: u64,
     ) -> Result<()> {
         let vote_ix = vote_instruction::vote(&vote_keypair.pubkey(), Vote::new(tick_height));
-        bank_client.process_instruction(&vote_keypair, vote_ix)
+        bank_client.send_instruction(&vote_keypair, vote_ix)
     }
 
     #[test]
@@ -150,7 +151,7 @@ mod tests {
         // needs to check that it's signed.
         let move_ix = system_instruction::transfer(&mallory_id, &vote_id, 1);
         let message = Message::new(vec![move_ix, vote_ix]);
-        let result = bank_client.process_message(&[&mallory_keypair], message);
+        let result = bank_client.send_message(&[&mallory_keypair], message);
 
         // And ensure there's no vote.
         let vote_account = bank.get_account(&vote_id).unwrap();
diff --git a/runtime/src/bank_client.rs b/runtime/src/bank_client.rs
index 2dc62caa62..9e217c12de 100644
--- a/runtime/src/bank_client.rs
+++ b/runtime/src/bank_client.rs
@@ -3,6 +3,7 @@ use solana_sdk::instruction::Instruction;
 use solana_sdk::message::Message;
 use solana_sdk::pubkey::Pubkey;
 use solana_sdk::signature::{Keypair, KeypairUtil};
+use solana_sdk::sync_client::SyncClient;
 use solana_sdk::system_instruction;
 use solana_sdk::transaction::{Transaction, TransactionError};
 
@@ -10,12 +11,8 @@ pub struct BankClient<'a> {
     bank: &'a Bank,
 }
 
-impl<'a> BankClient<'a> {
-    pub fn new(bank: &'a Bank) -> Self {
-        Self { bank }
-    }
-
-    pub fn process_message(
+impl<'a> SyncClient for BankClient<'a> {
+    fn send_message(
         &self,
         keypairs: &[&Keypair],
         message: Message,
@@ -26,24 +23,30 @@ impl<'a> BankClient<'a> {
     }
 
     /// Create and process a transaction from a single instruction.
-    pub fn process_instruction(
+    fn send_instruction(
         &self,
         keypair: &Keypair,
         instruction: Instruction,
     ) -> Result<(), TransactionError> {
         let message = Message::new(vec![instruction]);
-        self.process_message(&[keypair], message)
+        self.send_message(&[keypair], message)
     }
 
     /// Transfer `lamports` from `keypair` to `pubkey`
-    pub fn transfer(
+    fn transfer(
         &self,
         lamports: u64,
         keypair: &Keypair,
         pubkey: &Pubkey,
     ) -> Result<(), TransactionError> {
         let move_instruction = system_instruction::transfer(&keypair.pubkey(), pubkey, lamports);
-        self.process_instruction(keypair, move_instruction)
+        self.send_instruction(keypair, move_instruction)
+    }
+}
+
+impl<'a> BankClient<'a> {
+    pub fn new(bank: &'a Bank) -> Self {
+        Self { bank }
     }
 }
 
@@ -71,7 +74,7 @@ mod tests {
             .push(AccountMeta::new(jane_pubkey, true));
 
         let message = Message::new(vec![move_instruction]);
-        bank_client.process_message(&doe_keypairs, message).unwrap();
+        bank_client.send_message(&doe_keypairs, message).unwrap();
         assert_eq!(bank.get_balance(&bob_pubkey), 42);
     }
 }
diff --git a/runtime/src/loader_utils.rs b/runtime/src/loader_utils.rs
index 5b10e969ac..ee3cec7f38 100644
--- a/runtime/src/loader_utils.rs
+++ b/runtime/src/loader_utils.rs
@@ -4,6 +4,7 @@ use solana_sdk::instruction::{AccountMeta, Instruction};
 use solana_sdk::loader_instruction;
 use solana_sdk::pubkey::Pubkey;
 use solana_sdk::signature::{Keypair, KeypairUtil};
+use solana_sdk::sync_client::SyncClient;
 use solana_sdk::system_instruction;
 
