Systems and methods for providing messages to multiple subscribers

1. A computer-implemented method, comprising:

receiving a plurality of messages from a plurality of publishers;

assigning each of the messages to one of a plurality of channels, wherein each channel comprises an ordered plurality of messages;

storing messages of each of the channels in one or more respective storage buffers according to the order, wherein each storage buffer comprises a respective time-to-live of a first time duration;

for a particular channel, retrieving messages of the particular channel from respective storage buffers;

storing the retrieved messages of the particular channel in a delivery buffer according to the order, the delivery buffer comprising one or more data blocks, wherein each data block comprises a respective time-to-live of a second time duration; and

providing the messages stored in the delivery buffer to a plurality of subscribers of the particular channel.

2. The method of claim 1 , wherein providing the messages stored in the delivery buffer to the plurality of subscribers of the particular channel further comprises:

determining a connection status of a particular subscriber; and

based thereon, providing one or more of the messages stored in the delivery buffer to the particular subscriber.

3. The method of claim 1 , wherein storing the retrieved messages of the particular channel in the delivery buffer comprises:

storing retrieved messages of the particular channel earlier in the order in data blocks having times-to-live that will expire sooner than data blocks used to store retrieved messages of the particular channel later in the order.

4. The method of claim 1 , wherein the delivery buffer comprises a linked list of the data blocks, wherein retrieved messages last in the order of the particular channel are stored in a tail data block of the linked list.

5. The method of claim 1 , wherein:

the delivery buffer resides on a first computing node; and

the messages stored in the delivery buffer are provided to each of the plurality of subscribers through a respective computing process residing on the first computing node.

6. The method of claim 1 , wherein the delivery buffer comprises a visible area and an invisible area.

7. The method of claim 2 , further comprising:

determining that the particular subscriber has a pre-existing connection to the particular channel; and

based thereon, providing to the particular subscriber one or more messages stored in the delivery buffer including messages stored in one or more data blocks having respective times-to-live that have expired.

8. The method of claim 2 , further comprising:

determining that the particular subscriber has a new connection to the particular channel, and, based thereon;

(i) providing to the particular subscriber one or more messages stored in one or more of the data blocks having respective times-to-live that have not expired; and

(ii) preventing the particular subscriber from receiving one or more messages stored in one or more data blocks having respective times-to-live that have expired.

9. The method of claim 4 , wherein storing the retrieved messages of the particular channel in the delivery buffer further comprises:

removing from the linked list one or more data blocks at a head of the linked list, wherein the removed data blocks comprise respective times-to-live that have expired.

10. The method of claim 5 , wherein the storage buffers reside on respective second computing nodes that are different from the first computing node.

11. The method of claim 6 , wherein a subscriber with a pre-existing connection is permitted to access data from both the visible area and the invisible area.

12. The method of claim 6 , wherein a subscriber with a new connection is permitted to access data from the visible area and not permitted to access data from the invisible area.

13. A system, comprising:

one or more computers programmed to perform operations comprising:

receiving a plurality of messages from a plurality of publishers;

assigning each of the messages to one of a plurality of channels, wherein each channel comprises an ordered plurality of messages;

storing messages of each of the channels in one or more respective storage buffers according to the order, wherein each storage buffer comprises a respective time-to-live of a first time duration;

for a particular channel, retrieving messages of the particular channel from respective storage buffers;

storing the retrieved messages of the particular channel in a delivery buffer according to the order, the delivery buffer comprising one or more data blocks, wherein each data block comprises a respective time-to-live of a second time duration; and

providing the messages stored in the delivery buffer to a plurality of subscribers of the particular channel.

14. The system of claim 13 , wherein providing the messages stored in the delivery buffer to the plurality of subscribers of the particular channel further comprises:

determining a connection status of a particular subscriber; and

based thereon, providing one or more of the messages stored in the delivery buffer to the particular subscriber.

15. The system of claim 13 , wherein storing the retrieved messages of the particular channel in the delivery buffer comprises:

storing retrieved messages of the particular channel earlier in the order in data blocks having times-to-live that will expire sooner than data blocks used to store retrieved messages of the particular channel later in the order.

16. The system of claim 13 , wherein the delivery buffer comprises a linked list of the data blocks, wherein retrieved messages last in the order of the particular channel are stored in a tail data block of the linked list.

17. The system of claim 16 , wherein storing the retrieved messages of the particular channel in the delivery buffer further comprises:

removing from the linked list one or more data blocks at a head of the linked list, wherein the removed data blocks comprise respective times-to-live that have expired.

18. The system of claim 14 , further comprising:

determining that the particular subscriber has a pre-existing connection to the particular channel; and

based thereon, providing to the particular subscriber one or more messages stored in the delivery buffer including messages stored in one or more data blocks having respective times-to-live that have expired.

19. The system of claim 14 , further comprising:

determining that the particular subscriber has a new connection to the particular channel, and, based thereon:

(i) providing to the particular subscriber one or more messages stored in one or more of the data blocks having respective times-to-live that have not expired; and

(ii) preventing the particular subscriber from receiving one or more messages stored in one or more data blocks having respective times-to-live that have expired.

20. A non-transitory computer-readable storage device having instructions stored thereon that, when executed by one or more computers, cause the computers to perform operations comprising:

receiving a plurality of messages from a plurality of publishers;

assigning each of the messages to one of a plurality of channels, wherein each channel comprises an ordered plurality of messages;

storing messages of each of the channels in one or more respective storage buffers according to the order, wherein each storage buffer comprises a respective time-to-live of a first time duration;

for a particular channel, retrieving messages of the particular channel from respective storage buffers;

storing the retrieved messages of the particular channel in a delivery buffer according to the order, the delivery buffer comprising one or more data blocks, wherein each data block comprises a respective time-to-live of a second time duration; and

providing the messages stored in the delivery buffer to a plurality of subscribers of the particular channel.