Introduction The way I previously created messages
to send
to the GovTalk service I used the XMLDocument
to create the request. While this worked it left a number of problems; not least that for every message a special function would need
to created. This is OK for the short term but the biggest cost in any software project is maintenance and this would be a headache
to maintain. So the following is a somewhat better way of achieving the same thing. For the purposes of this article I am going
to be using the CompanyNumberSearch request of the GovTalk service – although this technique would work for any service that accepted XML. The C# functions which send and receive the messages remain the same. The magic sauce in this is the XSLT which defines the structure of the request, and the use of objects in conjunction with reflection
to provide the content. It is a bit like Sweet Chilli Sauce added
to Chicken on a bed of rice. So on
to the Sweet Chilli Sauce The Sweet Chilli Sauce The request
to search for a company based on it’s number is as follows; <GovTalkMessage xsi:schemaLocation="http://www.govtalk.gov.uk/CM/envelope http://xmlgw.companieshouse.gov.uk/v1-0/schema/Egov_ch-v2-0.xsd" xmlns="http://www.govtalk.gov.uk/CM/envelope" xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" xmlns:gt="http://www.govtalk.gov.uk/schemas/govtalk/core" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >
<EnvelopeVersion>1.0</EnvelopeVersion>
<Header>
<MessageDetails>
<Class>NumberSearch</Class>
<Qualifier>request</Qualifier>
<TransactionID>1</TransactionID>
</MessageDetails>
<SenderDetails>
<IDAuthentication>
<SenderID>????????????????????????????????</SenderID>
<Authentication>
<Method>CHMD5</Method>
<Value>????????????????????????????????</Value>
</Authentication>
</IDAuthentication>
</SenderDetails>
</Header>
<GovTalkDetails>
<Keys/>
</GovTalkDetails>
<Body>
<NumberSearchRequest xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://xmlgw.companieshouse.gov.uk/v1-0/schema/NumberSearch.xsd">
<PartialCompanyNumber>99999999</PartialCompanyNumber>
<DataSet>LIVE</DataSet>
<SearchRows>1</SearchRows>
</NumberSearchRequest>
</Body>
</GovTalkMessage>
This is the XML that we send
to the GovTalk Service and we get back a list of companies that match the criteria passed
A message is structured in two parts; The envelope which identifies the person sending the request, with the name of the request, and the body which gives the detail of the company we are looking for.
The Chilli
What makes it possible is the use of XSLT
to define the message – and serialization
to convert each request
object into XML.
To start we need
to create an
object which will represent the contents of the message we are sending. However there is a common properties in all the messages that we send
to Companies House. These properties are as follows
SenderId – the id of the person sending the message
SenderPassword – the password associated with Id
TransactionId – Unique identifier for the message
AuthenticationValue – authenticates the request
Because these properties are unique
to the Companies House message, and because they are shared with all messages they are perfect candidates for a base class.
The class is as follows;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Security.Cryptography;
using System.Text;
using System.Text.RegularExpressions;
using Microsoft.WindowsAzure.ServiceRuntime;
namespace CompanyHub.Services
{
public class GovTalkRequest
{
public GovTalkRequest()
{
try
{
SenderID = RoleEnvironment.GetConfigurationSettingValue("SenderId");
SenderPassword = RoleEnvironment.GetConfigurationSettingValue("SenderPassword");
TransactionId = DateTime.Now.Ticks.ToString();
AuthenticationValue = EncodePassword(String.Format("{0}{1}{2}", SenderID, SenderPassword, TransactionId));
}
catch (System.Exception ex)
{
throw ex;
}
}
/// <summary>
/// returns the Sender ID
to be used when communicating with the GovTalk Service
/// </summary>
public
String SenderID
{
get;
set;
}
/// <summary>
/// return the password
to be used when communicating with the GovTalk Service
/// </summary>
public
String SenderPassword
{
get;
set;
} // end SenderPassword
/// <summary>
/// Transaction Id - uses the Time and Date converted
to Ticks
/// </summary>
public
String TransactionId
{
get;
set;
} // end TransactionId
/// <summary>
/// calculate the authentication value that will be used when
/// communicating with
/// </summary>
public
String AuthenticationValue
{
get;
set;
} // end AuthenticationValue property
/// <summary>
/// encodes password(s) using MD5
/// </summary>
/// <param name="clearPassword"></param>
/// <returns></returns>
public static
String EncodePassword(String clearPassword)
{
MD5CryptoServiceProvider md5Hasher = new MD5CryptoServiceProvider();
byte[] hashedBytes;
UTF32Encoding encoder = new UTF32Encoding();
hashedBytes = md5Hasher.ComputeHash(ASCIIEncoding.Default.GetBytes(clearPassword));
String result = Regex.Replace(BitConverter.ToString(hashedBytes), "-", "").ToLower();
return result;
}
}
}
There is nothing particularly clever here, except for the EncodePassword method which hashes the value made up of the SenderId, Password and Transaction id.
