Adding gRPC Client generation from the existing protobuff files

ojp-grpc-client-go/README.md

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+# OJP gRPC Go Client (Application Layout)
+
+This folder contains a Go application client for OJP.
+It connects to `ojp-server` over gRPC and runs a simple CRUD flow.
+
+## Folder Structure
+
+```text
+ojp-grpc-client-go/
+  cmd/ojp-grpc-client/        # executable entrypoint (main package)
+  internal/client/            # client-side connection/load-balancing helpers
+  internal/gen/               # generated protobuf/gRPC Go stubs
+  scripts/                    # integration test runners
+  testdata/connection.csv     # test/demo CSV lines (not required in production)
+  testdata/postgres/init/     # postgres18 compose init SQL
+  testdata/mysql/init/        # mysql compose init SQL
+  testdata/mariadb/init/      # mariadb compose init SQL
+  docker-compose.postgres18.yml
+  docker-compose.mysql.yml
+  docker-compose.mariadb.yml
+  go.mod
+  go.sum
+```
+
+## Configuration
+
+Primary (normal use case):
+
+- `OJP_JDBC_LINE`
+
+Format:
+
+```text
+jdbc:ojp[host:port]_backendJdbcUrl,user,password
+```
+
+Example:
+
+```text
+jdbc:ojp[localhost:1059]_postgresql://localhost:5432/defaultdb,testuser,testpassword
+```
+
+## What `main` Does
+
+1. Parses connection values from env (`addr`, backend JDBC URL, user, password).
+2. Opens gRPC connection to OJP server.
+3. Runs CRUD on table `demo`:
+   - `CREATE TABLE IF NOT EXISTS`
+   - insert
+   - read
+   - update
+   - read
+   - delete
+   - read
+
+## Run the Client
+
+From `ojp-grpc-client-go`:
+
+```bash
+$env:OJP_JDBC_LINE='jdbc:ojp[localhost:1059]_h2:~/test,sa,'
+go run ./cmd/ojp-grpc-client
+```
+
+Expected output:
+
+```text
+READ after CREATE/INSERT:
+opResult: type=RESULT_SET_DATA uuid=...
+READ after UPDATE:
+opResult: type=RESULT_SET_DATA uuid=...
+READ after DELETE:
+opResult: type=RESULT_SET_DATA uuid=...
+```
+
+## Unit Tests
+
+Unit tests are in:
+
+- `cmd/ojp-grpc-client/main_test.go`
+
+Covered functions:
+
+- `parseOjpCsvLine`
+- `selectCsvLine`
+- `drainQueryStream` (with mock streaming client)
+
+Run:
+
+```bash
+go test ./cmd/ojp-grpc-client
+```
+
+## End-to-End Test (OJP + H2)
+
+### 1) Prepare OJP server drivers
+
+```bash
+cd ..\ojp-server
+bash -lc "tr -d '\r' < download-drivers.sh | bash"
+```
+
+This creates `ojp-server/ojp-libs/` and downloads H2 + other open-source JDBC drivers.
+
+### 2) Build project artifacts
+
+From repository root (`ojp/`):
+
+```bash
+mvn clean install "-DskipTests=true" "-Dgpg.skip=true" "-Dcheckstyle.skip=true"
+```
+
+### 3) Start OJP server
+
+From `ojp-server`:
+
+```bash
+java -Duser.timezone=UTC -Dojp.libs.path=.\ojp-libs -jar .\target\ojp-server-0.4.17-SNAPSHOT-shaded.jar
+```
+
+### 4) Run Go client against H2
+
+From `ojp-grpc-client-go`:
+
+```bash
+$env:OJP_JDBC_LINE='jdbc:ojp[localhost:1059]_h2:~/test,sa,'
+go run ./cmd/ojp-grpc-client
+```
+
+If you want to test using CSV test data:
+
+```bash
+$env:OJP_JDBC_CSV = Get-Content -Raw -Path .\testdata\connection.csv
+$env:OJP_JDBC_CSV_INDEX='0'
+Remove-Item Env:OJP_JDBC_LINE -ErrorAction SilentlyContinue
+go run ./cmd/ojp-grpc-client
+```
+
+## End-to-End Test (PostgreSQL 18 via Docker Compose)
+
+This repository now includes an automated PostgreSQL 18 + OJP + Go CRUD test setup.
+
+### PowerShell (recommended on Windows)
+
+From `ojp-grpc-client-go`:
+
+```powershell
+powershell -ExecutionPolicy Bypass -File .\scripts\run-postgres18-crud-test.ps1 -SkipBuild
+```
+
+Options:
+
+- Remove `-SkipBuild` to run Maven install before the test.
+
+What this script does:
+
+1. Starts `postgres:18` using `docker-compose.postgres18.yml`
+2. Waits for healthy Postgres
+3. Ensures PostgreSQL JDBC driver exists in `ojp-server/ojp-libs`
+4. (Optional) builds OJP modules
+5. Starts OJP server on dynamically selected free ports
+6. Runs `go run ./cmd/ojp-grpc-client` with `OJP_JDBC_LINE` targeting `testdb`
+
+### Bash
+
+From `ojp-grpc-client-go`:
+
+```bash
+bash scripts/run-postgres18-crud-test.sh -SkipBuild
+```
+
+The bash script is a standalone implementation that follows the same steps as the PowerShell version.
