How to consume a webservice with XMLports and HTTP POST

JohnP · 2008-01-31

I know the subject of consuming web services has been covered elsewhere in posts and documents. However, all of them seem to either use a simple string for the XML message or build it element by element. The problem is that the former is no good for large messages and the latter is a bit unwieldy, especially when we have XMLports available.

So here is a post showing how to use XMLports to handle the XML messages when you want to consume a webservice. The scenario is that we want to send a request for data to a webservice and get back one or more records. We will use HTTP POST to communicate with the webservice.

Start with the format of the request message:

(By the way, the website and webservice do NOT exist so do NOT bother trying to use them)

POST /DataService.asmx HTTP/1.1
Host: fat-aardvark.net
Content-Type: text/xml; charset=utf-8
SOAPAction: "http://tempuri.org/SelectData"

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <soap:Body>
    <SelectData xmlns="http://tempuri.org/" />
  </soap:Body>
</soap:Envelope>

To which the webservice responds with this:

HTTP/1.1 200 OK
Content-Type: text/xml; charset=utf-8
Content-Length: length

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Body>
    <SelectDataResponse xmlns="http://tempuri.org/">
      <SelectDataResult>
        <Data>
          <ID>int</ID>
          <Code>int</Code>
          <Type>int</Type>
          <Name>string</Name>
        </Data>
        <Data>
          <ID>int</ID>
          <Code>int</Code>
          <Type>int</Type>
          <Name>string</Name>
        </Data>
      </SelectDataResult>
    </SelectDataResponse>
  </soap:Body>
</soap:Envelope>

Note that the data element will be repeated once per record that is being returned.

We'll start by building an XMLport to create the request message.

TagName           TagType    SourceType  DataSource

soap:Envelope     Element    Text        <soap:Envelope>
  xmlns:soap      Attribute  Text        NS1
  xmlns:xsi       Attribute  Text        NS2
  xmlns:xsd       Attribute  Text        NS3
    soap:Body     Element    Text        <soap:Body>
      SelectData  Element    Text        <SelectData>
        xmlns     Attribute  Text        NS4

Add the following text constants to hold all the namespaces in the request

Name    ConstValue
NSpace1 http://schemas.xmlsoap.org/soap/envelope/
NSpace2 http://www.w3.org/2001/XMLSchema-instance
NSpace3 http://www.w3.org/2001/XMLSchema
NSpace4 http://tempuri.org/

And put them in the right values when we run the XMLport with this bit of code

OnPreXMLport()
NS1 := NSpace1;
NS2 := NSpace2;
NS3 := NSpace3;
NS4 := NSpace4;

Obviously, if you need to send some other data then you put the relevant code/elements/attributes into this XMLport.

Now we need an XMLport to handle the response. I know later XMLports allow you to read in XML namespace information but this example will strip that out of the response so that we don't have to worry about it. This will allow you to use this example in earlier systems too.

TagName                 TagType  SourceType  DataSource

Envelope                Element  Text        <Envelope>
  Body                  Element  Text        <Body>
    SelectDataResponse  Element  Text        <SelectDataResponse>
      SelectDataResult  Element  Text        <SelectDataResult>
        Data            Element  Text        <Data>
          ID            Element  Text        D1
          Code          Element  Text        D2
          Type          Element  Text        D3
          Name          Element  Text        D4

When this runs, it will read each record into the D1, D2, D3 & D4 global variables and you will then need to add code to the XMLport to do something with that data (remember that they will be text values). Alternatively, you could specify a table and replace the D1/2/3/4 with field names in that table. It's up to you what you do with the XMLport once it has the data.

Now for a codeunit to bring them together and do the dirty work.

Setup some global variables:

Name         DataType    Subtype
XP1          XMLport     <name of the first XMLport>
XP2          XMLport     <name of the second XMLport>
XMLDoc       Automation  'Microsoft XML, v5.0'.DOMDocument
XMLHttpConn  Automation  'Microsoft XML, v5.0'.ServerXMLHTTP
InStr        InStream
OutStr       OutStream

Add a function called SendMessage and setup a local variable:

Name         DataType    Subtype
TempTable    Record      TempBlob (set this as a temporary table!)

