BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Verifying availability of an IDispatch instance?          BorlandTalk.com Forum Index -> Delphi OLE Automation View previous topic :: View next topic   Author Message Jon Robertson Guest Posted: Thu Dec 02, 2004 8:27 pm    Post subject: Verifying availability of an IDispatch instance? Is there any generic way to verify that the server-side of an IDispatch instance is still available? I'm looking for something like this, although cleaner than inc/dec a reference counter. Also, I'm not sure whether this would verify the server was still available. (warning, ad-hoc code): function VerifyServerAvailable(MyInstance: IDispatch): Integer; begin Result := S_OK; // S_OK would indicate server is available // Possible Error Results: // RPC_E_DISCONNECTED: The object invoked has // disconnected from its clients. // RPC_S_OUT_OF_RESOURCES: Not enough resources are available // to complete this operation. // RPC_S_SERVER_UNAVAILABLE : The RPC server is unavailable. // RPC_S_CALL_FAILED: The remote procedure call failed. // RPC_S_CALL_FAILED_DNE: The remote procedure call failed // and did not execute. // etc try MyInstance.AddRef; MyInstance.Release; except on E:EOleSysError do Result := E.ErrorCode else raise; end; end; Thanks! -- Jon Robertson Borland Certified Advanced Delphi 7 Developer MedEvolve, Inc http://www.medevolve.com Back to top Pascal Chapuis Guest Posted: Fri Dec 03, 2004 8:53 am    Post subject: Re: Verifying availability of an IDispatch instance? "Re: Com Server Shut Down" ? http://groups.google.com/groups?th=1f29e7964a9b86a9&seekm=754n8k%24nep8%40forums.borland.com#link2 Result:=(TComServerHack (ComServer)).ObjectCount>0); Pascal "Jon Robertson" <jon.robertson (AT) medevolve (DOT) dontspamme.com> a écrit dans le message de news: 41af88b1$1 (AT) newsgroups (DOT) borland.com... Quote: Is there any generic way to verify that the server-side of an IDispatch instance is still available? I'm looking for something like this, although cleaner than inc/dec a reference counter. Also, I'm not sure whether this would verify the server was still available. (warning, ad-hoc code): function VerifyServerAvailable(MyInstance: IDispatch): Integer; begin Result := S_OK; // S_OK would indicate server is available // Possible Error Results: // RPC_E_DISCONNECTED: The object invoked has // disconnected from its clients. // RPC_S_OUT_OF_RESOURCES: Not enough resources are available // to complete this operation. // RPC_S_SERVER_UNAVAILABLE : The RPC server is unavailable. // RPC_S_CALL_FAILED: The remote procedure call failed. // RPC_S_CALL_FAILED_DNE: The remote procedure call failed // and did not execute. // etc try MyInstance.AddRef; MyInstance.Release; except on E:EOleSysError do Result := E.ErrorCode else raise; end; end; Thanks! -- Jon Robertson Borland Certified Advanced Delphi 7 Developer MedEvolve, Inc http://www.medevolve.com Back to top Jon Robertson Guest Posted: Fri Dec 03, 2004 3:55 pm    Post subject: Re: Verifying availability of an IDispatch instance? Pascal Chapuis wrote: Quote: "Re: Com Server Shut Down" ? http://groups.google.com/groups?th=1f29e7964a9b86a9&seekm=754n8k%24nep 8%40forums.borland.com#link2 Result:=(TComServerHack (ComServer)).ObjectCount>0); Thanks, but this isn't what I'm looking for. This would be a server side call, if I was writing the server object, to determine if any clients are connected to me. (We already do something similar in our DataSnap servers.) I'm looking for a way to verify, from the client side, that a server I am connected to (say Microsoft Word) still has a valid connection to that server. -- Jon Robertson Borland Certified Advanced Delphi 7 Developer MedEvolve, Inc http://www.medevolve.com Back to top Pascal Chapuis Guest Posted: Sat Dec 04, 2004 10:08 am    Post subject: Re: Verifying availability of an IDispatch instance? Client side would probably check the IUnknown.RefCount / ObjectCount (?) property _published_ by the server ??? I'm also interested by a "generic way"... Try...Except / RefCount / IMessageFilter / eventSink-callback ? Automation expert Please could you show the right solution ?... Pascal "Jon Robertson" <jon.robertson (AT) medevolve (DOT) dontspamme.com> a écrit dans le message de news: Quote: I'm looking for a way to verify, from the client side, that a server I am connected to (say Microsoft Word) still has a valid connection to that server. -- Jon Robertson Borland Certified Advanced Delphi 7 Developer MedEvolve, Inc http://www.medevolve.com Back to top Deborah Pate (TeamB) Guest Posted: Mon Dec 06, 2004 11:54 am    Post subject: Re: Verifying availability of an IDispatch instance? < function VerifyServerAvailable(MyInstance: IDispatch): Integer; Quote: Something to bear in mind is that Delphi calls IUnknown methods on interfaces behind