Each message inherits from this
object. So for the Company Number Search in addition
to the properties above we need a partial number, which dataset
to search – for the purposes of the project we only need
to search the LIVE set so this can be set in the constructor and the SearchRows. Again all are set as properties. With the SearchRows and DataSet initialized in the constructor.
public class CompanyNumberSearchRequest : GovTalkRequest, IDisposable
{
/// <summary>
///
/// </summary>
public CompanyNumberSearchRequest() : base()
{
DataSet = "LIVE";
SearchRows = 1;
}
/// <summary>
/// Company Number
to search against
/// </summary>
public
String PartialCompanyNumber { get; set; }
/// <summary>
/// What DataSet should be searched for the company
/// </summary>
public
String DataSet { get; set; }
/// <summary>
/// How many rows should be returned
/// </summary>
public int SearchRows { get; set; }
public void Dispose()
{
DataSet =
String.Empty;
PartialCompanyNumber =
String.Empty;
DataSet = "LIVE";
SearchRows = 1;
}
}
As well as inheriting from our base class, I have also inherited from IDisposable – not just because it is just plain good practice
to dispose of objects when coding, but it gives also gives us more versatility when using the
object.
There are four stages in making a request and this is reflected in the four methods we execute in making a call
to the Companies House service;
Create a request
Send a request
Check the status
If OK then get the results of the request
I’ve implemented each of these stages within a static class called Toolbox – which also means I don’t need
to create an instance of the class
to use it.
When making a request there are three stages;
Get the template for the message
Serialize the
object representing the message
Transform the serialized
object using a predefined XSLT file.
Each of my templates I have defined as an embedded resource. When retrieving a resource of this kind we have
to include the full namespace
to the resource. In making the code re-usable as much as possible I defined the full ‘path’ within the GetRequest method.
requestFile =
String.Format("CompanyHub.Services.Schemas.{0}", RequestFile);
So we now have the full path of the file within the assembly. Now all we need do is retrieve the assembly and get the resource.
asm = Assembly.GetExecutingAssembly();
sr = asm.GetManifestResourceStream(requestFile);
Once retrieved
So this can be returned
to the calling function and we now have a stream of XSLT
to define the message. Time now
to serialize the request
to create the other side of this message.
// Serialize
object containing Request, Load into XML Document
t = Obj.GetType();
ms = new MemoryStream();
serializer = new XmlSerializer(t);
xmlTextWriter = new XmlTextWriter(ms, Encoding.ASCII);
serializer.Serialize(xmlTextWriter, Obj);
ms = (MemoryStream)xmlTextWriter.BaseStream;
GovTalkRequest = Toolbox.ConvertByteArrayToString(ms.ToArray());
First off we need the type of the
object so we make a call
to the GetType method of the
object containing the Message properties.
Next we need a MemoryStream, XmlSerializer and an XMLTextWriter so these can be initialized.
The
object is serialized by making the call
to the Serialize method of the serializer
object. The result of that is then converted into a MemoryStream. That MemoryStream is then converted into a
string.
