Success of Diplomacy
As we know that the ‘dialogue’ is the first or basic need for the process of diplomacy to start and keep it going. It was always the part of Human Affairs since the evolution of ancient civilization when the leaders of tribe used to send their delegates to represent their say to the other group. The other higher forms of state craft like negotiation or adoption come later. If the dialogue has reached to any short of agreement/ bargain/ compromise that each party can live with, then it is a successful diplomacy. If even one party is not happy out of many then it will be a disagreement, as in an agreement all have to give up something to come to the amicable conclusion. Best part of this success is having a written treaty or agreement, while having all parties satisfied or happy with it.
Failure of Diplomacy
If two or more parties start a dialogue or process of negotiation then the process fails if any of the party or parties walks away or stops dialogues with greater difference or refuses to any kind of compromise while resuming hostility and trying not even the back channel of discussion then in that case the diplomacy is said to be failed.