UNIVERSITY OF WEST ATTICA
SCHOOL OF ENGINEERING
DEPARTMENT OF COMPUTER ENGINEERING AND INFORMATICS

---

Distributed Systems

Mathematical Equations using Remote Procedure Call (RPC)

Vasileios Evangelos Athanasiou
Student ID: 19390005

GitHub · LinkedIn

Supervisor: Doka Katerina, Senior Researcher

UNIWA Profile · LinkedIn

Athens, May 2023

---

Project Overview

This project involves creating a concurrent socket server using TCP AF_INET (Internet Domain) sockets in C. The server processes requests from clients to perform calculations based on two integer vectors and a real number. The computations are executed via Remote Procedure Calls (RPC) on a separate RPC server, which returns the results back to the client through the socket server.

---

Table of Contents

Section	Folder / File	Description
1	assign/	Assignment material
1.1	assign/DS-LAB-ASK-1-2022-23.pdf	Laboratory assignment description (English)
1.2	assign/ΚΣ-ΕΡΓΑΣΤΗΡΙΟ-ΑΣΚ-1-2022-23.pdf	Περιγραφή εργαστηριακής άσκησης (Greek)
2	docs/	Theoretical documentation
2.1	docs/Remote-Procedure-Call.pdf	Remote Procedure Call (RPC) theory (English)
2.2	docs/Απομακρυσμένη-Κλήση-Διαδικασίας.pdf	Απομακρυσμένη Κλήση Διαδικασίας – RPC (Greek)
3	src/	Source code implementation
3.1	src/Makefile	Build automation file
3.2	src/rpc.x	RPC interface definition (XDR specification)
3.3	src/rpc.h	RPC shared header file
3.4	src/rpc_xdr.c	XDR data serialization/deserialization
3.5	src/rpc_server.c	RPC server implementation
3.6	src/rpc_svc.c	RPC service-side stub code
3.7	src/rpc_client.c	RPC client implementation
3.8	src/rpc_clnt.c	RPC client-side stub code
3.9	src/socket_client.c	Low-level socket client implementation
4	README.md	Repository overview and usage instructions

---

Key Features

• Concurrent Server: The server handles multiple client requests concurrently using forked child processes.
• TCP Socket Communication: The clients connect to the server using TCP sockets to send and receive data.
• ONC RPC: The server, acting as an RPC client, communicates with an external RPC server to perform the required calculations.
• Remote Procedure Calls: The server uses three distinct RPC-based functions for calculations, depending on the user's choice:
  1. Inner Product of Two Vectors (X * Y)
  2. Average Value of Each Vector (X̄, Ȳ)
  3. Product r*(X + Y)

Program Workflow

1. Client Side:

   • The user selects the desired computation (inner product, average, or product).
   • The client sends the required data (n, vectors X and Y, and real number r) to the socket server.
   • The client waits for the result from the socket server, which is returned after processing.

2. Server Side:

   • The server accepts the client's connection and receives the computation request.
   • It forwards the data to the RPC server for processing.
   • The server receives the computed result from the RPC server and sends it back to the client.

3. RPC Server:

   • It performs the requested computation using the data provided by the socket server.

Requirements

• Operating System: Linux or any Unix-like system that supports TCP sockets and ONC RPC.
• Libraries:
  • ONC RPC (Open Network Computing Remote Procedure Call)
  • Sockets (sys/socket.h)
• Tools: rpcgen (for generating RPC stubs), GCC (for compiling C programs).

Installation and Usage

1. Clone the Repository

Download the repository to your local machine:

git clone https://github.com/Distributed-Systems-aka-Uniwa/RPC.git

2. Compile and Setup

1. Generate RPC Stubs

   First, generate the necessary stubs for the RPC Server and RPC Client using the rpcgen utility. The .x file defines the interface for the three procedures:

   rpcgen -a -C rpc.x
   

   This will generate:

   rpc.h: Header file defining the structures and procedure prototypes.

   rpc_clnt.c: RPC Client stub.

   rpc_svc.c: RPC Server stub.

2. Compile the RPC Server

   Compile the RPC Server which will handle the computation of the requested tasks.

3. Compile the Socket Server (also RPC Client)

   The Socket Server (also RPC Client) forwards computation requests to the RPC Server and relays results back to the client.

4. Automate the Compilation

   There is a Makefile which helps you to automate the compilation of the rpc_*.c files:

   make
   

5. Compile the Socket Client

   The Socket Client allows the user to select a computation task and provides the necessary data:

   gcc -o socket_client socket_client.c
   

3. Execute

1. Start the RPC Server

   First, start the RPC Server that will handle the remote computations:

   ./rpc_server
   

2. Start the Socket Server

   Next, start the Socket Server that acts as an intermediary between the Socket Clients and the RPC Server:

   ./rpc_client <port_number> <server_host>
   

3. Start the Socket Client

   Finally, start the Socket Client which will allow the user to input data and request computations:

   ./socket_client <port_number> <server_host>
   

---

Open the Documentation

1. Navigate to the docs/ directory
2. Open the report corresponding to your preferred language:
   • English: Remote-Procedure-Call.pdf
   • Greek: Απομακρυσμένη-Κλήση-Διαδικασίας.pdf