concat.sh

cat $1 $2 > $3

first.sh

date > $1
echo $FOO >> $1
echo $BAZ >> $1

simple.json

{
    "processes": [
        {
            "config": {
                "executor": {
                    "args": ["$one_first"],
                    "executable": "first.sh",
                    "env": {"FOO": "BAR", "BAZ": "$one_ENVVAR"}
                }
            },
            "function": "amqpCommand",
            "ins": [
              "one"
            ],
            "name": "first",
            "outs": [
              "two"
            ],
            "type": "dataflow"
        },
        {
            "config": {
                "executor": {
                    "args": ["$one_second"],
                    "executable": "first.sh"
                }
            },
            "function": "amqpCommand",
            "ins": [
              "one"
            ],
            "name": "first",
            "outs": [
              "three"
            ],
            "type": "dataflow"
        },
        {
            "config": {
                "executor": {
                    "args": ["$two_files", "$three_files", "$four_files"],
                    "executable": "concat.sh"
                }
            },
            "function": "amqpCommand",
            "ins": [
              "two", "three"
            ],
            "name": "mProjectPP",
            "outs": [
              "four"
            ],
            "type": "dataflow"
        }
    ],
    "signals": [
        {
            "name": "one",
            "first": "foo_1",
            "second": "foo_2",
            "ENVVAR": "blahblah"
        },
        {
            "name": "two",
            "files": "foo_1"
        },
        {
            "name": "three",
            "files": "foo_2"            
        },
        {
            "name": "four",
            "files": "outfile"
        }
    ],
    "ins": [0],
    "outs": [3]
}