ConvertByteArrayToString
This is a fairly simple function which uses an ASCIIEncoding
object found within the System.Text namespace
to convert an array of bytes into a
string.
public static
String ConvertByteArrayToString(byte[] bytes)
{
System.Text.ASCIIEncoding enc = new System.Text.ASCIIEncoding();
return enc.GetString(bytes);
}
I only put it into a function because I will be using this in various places.
The Sauce
When adding support for other messages outside of creating a new
object to store the properties of the message, the C# components do not need
to change. It is in the XSLT file that the versatility of the technique lies. The XSLT file determines the format of the message. For the CompanyNumberSearch the XSLT file is as follows;
<?xml version="1.0"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
<GovTalkMessage xsi:schemaLocation="http://www.govtalk.gov.uk/CM/envelope http://xmlgw.companieshouse.gov.uk/v1-0/schema/Egov_ch-v2-0.xsd" xmlns="http://www.govtalk.gov.uk/CM/envelope" xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" xmlns:gt="http://www.govtalk.gov.uk/schemas/govtalk/core" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >
<EnvelopeVersion>1.0</EnvelopeVersion>
<Header>
<MessageDetails>
<Class>NumberSearch</Class>
<Qualifier>request</Qualifier>
<TransactionID>
<xsl:value-of select="CompanyNumberSearchRequest/TransactionId"/>
</TransactionID>
</MessageDetails>
<SenderDetails>
<IDAuthentication>
<SenderID><xsl:value-of select="CompanyNumberSearchRequest/SenderID"/></SenderID>
<Authentication>
<Method>CHMD5</Method>
<Value>
<xsl:value-of select="CompanyNumberSearchRequest/AuthenticationValue"/>
</Value>
</Authentication>
</IDAuthentication>
</SenderDetails>
</Header>
<GovTalkDetails>
<Keys/>
</GovTalkDetails>
<Body>
<NumberSearchRequest xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://xmlgw.companieshouse.gov.uk/v1-0/schema/NumberSearch.xsd">
<PartialCompanyNumber>
<xsl:value-of select="CompanyNumberSearchRequest/PartialCompanyNumber"/>
</PartialCompanyNumber>
<DataSet>
<xsl:value-of select="CompanyNumberSearchRequest/DataSet"/>
</DataSet>
<SearchRows>
<xsl:value-of select="CompanyNumberSearchRequest/SearchRows"/>
</SearchRows>
</NumberSearchRequest>
</Body>
</GovTalkMessage>
</xsl:template>
</xsl:stylesheet>
The outer two tags define that this is a XSLT stylesheet and the root tag from which the nodes are searched for.
The GovTalkMessage is the format of the message that will be sent
to Companies House.
We first set up the XslCompiledTransform
object which will transform the XSLT template and the serialized
object into the request
to Companies House.
xslt = new XslCompiledTransform();
resultStream = new MemoryStream();
writer = new XmlTextWriter(resultStream, Encoding.ASCII);
doc = new XmlDocument();
The Serialize method require XmlTextWriter
to write the XML (writer) and a stream
to place the transferred
object into (writer). The XML will be loaded into an XMLDocument
object (doc) prior
to the transformation.
// create XSLT Template
xslTemplate = Toolbox.GetRequest(Template);
xslTemplate.Seek(0, SeekOrigin.Begin);
templateReader = XmlReader.Create(xslTemplate);
xslt.Load(templateReader);
I have stored all the templates as a series of Embedded Resources and the GetRequestCall takes the name of the template and extracts the relevent XSLT file.
/// <summary>
/// Gets the framwork XML which makes the request
/// </summary>
/// <param name="RequestFile"></param>
/// <returns></returns>
public static Stream GetRequest(String RequestFile)
{
String requestFile =
String.Empty;
Stream sr = null;
Assembly asm = null;
try
{
requestFile =
String.Format("CompanyHub.Services.Schemas.{0}", RequestFile);
asm = Assembly.GetExecutingAssembly();
sr = asm.GetManifestResourceStream(requestFile);
}
catch (Exception)
{
throw;
}
finally
{
asm = null;
}
return sr;
} // end private static stream GetRequest
We first take the template name and expand it
to include the full namespace
to the Embedded Resource I like
to keep all my schemas in the same directory and so the namespace reflects this. The rest is the default namespace for the project.
