Reqest and Response in XML

[srohit24]

Hi

I am working on a project that uses Basic authentication scheme (http://en.wikipedia.org/wiki/Basic_authentication_scheme) to authenticate a user.

I need to call a api in a website.I need to send the username and password in base64 format.

After the header has the host and authentication details, I need to send the request in this format.

=== Request ===

<request client_id="1" client_serial_number="abcded" version="0.1">
<call name="test.reverse">abc</call>
</request>

This is the responce that i should get if all goes well

=== Response ===

<response version="0.1">
<value>cba</value>
</response>

For the header request part, i am using the following code


QXmlStreamReader xml;
QHttp http;

void senddata::fetch()
{

QString username = "abc";
QString password = "12345";

xml.clear();

QUrl url(lineEdit->text());

http.setHost(url.host());
http.setUser(username,password);
connectionId = http.get(url.path());
}
I am reading the data here


void senddata::readData(const QHttpResponseHeader &resp)
{
if (resp.statusCode() != 200)
http.abort();
else {
xml.addData(http.readAll());
parseXml();// This funtion has nothing in it as of now
}
}

Is my code correct? How should i proceed?

How can i parse the response xml and get the data i need?

[srohit24]

can somebody help me with this??

[wysota]

For such simple things I would use QDomDocument instead of the stream reader.

[srohit24]

thanks for replying mate.

I think what u suggested is what i need for proper functioning

abt headers and data, how can I send the data along with the header? I am stuck here. :(

Can QDomDocument also manage the response as well as the QHttpResponseHeader?

[wysota]

QDomDocument is for parsing xml data, it has nothing to do with HTTP.

[srohit24]

thanks mate.

can somebody guide me as how i can send the data along with my header??

[wysota]

Did you notice QHttp::post() and QHttp::request()?

[srohit24]

ok.

int QHttp::request ( const QHttpRequestHeader & header, QIODevice * data = 0, QIODevice * to = 0 )

can you explain the function in a better way, than the explanation that is present in Qt Documentation?

what should i assign in the QHttpRequestHeader and in QIODevice?

this is the request header


QByteArray string ("username");
string.append(":");
string.append("12345");
QString converted = string.toBase64();
//qDebug() <<"String"<< string<<"converted" <<converted ;

QUrl url(lineEdit->text());

http.setHost(url.host());

connectionId = http.get(url.path());

this is the data that has to be sent along with the header.


void MainWindow::sendrequest()
{
QDomDocument doc("request");
QDomElement root = doc.createElement("request");
doc.appendChild(root);

QDomElement tag = doc.createElement("call");
root.appendChild(tag);

QDomText t = doc.createTextNode("abc");
tag.appendChild(t);

QString xml = doc.toString();
}

can u help me as how I should call the request function??

Will using QNetworkAccessManager for the request and response from a webpage, be easier?

thanks

[wysota]

"data" is a pointer to a QIODevice (such as QBuffer) containing the data the engine should send to the server as the request (i.e. the result of your sendrequest() method). As for the header - the least you have to provide is the method (GET or POST) and relative path of the URL that should be queried.

[srohit24]

thanks mate.

so i need to call the request, like this?
http.request( GET, xmlrequest);

I need to have the xml request like this

<request client_id="1" client_serial_number="abcded" version="0.1">
<call name="test.reverse">abc</call>
</request>

but after using this code,



QDomDocument doc("request");
QDomElement root = doc.createElement("request");
doc.appendChild(root);

QDomElement tag = doc.createElement("call");
QString name = "teci.test.reverse";
QString value = "abc";
tag.setAttribute(name,value);
root.appendChild(tag);

QString xmlrequest = doc.toString();


i am able to only this.

"<!DOCTYPE request>
<request>
<call test.reverse="abc" />
</request>

can you help me with this?

[wysota]

thanks mate.

so i need to call the request, like this?
http.request( GET, xmlrequest);

Not really, you have to match the argument types (and values of course).


I need to have the xml request like this

<request client_id="1" client_serial_number="abcded" version="0.1">
<call name="test.reverse">abc</call>
</request>

but after using this code,



QDomDocument doc("request");
QDomElement root = doc.createElement("request");
doc.appendChild(root);

QDomElement tag = doc.createElement("call");
QString name = "teci.test.reverse";
QString value = "abc";
tag.setAttribute(name,value);
root.appendChild(tag);

QString xmlrequest = doc.toString();


i am able to only this.

"<!DOCTYPE request>
<request>
<call test.reverse="abc" />
</request>

What more would you expect from the above code snippet?

[srohit24]

i want to exact copy of the request xml thats been given.

I am asking, what changes should i make to get the xml that will request the server.

