Android Question Passing xml in to web service

Alwinl · Jul 25, 2013

Hi,
I am using HTPUtils2 to communicate with a php web service, all is working great when passing in simple string args like this:

job1.PostString("http://srv/web/service.php", "arg1=aaa&arg2=bbb")

The problem is that I need to pass in an xml structure for one of the arguments (including all the usual </> tags and crlf's) - any ideas?

imbault · Jul 25, 2013

You can construct a string variable :

Here the variables :
Ws_Url is the URL of your web service
WS_Usertest the name of the service
WS_Labo, WS_sID parameters

B4X:

Dim jobtest As HttpJob
Dim endPoint As String
Dim requestSoapXML As String
ProgressDialogShow("login...")

   
    endPoint = WS_Url
   
    requestSoapXML = _
        "<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>" & _
            "<" & WS_Usertest & " xmlns='http://patrick.imbault.org/'>" & _
               "<sLab>" & WS_Labo & "</sLab>" & _
              "<sId>" & WS_sID & "</sId>" & _
            "</" & WS_Usertest & ">" & _
          "</soap:Body>" & _
        "</soap:Envelope>"
    Log(requestSoapXML )
   
    jobtest.Initialize("jobtestuser",Me)
    jobtest.PostString ( endPoint, requestSoapXML)
    jobtest.GetRequest.SetHeader("SOAPAction", "http://patrick.imbault.org/"  & WS_Usertest)
    jobtest.GetRequest.SetHeader("Content-Type", "text/xml; charset=utf-8")
    jobtest.GetRequest.Timeout = 15000

Alwinl · Jul 25, 2013

Thanks for the reply - lets say its not soap though. It is just a bunch of xml I want to pass as an argument to the web service.
Actually, the question may have more to do with escaping, say

dim arg2 as string
arg2 = "aa=b&b"
job1.PostString("http://srv/web/service.php", "arg1=aaa&" & arg2)

How would I escape arg2 to use it in this fashion?

MotoMusher · Jul 25, 2013

Depending on the webservice, they may accept the post as an attachment which will make your life much easier. The restful services I have dealt with all do. Write your xml string to a file and save it, then post the attachment. Here's what I do:

B4X:

Dim j as httpjob
j.PostFile(MyURL, MyFilePath, "MyFile.xml")

realblue · Jul 25, 2013

Use &lt like you use it in HTML

Alwinl · Jul 26, 2013

Thanks MotoMusher, uploading an xml file may be an option although I'd like to do everything in memory.

realblue - beside passing xml I still have the issue of how to escape, assuming I want to pass the value "aa&b=b" as below, surely the & in my data would conflict with the html escaping?

arg2 = "aa&b=b"
job1.PostString("http://srv/web/service.php", "arg1=aaa&arg2=" & arg2)

Also - am I right in assuming that although the arguments are built in a similar way to a GET, it is doing a POST ie. there is no limit on the length of data

Erel · Jul 28, 2013

You do not need to escape the XML as it is sent as a POST payload. PostString send a POST request. There is no length limit.

Alwinl · Jul 29, 2013

Thanks Erel, I have tested and it appears that escaping is required. With xml crlf's cause trouble and with simple text, embedded '&' or '=' are problematic. I don't know the internals of POST payloads but I think the issue is that with PostString the args are passed in a GET-style string, and as per my example above you would get unexpected behaviour without escaping.

Further tests have shown that using the URL type escaping ie. using '%20%' for spaces and '%0D%%0A%' for crlf. Seems to work better than the ampersand method eg. '&lt'

Alwinl · Aug 5, 2013

I have attached my routines here if anyone is interested in using them, one escapes xml and the other the post string. These seem to work just fine, usage is as follows:

xmldata = "<var1>" & EscapeXML("Greater>Less<") & "</var1>"
strdata = "This is a problem % & ="
post = "data1=" & EscapeURL(strdata) & "&data2=" & EscapeURL(xmldata)
job1.PostString("http://.......", post)

Please let me know if I am doing this the wrong way but I can't see any other way of achieving the code above without escaping

Erel · Aug 6, 2013

You can use XMLBuilder to build the XML string: http://www.b4x.com/android/forum/threads/anyone-using-xmlbuilder-with-b4a.16277/

Alwinl · Aug 6, 2013

Thanks Erel, the xml builder looks great. Assuming it does escape the xml data as I have done, you'd still need to use my 'EscapeURL' as per the snippit above for the post string.

Erel · Aug 7, 2013

You can use StringUtils.EncodeUrl to encode url characters.

Alwinl · Aug 7, 2013

Thanks Erel, so I re-invented that wheel

Android Question Passing xml in to web service

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