Then we get the currently executing assembly (which will contain the resources with the call
to GetExecutingAssembly() )
Finally we get a stream which contains the XSLT file. We use this stream and then load an XmlReader with the contents of the template, and that is in turn loaded into the XslCompiledTransform
object.
We convert the
object containing the message properties into Xml by serializing it; calling the Serialize() method of the XmlSerializer
object.
To set up the
object we do the following;
t = Obj.GetType();
ms = new MemoryStream();
serializer = new XmlSerializer(t);
xmlTextWriter = new XmlTextWriter(ms, Encoding.ASCII);
We first determine the type of the
object being transferred by calling GetType() We create an XmlSerializer
object by passing the type of the
object being serialized. The serializer writes
to a memory stream and that is linked
to an XmlTextWriter.
Next job is
to serialize the
object and load it into an XmlDocument.
serializer.Serialize(xmlTextWriter, Obj);
ms = (MemoryStream)xmlTextWriter.BaseStream;
xmlRequest = new XmlTextReader(ms);
GovTalkRequest = Toolbox.ConvertByteArrayToString(ms.ToArray());
doc.LoadXml(GovTalkRequest);
Time
to transform the XML
to construct the full request.
xslt.Transform(doc, writer);
resultStream.Seek(0, SeekOrigin.Begin);
request = Toolbox.ConvertByteArrayToString(resultStream.ToArray());
So that creates the full request
to be sent
to Companies House.
Sending the request
So far we have a
string with a request for the Companies House service. Now we need
to send the request
to the Companies House Service.
Configuration within an Azure project
There are entire blog entries written about configuration within an Azure project – most of this is out of scope for this article but the following is a summary.
Configuration is defined in two files within the parent project *.csdef which contains the definition of configuration setting.
<?xml version="1.0" encoding="utf-8"?>
<ServiceDefinition name="OnlineCompanyHub" xmlns="http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceDefinition">
<WebRole name="CompanyHub.Host">
<InputEndpoints>
<InputEndpoint name="HttpIn" protocol="http" port="80" />
</InputEndpoints>
<ConfigurationSettings>
<Setting name="DiagnosticsConnectionString" />
<Setting name="DataConnectionString" />
</ConfigurationSettings>
</WebRole>
<WebRole name="CompanyHub.Services">
<InputEndpoints>
<InputEndpoint name="HttpIn" protocol="http" port="8080" />
</InputEndpoints>
<ConfigurationSettings>
<Setting name="DiagnosticsConnectionString" />
<Setting name="SenderId"/>
<Setting name="SenderPassword" />
<Setting name="GovTalkUrl"/>
</ConfigurationSettings>
</WebRole>
<WorkerRole name="CompanyHub.Worker">
<ConfigurationSettings>
<Setting name="DiagnosticsConnectionString" />
</ConfigurationSettings>
</WorkerRole>
</ServiceDefinition>
Above is the configuration definition from the project. What we are interested in however is the ConfigurationSettings tag of the CompanyHub.Services WebRole.
There are four configuration settings here, but at the moment we are interested in the second
to forth settings; SenderId, SenderPassword and GovTalkUrl
The value of these settings are defined in the ServiceDefinition.cscfg file;
<?xml version="1.0"?>
<ServiceConfiguration serviceName="OnlineCompanyHub" xmlns="http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceConfiguration">
<Role name="CompanyHub.Host">
<Instances count="2" />
<ConfigurationSettings>
<Setting name="DiagnosticsConnectionString" value="UseDevelopmentStorage=true" />
<Setting name="DataConnectionString" value="UseDevelopmentStorage=true" />
</ConfigurationSettings>
</Role>
<Role name="CompanyHub.Services">
<Instances count="2" />
<ConfigurationSettings>
<Setting name="DiagnosticsConnectionString" value="UseDevelopmentStorage=true" />
<Setting name="SenderId" value="UserID"/>
<Setting name="SenderPassword" value="Password"/>
<Setting name="GovTalkUrl" value="http://xmlgw.companieshouse.gov.uk/v1-0/xmlgw/Gateway"/>
</ConfigurationSettings>
</Role>
<Role name="CompanyHub.Worker">
<Instances count="2" />
<ConfigurationSettings>
<Setting name="DiagnosticsConnectionString" value="UseDevelopmentStorage=true" />
</ConfigurationSettings>
</Role>
</ServiceConfiguration>
Look for the Role tag that contains our project name (CompanyHub.Services).
