BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Object Serialization Goto page 1, 2  Next          BorlandTalk.com Forum Index -> Delphi OO design View previous topic :: View next topic   Author Message Hechicero Guest Posted: Wed Feb 09, 2005 3:39 pm    Post subject: Object Serialization Hi, I am programing an object serializer that unses RTTI in Delphi 7 and has the following functionality : it backups the state of every published property so they can be restored later through this serializer. It also transform the objecto to an XML string and Vice-Versa. The thing is this. I want to serialize an object A wich has a reference to another object B. The serializer creates an XML for A only contanining A properties, but not B properties. The solution I found in the first version of the serializer is to store Bs memory address in the XML. Something like this A to XML (XML is not exactly as it is shown) .... <Propertie> <PropertyName>StringProp</PropertyName> <PropertyType>string</PropertyName> <Value>John Doe</Value> </Propertie> <Propertie> <PropertyName>ObjectProp</PropertyName> <PropertyType>Object</PropertyName> <Value>Address(#65E4286E)</Value> </Propertie> .... The serializer works perfectly. But the problem is this. I dont feel very confortable using memory addres and most importantly, If I wanted to migrate my serializer to .NET, how should I do it. I am not a very experienced .NET programing but as far as I know you cannot work with pointers in .NET. Esteban Calabria Back to top Joanna Carter (TeamB) Guest Posted: Wed Feb 09, 2005 3:42 pm    Post subject: Re: Object Serialization "Hechicero" <accesosecuencial (AT) yahoo (DOT) com.ar> a écrit dans le message de news: [email]420a2eaf (AT) newsgroups (DOT) borland.com[/email]... Quote: The serializer works perfectly. But the problem is this. I dont feel very confortable using memory addres and most importantly, If I wanted to migrate my serializer to .NET, how should I do it. You cannoy serialize memory addresses as it is not guaranteed over multiple executions. You need to include an integer ID for every object and have a mechanism for allocating those IDs uniquely to every object when it is first serialized. Joanna -- Joanna Carter (TeamB) Consultant Software Engineer TeamBUG support for UK-BUG TeamMM support for ModelMaker Back to top Jim Cooper Guest Posted: Wed Feb 09, 2005 3:51 pm    Post subject: Re: Object Serialization Quote: I am not a very experienced .NET programing but as far as I know you cannot work with pointers in .NET. Umm, but there is already a serializer in .NET. Will that not work for you? Cheers, Jim Cooper __________________________________________ Jim Cooper [email]jcooper (AT) tabdee (DOT) ltd.uk[/email] Tabdee Ltd http://www.tabdee.ltd.uk TurboSync - Connecting Delphi to your Palm __________________________________________ Back to top Hechicero Guest Posted: Wed Feb 09, 2005 4:29 pm    Post subject: Re: Object Serialization Yes of course. As a matter of fact I would do that if i had to serlialize objects in .NET. The thing that came to my mind if I wanted to translate it to .NET just for the fun of doing it... Is it possible? Back to top Hechicero Guest Posted: Wed Feb 09, 2005 4:30 pm    Post subject: Re: Object Serialization Thanks Johana, I thought so but... By the way... if the serializer is meant to be used only in the same execution and you want to reutilize in many projects where not necesarily every object has an ID, do you have a miracolus idea of how to do it? As far as I my see it cannot be done . Esteban Calabria Back to top Marc Rohloff [TeamB] Guest Posted: Thu Feb 10, 2005 2:46 am    Post subject: Re: Object Serialization On Wed, 9 Feb 2005 12:39:17 -0300, Hechicero wrote: Quote: I am programing an object serializer that unses RTTI in Delphi 7 and has the following functionality : it backups the state of every published property so they can be restored later through this serializer. It also transform the objecto to an XML string and Vice-Versa. The thing is this. I want to serialize an object A wich has a reference to another object B. The serializer creates an XML for A only contanining A properties, but not B properties. The solution I found in the first version of the serializer is to store Bs memory address in the XML. Something like this You may want to look at QuickRTTI (www.bigattichouse.com) which already does a lot of this. I don't know how it handles the object references though. -- Marc Rohloff [TeamB] marc rohloff -at- myrealbox -dot- com Back to top Martin Harvey (Demon Acco Guest Posted: Sat Feb 12, 2005 8:22 am    Post subject: Re: Object Serialization On Wed, 9 Feb 2005 13:30:04 -0300, "Hechicero" <accesosecuencial (AT) yahoo (DOT) com.ar> wrote: Quote: Thanks Johana, I thought so but... By the way... if the serializer is meant to be used only in the same execution and you want to reutilize in many projects where not necesarily every object has an ID, do you have a miracolus idea of how to do it? Yes. It looks like we're working on very similar systems: I'm developing an object streaming system which will encode / decode to/from XML, and also a binary format, which I suspect will look distinctly like a TLV / KLV encoding. The only way to do it is to make every object instance call a registration routine in the streaming system, and generate a unique ID per transaction. Actually this isn't as bad as it sounds: if you want to stream just about anything, you may have to make the objects implement helper functions that will enumerate fields in records / arrays recursively. Just a couple of thoughts: 1. How are you doing your XML parsing? 