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vb.net : Serialization questions
My app is near completed for the basic feature of version 1.0.
I have an extensive object model and I now want to persist my objects using serialization. I have chosen binaryformatter to serialize, and custom serialization, which I understand will allow me the flexibility of not breaking old things when I add members to classes in the future and send to existing customers. 1.) is there anything else to consider with the custom serialization 2.) when doing the info.addvalue in GetObjectData, if one of the members of my class is an instance of another class, do I go ahead and add it--and that somehow calls the serialization process of that class to fullfill this? 3.) some of my classes are collections. They inherited from collectionbase. Is collection base not serializable? Assuming it may not be serializable, the documentation says serialization will fail. If so, how in the world can I handle this issue? I need to serialize all items of the collection base and then deserialize them. Are there any other comments about this? Any other gotchas? Thanks a bunch. Shane
SSStory,
The nicest I have seen, I cannot make it nicer. \\\Tom Shelton Private Function SerializeFontObject(ByVal fnt As Font) As String Dim bf As New BinaryFormatter Dim mem As New MemoryStream Try bf.Serialize(mem, fnt) Return Convert.ToBase64String(mem.ToArray()) Catch Return String.Empty Finally mem.Close() End Try End Function Private Function DeserializeFontObject(ByVal fnt As String) As Font Dim bf As New BinaryFormatter Dim mem As New MemoryStream(Convert.FromBase64String(fnt)) Try Return DirectCast(bf.Deserialize(mem), Font) Finally If Not mem Is Nothing Then mem.Close() End If End Try End Function //// I hope this helps a little bit? Cor
Thanks for trying.
I don't see how this answers either of my questions. I do already know how to do the binary formatter and I have that code in place. Just having trouble as mentioned in the original question, knowing for one how do I serialize a class that inherits from collectionbase which apparently isn't serializable. And the other question also. A third could be how do I find out if a class is serializable if I don't have the source--like CollectionBase? Thanks Cor, Shane [quoted text, click to view] "Cor Ligthert" <notmyfirstname@planet.nl> wrote in message news:%23CW2C$0NFHA.3668@TK2MSFTNGP14.phx.gbl... > SSStory, > > The nicest I have seen, I cannot make it nicer. > > \\\Tom Shelton > Private Function SerializeFontObject(ByVal fnt As Font) As String > Dim bf As New BinaryFormatter > Dim mem As New MemoryStream > Try > bf.Serialize(mem, fnt) > Return Convert.ToBase64String(mem.ToArray()) > Catch > Return String.Empty > Finally > mem.Close() > End Try > End Function > > > Private Function DeserializeFontObject(ByVal fnt As String) As Font > Dim bf As New BinaryFormatter > Dim mem As New MemoryStream(Convert.FromBase64String(fnt)) > Try > Return DirectCast(bf.Deserialize(mem), Font) > Finally > If Not mem Is Nothing Then > mem.Close() > End If > End Try > End Function > //// > > I hope this helps a little bit? > > Cor > >
Attributes are listed in the docs. CollectionBase docs say: <Serializable> MustInherit Public Class CollectionBase Implements IList, ICollection, IEnumerable So, yes, CollectionBase is serializable. Best regards, Sam On Sat, 2 Apr 2005 15:43:58 -0600, "SStory" [quoted text, click to view] <TheStorys@TAKEOUTTHISSPAMBUSTERsofthome.net> wrote: >Thanks for trying. >I don't see how this answers either of my questions. >I do already know how to do the binary formatter and I have that code in >place. Just having trouble as mentioned in the original question, knowing >for one how do I serialize a class that inherits from collectionbase which >apparently isn't serializable. > >And the other question also. > >A third could be how do I find out if a class is serializable if I don't >have the source--like CollectionBase? > >Thanks Cor, > >Shane B-Line is now hiring one Washington D.C. area VB.NET developer for WinForms + WebServices position. Seaking mid to senior level developer. For information or to apply e-mail resume to