+
+## End-to-End Test (MySQL via Docker Compose)
+
+From `ojp-grpc-client-go`:
+
+```powershell
+powershell -ExecutionPolicy Bypass -File .\scripts\run-mysql-crud-test.ps1 -SkipBuild
+```
+
+Or:
+
+```bash
+bash scripts/run-mysql-crud-test.sh -SkipBuild
+```
+
+This follows the same steps as the PostgreSQL script:
+
+1. Starts `mysql:8.4` using `docker-compose.mysql.yml`
+2. Waits for healthy MySQL
+3. Ensures MySQL JDBC driver exists in `ojp-server/ojp-libs`
+4. (Optional) builds OJP modules
+5. Starts OJP server on dynamically selected free ports
+6. Runs `go run ./cmd/ojp-grpc-client` with MySQL `OJP_JDBC_LINE`
+
+## End-to-End Test (MariaDB via Docker Compose)
+
+From `ojp-grpc-client-go`:
+
+```powershell
+powershell -ExecutionPolicy Bypass -File .\scripts\run-mariadb-crud-test.ps1 -SkipBuild
+```
+
+Or:
+
+```bash
+bash scripts/run-mariadb-crud-test.sh -SkipBuild
+```
+
+This follows the same steps as the PostgreSQL script:
+
+1. Starts `mariadb:11` using `docker-compose.mariadb.yml`
+2. Waits for healthy MariaDB
+3. Ensures MariaDB JDBC driver exists in `ojp-server/ojp-libs`
+4. (Optional) builds OJP modules
+5. Starts OJP server on dynamically selected free ports
+6. Runs `go run ./cmd/ojp-grpc-client` with MariaDB `OJP_JDBC_LINE`
+
+## End-to-End Test (DB2 via Docker Compose)
+
+From `ojp-grpc-client-go`:
+
+```powershell
+powershell -ExecutionPolicy Bypass -File .\scripts\run-db2-crud-test.ps1 -SkipBuild
+```
+
+Or:
+
+```bash
+bash scripts/run-db2-crud-test.sh -SkipBuild
+```
+
+This follows the same steps as the PostgreSQL script:
+
+1. Starts `icr.io/db2_community/db2` using `docker-compose.db2.yml` with a dynamically assigned host port
+2. Waits for healthy DB2 (up to 10 min, 5s intervals)
+3. Ensures DB2 JDBC driver (`jcc-*.jar`) exists in `ojp-server/ojp-libs`
+4. (Optional) builds OJP modules
+5. Starts OJP server on dynamically selected free ports
+6. Runs `go run ./cmd/ojp-grpc-client` with DB2 `OJP_JDBC_LINE`
+
+> **Note:** DB2 uses a stricter SQL dialect. The `demo` table creation requires `NOT NULL` on primary key columns — 
+> this is already handled in the Go clients CREATE TABLE statement.
+
+## End-to-End Test (SQL Server via Docker Compose)
+
+From `ojp-grpc-client-go`:
+
+```powershell
+powershell -ExecutionPolicy Bypass -File .\scripts\run-mssql-crud-test.ps1 -SkipBuild
+```
+
+Or:
+
+```bash
+bash scripts/run-mssql-crud-test.sh -SkipBuild
+```
+
+This follows the same steps as the PostgreSQL script:
+
+1. Starts `mcr.microsoft.com/mssql/server:2022-latest` using `docker-compose.mssql.yml` with a dynamically assigned host port
+2. Waits for healthy MSSQL (up to 4 min, 3s intervals)
+3. Ensures MSSQL JDBC driver (`mssql-jdbc-*.jar`) exists in `ojp-server/ojp-libs`
+4. (Optional) builds OJP modules
+5. Starts OJP server on dynamically selected free ports
+6. Runs `go run ./cmd/ojp-grpc-client` with SQL Server `OJP_JDBC_LINE`
+
+## End-to-End Test (Oracle XE via Docker Compose)
+
+From `ojp-grpc-client-go`:
+
+```powershell
+powershell -ExecutionPolicy Bypass -File .\scripts\run-oracle-crud-test.ps1 -SkipBuild
+```
+
+Or:
+
+```bash
+bash scripts/run-oracle-crud-test.sh -SkipBuild
+```
+
+This follows the same steps as the PostgreSQL script:
+
+1. Starts `gvenzl/oracle-xe` using `docker-compose.oracle.yml` with a dynamically assigned host port
+2. Waits for healthy Oracle (up to 6 min, 4s intervals)
+3. Ensures Oracle JDBC driver (`ojdbc*.jar`) exists in `ojp-server/ojp-libs`
+4. (Optional) builds OJP modules
+5. Starts OJP server on dynamically selected free ports
+6. Runs `go run ./cmd/ojp-grpc-client` with Oracle `OJP_JDBC_LINE`