SVM: add a sample stand-alone application based on SVM

Cargo.toml

@@ -144,7 +144,13 @@ members = [
     "zk-token-sdk",
 ]
 
-exclude = ["programs/sbf", "svm/tests/example-programs"]
+exclude = [
+    "programs/sbf",
+    "svm/json-rpc-example/json-rpc-client",
+    "svm/json-rpc-example/json-rpc-program",
+    "svm/json-rpc-example/json-rpc-server",
+    "svm/tests/example-programs",
+]
 
 resolver = "2"
 

svm/json-rpc-example/README.md

@@ -0,0 +1,31 @@
+This is an example application using SVM to implement a tiny subset of
+Solana RPC protocol for the purpose of simulating transaction
+execution without having to use the entire Solana Runtime.
+
+The exmample consists of two host applications
+- json-rpc-server -- the RPC server that accepts incoming RPC requests
+  and performs transaction simulation sending back the results,
+- json-rpc-client -- the RPC client program that sends transactions to
+  json-rpc-server for simulation,
+
+and
+
+- json-rpc-program is the source code of on-chain program that is
+  executed in a transaction sent by json-rpc-client.
+
+To run the example, compile the json-rpc-program with `cargo
+build-sbf` command. Using solana-test-validator create a ledger, or
+use an existing one, and deploy the compiled program to store it in
+the ledger. Using agave-ledger-tool dump ledger accounts to a file,
+e.g. `accounts.out`. Now start the json-rpc-server, e.g.
+```
+cargo run --manifest-path json-rpc-server/Cargo.toml -- -l test-ledger -a accounts.json
+```
+
+Finally, run the client program.
+```
+cargo run --manifest-path json-rpc-client/Cargo.toml -- -C config.yml -k json-rpc-program/target/deploy/helloworld-keypair.json -u localhost
+```
+
+The client will communicate with the server and print the responses it
+recieves from the server.

svm/json-rpc-example/config.yml

@@ -0,0 +1,7 @@
+---
+json_rpc_url: http://127.0.0.1:8899
+websocket_url: ''
+keypair_path: svm/examples/test.json
+address_labels:
+  '11111111111111111111111111111111': System Program
+commitment: confirmed