Add another function called RemoveNamespace which has the parameters:

Var  Name         DataType    Subtype
No   Source       Automation  'Microsoft XML, v5.0'.DOMDocument
Yes  Destination  Automation  'Microsoft XML, v5.0'.DOMDocument

and the local variables:

Name           DataType    Subtype
TempTable      Record      TempBlob (set this as a temporary table!)
XMLStyleSheet  Automation  'Microsoft XML, v5.0'.DOMDocument
StyleOutStr    OutStream		
StyleInStr     InStream

Now add the code as follows:

======================================================
OnRun()
======================================================

SendMessage;

======================================================
SendMessage()
======================================================

//setup the temporary table so that we can handle the XML without saving it to disk first
//create a couple of streams to transfer the data in and out of the BLOB field
CLEAR(TempTable);
TempTable.Blob.CREATEINSTREAM(InStr);
TempTable.Blob.CREATEOUTSTREAM(OutStr);

//the request XMLport fills the BLOB with the XML message
CLEAR(XP1);
XP1.SETDESTINATION(OutStr);
XP1.EXPORT;

//load the message into the XML automation variable
IF ISCLEAR(XMLDoc) THEN
  CREATE(XMLDoc);
XMLDoc.load(InStr);

//this is for diagnostics only, so you can see what the XMLport actually produced
XMLDoc.save('C:\Temp\XMLRequest.txt');

//create the HTTP connector
IF ISCLEAR(XMLHttpConn) THEN
  CREATE(XMLHttpConn);

//tell it where the web service is located
XMLHttpConn.open('POST','http://fat-aardvark.net/DataService.asmx',FALSE);

//set some values in the request header depending on what the service requires
XMLHttpConn.setRequestHeader('Host','fat-aardvark.net');
XMLHttpConn.setRequestHeader('SOAPAction','http://tempuri.org/SelectData');
XMLHttpConn.setRequestHeader('Content-Type','text/xml');

//actually send the message
XMLHttpConn.send(XMLDoc);

//get the response
XMLDoc.load(XMLHttpConn.responseXML);

//tell us if we got an error (it is 200 because the response definition said "200 OK")
IF XMLHttpConn.status <> 200 THEN BEGIN
  MESSAGE('Status %1 %2',XMLHttpConn.status,XMLHttpConn.statusText);
  EXIT;
END;

//this is for diagnostics only, so you can see what you got back
XMLDoc.save('C:\Temp\XMLResponse1.xml');

//take away the namespaces
RemoveNamespace(XMLDoc,XMLDoc);

//this is for diagnostics only, so you can see what it looks like after the namespaces have gone
XMLDoc.save('C:\Temp\XMLResponse2.xml');

//fill the BLOB with the response XML
XMLDoc.save(OutStr);

//the response XMLport reads the data from the BLOB and processes it
CLEAR(XP2);
XP2.SETSOURCE(InStr);
XP2.IMPORT;

======================================================
RemoveNamespace
======================================================

//this has been taken from a Microsoft knowledgebase aricle and strips out the
//namespaces from an XML message using a style sheet

