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<br />VAX server process <br /> <br />Observer client <br />process <br /> <br />The vAX. data server process is continuously connected to the socket on dbserver <br />which receives data., and when new data becomes available, it sends the data through <br />the socket. <br /> <br />The server application which sends data from the VAX to dbserver is initiated with <br />the following commands: <br /> <br />$ set def [dms.rtcm.uppl] <br /> <br />$ @startupp <br /> <br />The dbserver client process is continuously available at the VAX socket for incoming <br />data. When data arrives, it is processed and inserted into the SPWRMS database. <br /> <br />The routines which process the data received from the VAX perform several opera- <br />tions: <br /> <br />J. Check The Data Flag. Each piece of data received from the VAX may be <br />flagged with characters indicating information such as whether the data was <br />extrapolated beyond the range of the rating tables. Flagged data is ignored and <br />not loaded into the SPWRMS database. <br /> <br />2. Look Up The SPWRMS Station Code. The State 8-character station name <br />(e.g., GRELOVCO) and the associated data types (e.g., DISCHRG, ELEV. and <br />Q_I are resolved into SPWRMS station codes (e.g., GRELOVCO, GRELOVEL. <br />and GRELOVFL) by querying the station_code_lu table in the SPWRMS data- <br />base. <br /> <br />3. Insert Values Into SPWRMS Database. The data values read from the VAX are <br />inserted into the SPWRMS database if not already present in the streamflow <br />table. <br /> <br />The dbserver client process is started with the following command: <br /> <br />data_client_ucx codwrvx 5000 <br /> <br />1.4 Architectural Design <br /> <br />The SPWRMS application is composed of several components that provide the <br />connection between raw data and what the user Sees on the computer screen. These <br />components comprise the basic architecture of SPWRMS (see Figure I). <br /> <br />Three elements form the information foundation of SPWRMS: the relational data- <br />base, the ArclInfo coverages (maps), and the in-memory graph. The database is the <br />repository for all dynamic data managed by SPWRMS; the ArclInfo coverages supply <br />all the spatial data for the system; and the in-memory graph is constructed by the <br />system to provide a mechanism to access the data more quickly and efficiently. <br /> <br />The SPWRMS DMI, Data Management Interface, is the heart of the system. The <br />DMI is responsible for answering all requests for data and submissions of data from <br />other system components; it is the interface between the data sources and the rest of <br />the system. The DMI constructs the in-memory graph, then uses a combination of the <br />graph and the other data sources to handle all data requests. For example, when a user <br />wishes to view the Water Information Sheet for District 23, the DMI is the system <br />component that assembles the sheet for display. The DMI gets the names for the <br /> <br />4 <br />