Having configured the parameters we can now transmit the request. This is done by ‘POST’ing a stream of XML
to the Companies House servers.
govTalkUrl = RoleEnvironment.GetConfigurationSettingValue("GovTalkUrl");
request = WebRequest.Create(govTalkUrl);
request.Method = "POST";
request.ContentType = "text/xml";
writer = new StreamWriter(request.GetRequestStream());
writer.WriteLine(RequestMessage);
writer.Close();
We use the WebRequest
object to send the
object. Set the method of sending
to ‘POST’ and the type of data as text/xml. Once set up all we do is write the request
to the writer – this sends the request
to Companies House.
Did the Request Work Part I – Getting the response
Having sent a request – we now need the result of that request.
response = request.GetResponse();
reader = response.GetResponseStream();
result = Toolbox.ConvertByteArrayToString(Toolbox.ReadFully(reader));
The WebRequest
object has a GetResponse() method which allows us
to get the response sent back. Like many of these calls the results come in the form of a stream which we convert into a
string.
Did the Request Work Part II – Translating the Response
Much like XSLT and XML were used
to create the original request, so it can be used
to extract the response and by deserializing the result we create an
object that contains the response.
Did it work?
It would be really great if everything worked all the time. Of course if it did then I don’t suppose people would pay me and others the big bucks so that our programmes do not
a) Collapse in a heap (this is an area of memory)
b) Blow every fuse in the place in a shower of sparks (this will probably not happen this being real life and not a Hollywood movie, but it was possible
to blow the sound system of a BBC Model B with a poorly coded setting)
c) Go nuts and trap everyone outside the airlock (this was from a movie, and unless NASA get a manned moon/mars mission set up unlikely
to happen)
d) Go nuts and take over the world (this was also from a movie, but please note life has a habit of being of exceeding the wildest imaginations of Hollywood writers (note writers – Hollywood executives have no imagination and judging by recent output of that town have turned plagiarism into an art form).
e) Freeze in total confusion because the cleaner pulled the plug
to the internet router (this has happened)
So anyway – we need
to check
to see if our request actually worked. Within the GovTalk response there is a section that details the status of the message and a description of what went wrong (if anything did). I have defined an XSLT template which will extract these into an XML document.
<?xml version="1.0"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:ev="http://www.govtalk.gov.uk/CM/envelope"
xmlns:gt="http://www.govtalk.gov.uk/schemas/govtalk/core"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<xsl:template match="/">
<GovTalkStatus xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<Status>
<xsl:value-of select="ev:GovTalkMessage/ev:Header/ev:MessageDetails/ev:Qualifier"/>
</Status>
<Text>
<xsl:value-of select="ev:GovTalkMessage/ev:GovTalkDetails/ev:GovTalkErrors/ev:Error/ev:Text"/>
</Text>
<Location>
<xsl:value-of select="ev:GovTalkMessage/ev:GovTalkDetails/ev:GovTalkErrors/ev:Error/ev:Location"/>
</Location>
<Number>
<xsl:value-of select="ev:GovTalkMessage/ev:GovTalkDetails/ev:GovTalkErrors/ev:Error/ev:Number"/>
</Number>
<Type>
<xsl:value-of select="ev:GovTalkMessage/ev:GovTalkDetails/ev:GovTalkErrors/ev:Error/ev:Type"/>
</Type>
</GovTalkStatus>
</xsl:template>
</xsl:stylesheet>
Only thing different about previous XSL files is the references
to two namespaces ev & gt. These are defined in the GovTalk response at the top of the response;
xsi:schemaLocation="http://www.govtalk.gov.uk/CM/envelope http://xmlgw.companieshouse.gov.uk/v1-0/schema/Egov_ch-v2-0.xsd"
xmlns="http://www.govtalk.gov.uk/CM/envelope"
xmlns:dsig="http://www.w3.org/2000/09/xmldsig#"
xmlns:gt="http://www.govtalk.gov.uk/schemas/govtalk/core"
If we do not put these references into the XSLT template then the XslCompiledTransform
object will not be able
to find the relevant tags.