TempTable.Blob.CREATEOUTSTREAM(StyleOutStr);
TempTable.Blob.CREATEINSTREAM(StyleInStr);
StyleOutStr.WRITETEXT('<?xml version="1.0" encoding="UTF-8"?>');
StyleOutStr.WRITETEXT('<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">');
StyleOutStr.WRITETEXT('<xsl:output method="xml" encoding="UTF-8" />');
StyleOutStr.WRITETEXT('<xsl:template match="/">');
StyleOutStr.WRITETEXT('<xsl:copy>');
StyleOutStr.WRITETEXT('<xsl:apply-templates />');
StyleOutStr.WRITETEXT('</xsl:copy>');
StyleOutStr.WRITETEXT('</xsl:template>');
StyleOutStr.WRITETEXT('<xsl:template match="*">');
StyleOutStr.WRITETEXT('<xsl:element name="{local-name()}">');
StyleOutStr.WRITETEXT('<xsl:apply-templates select="@* | node()" />');
StyleOutStr.WRITETEXT('</xsl:element>');
StyleOutStr.WRITETEXT('</xsl:template>');
StyleOutStr.WRITETEXT('<xsl:template match="@*">');
StyleOutStr.WRITETEXT('<xsl:attribute name="{local-name()}"><xsl:value-of select="."/></xsl:attribute>');
StyleOutStr.WRITETEXT('</xsl:template>');
StyleOutStr.WRITETEXT('<xsl:template match="text() | processing-instruction() | comment()">');
StyleOutStr.WRITETEXT('<xsl:copy />');
StyleOutStr.WRITETEXT('</xsl:template>');
StyleOutStr.WRITETEXT('</xsl:stylesheet>');
IF ISCLEAR(XMLStyleSheet) THEN
  CREATE(XMLStyleSheet);
XMLStyleSheet.load(StyleInStr);
IF ISCLEAR(Destination) THEN
  CREATE(Destination);
Source.transformNodeToObject(XMLStyleSheet,Destination);

There you go. Hope it helps someone out there.
No warranty express or implied.
Cheers
John

ajhvdb · 2008-02-01

Thx, looks very detailed but i'm little bit lost in which situation I can use this. Can I use this in a NAS to NAS situation? Does this use the MSMQ?
A link for more info would be appreciated..

JohnP · 2008-02-01

Simple answer first. No, this does not use MSMQ. This is for direct communication with a third party webservice. Whether you initiate this communication from an object running in NAS or from elsewhere in Navision is up to you.

Example 1: You are doing a telesales system and you want to validate a credit card and get an authorisation while the customer is on the phone. You find a credit card service provider and they give you details of their webservice. You send a request with the credit card details and they send you an authorisation number if the card is OK or an error if it is not. For this, you would have a form in NAV where you enter the details and then the user clicks a button to call this code. It takes the details they have entered and uses the first XMLport to format the request. The response XMLport then updates the payment details with the authorisation it receives.

Example 2: It is not uncommon for companies to want to trade through a website but they don't want the hassle of administering it themselves so they buy the service from a provider. The provider hosts & maintains the website and holds the data in their own database. You now need to get the orders from that database and keep the website updated with prices and stock levels. The provider gives you details of a webservice that you can use to read/write your data. You would then create a codeunit to run in NAS uses this code to periodically send a request for orders to the website which then responds with a list of orders that you import through the XMLport. Conversely, you format a request that tells the website how much stock you have of an item and the website responds with an acknowledgement.

This is all about consuming somebody else's webservice, not communicating with another NAV database (there maybe a NAV database behind the webservice but that isn't something that you need to know when you are consuming the service).

Cheers
John

ajhvdb · 2008-02-01

I'm a bit new on xmlports...Is this like a waiting http service? or just a way to send an xml file to a website which answers with a new xml file?

JohnP · 2008-02-04

An XMLport is like a dataport except that it uses XML files instead of text files. In other words it serializes & de-serializes XML.

Correct. It is a way of sending an XML file to a webservice and getting an XML file in return. That exchange may be you requesting something from the webservice or you telling the webservice to do something and it responds telling you that it has done it.

Cheers
John

ajhvdb · 2008-02-04

Can the NAS wait on a port for requests? or is this done by the msmq from iis? (lot of questions, sorry)

garak · 2008-02-04

the nas can wait on an port. tak a look into CU 7700 (ADCS NAS Startup)

ehs · 2008-03-17

Hello John,

Thanks for your detailed description on the xml port webservice caller.

