Bhole, R B

Das-Gupta, S

Pal, S

CERN Document Server

INTEGRATING ACOP WITH UNIVERSAL GUI FOR ACCELERATORSS.Dasgupta, R.B. Bhole & Sarbajit PalVariable Energy Cyclotron Centre1/ AF Bidhan Nagar, Calcutta 700 064AbstractThe Java-based universal sharable GUI developmentwork[4] proceeded with incorporation of MSChartActiveX so far, for graph displays of acceleratorparameters. To gain from the accelerator control orientedfeatures of the ’Graph Control’ devised at ACOP(Accelerator Component Oriented Programming)workgroup [3], acop.ocx has been integrated in the"Universal MMI Applet" container. The ’device name’property is resolved at a level just below, and acorresponding GUI is activated. The selected GUI objecthas properties and methods to make transactions with thedevices through a compliant dll. The dll in our case, isbeing developed to facilitate distributed data access bycommunicating with an Active Server Page running onthe data base server, containing the control systemdynamic data[2].1  INTRODUCTIONAn effort to integrate ACOP ActiveX control in ourpreviously made applet prepared for the development ofUniversal MMI, has been undertaken.Full incorporation of ACOP into a Microsoft J++container appeared to be very restricted as yet. The majorpart of the work reported here, was to incorporateconnectivity between our Universal MMI and the controldatabase. In the ACOP methodology, an ACOP.DLL isnecessary to interface the control database or data sourceto the application client. The data acquisition DLL’s toaccess the device data from a remote data server machinehave been implemented by using UDP sockets. Dynamicupdating of data at the client site is also provided in thisprocess. While ACOP compliance in the interfaces ofthese DLLs are being prepared, these have been used in aVB document and data access from an Universal MMIbased on this VB document, instead of a Java applet, arecarried out.Many of the method calls in the rendition part ofACOP need variant type parameters. The Java VARIANTclass of Microsoft in VJ++ could not be successfully usedfor passing arrays of any kind. The Universal MMI basedon the Java language, for platform independence, couldnot therefore be integrated with ACOP, for graph plotting,as planned. Instead the data rendition part of the ACOPhas been also used in this VB document and accessedfrom a browser client.2  DATA TRANSACTION SCHEMEOur database is kept in an Oracle server, residing in adedicated NT Machine as shown in  Figure 1.Figure 1: Client Server NW Scheme The client browser accesses the data from the serverdatabase through a UDP transaction. For the client severcommunication, a WinSock control is used to connect to aremote machine and exchange data using User DatagramProtocol (UDP) and this control doesn’t have a visibleinterface at run time. Creating a UDP application issimpler because the protocol doesn’t require an explicitconnection. To send data between two controls, theRemoteHost property is set to the name of the othercomputer. The RemotePort property to the LocalPortproperty of the second control is set and Bind method isinvoked to specifying the LocalPort to be used. Bothcomputers can be considered "equal" in the relationship,but the server broadcasts only the parameter values whichhave changed recently on a particular port.Figure 2: Data Transaction SchemeInternational Conference on Accelerator and Large Experimental Physics Control Systems609International Conference  Accel rator and L rge Experim ntal Physics Control Systems, 1999, Trieste, ItalyFigure 3: VB Document based DB access MMIThe scheme (shown in Figure 2) implementedpresently uses the ‘ADO’ (Active Data Object)component which is the most recent addition. Theprevious ‘DAO’ (Data Access Object) allowedprogrammers to access the Microsoft Access databaseonly, whereas ‘ADO’ can access all major databases.With ‘ADO’ incorporated, the application sees three typesof objects i.e. connection, command and Recordsetobjects. These objects establish connection, executecommands against the database and hold the recordretrieved from the database or the records to be updatedon the databases.  The ODBC data source manager in theWindows Control Panel sets up ODBC data source andData Source Name (DSN). In Visual Basic code, anODBC connect string is used to establish a connection tothe data source. To access a data source in the code,‘connect’ string is required by the ODBC driver to locateand connect to a data source. For accessing ODBC data,the data source is to be registered using the ODBC datasource manager. The data source in the Windows Registrymakes the information available to applications. The setupfor each ODBC data source varies because each datasource driver requires a different set of information. TheConnect string is used to create a linked TableDef objectthat points to data within an ODBC data source. ARecordset object on the linked database table containsODBC data that can be manipulated using the propertiesand methods of a Recordset object.3  ACOP INTEGRATIONACOP ActiveX component, has been used as a servercomponent which has enabled using even a smaller sizeclient. It is found that until the release of Visual Studio 6,the Java and ActiveX communication is limited to“string” parameters only. Therefore, an ActiveXdocument created in Visual Basic that can run on acontainer like Internet Browser was implemented.The ActiveX document is easy to create anddistribute. The ActiveX Document has been developed inthe Visual Basic Environment from where all parameterof ACOP could be set and various methods supported byACOP could be readily used for on line graphical displayof acquired data. Figure 3 and Figure 4 depict higher leveldevice parameter group formation and displaying on theACOP graph after acquiring the current value from thecentral database server.610Figure 4: ACOP rendition in Universal MMI4  CONCLUDING COMMENTSAt the time of this writing, one can not reliably useany type for a property other than string class. Eventhough the Microsoft documentation shows that one canuse other classes, the reality is that only the String classwill allow one to actually use the properties in theenvironment that normally supports Java applets andActiveX controls.The client server transaction between client browserand server application is more versatile and fast. Thequickest response in the local data transaction is achievedby using ‘ADO’. Whereas, the dynamic graphical displayis ensured by the ACOP control. The used WINSOC andACOP control in the web-page if not available at theclient machine can be downloaded dynamically from theserver. Once downloaded on the client site, it is installedand does not require further downloading unless thesource at the server is modified which provides easydistribution of the updated application.This scheme can also be implemented by Client-sidescripting using Visual Basic or Visual Java Script. Evenlighter clients can be implemented by HTML at the clientside and using server side scripting where the internetserver does all the work.The advantage of platform independence of a Javaapplet MMI must wait until full workability of ActiveXon Java is easily attainable. Until that time, ACOPActiveX in a VB document is conveniently used with theniceties of both. When using ACOP ActiveX, one forgoescross platform compatibility because ActiveX is strictlyusable in the Microsoft environment. One can as well useACOP in VB environment, where it integrates seamlessly,if the above constraint is acceptable.REFERENCES[1] I.Deloose, P.Duval, H.Wu, "The Use of ACOP Toolsin Writing Control System Software", ProceedingICALEPS'97.[2] Sarbajit Pal, S. Dasgupta, "Advancement TowardsDevelopment of Shareable Accelerator MMI",Proceeding PCaPAC'99.[3] Philip Duval, H. Wu, "Using ACOP in HERA ControlApplications", Proceeding PCaPAC'99.[4]  S. Dasgupta, Isamu Abe, "Sharable GUI Objects forthe Operator's  Console", Proceeding ICALEPS'97611

Integrating ACOP with Universal GUI for Accelerators

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