Notes for Codefellows Code 401 301 201 and 102
aws FIFO queues have essentially the same features as standard queues, but provide the added benefits of supporting ordering and exactly-once processing. FIFO queues provide additional features that help prevent unintentional duplicates from being sent by message producers or from being received by message consumers.
stackoverflow TCP/IP cannot guarantee that all data that have been sent will also be received. But even if it would guarantee it that is not what you need. What sender actually needs is to know if it does not have to send data again, and that usually implies if sent data has been processed on receivers side. If sender needs to know this then communication protocol must be changed so that sender can receive a confirmation by the receiver that it can safely assume that data has been processed. Also, sender must at certain point proclaim a time-out (and close the socket) if receiver did not send back the confirmation on time (and in your code you must decide what to do about it, maybe save data to be sent at later time, or raise an alert to the user). Also receiver must handle the situation where the same data is being sent twice (as last item in previous connection, and as another item in new connection) and not treat this data as two distinct pieces of data.
wiki observer pattern
gurock Event-driven application architecture provides a lot of power. But it also creates challenges for test practitioners. However, the good news is that these challenges are well-known. Companies that are successful in testing event-driven application architecture understand the asynchronous nature of the paradigm. They weave aggregated logging and distributed tracing into every level of test activity, from unit testing to system-wide performance testing.
wiki first in first out queue
wiki Pub/Sub is an asynchronous messaging service that decouples services that produce events from services that process events.
Skim the following materials in preparation for the upcoming lecture. Note the following as you browse the material, and be prepared to participate in discussions during lecture