Can you give us an example on how to make Navision work the other way around - as a webservice receiving request as xml documents from sockets and sending back answers ?

I did look into CU 7700, but can you please show me how to incorporate the NAS as a webservice with your example so that Navision is listening for the xml's and then replies with a new xml file to the request ?

mabl4367 · 2009-04-06

Hello

I'm trying to use this with NAV 3.70. I ran into trouble when I got to:

Name DataType Subtype
TempTable Record TempBlob (set this as a temporary table!)

I can not find the subtype "TempBlob". Should I create this table? If so what filed(s) and properties should I give it?

kine · 2009-04-06

Yes, you can. It is only table with two fields - primary key (integer) and blob field.

anon2132 · 2010-02-17

Thanks for much for this... really interesting, got it working today. Great post.

chander · 2010-09-22

Hi, could someone please help, as i am getting the below shown error

" This message is for C/AL programmers:

The call to member save failed. msxml3.dll returned the following message:
The system cannot find the path specified."

I have registered the msxml3.dll(SP7) using regsvr32, I have tried using the automation variable 'Microsoft XML, v6.0'.ServerXMLHTTP'
'Microsoft XML, v4.0'.ServerXMLHTTP' but could not found 'Microsoft XML, v5.0'.ServerXMLHTTP', considering the v4.0 , v5.0 as the version of xml, i tried looking for msxml5.0.dll as well but it says that it specifically meant for office products, which i don't have installed currently on my system.

So, My question is, "Is it important to use only 'Microsoft XML, v5.0'.ServerXMLHTTP" if yes do i need to have msxml5.dll
if not important then it means i can use other versions, then why i am getting the error of msxml3.dll

Your help will be highly appreciated.

Thanks
Chander

Aravindh_Navision · 2011-01-04

Hi Guys,

I am also facing the same error popping.

" This message is for C/AL programmers:

The call to member save failed. msxml3.dll returned the following message:
The system cannot find the path specified."

Can anyone tell what and why it is?

Thanks,
Aravindh

Kisu · 2011-09-05

I'm also getting this error, has anyone found a solution for this?

rrrmmm · 2012-01-03

That's the xml dom document 3.0 msxml3.dll article you all are looking for..

Prajeesh_Nair · 2014-08-07

Have any one tried this in Nav 13 R2.
I have modified the Code a little bit like the following, but still i am getting an error.

//setup the temporary table so that we can handle the XML without saving it to disk first
//create a couple of streams to transfer the data in and out of the BLOB field
CLEAR(TempTable);
TempTable.Blob.CREATEINSTREAM(InStr);
TempTable.Blob.CREATEOUTSTREAM(OutStr);

//the request XMLport fills the BLOB with the XML message
CLEAR(XP1);
XP1.SETDESTINATION(OutStr);
XP1.EXPORT;

//load the message into the XML automation variable

IF ISCLEAR(XMLDoc) THEN
CREATE(XMLDoc,FALSE,TRUE);
XMLDoc.load(InStr);

//this is for diagnostics only, so you can see what the XMLport actually produced
XMLDoc.save('C:\Temp\XMLRequest.txt');

Microsoft Dynamics NAV

Streams cannot be used with client-side invoked automation objects.

OK

Any idea to solve this or is there a new version of this codes to work in nav 13 r2?

kine · 2014-08-11

as in error described. You cannot use the ".save" when the automation is Client-side.

I am using dotnet assemblies to call webservices. Best is to not use automations at all in NAV 2013.

vnproc · 2019-08-03

Today I found this topic. This is the theme I need to get data from the web services. Then import into the table on NAV. Currently, I am using NAV 2013
I tried creating the tutorial. But there is no run and notified error: Streams không thể sử dụng với invoked automation objects-side client. -> at line XMLDoc.load (InStr);
If you have an example of this method please share.
Thanks very much

RockWithNAV · 2019-08-05

See if this helps
https://rockwithnav.wordpress.com/2016/02/23/consume-net-webservice-dotnet-data-type/

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