cool. I did finally find that in MSDN--DUH. Just was looking for it in the
object browser for some reason. The other question was.... if a member of my class is a class, does deserializer also call the mechanism for that member class automatically and handle it for you? (assuming it is a <serializable> class of course) Thanks, Shane [quoted text, click to view] "Samuel R. Neff" <blinex@newsgroup.nospam> wrote in message news:k4f251thiou34qvi2ljltddhnvbijqu6tm@4ax.com... > > Attributes are listed in the docs. CollectionBase docs say: > > <Serializable> > MustInherit Public Class CollectionBase > Implements IList, ICollection, IEnumerable > > So, yes, CollectionBase is serializable. > > Best regards, > > Sam > > > On Sat, 2 Apr 2005 15:43:58 -0600, "SStory" > <TheStorys@TAKEOUTTHISSPAMBUSTERsofthome.net> wrote: > >>Thanks for trying. >>I don't see how this answers either of my questions. >>I do already know how to do the binary formatter and I have that code in >>place. Just having trouble as mentioned in the original question, knowing >>for one how do I serialize a class that inherits from collectionbase which >>apparently isn't serializable. >> >>And the other question also. >> >>A third could be how do I find out if a class is serializable if I don't >>have the source--like CollectionBase? >> >>Thanks Cor, >> >>Shane > > B-Line is now hiring one Washington D.C. area VB.NET > developer for WinForms + WebServices position. > Seaking mid to senior level developer. For > information or to apply e-mail resume to > sam_blinex_com.
Yes, it serializes the entire object graph (hierarchy). Sam On Tue, 5 Apr 2005 11:04:56 -0500, "Shane Story" [quoted text, click to view] <shanesREMOVETHIS@dv-corp.com> wrote: B-Line is now hiring one Washington D.C. area VB.NET >cool. I did finally find that in MSDN--DUH. Just was looking for it in the >object browser for some reason. > >The other question was.... > >if a member of my class is a class, does deserializer also call the >mechanism for that member class automatically and handle it for you? >(assuming it is a <serializable> class of course) > >Thanks, > >Shane > >"Samuel R. Neff" <blinex@newsgroup.nospam> wrote in message >news:k4f251thiou34qvi2ljltddhnvbijqu6tm@4ax.com... >> >> Attributes are listed in the docs. CollectionBase docs say: >> >> <Serializable> >> MustInherit Public Class CollectionBase >> Implements IList, ICollection, IEnumerable >> >> So, yes, CollectionBase is serializable. >> >> Best regards, >> >> Sam >> developer for WinForms + WebServices position. Seaking mid to senior level developer. For information or to apply e-mail resume to
Thanks Samuel.
Considering what else I have read on the subject, it seems that if you serialize and object and later make any changes, that the things serialized before the change would not be readable. For this reason custom serialization seems better. Would you agree? Thanks [quoted text, click to view] "Samuel R. Neff" <blinex@newsgroup.nospam> wrote in message news:sud551hat4kd8bnv4eb63rp1rd16nsf13i@4ax.com... > > Yes, it serializes the entire object graph (hierarchy). > > Sam > > > On Tue, 5 Apr 2005 11:04:56 -0500, "Shane Story" > <shanesREMOVETHIS@dv-corp.com> wrote: > >>cool. I did finally find that in MSDN--DUH. Just was looking for it in >>the >>object browser for some reason. >> >>The other question was.... >> >>if a member of my class is a class, does deserializer also call the >>mechanism for that member class automatically and handle it for you? >>(assuming it is a <serializable> class of course) >> >>Thanks, >> >>Shane >> >>"Samuel R. Neff" <blinex@newsgroup.nospam> wrote in message >>news:k4f251thiou34qvi2ljltddhnvbijqu6tm@4ax.com... >>> >>> Attributes are listed in the docs. CollectionBase docs say: >>> >>> <Serializable> >>> MustInherit Public Class CollectionBase >>> Implements IList, ICollection, IEnumerable >>> >>> So, yes, CollectionBase is serializable. >>> >>> Best regards, >>> >>> Sam >>> > B-Line is now hiring one Washington D.C. area VB.NET > developer for WinForms + WebServices position. > Seaking mid to senior level developer. For > information or to apply e-mail resume to > sam_blinex_com.
