XML and Delphi problem

Question

I am trying to implement a protocol which I will use for my application to communicate with a server. The problem is that the server is using XML so I tried to send a string to the server containing xml but I get only errors.

When I send this :

mymsg: String = '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'+
'<m:outgoingEngineMessage xmlns:c="http://www.bvb.ro/xml/ns/arena/gw/constraints"'+
'xmlns:m="http://www.bvb.ro/xml/ns/arena/gw/msg"'+
'xmlns:xsi=&quot;http://www.w3.org/2001/XMLSchema-instance&quot;&gt;'+
'&lt;content xsi:type=&quot;HeartBeatcmd&quot;&gt;'+
'&lt;/content&gt;'+
'&lt;csq&gt;100212&lt;/csq&gt;'+
'&lt;/m:outgoingEngineMessage&gt;';

I receive an error saying:

Element type "m:outgoingEngineMessage" must be followed by either attribute specifications, "&gt ;" or "/&gt ;"

When I send this:

mymsg : String = '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'+
    '&lt;m:outgoingEngineMessage xmlns:c=&quot;http://www.bvb.ro/xml/ns/arena/gw/constraints"'+
    'xmlns:m="http://www.bvb.ro/xml/ns/arena/gw/msg"'+
    'xmlns:xsi=&quot;http://www.w3.org/2001/XMLSchema-instance&quot;&gt;'+
    '&lt;content xsi:type=&quot;HeartBeatcmd&quot;&gt;'+
    '&lt;/content&gt;'+
    '&lt;csq&gt;100212&lt;/csq&gt;'+
    '&lt;/m:outgoingEngineMessage&gt;'

I get: Element not allowed in prolog...

Can some one enlighten me what I am doing wrong? I have never worked with xml files before. Is there a function to convert xml to utf8 correctly? please explain.

if you search the web for example documents with "xmlns:xsi" it is easy to see they use a quote like xmlns:xsi="... and not xmlns:xsi=&quot..., and other obvious differences like a closing </whatever> tag for the root element. In your example, the terminating </m:outgoingEngineMessage> is missing. — mjn
– mjn, Commented Jul 13, 2011 at 8:41
Ouch! Don't "hand-generate" the XML - use a library to do this. It will save you a lot of trouble in the long run. — Misha
– Misha, Commented Jul 13, 2011 at 11:10

mjn · Accepted Answer · 2011-07-13 08:35:05Z

6

The safest way to generate 'well-formed' XML is using an XML library like NativeXml, OmniXML (both open source) or the MSXML library (Delphi provides a wrapper for it).

answered Jul 13, 2011 at 8:35

mjn

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Nat · Accepted Answer · 2011-07-13 09:46:04Z

4

You also need to put a space at the end of each line where the line break is between attributes. You are in effect jamming them all together:

<m:outgoingEngineMessage xmlns:c="http://www.bvb.ro/xml/ns/arena/gw/constraints"'+
'xmlns:m="http://www.bvb.ro/xml/ns/arena/gw/msg"'+
'xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">'

will produce:

<m:outgoingEngineMessage xmlns:c="http://www.bvb.ro/xml/ns/arena/gw/constraints"xmlns:m="http://www.bvb.ro/xml/ns/arena/gw/msg"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

To fix this, you need to do something like the following (based on @The_Fox's code):

mymsg: String = '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'+
'<m:outgoingEngineMessage xmlns:c="http://www.bvb.ro/xml/ns/arena/gw/constraints" '+
//                                                          see the space here --^
'xmlns:m="http://www.bvb.ro/xml/ns/arena/gw/msg" '+
//                                   and here --^
'xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">'+
'<content xsi:type="HeartBeatcmd">'+
'</content>'+
'<csq>100212</csq>'+
'</m:outgoingEngineMessage>';

answered Jul 13, 2011 at 9:46

Nat

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1 Comment

Nat Over a year ago

Yes, there are a few of us around :)

The_Fox · Accepted Answer · 2011-07-13 11:09:35Z

1

You are escaping < and > where you shouldn't. Only escape those entities when they are not part of the xml.

Like this:

<content foo="bar">
2 + 2 &gt; 3
</content>

And not like this:

&lt;content foo=&quot;bar%quot;&gt;
2 + 2 &gt; 3
&lt;/content&gt;

So your xml would look like this:

mymsg: String = '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'+
'<m:outgoingEngineMessage xmlns:c="http://www.bvb.ro/xml/ns/arena/gw/constraints" '+
'xmlns:m="http://www.bvb.ro/xml/ns/arena/gw/msg" '+
'xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">'+
'<content xsi:type="HeartBeatcmd">'+
'</content>'+
'<csq>100212</csq>'+
'</m:outgoingEngineMessage>';

edited Jul 13, 2011 at 11:09

answered Jul 13, 2011 at 8:56

The_Fox

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3 Comments

opc0de Over a year ago

I still get this error message : Element type "m:outgoingEngineMessage" must be followed by either attribute specifications, ">" or "/>".

mjn Over a year ago

XML- and XHTML-documents must have white wpaces between the Attributes, the code however builds .../constraints"xmlns:m="http..., better show the correct XML code (instead of the Delphi constant declaration)

Nat Over a year ago

Put a space before you close the string for each line, for instance ...gw/constants" ' +

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