[srohit24]

i have made some changes to my code

I first need to get the Client id and the serial no



//This is how i need to send the request
=== Request ===

<request version="0.1">
<call name="client.create">
<client>
<kind>MOBILE</kind>
<name>API Test suite 7936</name>
</client>
</call>
</request>

//This is what i will get, if everything goes well

=== Response ===

<response version="0.1">
<client id="1">
<name>API Test suite 7936</name>
<kind>MOBILE</kind>
<serial_number>a09b4d3b-08b7-4cdf-bf3c-a5a8fb27ee1f</serial_number>
<added_on>2009-06-25 12:33:49.182287</added_on>
<enabled>True</enabled>
</client>
</response>



My code to send the request is this


void MainWindow::fetch()
{

QByteArray string ("username");
string.append(":");
string.append("12345");
QString converted = string.toBase64();

xml.clear();

QUrl url("http://something/");

http.setHost(url.host(),url.port(80));
http.setUser(converted);
connectionId = http.get(url.path());

sendrequest();
http.post(url.path(),xmlrequest);

}

void MainWindow::sendrequest()
{
QDomDocument doc;
QDomElement root = doc.createElement("request");
root.setAttribute("version", "0.1");
doc.appendChild(root);

QDomElement tag = doc.createElement("call");
tag.setAttribute("name","teci.client.create");
root.appendChild(tag);

QDomElement tag1 = doc.createElement("client");
tag.appendChild(tag1);

QDomElement tag2 = doc.createElement("kind");
QDomText t = doc.createTextNode("MOBILE");
tag2.appendChild(t);
tag1.appendChild(tag2);

QDomElement tag3 = doc.createElement("name");
t = doc.createTextNode("API Test suite 7936");
tag3.appendChild(t);
tag1.appendChild(tag3);

xmlrequest.append(doc.toString());
qDebug() << xmlrequest.data();
}

output i am getting is this



<request version="0.1" >
<call name="client.create" >
<client>
<kind>MOBILE</kind>
<name>API Test suite 7936</name>
</client>
</call>
</request>

Received error during HTTP fetch.

What should I do to get the program working?

The request is according to the specification. What am i missing here?

[wysota]

Why are you sending both get and post? And how do you process the responses?

[srohit24]

i have a function to read the xml and then to parse it.

but as i am getting a error during fetch, i didnt show the code.

abt both get and post, i am not sure which one I should be using. so i was trying both of them

[wysota]

You should use POST if you want to send some data to the server.

[srohit24]

ok. i have made the change ( using http.post now)

but still the same problem

Received error during HTTP fetch.

I have the following code to read the data and to check if the server has finished sending


void RSSListing::readData(const QHttpResponseHeader &resp)
{
qDebug() << "XML"<<http.readAll();
if (resp.statusCode() != 200)
http.abort();
else {
xml.addData(http.readAll());
parseXml();
}
}


void RSSListing::finished(int id, bool error)
{
if (error) {
qWarning("Received error during HTTP fetch.");
lineEdit->setReadOnly(false);
abortButton->setEnabled(false);
fetchButton->setEnabled(true);
}
else if (id == connectionId) {
lineEdit->setReadOnly(false);
abortButton->setEnabled(false);
fetchButton->setEnabled(true);
}
}

[wysota]

And when exactly does the error occur?

[srohit24]

I have a UI, which has 2 buttons and a text area

When i click on the 1st button, the fetch function is called.
The 2nd button is abort

When i click on the fetch button, the http sends the data.

But i am not able to receive anything from the server

[wysota]

Try to get more details about the request/response that triggers the error. What does QHttp::errorString() return?

[srohit24]

I getting "Unknown error" as the output for the error string, when i use it in the fetch function

But when i use it in the finished function, am getting "Authentication required".

But i am passing the username and password in the variable converted under http.setUser.

any ideas as to what might be the problem??

[wysota]

Use a network sniffer to see how your request looks like when it leaves your network interface. See if the proper auth data is contained in the http request.

[srohit24]

i used the network sniffer

here is what i got, in packets



HOST

.à ügÇT.¡„Ï3ˆd.>
/.!E.
-ú@.€JT;\*I®…R\.P²4Þ� �*·}ÓPÿÿ)¥..POST /api/ HTTP/1.1
Connection: Keep-Alive
Host: ionlab.webfactional.com
content-length: 162

<request version="0.1" >
<call name="teci.client.create" >
<client>
<kind>MOBILE</kind>
<name>API Test suite 7936</name>
</client>
</call>
</request>