Unfortunately there's a huge leap between XmlSerializer and custom serialization--quick and dirty vs totally do it yourself. There are lots issues that XmlSerializer doesn't address and for that reason a lot of people (most it seems) recommend doing it yourself. XmlSerializer does do a good job for what it's programmed to do, so if you can use it in your situation I'd suggest doing so--you can always switch to custom if you really need more functionality. We of course have the same concerns over versioning that you do and have an architecture to get around it (well, planned architecture) by using a bookmarked XML reader combined with XSLT. Basically, we'll read the XML up to a Version attribute on the root element. If that matches the current, then reset the reader to the beginning and process as normal. If the version is old, then reset the reader and perform a transformation on it to get the new format (requires writing XSLT, which some consider more complicated then writing a custom serializer). If the version is newer, then cancel or take whatever action is appropriate in your application. Here's a bookmarked XML reader from MS: http://msdn.microsoft.com/XML/BuildingXML/XMLinNETFramework/default.aspx?pull=/library/en-us/dnxmlnet/html/XmlBkMkRead.asp It has some issues of it's own--it won't even compile as distributed. But once they're fixed, it seems to work pretty well (fixes: invalid boolean check at end with bool != null, and a Debug.Assert that always gets triggered). HTH, Sam On Tue, 5 Apr 2005 14:41:12 -0500, "Shane Story" [quoted text, click to view] <shanesREMOVETHIS@dv-corp.com> wrote: >Thanks Samuel. > >Considering what else I have read on the subject, it seems that if you >serialize and object and later make any changes, that the things serialized >before the change would not be readable. For this reason custom >serialization seems better. Would you agree? > >Thanks > B-Line is now hiring one Washington D.C. area VB.NET developer for WinForms + WebServices position. Seaking mid to senior level developer. For information or to apply e-mail resume to
Thanks Samuel for all of your help.
I am trying to use binaryformatter. I have no trouble saving (serializing), but when I go to deserialize I always get errors. It appears that I cannot set a breakpoint or anything to discover where the problem is. I am serializing by implementing ISerializable: The GetObjectData method & the custom Constructor. The last problem I got was an exception--TargetInvocationException class to be exact. My object model has things like the following to deal with: MDIForm (which has a bunch of frmA's) frmA which has a Workspace object. This object has some members and then some other objects. for the sake of this newsgroup let me give an example scenario and see what I should do. Workspace has a reference to the form that "owns" it (this is not serializable of course). So imagine class workspace private A as single private B as single private ParentForm as frmA private objSomething as Something end class class Something 'class something has a reference to the parentworkspace to which it belongs private ParentWorkSpace as workspace end class my thought was, in GetDataObject for workspace object to just do the following: info.addvalue("A",A) info.addvalue("B",B) info.addvalue("objSomething",Something) and then in the specialized contstructor for deserializing A=info.getsingle("A") B=info.getsingle("B") objSomething=ctype(info.getvalue("objSomething",gettype(something)),somethin g) 'then at this point, maybe call a method on objSomething to set the parent workspace object 'reference to this object objSomething.SetParentWorkspace=me I would do the same thing to the Workspace object itself after being deserialized, it would set the ParentForm with a method. Am I on the wrong track? Any ideas, from you or any other group member about the exception. Also any ideas on how to debug this stuff, since it seems to just happen and not allow me to step into the call, which I assume just eventually calls the constructor. Thanks for all your help. Shane [quoted text, click to view] "Samuel R. Neff" <blinex@newsgroup.nospam> wrote in message news:otq551h4a416lte26fm6235rjhqpo484go@4ax.com... > > Unfortunately there's a huge leap between XmlSerializer and custom > serialization--quick and dirty vs totally do it yourself. There are > lots issues that XmlSerializer doesn't address and for that reason a > lot of people (most it seems) recommend doing it yourself. > > XmlSerializer does do a good job for what it's programmed to do, so if > you can use it in your situation I'd suggest doing so--you can always > switch to custom if you really need more functionality. We of course > have the same concerns over versioning that you do and have an > architecture to get around it (well, planned architecture) by using a > bookmarked XML reader combined with XSLT. > > Basically, we'll read the XML up to a Version