2. Is the streamable clase class in your library going to be fixed or are you going to write it in such a manner that the base class can be changed from project to project? MH. Back to top Martin Harvey (Demon Acco Guest Posted: Sat Feb 12, 2005 11:43 pm    Post subject: Re: Object Serialization On Wed, 9 Feb 2005 12:39:17 -0300, "Hechicero" <accesosecuencial (AT) yahoo (DOT) com.ar> wrote: Quote: PropertyName>ObjectProp</PropertyName PropertyType>Object</PropertyName Value>Address(#65E4286E) I notice that this grammer is not neccesarily LL(1) - depending on what's in the value field, you might end up having to look ahead more than 1 token. How are you parsing it.. is your parser hand written? MH. Back to top Hechicero Guest Posted: Tue Feb 15, 2005 1:10 pm    Post subject: Re: Object Serialization Martin, The idea of registering the objects that are going to be serialized so that they are given an internal OID for serialization is a good one!. I want the serializer to be independent from the base class of each object and to be reutilizable in many projects.. For now the XML we use is actually a binary format so I havent dealed with XML parsing yet. The serialized object, for now, is never persisted to disk Esteban Back to top Martin Harvey (Demon Acco Guest Posted: Tue Feb 15, 2005 11:38 pm    Post subject: Re: Object Serialization On Tue, 15 Feb 2005 10:10:02 -0300, "Hechicero" <accesosecuencial (AT) yahoo (DOT) com.ar> wrote: Quote: Martin, The idea of registering the objects that are going to be serialized so that they are given an internal OID for serialization is a good one!. I want the serializer to be independent from the base class of each object and to be reutilizable in many projects.. Ah, ok. In that case, you might want to consider an earlier set of posts under the topic "WANTED! Object streaming system" where I discussed a simple solution to this problem which I'll call (for the sake of a better word) a "heirarchy plug-in". Google groups for the subject, and I'm sure it'll pop up fairly quick. My streaming system hasn't got far I'm afraid... I've been busy at work. I got as far as defining an intermediate representation for all the data I wanted, wich was doing to fit into the scheme like this: Read from stream: Write to stream: <stream> <stream> <lexer> <token writer> <parser> <grammar generator> <intermed. rep> <intermed. rep> <stream manager> <stream amanger> <heirarchy plugin> <heirarchy plugin> <datastructure> <datastructure> Hopefully, this I was going to allow the plug-in to support custom written streaing stuff so that you can support nested records / arrays - although they will of course not be backed by RTTI. I've only spent an hour or so on it (miserably slow progress), but the definition looks like this - as you can see, my ID's are simply an integer - not much here yet! What I think will interest you in the Defn's below is TSSI transaction, and the declarations in TSSIPropertyData for record, array and class types. unit SSIntermediates; { Copyright (c) Martin Harvey 2005. This unit defines the intermediate representation of data in the streaming system. } interface uses Trackables; type TSSIntermediate = class (TTrackable); //TODO - Can't think of anythign to put here at the mo. TSSIList = class(TSSIntermediate) private protected public destructor Destroy; override; destructor DestroySelfOnly; override; published end; TSSITransaction = class(TSSIntermediate) private FInstances: TSSIList; //List of TSSIInstance FInstancesData: TSSIList; //List of TSSIInstanceData protected public destructor Destroy; override; destructor DestroySelfOnly; override; published end; TSSIInstance = class(TSSIntermediate) private FClassTypeString: string; FObjId: integer; protected public published end; TSSIInstanceData = class(TSSIntermediate) private FObjId: integer; FProperties: TSSIList; //List of TSSIProperty protected public destructor Destroy; override; destructor DestroySelfOnly; override; published end; { Quick reminder from TypInfo: TTypeKind = (tkUnknown, tkInteger, tkChar, tkEnumeration, tkFloat, tkString, tkSet, tkClass, tkMethod, tkWChar, tkLString, tkWString, tkVariant, tkArray, tkRecord, tkInterface, tkInt64, tkDynArray); TTypeKinds = set of TTypeKind; TOrdType = (otSByte, otUByte, otSWord, otUWord, otSLong); TFloatType = (ftSingle, ftDouble, ftExtended, ftComp, ftCurr); Properties that can be got and set via TypInfo that concern us boil down to: Ord, str, Float, Int64 (no need to worry about variants, methods &c) We also