{
    "description": "Monitoring a topology that is required to be a replica set", 
    "phases": [
        {
            "outcome": {
                "events": [
                    {
                        "topology_opening_event": {
                            "topologyId": "42"
                        }
                    }, 
                    {
                        "topology_description_changed_event": {
                            "newDescription": {
                                "servers": [
                                    {
                                        "address": "a:27017", 
                                        "arbiters": [], 
                                        "hosts": [], 
                                        "passives": [], 
                                        "type": "Unknown"
                                    }, 
                                    {
                                        "address": "b:27017", 
                                        "arbiters": [], 
                                        "hosts": [], 
                                        "passives": [], 
                                        "type": "Unknown"
                                    }
                                ], 
                                "topologyType": "ReplicaSetNoPrimary"
                            }, 
                            "previousDescription": {
                                "servers": [], 
                                "topologyType": "Unknown"
                            }, 
                            "topologyId": "42"
                        }
                    }, 
                    {
                        "server_opening_event": {
                            "address": "a:27017", 
                            "topologyId": "42"
                        }
                    }, 
                    {
                        "server_opening_event": {
                            "address": "b:27017", 
                            "topologyId": "42"
                        }
                    }, 
                    {
                        "server_description_changed_event": {
                            "address": "a:27017", 
                            "newDescription": {
                                "address": "a:27017", 
                                "arbiters": [], 
                                "hosts": [
                                    "a:27017", 
                                    "b:27017"
                                ], 
                                "passives": [], 
                                "primary": "a:27017", 
                                "setName": "rs", 
                                "type": "RSPrimary"
                            }, 
                            "previousDescription": {
                                "address": "a:27017", 
                                "arbiters": [], 
                                "hosts": [], 
                                "passives": [], 
                                "type": "Unknown"
                            }, 
                            "topologyId": "42"
                        }
                    }, 
                    {
                        "topology_description_changed_event": {
                            "newDescription": {
                                "servers": [
                                    {
                                        "address": "a:27017", 
                                        "arbiters": [], 
                                        "hosts": [
                                            "a:27017", 
                                            "b:27017"
                                        ], 
                                        "passives": [], 
                                        "primary": "a:27017", 
                                        "setName": "rs", 
                                        "type": "RSPrimary"
                                    }, 
                                    {
                                        "address": "b:27017", 
                                        "arbiters": [], 
                                        "hosts": [], 
                                        "passives": [], 
                                        "type": "Unknown"
                                    }
                                ], 
                                "setName": "rs", 
                                "topologyType": "ReplicaSetWithPrimary"
                            }, 
                            "previousDescription": {
                                "servers": [
                                    {
                                        "address": "a:27017", 
                                        "arbiters": [], 
                                        "hosts": [], 
                                        "passives": [], 
                                        "type": "Unknown"
                                    }, 
                                    {
                                        "address": "b:27017", 
                                        "arbiters": [], 
                                        "hosts": [], 
                                        "passives": [], 
                                        "type": "Unknown"
                                    }
                                ], 
                                "topologyType": "ReplicaSetNoPrimary"
                            }, 
                            "topologyId": "42"
                        }
                    }
                ]
            }, 
            "responses": [
                [
                    "a:27017", 
                    {
                        "hosts": [
                            "a:27017", 
                            "b:27017"
                        ], 
                        "ismaster": true, 
                        "maxWireVersion": 4, 
                        "minWireVersion": 0, 
                        "ok": 1, 
                        "primary": "a:27017", 
                        "setName": "rs", 
                        "setVersion": 1.0
                    }
                ]
            ]
        }
    ], 
    "uri": "mongodb://a,b/?replicaSet=rs"
}