the scenes. So if the server is no longer available, calling your function will probably cause an exception that your try..except can't catch (and not just because EOleSysError is for IDispatch errors). You might use a variant to avoid behind-the-scenes QueryInterfaces. This is not beautiful, but can be useful in extremis: function ServerAvailable(const Server: Variant): boolean; begin try Server.GetTypeInfoCount; Result := True; except on E: EOleSysError do Result := E.Message = 'Member not found'; end; end; -- Deborah Pate (TeamB) http://delphi-jedi.org TeamB don't see posts sent via Google or ISPs Use the real Borland server: newsgroups.borland.com http://www.borland.com/newsgroups/genl_faqs.html Back to top Jon Robertson Guest Posted: Mon Dec 06, 2004 8:03 pm    Post subject: Re: Verifying availability of an IDispatch instance? Deborah Pate (TeamB) wrote: Quote: Delphi calls IUnknown methods on interfaces behind the scenes. You might use a variant to avoid behind-the-scenes QueryInterfaces. This is not beautiful, but can be useful in extremis: Thanks Deborah! PS Are you available for consulting? We've struggled with the same COM/DCOM/Automation/IDispatch type problems for a while. We keep trying something different, only to find new problems. I haven't asked Management yet, but if you are available, I'd like to pursue it further. Feel free to email me at jonrobertson at medevolve dot com. -- Jon Robertson Borland Certified Advanced Delphi 7 Developer MedEvolve, Inc http://www.medevolve.com Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> Delphi OLE Automation All times are GMT Page 1 of 1   Jump to: Select a forum C++ Builder Newsgroups----------------C++ BuilderC++ Builder (ActiveX)C++ Builder (Announcements)C++ Builder (Command Line Tools)C++ Builder DatabasesC++ Builder Databases (ADO)C++ Builder Databases (Desktop)C++ Builder Databases (InterBase Express)C++ Builder Databases (Multi-Tier)C++ Builder Databases (SQL Servers)C++ Builder (Graphics)C++ Builder (IDE)C++ Builder (Internet)C++ Builder (Internet Socket)C++ Builder (Internet Web)C++ Builder (Jobs)C++ Builder (Language)C++ Builder (Language C++)C++ Builder (Compatibility with MFC)C++ Builder (Native API)C++ Builder (Non-Technical)C++ Builder (Students)C++ Builder (Third Party Tools)C++ Builder (Upgrade)C++ Builder (VCL)C++ Builder (VCL Components Usage)C++ Builder (VCL Components Development)C++ Builder (VCL Usage)C++ Builder (WinAPI)C++ Builder Installation Delphi Newsgroups----------------Delphi (General)Delphi ActiveX Controls UsageDelphi ActiveX Controls DevelopmentDelphi As400Delphi DatabasesDelphi Databases (ADO)Delphi Databases (dbExpress)Delphi Databases (Desktop)Delphi Databases (InterBase Express)Delphi Databases (Multi-Tier)Delphi Databases (SQL Servers)Delphi DeploymentDelphi GraphicsDelphi IDEDelphi InternationalizationDelphi InternetDelphi Internet Isapi-WebBrokerDelphi Internet WebSnapDelphi Internet WinsockDelphi JobsDelphi Language BASMDelphi Language ObjectPascalDelphi Model Driven Architecture (General)Delphi Model Driven Architecture (Third Party)Delphi MultimediaDelphi Native APIDelphi Non-TechnicalDelphi ObjectPascalDelphi OLE AutomationDelphi OO designDelphi OpenToolsAPIDelphi Reporting-ChartingDelphi RTLDelphi StudentsDelphi TeamSourceDelphi Thirdparty ToolsDelphi Thirdparty Tools (General)Delphi Thirdparty Tools (IntraWeb)Delphi Thirdparty Tools (RaveReports)Delphi UpgradeDelphi VCLDelphi VCL ComponentsDelphi VCL Components UsingDelphi VCL Components WritingDelphi WebServices SOAPDelphi WinAPIDelphi XMLDelphi Installationcomp.lang.pascal.delphi.components.misccomp.lang.pascal.delphi.components.usagecomp.lang.pascal.delphi.components.writingcomp.lang.pascal.delphi.databasescomp.lang.pascal.delphi.misccomp.sources.delphi JBuilder Newsgroups----------------JBuilderJBuilder AnnouncementsJBuilder Applet IssuesJBuilder As400JBuilder CompilerJBuilder CORBA/RMIJBuilder DatabasesJBuilder DB SwingJBuilder DebuggerJBuilder DeploymentJBuilder DocumentationJBuilder EnterpriseJBuilder HandheldJBuilder IDEJBuilder JavaJBuilder JavaAPIJBuilder Java LanguageJBuilder Java SwingJBuilder Java BeansJBuilder Java Beans UsageJBuilder Java Beans DevelopmentJBuilder JBCLJBuilder JDataStoreJBuilder JobsJBuilder LinuxJBuilder MacintoshJBuilder & MobileSetJBuilder MultiLingual AppsJBuilder Non-TechnicalJBuilder OpenToolsJBuilder Servlets (JSP)JBuilder StudentsJBuilder Team DevelopmentJBuilder Thirdparty ToolsJBuilder UpgradeJBuilder Installation InterBase Newsgroups----------------InterBaseInterBase Bug DiscussionInterBase GeneralInterBase IBConsoleInterBase OpenSourceInterBase ReplicationInterBase SQLInterBase ThirdpartyInterBase Installation Miscellaneous Borland Newsgroups----------------AppCenterAppServerEnteraVisiBroker  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.