attribute on the root > element. If that matches the current, then reset the reader to the > beginning and process as normal. > > If the version is old, then reset the reader and perform a > transformation on it to get the new format (requires writing XSLT, > which some consider more complicated then writing a custom > serializer). > > If the version is newer, then cancel or take whatever action is > appropriate in your application. > > Here's a bookmarked XML reader from MS: > > http://msdn.microsoft.com/XML/BuildingXML/XMLinNETFramework/default.aspx?pull=/library/en-us/dnxmlnet/html/XmlBkMkRead.asp > > It has some issues of it's own--it won't even compile as distributed. > But once they're fixed, it seems to work pretty well (fixes: invalid > boolean check at end with bool != null, and a Debug.Assert that always > gets triggered). > > HTH, > > Sam > > > On Tue, 5 Apr 2005 14:41:12 -0500, "Shane Story" > <shanesREMOVETHIS@dv-corp.com> wrote: > > >Thanks Samuel. > > > >Considering what else I have read on the subject, it seems that if you > >serialize and object and later make any changes, that the things serialized > >before the change would not be readable. For this reason custom > >serialization seems better. Would you agree? > > > >Thanks > > > > B-Line is now hiring one Washington D.C. area VB.NET > developer for WinForms + WebServices position. > Seaking mid to senior level developer. For > information or to apply e-mail resume to > sam_blinex_com.
Both classes need to have the "<serializeable()>" attribute before you can
properly serialize/deserialize. FYI, and you may already know this, if the number of members in either of the classes changes, it'll render your serialized object useless -- meaning that deserialization of your object will throw exceptions. If I were you I would look at XML serialization if you want to persist the state of your application. I know that there are a lot of developers out there who will probably flame me for say so, but you can essentially use *.config files to save the information. Config files are troublesome in that some systems you might deploy on have strict security settings for user accounts, and most will only have ONE location in which to write to. There are ways to find out where these locations are (based on the user account...) check out references to "IsolatedStorage" (C:\Documents and Settings\<user>\Local Settings\Application Data\IsolatedStorage). If you go with the *.config file route, take some time to explore google for the pros and cons. I'm personally using it in an application I'm developing, and it seems to be working well with different security settings/user accounts. --
Thanks for the opinion.
Seems ridiculous that something so vital, is so difficult. I was thinking if I did custom serialization that my object wouldn't be trashed even if I added a new param because I could check for that. The problems I get are such as: 1.) in GetObjectData, for a class that inherits CollectionBase I write out normal members, then I think I am supposed to do mybase.GetObjectData(info,context) to let collectionbase do its serialization, but that seems to be private and unaccessable, so I can't seem to do this. Is this true? Do I need to call this for each member of my class that is actually another class? 2.) When something goes wrong I don't really know how to debug it. Anyone have any comments on these comments. Thanks again, Shane "Chris Murphy via DotNetMonster.com" <forum@DotNetMonster.com> wrote in message news:010781a330864711a010e54d9f4642a9@DotNetMonster.com... [quoted text, click to view] > Both classes need to have the "<serializeable()>" attribute before you can > properly serialize/deserialize. FYI, and you may already know this, if the > number of members in either of the classes changes, it'll render your > serialized object useless -- meaning that deserialization of your object > will throw exceptions. > > If I were you I would look at XML serialization if you want to persist the > state of your application. I know that there are a lot of developers out > there who will probably flame me for say so, but you can essentially use > *.config files to save the information. Config files are troublesome in > that some systems you might deploy on have strict security settings for > user accounts, and most will only have ONE location in which to write to. > There are ways to find out where these locations are (based on the user > account...) check out references to "IsolatedStorage" (C:\Documents and > Settings\<user>\Local Settings\Application Data\IsolatedStorage). If you > go > with the *.config file route, take some time to explore google for the > pros > and cons. I'm personally using it in an application I'm developing, and it > seems to be working well with different security settings/user accounts. > > -- > Message posted via http://www.dotnetmonster.com
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