Note: this is a forked version of the original library which uses Gson instead of Json.org for the Java part. The rationable behind this is a problematic license of the Json.org, which requires that "The Software shall be used for Good, not Evil.". Sometimes it's hard to tell what is good and what is evil :(, especially in a corporate environment.

1. Introduction

ProcBridge is a lightweight socket-based IPC (Inter-Process Communication) protocol. The goal is to provide an consistency and convenient way for developers to implement inter-process applications. Currently we have Java and Python implementations. More languages will be supported in the future.

Communication Model

ProcBridge is based on Request-Response model. Server provides a group of APIs and clients send requests to them. All the communications use arbitrary JSON objects to carry higher-level data. The following diagram uses pseudocode to give you a general idea about how ProcBridge works.

The next version of ProcBridge will also support Event-Based model, which unifies the communication code between server side and client side.

Latest Version

• Java: 1.0.2
• Python: 1.0.2

Compatibility Notes

• Java: 8+
• Python: 3.5+

If you need to use ProcBridge on an earlier version runtime, feel free to open an issue or folk my repo.

2. Download

2.1 Java

Maven

<dependency>
    <groupId>co.gongzh.procbridge</groupId>
    <artifactId>procbridge</artifactId>
    <version>1.0.2</version>
</dependency>

Gradle

compile 'co.gongzh.procbridge:procbridge:1.0.2'

Jar

You can download jars on releases page.

Source Code

The Java/ProcBrdige directory is a IntelliJ IDEA project. You can import it in latest version of IntelliJ IDEA IDE and compile it using JDK 8 or higher version.

2.2 Python

PyPI (pip)

pip install procbridge

Source Code

The Python/ProcBrdige directory is a PyCharm project. You can import it in latest version of PyCharm Community IDE and compile it using Python 3.5 or higher version.

3. Examples

With ProcBridge, clients can send high-level requests to server. Each request has two parts: an API name and an optional JSON body. The API name is any non-empty string that defined on server-side. The JSON body can by any valid JSON. The server will handle the request and send response back to clients, which is also an arbitrary JSON object.

In the following examples, the server defines two APIs. One is echo, which directly send back the JSON object sent from client. The other is add, which sums up a group of integers and send the result back to client.

3.1 Python Example

• Server

host = '127.0.0.1'
port = 8077

def request_handler(api: str, arg: dict) -> dict:
    if api == 'echo':
        return arg
    elif api == 'add':
        return {'result': sum(x for x in arg['elements'])}
    else:
        raise Exception('unknown api')

server = ProcBridgeServer(host, port, request_handler)
server.start()

• Client

host = '127.0.0.1'
port = 8077

client = ProcBridge(host, port)

print(client.request('echo', {}))  # prints "{}"

print(client.request('add', {      # prints "{result: 15}"
    'elements': [1, 2, 3, 4, 5]
}))

3.2 Java Example

• Server

int port = 8877;
long timeout = 10000; // 10 seconds

ProcBridgeServer server = new ProcBridgeServer(port, timeout, new Object() {

    @APIHandler JSONObject echo(JSONObject arg) {
        return arg;
    }

    @APIHandler JSONObject add(JSONObject arg) {
        JSONArray elements = arg.getJSONArray("elements");
        int sum = 0;
        for (int i = 0; i < elements.length(); i++) {
            sum += elements.getInt(i);
        }
        JSONObject result = new JSONObject();
        result.put("result", sum);
        return result;
    }

});

server.start();

• Client

String host = "127.0.0.1";
int port = 8877;
long timeout = 10000; // 10 seconds

ProcBridge pb = new ProcBridge(host, port, timeout);
JSONObject resp;

resp = pb.request("echo", "{}");
System.out.println(resp); // prints "{}"

resp = pb.request("add", "{elements: [1, 2, 3, 4, 5]}");
System.out.println(resp); // prints "{result: 15}"

4. Development Plan

Add later.

5. Protocol Design

• FLAG (2 bytes): two fixed ASCII charactors 'p' and 'b' in lowercase
• VERSION (2 bytes): 0x1 and 0x0 indicate the major/minor version of the protocol
• STATUS CODE (1 bytes): a flag that indicates the body is a request or response
• RESERVED BYTES (2 bytes)
• BODY LENGTH (4 bytes): an unsigned little-endian integer
• BODY: an UTF-8 encoded JSON text, always an JSON object { ... }.

6. Contacts

Feel free to open issues or contact me:

• Gong Zhang (gong@me.com)