onGetServiceInfoClick: function(idKnowledgeBase) {
				var serviceData = {
					KnowledgeBaseID: this.get("PrimaryColumnValue")
				};
				ServiceHelper.callService("CustomConfigurationService", "GetTransformValue",
				function(response) {
					var result = response.GetTransformValueResult;
					this.renderDownloadFile(result);
				}, serviceData, this);
			},
 
			renderDownloadFile: function (data) {
				var esqKnowledgeBaseFile = Ext.create("Terrasoft.EntitySchemaQuery", {
					"rootSchemaName": "KnowledgeBaseFile"
				});
				esqKnowledgeBaseFile.addColumn("Id");
				esqKnowledgeBaseFile.addColumn("KnowledgeBase");
				esqKnowledgeBaseFile.addColumn("Name");
				esqKnowledgeBaseFile.filters.addItem(Terrasoft.createColumnFilterWithParameter(
					Terrasoft.ComparisonType.EQUAL, "KnowledgeBase", this.get("PrimaryColumnValue")));
				esqKnowledgeBaseFile.getEntityCollection(function(resultKnowledgeBaseFile) { 
					if (resultKnowledgeBaseFile.success) {
						var textFileAsBlob = new Blob([data], {type:'application/pdf'});
						var fileNameToSaveAs = resultKnowledgeBaseFile.collection.getByIndex(0).get("Name");
 
						var downloadLink = document.createElement("a");
						downloadLink.download = fileNameToSaveAs;
						downloadLink.innerHTML = "Download File";
						if (window.webkitURL != null) {
							downloadLink.href = window.webkitURL.createObjectURL(textFileAsBlob);
						} else {
							downloadLink.href = window.URL.createObjectURL(textFileAsBlob);
							downloadLink.onclick = destroyClickedElement;
							downloadLink.style.display = "none";
							document.body.appendChild(downloadLink);
						}
						downloadLink.click();
					}
				}, this);
			},

public class CustomConfigurationService
    {
        [OperationContract]
        [WebInvoke(Method = "POST", RequestFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.Wrapped,
        ResponseFormat = WebMessageFormat.Json)]
        public MemoryStream GetTransformValue(string KnowledgeBaseID)
        {
            var UserConnection = (UserConnection)HttpContext.Current.Session["UserConnection"];
            var KnowledgeBaseFileESQ = new EntitySchemaQuery(UserConnection.EntitySchemaManager, "KnowledgeBaseFile");
            KnowledgeBaseFileESQ.AddAllSchemaColumns();
            var KnowledgeBaseIDFilter = KnowledgeBaseFileESQ.CreateFilterWithParameters(FilterComparisonType.Equal, "KnowledgeBase", new Guid(KnowledgeBaseID));
            KnowledgeBaseFileESQ.Filters.Add(KnowledgeBaseIDFilter);
            var KnowledgeBaseFileEnteties = KnowledgeBaseFileESQ.GetEntityCollection(UserConnection);
 
            var data = KnowledgeBaseFileEnteties[0].GetColumnValue("Data") as byte[];
            var result = new MemoryStream(data);
 
            return result;
        }
    }

var textFileAsBlob = new Blob(data, {type:'application/pdf'});

<a target='_self' href='http://localhost:8087/0/rest/FileService/GetFile/e9eafee9-c4e4-4793-ad0a-003bd2c6a9b4/564a97fc-7290-4343-b45e-8f466e5fad5b"'></a>

function SaveURLAsFileToDatabase(URL, Dataset, DataFieldName) {
	var Extention = ExtractFileExtension(URL);
	if (IsEmptyValue(Extention)) {
		return;
	}
	var FileName = ExtractFileName(URL);
	var xml = new ActiveXObject("Microsoft.XMLHTTP");
	xml.Open("GET", URL, false);
	xml.Send();
	var oStream = new ActiveXObject("Adodb.Stream");
	var adTypeBinary = 1;
	var adSaveCreateOverWrite = 2;
	var adSaveCreateNotExist = 1;
	oStream.Type = adTypeBinary;
	oStream.Open();
	oStream.Write(xml.responseBody);
	var NewFileName = GetTemporaryFileName(FileName, true);
	oStream.SaveToFile(NewFileName, adSaveCreateNotExist);
	oStream.Close();
	SaveFileToDataset(NewFileName, Dataset, 'FileData');
	var FileObject = GetFileSystemObject();
	FileObject.DeleteFile(NewFileName);
}