SERVER

.¡„Ï3.à ügÇTˆd.>
D.!E.
B“i@.6Ю…R;\*I.P\*� �}Ó²4ßÁP Z..HTTP/1.1 401 Authorization Required
Server: nginx
Date: Thu, 02 Jul 2009 14:41:37 GMT
Content-Type: text/html; charset=utf-8
Transfer-Encoding: chunked
Connection: keep-alive
Vary: Cookie
WWW-Authenticate: Basic realm="TrackEveryCoin API"

16
Authorization Required
0

HOST

.à ügÇT.¡„Ï3ˆd.>
Å .!E.
ˆÿ@.€Iô;\*I®… R\.P²4ßÁ*·~Ã*Pþå¾I..POST /api/ HTTP/1.1
Connection: Keep-Alive
Host: ionlab.webfactional.com
content-length: 162
Authorization: Basic QXV0aG9yaXphdGlvbiA6IGMzSnZhR2wwTWpSQVoyMWhhV3d1WT I5dE9qRXlNelExOg==

<request version="0.1" >
<call name="teci.client.create" >
<client>
<kind>MOBILE</kind>
<name>API Test suite 7936</name>
</client>
</call>
</request>


SERVER

.¡„Ï3.à ügÇTˆd.>
D.!E.
B“j@.6Ï®…R;\*I.P\*Â� �~Ã*²4á!PPSk..HTTP/1.1 401 Authorization Required
Server: nginx
Date: Thu, 02 Jul 2009 14:41:37 GMT
Content-Type: text/html; charset=ut-8
Transfer-Encoding: chunked
Connection: keep-alive
Vary: Cookie
WWW-Authenticate: Basic realm="TrackEveryCoin API"

16
Authorization Required
0


Before the complete data is being sent, i am getting the authentication required error

[wysota]

You are not sending the authentication data. Make sure you use setUser() early enough in the flow. Also consider switching from QHttp to QNetworkAccessManager, it's easier to use it.

[srohit24]

i got it working mate. thanks for ur help

here is the code that works


void RSSListing::fetch()
{
lineEdit->setReadOnly(true);
fetchButton->setEnabled(false);
abortButton->setEnabled(true);
treeWidget->clear();
xml.clear();

QByteArray string ("username");
string.append(":");
string.append("12345");
QString encoded = string.toBase64();
qDebug() <<"String"<< string <<"Encoded" <<encoded ;

QUrl url("something/api/");
url.setUserName("username");
url.setPassword("12345");

QHttpRequestHeader header("POST","/api/");
header.setValue("Host",url.host());
header.setValue("Path",url.path());
header.setValue("Authorization","Basic " + encoded);

http.setHost(url.host(),url.port(80));

sendrequest();
connectionId = http.request(header,xmlrequest);
}

I am getting the response as per the specifications.

While parsing, is it possible to go to a particular tag, say skip the 1st 3 tags and go directly to the 4th one?

The first few tags in the response is redundant, i dont want to waste time parsing through them.

thanks

[srohit24]

My parsing code is this.


void MainWindow::parseXml()
{

while (!xml.atEnd())
{
xml.readNext();

if (xml.isStartElement())
{
currentTag = xml.name().toString();
qDebug() << "Current tag"<< currentTag ;

}
else if (xml.isEndElement())
{
if (xml.name() == "response")
{

QTreeWidgetItem *item = new QTreeWidgetItem;
item->setText(0, titleString);
item->setText(1, linkString);
treeWidget->addTopLevelItem(item);

titleString.clear();
linkString.clear();
}

}
else if (xml.isCharacters() && !xml.isWhitespace())
{
if (currentTag == "client")
titleString += xml.attributes().value("id").toString();
else if (currentTag == "serial_number")
linkString += xml.text().toString();
}
}
if (xml.error() && xml.error() != QXmlStreamReader::PrematureEndOfDocumentError) {
qWarning() << "XML ERROR:" << xml.lineNumber() << ": " << xml.errorString();
http.abort();
}
}



<response version="0.1">
<client id="1">
<name>API Test suite 7936</name>
<kind>MOBILE</kind>
<serial_number>a09b4d3b-08b7-4cdf-bf3c-a5a8fb27ee1f</serial_number>
<added_on>2009-06-25 12:33:49.182287</added_on>
<enabled>True</enabled>
</client>
</response>

I am able to get the serial no from the response, but to get the value of id in client tag is proving hard.

how can i get the value from a attribute and convert it into string??

[wysota]

See QXmlStreamReader::attributes() and QXmlStreamAttributes::value().

[srohit24]

thanks mate.

I was trying to find the tag when it was already parsed. Fixed it. working now.

Can you tell me a method through which i can go directly to a particular tag in the QXMLStreamHeader??

I want to skip the 1st 3 tags and go directly to the 4th one.

[wysota]

Consider using QDomDocument instead of the stream reader. It is easier to manipulate the xml there.