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PBNIWRITTEN BYDAVID HUOCalling PowerBuilderNVOs in C#PBNI answers the callHow can we reuse Power-Builder NVOs in .NET applications?Before PowerBuilder9.0, the answer was Power-Builder automation or a three-tiersolution.In the latter case that meant hostingall the NVOs in EAServer as middle-tiercomponents. Beginning with version 9,PowerBuilder offers a new interface tointeract with the PowerBuilder VM – thePowerBuilder Native Interface (PBNI).In this article I will explain how to usePBNI in unmanaged C++ code and marshalthe parameters to C# managedcode so that you can invoke Power-Builder NVOs from C#.FIGURE 1 |Java-based applications can use JNIto invoke PowerBuilder via PBNI.• Many PowerBuilder built-in featurescan be moved to PowerBuilder extensionsso that the PowerBuilder corecan be very small and the deploymentsize can vary depending onwhich features the user needs.using the PowerBuilder librarypainter. Right-click the method in theNVO and select “Properties”. The signaturestring is shown in the “Signature”text field (see Figure 2). Anotherway to do it is using pbsig100.exe,which is a command-line toolshipped with PBNI SDK:AUTHOR BIODavid Huo works forthe Sybase Waterlooconsultant team.Introducing PBNI (Power-Builder Native Interface)PBNI is a new feature introducedwith PowerBuilder 9.0. It is only availablein the enterprise versions and isinstalled under %PowerBuilderinstall%\ SDK\PBNI. You can find allthe required header files to use PBNIunder the include directory.PBNI is a standard programminginterface that enables developers toextend the functionality of PowerBuilder.Using PBNI, you can create visual andnonvisual extensions to PowerBuilder(including marshaler extensions) andalso embed the PowerBuilder virtualmachine (PBVM) into C++ applications.Compared with PowerBuilder automation,PBNI has many advantages:• It is not just reusing existing NVOs.PowerBuilder can be extended usingPBNI to provide capabilities such asXML parsing and Web service integration.• The solution is not COM-based,therefore no registry settings arerequired and it can be deployed tonon-Windows platforms.• More languages can reuse Power-Builder components; for example,How It WorksPBNI provides predefined C++ interfacesto allow the PBVM interact to withother languages (see Figure 1). Table 1describes some important interfaces.Calling PowerBuilder NVOfrom Unmanaged CodeTo invoke a PowerBuilder NVO usingPBNI, you need to follow these steps:1. Identify the required PowerBuilderlibrary files and the method signaturestring in the NVO. This can be donepbsig100 .Here is a sample output ofpbsig100.exe showing the methods’signature strings of NVO n_automation:PB Object Name: automationPB Object Name: n_automationpublic function string fn_barcode(string specimenid, stringInterfaceDescriptionsIPB_VMUsed to load PowerBuilder objects in third-party applications andinteroperate with the PowerBuilder virtual machine (PBVM).IPB_Session interface An abstract interface that defines methods for performing variousactions such as accessing PowerScript data, creating PowerBuilderobjects, and calling PowerScript functions.IPB_ValueRepresents a PowerBuilder value, which could be one of the Power-Builder standard datatypes such as integer, long, string, and so forth.It provides information about each variable, including its type, nullflag, access privileges, array or simple type, and reference type.IPB_Arguments Represents the arguments passed to a PowerScript function andused to access the data.PBCallInfo (structure) Used to hold data and return type information for calls betweenextensions and the PBVM.TABLE 1 |24 PBDJ volume12 issue11pbdj.sys-con.com