json Webservice that will pass Base64 code that will convert to image - json

Question

Specification:
Server 2012
Framework 3.5
I have already deployed my webservice in the server http://ipaddress/eSignatureWS.asmx?op=SaveImg.
Problem: when i change the ajax dataType to "json" or "text" it has an Internal Server Error, but when i used "script" it won't have an error but it don't save the image. When i try it locally it works using "json"/"text" but when i deployed it won't work anymore.
So here's my code:
Jquery
function signatureSave() {
var canvas = document.getElementById("newSignature"); // save canvas image as data url (png format by default)
var data = canvas.toDataURL("image/png");
var signatureData = data.replace(/^data:image\/(png|jpg);base64,/, "");
var donum = "sampleImg"; //imagename
$.support.cors = true;
//var imgData = JSON.stringify(signatureData);
$.ajax({
type: "Post",
async: false,
url: "http://ipaddress/eSignatureWS.asmx?op=SaveImg",
data: { "filename": donum, "imgBit": signatureData },
dataType: "json",
success: function (data) { //alert(data);
if (data.match("true")) {
document.getElementById('errorImage').innerHTML = "Successfully Submitted!";
}
else {
document.getElementById('errorImage').innerHTML = "Error occured.";
}
},
error: function (XMLHttpRequest, testStatus, errorThrown) {
document.getElementById('errorImage').innerHTML = errorThrown;
alert(XMLHttpRequest + testStatus + errorThrown);
}
})
Webservice
[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public string SaveImg(string filename, string imgBit)
{
try
{
string filepath = WebConfigurationManager.AppSettings["ImgLocation"].ToString();
string imgPath = filepath + filename + ".png";
//creates a png image signature
using (FileStream fs = new FileStream(imgPath, FileMode.Create))
{
using (BinaryWriter bw = new BinaryWriter(fs))
{
byte[] data = Convert.FromBase64String(imgBit);
bw.Write(data);
bw.Close();
JavaScriptSerializer js = new JavaScriptSerializer();
string strJSON = js.Serialize("true");
return strJSON;
}
}
}
catch (Exception ex)
{
}
}

Answer 1

Check the edit section!
I'm guessing you're not aware of the "maxJsonLength" attribute which is set to 100KB by default, in ASP.NET. I wasn't aware of that till the latest search I had to make about the same subject :)
In the Web.Config file you can change this default limitation to your needs.
<configuration>
<system.web.extensions>
<scripting>
<webServices>
<jsonSerialization maxJsonLength="1000000"/>
</webServices>
</scripting>
</system.web.extensions>
</configuration>
That one is 1.000.000 bytes which is ~1MB. You can set higher values if you need to send bigger files through your webservice.
Check that and please let me know if it works.
EDIT: I recently found out that this is not the only setting you should make. You should also set the "maxRequestLength" attribute of the httpruntime node in web.config file, like:
<system.web>
<httpRuntime targetFramework="4.5" maxRequestLength="10000" executionTimeout="10800" />
</system.web>
Here, maxRequestLength is in KBs, so 10000 means ~10MBs (9,77MB exactly). If users have low bandwidths and your requestlength requirement is bigger than 10MB, then you can set executionTimeout attribute to a higher value. That is in seconds, so 10800 means 3 hours.
I think you got the picture here.
Cheers!