Big picture questions - cleanest method for creating an XML file
B. Chernick
is this: This will be in VB/VS 2005/ winforms. I have a DTD, a sample XML,
and an outside data source I will use to populate the XML. In general I
think I know how to create elements and attributes and I'm sure I can hack
something together but I'm wondering if I'm missing (or forgetting) a better
way (other than a long line of hard-coded CreateElement commands).
Suggestions please.
-----
A related problem: the XML header, for lack of a better term. If we assume
creation of an XmlDocument object from scratch, how do I add the header
elements? I cannot find any discussion of this. (Feel free to correct my
terminology.)
This is what I'm referring to -
<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE SOME TEXT "DTDName.dtd">
<?xml-stylesheet href="SampleXml.xslt" type="text/xsl" ?>
Joe Fawcett
document is serialised and isn't always needed, it depends on the encoding
used.
I agree that creating documents by dozens of CreateXXX statements is not
nice.
How changeable are the documents. I often start with a template, either a
string constant, in a resource file or an actual file and load this first.
Then I alter it as needed.
--
Joe Fawcett (MVP - XML)
"B. Chernick" <BChe...@discussions.microsoft.com> wrote in message
news:D332B170-4DDF-4D4B...@microsoft.com...
Martin Honnen
> I am not accustomed to creating xml files programmatically. The big picture
> is this: This will be in VB/VS 2005/ winforms. I have a DTD, a sample XML,
> and an outside data source I will use to populate the XML. In general I
> think I know how to create elements and attributes and I'm sure I can hack
> something together but I'm wondering if I'm missing (or forgetting) a better
> way (other than a long line of hard-coded CreateElement commands).
> Suggestions please.
If you convert the DTD into a schema then you can use XML
serialization/deserialization:
http://msdn.microsoft.com/en-us/library/90c86ass(VS.80).aspx
You can use the xsd.exe tool to create .NET classes from the schema.
If you have relational data then you can also consider to populate a
DataSet and use its WriteXml method.
> This is what I'm referring to -
>
> <?xml version="1.0" encoding="utf-8" ?>
That is the XML declaration, it is created by the WriteStartDocument
method of XmlWriter
http://msdn.microsoft.com/en-us/library/system.xml.xmlwriter.writestartdocument.aspx
or using CreateXmlDeclaration
http://msdn.microsoft.com/en-us/library/system.xml.xmldocument.createxmldeclaration.aspx
in the DOM model.
> <!DOCTYPE SOME TEXT "DTDName.dtd">
That is a document type declaration, created using WriteDocType
http://msdn.microsoft.com/en-us/library/system.xml.xmlwriter.writedoctype.aspx
of XmlWriter or using CreateDocumentType
http://msdn.microsoft.com/en-us/library/system.xml.xmldocument.createdocumenttype.aspx
method of XmlDocument.
> <?xml-stylesheet href="SampleXml.xslt" type="text/xsl" ?>
That is a a processing instruction with the name 'xml-stylesheet' and
the data 'href="SampleXml.xslt" type="text/xsl"' so you create it using
WriteProcessingInstruction of XmlWriter
http://msdn.microsoft.com/en-us/library/system.xml.xmlwriter.writeprocessinginstruction.aspx
or using CreateProcessingInstruction
http://msdn.microsoft.com/en-us/library/system.xml.xmldocument.createprocessinginstruction.aspx
of XmlDocument.
--
Martin Honnen --- MVP XML
http://JavaScript.FAQTs.com/
B. Chernick
This, so far as I know, is not a standard Dot Net situation. The purpose of
the program, if it ever gets written, is to extract data from an Excel
spreadsheet and plug it into a standalone XML file. I'm afraid I've been
given very little of the big picture. I think it eventually gets fed into
some mainframe system.
B. Chernick
questions I've been wondering about. However in this particular situation, I
don't believe converting the DTD to an xsd is an option. The output has to
go to some legacy system that I don't have control over (so far as I know).
(I would have to translate the DTD manually, right? There's no wizard or
utility for such a conversion? If I am not mistaken, DTDs obsolete and
there's little or no support for them in Dot Net?)
Martin Honnen
> (I would have to translate the DTD manually, right? There's no wizard or
> utility for such a conversion? If I am not mistaken, DTDs obsolete and
> there's little or no support for them in Dot Net?)
There are tools like Xml editors
(http://www.stylusstudio.com/dtd/convert_dtd_to_schema.html) or Trang
(http://www.thaiopensource.com/relaxng/trang.html) that can translate a
DTD to a W3C schema.
As for .NET, it has support for validating an XML document against a DTD
but besides that its API are pretty much focussed on W3C XML schemas.
B. Chernick
> but besides that its API are pretty much focussed on W3C XML schemas.
problematic as well, especially for adhoc projects. :-)
On an earlier point, the use of WriteDocType, I am ready to tear my hair
out. I have this code and I cannot get it to work. I keep getting the error
'The '' character, hexiadecimal value 0x20, cannot be included in a name.'
Frankly I'm out of my league here. I cannot find any reference for the error
or WriteDocType that I can understand. Here's my test code:
Dim w As XmlWriter = XmlWriter.Create("Out.xml")
w.WriteStartDocument()
w.WriteDocType("SOME TEXT", Nothing, Nothing, "DTDName.dtd")
w.Close()
I've tried a number of variations on that including """DTDName.dtd""". What
do I have to do to get this one simple line of xml out to the file?
