Category Archives: Code

Software Development

Sending large byte[] of binary data through WCF – a simple approach

You can send large streams of data through WCF in two ways: by streaming or by buffer. How to enable streaming is discussed here but has the significant restriction that if you stream, you can only have one (yes, 1) parameter into and out of the service. If your goal is just to pass largish objects such as a spreadsheet or a PDF as part of a service operation this could be a significant hurdle to code around.

“By buffer” means that your large data can be handled with no special treatment at all: it is sent, read into memory (the buffer), and processed just like small messages are. You must understand that buffering means the whole message is buffered; As of early 21st century, that fine on most servers for muliti-megabyte data, but not fine for gigabytes of data.

The simple way to handles megabyte messages is to create a binding Configuration with 2 or 3 parameters increased:

        <binding name="basicHttpFor2MBMessage" maxBufferSize="2097152" maxReceivedMessageSize="2097152">
          <readerQuotas maxArrayLength="2097000" />

and have your service endpoint use it:

<endpoint address="" binding="basicHttpBinding" bindingConfiguration="basicHttpFor2MBMessage" contract="yourContractName>

Voila. You can now send a 2MB large array through SOAP to WCF.

If your large array is binary data, you declare it in your service classes as byte[], which is why you need the maxArrayLength setting. If you are creating test messages by hand or in a testing tool, you also need to know how to represent binary data in a SOAP message.
The usual answer is, use base64 encoding and it should just work, thus:

<soapenv:Envelope xmlns:soapenv="" xmlns:dat="http://MyServiceName">
         <dat:Pdf>JVBE ... <i>base64 encoded string</i> .... JUVPRgo=</dat:contractPdf>



The WCF default small buffer and message sizes are a guard against DoS attacks so if your service is publicly visible this would leave it less well guarded.


How fast does your service process large requests?

If (Expected Peak Requests Per Minute) * (Seconds to Process a Request) is bigger than 60 (Seconds in a Minute) then you need more horsepower.

How much memory do you have?

If (Size of Message * Requests per Hour) – (Speed at which WCF frees up an hour’s worth of used buffers) is bigger than your available memory then you’ll fall over. Alas there is no simple setting for ‘Speed at which WCF frees up an hour’s worth of used buffers’ so that calculation is a problem for another blog post. If you might have a problem, you can use PerfMon to watch memory behaviour during a stress test.

dotCover config file for command line NUnit test coverage

So you want to produce a coverage report for your .Net project, preferably from the command line? If you use dotCover and NUnit then this:

<?xml version="1.0" encoding="utf-8"?>
    <Executable><!-- Path to your NUnit bin directory e.g.  -->C:\Program Files\NUnit 2.5.10\bin\net-2.0\nunit-console.exe</Executable>
    <WorkingDir><!-- This path works for running dotCover with a config file in the project directory-->bin\Debug\</WorkingDir>
    <Arguments><!-- The dlls containing NUnit tests. Space delimited if more than one-->My.Tests.dll My.MoreTests.dll</Arguments>
    <Output><!-- Path to where I want the report. Can be relative or absolute -->My.Tests.Coverage.html</Output>
            <FilterEntry><!--  _ "Module" means project _ --><ModuleMask>*</ModuleMask></FilterEntry>
            <FilterEntry><!--  _ "Module" means project _ --><ModuleMask>My.Tests</ModuleMask></FilterEntry>
            <FilterEntry><!-- namespaces can be filter with a ClassMask with * wildcard --><ClassMask>Namespaces.For.AutogeneratedCode.*</ClassMask></FilterEntry>

will allow you, from the command line, to type:

dotCover analyse MyConfigFileName.xml

and generate coverage reports. Assuming that dotCover is in your path of course.
I like to set the filters to exclude coverge report on the test project itself as well as autogenerated code.

Covering Multiple Test Projects In One Run

  • Set your working directory to be a parent of all the test projects, e.g. the solution directory.
  • List the full relative paths to each Test dll, space limited:
    <Arguments>Web.Tests\bin\Debug\MyProject.Web.Tests.dll Implementation.Tests\bin\Debug\MyProject.Implementation.Tests.dll</Arguments>

Filtering and more advanced coverage configs

  • Look down the right hand side of the page here : for documentation, such as it is.
  • Filtering is covered here:
  • More complex stuff is touched on here:

Use SqlExpress or Sql Server for Asp.Net Session

Problems using Sql Server or Sql Express for Asp.Net Session State

So you’ve run aspnet_regsql.exe -S .\SqlExpress -E -ssadd -sstype p or something like that, after following instructions about Asp.Net Session State Modes (in particular noting the instructions about the Agent XP setting for SqlExpress if you’re using SqlExpress) and you’ve set your web.config sessionState section; and you hoped that aspnet_regsql might do something useful like give permissions to your machine’s AspNet account to use the session state and it would all Just Work. Aaah. You can hope.

Error messages when setting up Asp.Net to use SqlServer Session State

Cannot open database requested in login ‘ASPState’. Login failed for user {MachineName}\ASPNET

Unable to use SQL Server because ASP.NET version 2.0 Session State is not installed on the SQL server. Please install ASP.NET Session State SQL Server version 2.0 or above

Failed to login to session state SQL server for user ‘AspNetSqlLogin’

Example Web.Config section

    sqlConnectionString="Data Source=.\SqlExpress;Integrated Security=SSPI;"

Solution: Give permissions on Sql Server to your AspNet account

Note the username from your error page telling you what account Asp.Net is using to login to your server. Then, in Sql Management Studio or somesuch:

  1. Create a login for that Windows user
  2. Add the login as a user to your AspState database
  3. Give permissions to that user in that database by making it a member of the owner role

I first tried making the AspNet account a member of the db_reader & db_writer roles, but that didn’t work; making it a database owner did work.

But I put SessionState on a Sql Server instance on a different machine

Then you’re hopefully running your servers within a domain and you can set Asp.Net to run under a domain account, and you can give permissions on Sql server to that domain account.
Or, you create a new Sql Server login. Similar to the above process, but instead of finding an existing Windows login in Sql Management Studio, you create a new Sql Server login). The you specify a connection string with a Sql Security instead of Integrated Security: sqlConnectionString="Data Source=.\SqlExpress;User Id=SqlLoginForAspNet;Password=XXXXXX;

But I get a

Failed to login to session state SQL server for user


Login failed for user ‘AspNetSqlLogin’. The user is not associated with a trusted SQL Server connection

That’s because your Sql Server has been configured for Windows Authentication Mode only. Configure it for both Windows and Sql Server Authentication Mode via the Database Properties – Security tab.
When the Gui tells you to restart Sql Server you can do so like this:
[dos]net stop “Sql Server (SQLExpress)”
net start “Sql Server (SQLExpress)”[/dos]
Or do it from Control Panel — Services.

Visual Studio creates unwanted directories for a new solution

So, all you want is to create a new visual studio project called MyProject in a SINGLE directory called MyProject. But behold, Visual Studio has created a million levels of directories called \MyProject\MyProject\MyProject for your project. And put it all all in source control to boot.

  1. Specify your project name
  2. Specify the parent directory for MyProject
  3. Untick ‘Create Solution Directory

Visual Studio Create Project dialog highlighting the input fields for project name, existing parent directory and the unticked Create Solution Directory option

Visual Studio Create Project dialog