Remote Data Streaming Interface

Even if the functionality provided MDSplus remote d ata access includes the necessary support for remot e data streaming, a specific interface for data strea ming is currently not available. Data streaming in MDSplus is provided using the Segment abstraction: a signal from a long lasting experiment can be stored in th e pulse file segment by segment, that is, by storing the se t of samples currently available, and appending the m to the currently stored signal. At any time, even conc urrently with writing, it is possible to read the s ignal stored so far, making in principle possible to develop onl ine application handling data streaming during oper ation. The same operations can be performed remotely throu gh the MDSplus remote data access layer, thus allowing remote data streaming operations. The purpose of this document is to propose an Appli cation Programming Interface (API) for simplifying the management of the remote data streaming ability of MDSplus. Application program can therefore register and then receive data chunks as soon as they are av ailable, hiding the management of MDSplus segments. Remote streaming interface will adopt the "Publish Subscribe" pattern, that is, data stream listeners will register for a given source of data (a data item in the remote MDSplus pulse file) and they will be la ter notified asynchronously whenever one or more data s amples are available.