Deserialization is a fairly simple activity.
encoder = new ASCIIEncoding();
ms = new MemoryStream(encoder.GetBytes(statusXML));
serializer = new XmlSerializer(typeof(GovTalkStatus));
xmlTextWriter = new XmlTextWriter(ms, Encoding.ASCII);
messageStatus = (GovTalkStatus)serializer.Deserialize(ms);
We set up a serialization
object using the
object type containing the error state and pass
to it the results of a transformation between the XSLT above and the GovTalk response.
Now we have an
object containing any error state, and the error message. All we need
to do is check the status. If there is an error then we can flag an error. If not then we extract the results and pass that as an
object back
to the calling function. We go this by guess what – defining an XSLT template for the result and using that
to create an Xml Stream which can be deserialized into a .Net
object. In this instance the XSLT
to create the result of a Company Number Search is;
<?xml version="1.0" encoding="us-ascii"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:ev="http://www.govtalk.gov.uk/CM/envelope"
xmlns:sch="http://xmlgw.companieshouse.gov.uk/v1-0/schema"
exclude-result-prefixes="ev">
<xsl:template match="/">
<CompanySearchResult xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<CompanyNumber>
<xsl:value-of select="ev:GovTalkMessage/ev:Body/sch:NumberSearch/sch:CoSearchItem/sch:CompanyNumber"/>
</CompanyNumber>
<CompanyName>
<xsl:value-of select="ev:GovTalkMessage/ev:Body/sch:NumberSearch/sch:CoSearchItem/sch:CompanyName"/>
</CompanyName>
</CompanySearchResult>
</xsl:template>
</xsl:stylesheet>
and the
object definition is;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
namespace CompanyHub.Services
{
public class CompanySearchResult
{
public CompanySearchResult()
{
CompanyNumber =
String.Empty;
CompanyName =
String.Empty;
}
public
String CompanyNumber { get; set; }
public
String CompanyName { get; set; }
}
}
Our entire code
to make calls
to send a request, and interpret the results are;
String request =
String.Empty;
String response =
String.Empty;
GovTalkStatus status = null;
fault = null;
try
{
using (CompanyNumberSearchRequest requestObj = new CompanyNumberSearchRequest())
{
requestObj.PartialCompanyNumber = CompanyNumber;
request = Toolbox.CreateRequest(requestObj, "CompanyNumberSearch.xsl");
response = Toolbox.SendGovTalkRequest(request);
status = Toolbox.GetMessageStatus(response);
if (status.Status.ToLower() == "error")
{
fault = new HubFault()
{
Message = status.Text
};
}
else
{
Object obj = Toolbox.GetGovTalkResponse(response, "CompanyNumberSearchResult.xsl", typeof(CompanySearchResult));
}
}
}
catch (FaultException<ArgumentException> ex)
{
fault = new HubFault()
{
FaultType = ex.Detail.GetType().FullName,
Message = ex.Detail.Message
};
}
catch (System.Exception ex)
{
fault = new HubFault()
{
FaultType = ex.GetType().FullName,
Message = ex.Message
};
}
finally
{
}
Wrap up
So there we have it – a reusable set of functions
to send and interpret XML results from an internet based service. The code is reusable with a little change with any service which uses XML as a transport mechanism – and as for the Companies House GovTalk service all I need
to do is create various objects for the result and message sent and the relevent XSLT files. I might need minor changes for other services but something like 70-90% will be exactly the same.