need to add support for records, arrays and class references } TSSIMajorType = (sMajOrd, sMajStr, sMajFloat, sMajInt64, sMajRec, sMajArray, sMajClass); TSSIMinorType = (mitNone, //Major types without a subtype //Ordinals mitOSbyte, mitOUByte, mitOSWord, mitOUword, mitOSLong //Floats mitFSingle, mitFDouble, mitFExtended); TSSIPropertyData = record PropType: TSSIMajorType; PropSubType: TSSIMinorType; PropName: string; //Just the name of this property, not considering //enclosing properties. case TSSIMajorType of sMajOrd: ( OrdData: Longint ); sMajStr: ( StrData: string ); sMajFloat: ( FloatData: extended ); sMajInt64: ( Int64Data: Int64 ); sMajRec, sMajArray: ( Items: TSSIList; ); //Records contain a list of TSSIProperty where the prop name corresponds //to the field in the data. //Arrays contain a list of TSSIProperty where the prop name is the integer //index in the array (e.g. "1", "2" etc). sMajClass: ( ObjId: string ); end; end; TSSIProperty = class(TSSIntermediate) private FPropData: TSSIPropertyData; protected public destructor Destroy; override; destructor DestroySelfOnly; override; published end; implementation end. Back to top Guenther Wimpassinger Guest Posted: Thu Mar 10, 2005 1:29 pm    Post subject: Re: Object Serialization "Joanna Carter (TeamB)" <joanna (AT) nospam (DOT) co.uk> schrieb Quote: "Hechicero" <accesosecuencial (AT) yahoo (DOT) com.ar> a écrit dans le message The serializer works perfectly. But the problem is this. I dont feel very confortable using memory addres and most importantly, If I wanted to migrate my serializer to .NET, how should I do it. You cannoy serialize memory addresses as it is not guaranteed over multiple executions. You need to include an integer ID for every object and have a mechanism for allocating those IDs uniquely to every object when it is first serialized. Is the memory address of an object usable as an ID? The IDs are not ordered nor they are autoincrementing, but does that really matter? In .NET maybe you have to reimplement the "ID" property. just an idea Guenther Back to top Jim Cooper Guest Posted: Thu Mar 10, 2005 2:06 pm    Post subject: Re: Object Serialization Quote: Is the memory address of an object usable as an ID? No, since it will be different every time the object is loaded. You will get different objects having the same ID in different sessions and so on - a bit of a nightmare You also could not make a copy of an object. In the storage mechanism you need to link objects together by ID, so you cannot go changing it all the time, and they need to be unique (at least within an object type). Quote: The IDs are not ordered nor they are autoincrementing, but does that really matter? IDs do not have to be ordered or autoincrementing (eg GUIDs are neither) It isn't essential to use integers as IDs (although they tend to be quicker used as primary keys in databases the difference is not usually noticeable). I use GUIDs since disconnected users can still create objects and there isn't the hassle of reconciling IDs later on. Cheers, Jim Cooper __________________________________________ Jim Cooper [email]jcooper (AT) tabdee (DOT) ltd.uk[/email] Tabdee Ltd http://www.tabdee.ltd.uk TurboSync - Connecting Delphi to your Palm __________________________________________ Back to top Martin Harvey (Demon Acco Guest Posted: Thu Mar 10, 2005 9:05 pm    Post subject: Re: Object Serialization On Thu, 10 Mar 2005 14:29:20 +0100, "Guenther Wimpassinger" <gw_spam (AT) pickem (DOT) at> wrote: Quote: Is the memory address of an object usable as an ID? It depends. For the sort of serialisation I am doing (streaming to and from disk) in theory, Yes ... because the ID's are simply used to look up in a table sufficient information to re-create the class. However, if you want ID's where you want to be able to compare them on the fly, and not simply perform a creation from disk or a save to disk, then probably not. MH. Back to top Martin Harvey (work) Guest Posted: Tue Mar 29, 2005 12:22 pm    Post subject: Re: Object Serialization "Hechicero" <accesosecuencial (AT) yahoo (DOT) com.ar> wrote Quote: Hi, I am programing an object serializer that unses RTTI in Delphi 7 and has the following functionality : it backups the state of every published property so they can be restored later through this serializer. It also transform the objecto to an XML string and Vice-Versa. By the way, I've just written mine. It's currently in testing. I still have a few small bugs to fix. How far through have you got? I'd estimate, depending on how extensible your system needs to be that you're looking at about 5,000 lines of code roughly .... MH. Back to top Martin Harvey (work) Guest Posted: Tue Mar 29, 2005 12:31 pm    Post subject: Re: Object Serialization Quote: Value>John Doe</Value By the way ... are you "escaping" strings correctly? What happens if I put a string in: This ' is ' a string containing a MH. Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> Delphi OO design All times are GMT Goto page 1, 2  Next Page 1 of 2   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.