<!DOCTYPE SOME TEXT "DTDName.dtd">
Thanks
Martin Honnen
> Dim w As XmlWriter = XmlWriter.Create("Out.xml")
> w.WriteStartDocument()
> w.WriteDocType("SOME TEXT", Nothing, Nothing, "DTDName.dtd")
Well the first argument is the root element name and an element name is
not allowed to contain a space so you need to decide which root element
name you want (e.g. "some-name" or "some_name") and write that out. You
can't use "SOME TEXT" as the space is not allowed.
B. Chernick
<!DOCTYPE BDD SYSTEM "EAI.dtd">
Are you saying that this violates XML standards in general?
(Actually I should explain that for some reason I was convinced that the
last parm of the line was the problem. I didn't realize it was the first.
This works: w.WriteDocType("BDD-SYSTEM", Nothing, Nothing, "EAI.dtd")
but results in <!DOCTYPE BDD-SYSTEM [EAI.dtd]> Why the brackets and is
there any way to get rid of them?)
Martin Honnen
> The actual sample xml I was originally given has a line of:
>
> <!DOCTYPE BDD SYSTEM "EAI.dtd">
>
> Are you saying that this violates XML standards in general?
No, it does not. The "BDD" is the root element name and "EAI.dtd" is the
system identifier.
> (Actually I should explain that for some reason I was convinced that the
> last parm of the line was the problem. I didn't realize it was the first.
> This works: w.WriteDocType("BDD-SYSTEM", Nothing, Nothing, "EAI.dtd")
>
> but results in <!DOCTYPE BDD-SYSTEM [EAI.dtd]> Why the brackets and is
> there any way to get rid of them?)
Use
w.WriteDocType("BDD", Nothing, "EAI.dtd", Nothing)
to produce the line you posted above. The "SYSTEM" string will be
automatically added as you pass in a third argument string, the system
identifier.
See also the online documentation
http://msdn.microsoft.com/en-us/library/system.xml.xmlwriter.writedoctype.aspx
or your local MSDN copy which explains the four arguments.
Joe Fawcett
>I don't mean to be rude but I'm afraid I didn't understand much your reply.
>
> This, so far as I know, is not a standard Dot Net situation.
The purpose of
> the program, if it ever gets written, is to extract data from an Excel
> spreadsheet and plug it into a standalone XML file. I'm afraid I've been
> given very little of the big picture. I think it eventually gets fed into
> some mainframe system.
>
You said you wanted a way to avoid creating the whole file by hand, the file
matches a known schema. So I suggested that start with an XML template that
matched the schema and then make alterations to it based on the external
data.
B. Chernick
I could have ever gotten that from that documentation.
B. Chernick
then make alterations to it based on the external data."
Thanks but once again, I have no idea what you just said. I have no idea
what an XML Template is either or how to use it, and the only reference I can
find in Help has something to do with SQL Server. Is there an actual demo
you can point me to that illustrates your suggestion? Perhaps this is purely
a matter of terminology.
(Unfortunately my job requires me to bounce between many different
technologies and XML is one that I have not had the time or need to focus on
for long.)
Thanks.
Martin Honnen
> "So I suggested that start with an XML template that matched the schema and
> then make alterations to it based on the external data."
>
> Thanks but once again, I have no idea what you just said. I have no idea
> what an XML Template is either or how to use it, and the only reference I can
> find in Help has something to do with SQL Server. Is there an actual demo
> you can point me to that illustrates your suggestion? Perhaps this is purely
> a matter of terminology.
Imagine you need to create XHTML documents, instead of starting from
scratch and each time creating the html element, the head element, the
body element you could simply create an XHTML document already
containing the html, the head, and the body element and use that as a
"template", meaning you would use System.Xml.XmlDocument and load that
"template" document and then use the DOM to manipulate it as needed
(e.g. add the title, add headings, add paragraphs) and save as needed.
That is all what Joe tried to suggest, at least if I understand him
correctly. So the XML "template" is nothing but an XML file with the
structure you need for all your XML documents you want to create.
B. Chernick
It's easy enough to load an existing file. You mean load the doc and search
for the various elements in order to change their values?
(I use bits and pieces of XML technology as needed and I try to learn new
things but I feel there is some central concept I have yet to discover, let
alone master. Business as usual.)
As long as we are on the subject of 'templates', refresh my memory. If I
am creating a VS2005 VB Winforms project, it is possible to include an
existing XML file as a file of the project. However I see no simple to
access it programmatically. Am I forgetting something?
Martin Honnen
> Ok. Now I think I see. In a manner of speaking, I've already done that.
> It's easy enough to load an existing file. You mean load the doc and search
> for the various elements in order to change their values?
Yes, or add additional child elements (as in my XHTML example).
> As long as we are on the subject of 'templates', refresh my memory. If I
> am creating a VS2005 VB Winforms project, it is possible to include an
> existing XML file as a file of the project. However I see no simple to
> access it programmatically. Am I forgetting something?
Well whether the XML file is part of the project or not, the APIs to
access it programmatically are e.g. XmlReader, XPathDocument,
XmlDocument, XmlSerializer and others.
Or are you talking about adding the XML to an assembly as a resource and
want to read out the resource?
B. Chernick
problem of locating it in order to use those methods you mentioned.
On the other hand, I'm not sure I've ever added an XML file as a resource.
I'm going to have to try that.