Stack-based communications systems and methods

1. A computer system configured to support a conversation between a user and a virtual assistant, the computer system comprising:

a memory; and

at least one processor coupled to the memory and configured to

receive, from the virtual assistant, a fulfillment request specifying a first intent,

push a first item onto a conversation stack stored in the memory, the first item including an identifier of the first intent,

dispatch the first intent to an action handler registered to receive the first intent,

receive, from the action handler, one or more instructions to manipulate the conversation stack,

manipulate the conversation stack in accordance with the one or more instructions including pushing a second item onto the conversation stack, the second item including an identifier of a second intent,

peek at the second item in the conversation stack to generate a response to the user regarding the second intent;

transmit a fulfillment response to the virtual assistant, the fulfillment response comprising the response to the user; and

store the conversation stack in the memory for subsequent processing within the conversation.

2. The computer system of claim 1 , wherein the action handler is a first action handler and to peek comprises to dispatch the second intent to a second action handler associated with the second intent.

3. The computer system of claim 1 , wherein the fulfillment request comprises a full representation of the conversation stack.

4. The computer system of claim 1 , wherein the fulfillment request comprises a session identifier, and the at least one processor is further configured to store, in the memory, an association between the conversation stack and the session identifier.

5. The computer system of claim 1 , wherein the intent is a first intent, the fulfillment request is a first fulfillment request, and the at least one processor is further configured to:

receive a second fulfillment request comprising a second intent;

call the action handler with the second intent to determine whether the action handler can process the second intent; and

process a response message from the action handler.

6. The computer system of claim 5 , wherein the response message specifies a response to the user and at least one instruction to manipulate the conversation stack and the at least one processor is further configured to:

append the response to the user to another response to the user; and

manipulate the conversation stack in accordance with the at least one instruction.

7. The computer system of claim 5 , wherein the response message specifies no additional action and the at least one processor is further configured to take no additional action regarding the response message.

8. The computer system of claim 5 , wherein the item is a first item and the at least one processor is further configured to call the action handler to indicate that a second item will be placed atop the item prior to pushing the second item onto the conversation stack.

9. A method of supporting a conversation between a virtual assistant and a user, the method comprising:

receiving, from the virtual assistant, a fulfillment request specifying a first intent;

pushing a first item onto a conversation stack stored in memory, the first item including an identifier of the first intent;

dispatching the first intent to an action handler registered to receive the first intent;

receiving, from the action handler, a response message including a response to the user and one or more instructions to manipulate the conversation stack;

manipulating the conversation stack in accordance with the one or more instructions including pushing a second item onto the conversation stack, the second item including an identifier of a second intent;

peeking at the second item in the conversation stack to generate an additional response to the user regarding the second intent;

appending the additional response to the user to the response to the user;

storing the conversation stack in the memory for subsequent processing within the conversation; and

transmitting a fulfillment response to the virtual assistant to continue the conversation, the fulfillment response comprising the response to the user.

10. The method of claim 9 , wherein the action handler is a first action handler and peeking comprises dispatching the second intent to a second action handler registered to receive the second intent.

11. The method of claim 9 , wherein receiving the fulfillment request comprises receiving a full representation of the conversation stack.

12. The method of claim 9 , wherein receiving the fulfillment request comprises receiving a session identifier, and the method further comprises storing, in the memory, an association between the conversation stack and the session identifier.

13. The method of claim 9 , wherein the intent is a first intent, the response message is a first response message, the fulfillment request is a first fulfillment request, and the method further comprises:

receiving a second fulfillment request comprising a second intent;

calling the action handler with the second intent to determine whether the action handler can process the second intent; and

processing a second response message from the action handler.

14. The method of claim 13 , wherein the response to the user is a first response to the user, the second response message comprises a second response to the user and at least one instruction to manipulate the conversation stack, and the method further comprises:

appending the first response to the user to the second response to the user; and

manipulating the conversation stack in accordance with the at least one instruction.

15. The method of claim 13 , wherein the item is a first item and the method further comprises calling the action handler to indicate that a second item will be placed atop the first item prior to pushing the second item onto the conversation stack.

16. A non-transitory computer readable medium storing executable sequences of instructions to implement a conversation stack supporting a conversation between a user and a virtual assistant, the sequences of instructions comprising instructions to:

receive, from a virtual assistant, a fulfillment request specifying a first intent;

push a first item onto a conversation stack stored in a memory, the first item including an identifier of the first intent;

dispatch the intent to an action handler registered to receive the intent;

manipulate the conversation stack in accordance with one or more instructions received from the action handler including pushing a second item onto the conversation stack, the second item including an identifier of a second intent;

peek at the second item in the conversation stack to generate a response to the user regarding the second intent;

store the conversation stack in the memory for subsequent processing within the conversation;

store the response to the user in a fulfillment response; and

transmit the fulfillment response to the virtual assistant.

17. The non-transitory computer readable medium of claim 16 , wherein the action handler is a first action handler and to peek comprises to dispatch the second intent to a second action handler registered to receive the second intent.