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Live_FeedsLive Feeds are real time data, such as stock prices or fx rates, that are fetched from live feed providers and displayed on the spreadsheet.
Deriscope is capable of retrieving live feeds both synchronously and asynchronously from these Live Feeds Providers.
The synchronous mode is the simplest and derives its name from the fact that the time demanding process of acquiring the data from the provider's server runs synchronously with everything else Excel is doing at that time.
One says that a process A runs synchronously with another process B, if both processes run on the same execution thread, which simply means that while one process is active, the other process cannot run simultaneously but must wait until the active process finishes its job.
Using thread terminology then, the synchronous mode means that the data acquisition process runs on the same thread as the main (user interface) Excel thread.
The asynchronous mode is more complex and derives its name from the fact that the data acquisition process runs asynchronously with everything else Excel is doing at that time.
One says that a process A runs asynchronously with another process B, if the two processes run parallel to each other on separate execution threads, which simply means that both processes can be active on the same time.
Using thread terminology again, the asynchronous mode means that the data acquisition process runs on the same thread as the main (user interface) Excel thread.
Deriscope implements synchronous live feeds through the Excel formula named dsLiveGet
The asynchronous live feeds acquisition requires the following two steps:
STEP 1: Start a live feeds engine using anyone of the two special Excel formulas dsLiveStartEngine or dsLive
If you choose dsLive approach, you must first create an object of type Live Engine and pass its handle name as the single input argument to dsLive
The chosen formula must run only once in order to start the asynchronous thread of acquiring the live data from the provider's server at regular time intervals.
STEP 2: Display the live feeds acquired by the engine already kicked off in the previous step by using anyone of the two special Excel formulas dsLiveGet or dsLive
If you choose the dsLive approach, you must first create an object of type Live Display Async and pass its handle name as the single input argument to dsLive
Note the dsLiveGet is declared volatile so that it automatically runs as soon as new feeds arrive and a recalculation event is raised.
Provided Excel is in automatic calculation mode, such a recalculation event is raised automatically upon the arrival of new feeds if the Auto Refresh setting is turned ON.
Also note that dsLive is not declared volatile, which means you should replace it with its volatile version if you want to have the benefits mentioned above.