How To Create a Geode Client in 10 Easy Steps

Start a Geode locator, start a Geode server, and create a region with the following gfsh commands:

gfsh>start locator --name=locator --bind-address=localhost --port=10334
...
gfsh>start server --name=server --bind-address=localhost --server-port=40404 --J=-Dgeode.feature-protobuf-protocol=true
...
gfsh>create region --name=SampleData --type=REPLICATE
Member | Status
------ | ----------------------------------------
server | Region "/SampleData" created on "server"

Generate the language bindings from the message definitions using the relevant target language Protobuf library using the appropriate Protobuf utility such as protoc. Example:

$PROTOBUF/bin/protoc -I=$PROTOBUF/include/ -I=`pwd` --java_out=`pwd` v1/*.proto

Within your application, build a NewConnectionHandshake message, write it in a delimited fashion to the socket. 

NewConnectionHandshake{
    majorVersion: 1
	minorVersion: 1
}

Read the handshake response message in a delimited fashion from your socket. Note that your implementation language may not provide an API to explicitly read and/or write delimited messages. These messages are prepended with the message length encoded as a varint value. If you do not have an appropriate API, you may need to read and decode this value first, in order to determine how much data to read from the network to receive a complete message.
Also be aware that messages may not arrive in one packet and may require multiple read() calls to receive all data from the network.  The response should match the following:

HandshakeAcknowledgement {
    serverMajorVersion: 1
    serverMinorVersion: 1
    handshakePassed: true
}

To exercise the protocol to interact with the server, within your application build a put request message to put the value bar for the key foo, write it in a delimited fashion to the socket, and read the put response message in a delimited fashion from it.

message {
    request {
         putRequest {
             regionName: "SampleData"
             entry {
             key {
                 stringResult: "foo"
             }
             value {
                 stringResult: "bar"
             }
        }
    }
}

message {
    response {
        putResponse {}
    }
}

If an error occurs, your message will contain an ErrorResponse:

message {
    response {
        errorResponse {
            errorCode: 2100
            message: "Region passed by client did not exist: FOO"
        }
    }
}

Outside your application, verify that the put request message took effect with the following gfsh command:

gfsh>get --region=SampleData --key=foo
Result      : true
Key Class   : java.lang.String
Key         : foo
Value Class : java.lang.String
Value       : bar