 pub fn load_program(
@@ -23,7 +24,7 @@ pub fn load_program(
         loader_id,
     );
     bank_client
-        .process_instruction(&from_keypair, instruction)
+        .send_instruction(&from_keypair, instruction)
         .unwrap();
 
     let chunk_size = 256; // Size of chunk just needs to fit into tx
@@ -32,14 +33,14 @@ pub fn load_program(
         let instruction =
             loader_instruction::write(&program_pubkey, loader_id, offset, chunk.to_vec());
         bank_client
-            .process_instruction(&program_keypair, instruction)
+            .send_instruction(&program_keypair, instruction)
             .unwrap();
         offset += chunk_size as u32;
     }
 
     let instruction = loader_instruction::finalize(&program_pubkey, loader_id);
     bank_client
-        .process_instruction(&program_keypair, instruction)
+        .send_instruction(&program_keypair, instruction)
         .unwrap();
 
     program_pubkey
diff --git a/runtime/src/system_instruction_processor.rs b/runtime/src/system_instruction_processor.rs
index 78a345b179..2bf16fc56c 100644
--- a/runtime/src/system_instruction_processor.rs
+++ b/runtime/src/system_instruction_processor.rs
@@ -110,6 +110,7 @@ mod tests {
     use solana_sdk::genesis_block::GenesisBlock;
     use solana_sdk::instruction::{AccountMeta, Instruction, InstructionError};
     use solana_sdk::signature::{Keypair, KeypairUtil};
+    use solana_sdk::sync_client::SyncClient;
     use solana_sdk::system_program;
     use solana_sdk::transaction::TransactionError;
 
@@ -300,7 +301,7 @@ mod tests {
             account_metas,
         );
         assert_eq!(
-            bank_client.process_instruction(&mallory_keypair, malicious_instruction),
+            bank_client.send_instruction(&mallory_keypair, malicious_instruction),
             Err(TransactionError::InstructionError(
                 0,
                 InstructionError::MissingRequiredSignature
diff --git a/sdk/src/lib.rs b/sdk/src/lib.rs
index 0ed8c2bd3c..06db2cd920 100644
--- a/sdk/src/lib.rs
+++ b/sdk/src/lib.rs
@@ -13,6 +13,7 @@ pub mod pubkey;
 pub mod rpc_port;
 pub mod short_vec;
 pub mod signature;
+pub mod sync_client;
 pub mod system_instruction;
 pub mod system_program;
 pub mod system_transaction;
diff --git a/sdk/src/sync_client.rs b/sdk/src/sync_client.rs
new file mode 100644
index 0000000000..96addc3fd9
--- /dev/null
+++ b/sdk/src/sync_client.rs
@@ -0,0 +1,33 @@
+//! Defines a trait for blocking (synchronous) communication with a Solana server.
+//! Implementations are expected to create tranasctions, sign them, and send
+//! them with multiple retries, updating blockhashes and resigning as-needed.
+
+use crate::instruction::Instruction;
+use crate::message::Message;
+use crate::pubkey::Pubkey;
+use crate::signature::Keypair;
+use crate::transaction::TransactionError;
+
+pub trait SyncClient {
+    /// Create a transaction from the given message, and send it to the
+    /// server, retrying as-needed.
+    fn send_message(&self, keypairs: &[&Keypair], message: Message)
+        -> Result<(), TransactionError>;
+
+    /// Create a transaction from a single instruction that only requires
+    /// a single signer. Then send it to the server, retrying as-needed.
+    fn send_instruction(
+        &self,
+        keypair: &Keypair,
+        instruction: Instruction,
+    ) -> Result<(), TransactionError>;
+
+    /// Transfer lamports from `keypair` to `pubkey`, retrying until the
+    /// transfer completes or produces and error.
+    fn transfer(
+        &self,
+        lamports: u64,
+        keypair: &Keypair,
+        pubkey: &Pubkey,
+    ) -> Result<(), TransactionError>;
+}