IT / Administration / Development / other stuff

Saturday, December 3, 2016

SQL Server - Providing Demo Data (temporary)

Today I found a new solution to provide temporary data! Additionally to creating a table (not really temporary), creating a temp table (create table #xy) and declare a table variable (declare @xy table(...)) there is also the possibility to put values directly into a select statement:

select * from

(

values

(1,2,3),

(2,3,4),

(3,4,5)

) as myValues (nr1, nr2, nr3);

this looks quite easy and can be very useful in a with block, because you can use this adhoc-values like a table and if it is necessary you can move them very easily into a table.

with config as (

select * from ( values ('dataFolder', '/home/...') as config (key, val)

)

select

dataFolder.Value + data.FileName, data.Content

from

data, config dataFolder

where

dataFolder.Key = 'dataFolder'

... but this is probably not the best show case... I think demonstration / training about SQL would be a better use-case (e.g.: showing how join statements work or stuff like this... would be the first training explaining "with" before "join" :-) ... nevertheless I was fascinated and love this feature...).

kr,

Daniel

Tuesday, November 29, 2016

Powershell-code inside of my application

Hi,

I wanted to combine powershell and my .net application. In fact this works quite easily. The following link was quite helpful to make this work: https://blogs.msdn.microsoft.com/kebab/2014/04/28/executing-powershell-scripts-from-c/

We see here that an assembly has to be added (System.Management.Automation), but that's more or less it... I encapsulated the invocation of the powershell code into the following class

using System.Management.Automation;
using System.Collections.ObjectModel;

class PSExecutor
{
    protected Collection<PSObject> Execute(string command, params Tuple<string, object>[] parameters)
    {
        using (PowerShell PowerShellInstance = PowerShell.Create())
        {
            // add a script that creates a new instance of an object from the caller's namespace
            PowerShellInstance.AddScript(command);
            parameters.ToList().ForEach(x => PowerShellInstance.AddParameter(x.Item1, x.Item2));

            return PowerShellInstance.Invoke();
        }
    }
}

... so we can use this class as a base class (if you want to call the execution of the code directly: change method Execute to be public). The following snippet is an example how to use the base class:

    // https://gallery.technet.microsoft.com/Get-WindowsUpdatesps1-7c82c1f4
    class GetWindowsUpdatePSExecutor : PSExecutor
    {
        public Collection<PSObject> Execute()
        {
            return base.Execute(
@"
$UpdateSession = New-Object -ComObject 'Microsoft.Update.Session'
$UpdateSearcher = $UpdateSession.CreateUpdateSearcher()
$SearchResult = $UpdateSearcher.Search(""IsInstalled=0"") # ""IsInstalled=0 and Type='Software' and IsHidden=0""
$SearchResult.Updates |Select-Object -Property Title, Description, SupportUrl, UninstallationNotes, RebootRequired
");
        }
    }

... with the snippet above you can check the OS for pending windows updates.

kr,
Daniel

Friday, September 16, 2016

SQL Server: GO with count | delete table in chunks

Hi,

I was asked to delete parts of a table. Unfortunately the amount of rows was to big to delete them all in a single shot (TLog would exceed the file limit). I tried a different approach deleting the table in chunks using a loop, but this still executes as a single transaction.

Then I thought I could solve the problem by using a top statement and using go... afterwards I would copy these lines some thousand times and go for a coffee... but than the msdn article about go ( https://msdn.microsoft.com/en-us/library/ms188037.aspx ) opened up a very nice alternative.

Go can have an argument "count" with the following description:

count
Is a positive integer. The batch preceding GO will execute the specified number of times.

... nice, but how will it be executed? Statement-Block COUNT times and then one go (same problem like in the loop scenario) or is it a COUNT times series of statement, go, statement, go,...

I was not able to find the answer so I checked it myself with the following code:

waitfor delay '00:01:00'
go 3

the session-details of the activity monitor showed the single waitfor - statement. Proof enough that go with count creates a statement-go-statement-go series which perfectly solves my problem of the first section (see https://technet.microsoft.com/en-us/library/ms175486(v=sql.105).aspx ).

delete top (5000) from table where x = 123;
go 10000

kind regards,
Daniel

Wednesday, August 3, 2016

Dates in WCF - JavaScript communication over JSON

Hi,

today we had really big troubles with WCF and javascript communication. We wanted to send dates over the wire and use its value for additional libraries (which rely on type Date). After hours of playing around I finally solved it with JSON.parse.

Different approaches starting from overriding the WCF object serializer till writing a custom json parser libraries had been tried but finally all these are very unstable.

Resources I found to solve the problem
- Hanselman ... describing my problem
- Stackoverflow ... similar issue (solution mentioned)
- Documentation ... after knowing the solution a perfect page :-)

JavaScript/HTML testproject follows...

kind regards,
Daniel

<html><head></head><body>

<script>
function test() {

var objectString = '{"name" : "Daniel", "date" : "\/Date(1293034567877)\/"}';

//___________________________________________________________________________________
//

var objectDataWithParse =  JSON.parse(objectString);

var objectDataWithDate = {
    "name": objectDataWithParse.name,
    "date": new Date(parseInt(objectDataWithParse.date.substr(6, objectDataWithParse.date.length-8)))
};

function parseReviver(key, value) {
    var a;
    if (typeof value === 'string') {
        if(value.substr(0, 6) == '\/Date(') {

            alert(value.substr(6, value.length-8));
            return new Date(parseInt(value.substr(6, value.length-8)))
        }
    }
    return value;
};

var objectDataWithReviver = JSON.parse(objectString, parseReviver);

//___________________________________________________________________________________
//

var outObj = {};
outObj = objectDataWithDate;
outObj = objectDataWithParse;
outObj = objectDataWithReviver;

//___________________________________________________________________________________
//

document.getElementById('outputDIV_json').innerHTML = objectString;
document.getElementById('outputDIV_name').innerHTML = outObj.name;
document.getElementById('outputDIV_date').innerHTML = outObj.date;

};
</script>

<div>
<button onclick="test()" >test</button>
</div>
<hr />
<div id="outputDIV_json" ></div>
<div id="outputDIV_name" style="float:left;margin-right: 5px;margin-top: 5px; background: lightgreen"></div>
<div id="outputDIV_date" style="float:left;margin-right: 0px;margin-top: 5px; background: orange"></div>

</body></html>

Sunday, June 26, 2016

Castle and WCF (3)

Hi,

I went through hell to get this stuff work, but finally I got it. As partly mentioned in part 2 of this series I wanted to create an IIS hosted rest-service without the need of adding a svc-file. So I created an empty web-project, added a global.asax file and added the following code in the Application_Start method:

WindsorContainer container = new WindsorContainer();

ServiceHostFactoryBase factory = new WindsorServiceHostFactory<RestServiceModel>(container.Kernel);

container.AddFacility<WcfFacility>(f => f.CloseTimeout = TimeSpan.Zero)

.Register(Component.For<IMyService>()

.ImplementedBy<MyService>()

.LifeStyle.Is(Castle.Core.LifestyleType.Singleton));

RouteTable.Routes.Add(new ServiceRoute("MyService", factory, typeof(IMyService)));

There is no need to configure the service in the web.config-file except ASP.NET Compatibility which is needed by the Routes.Add code-line.

kind regards,
Daniel

Friday, June 17, 2016

Castle and WCF (2)

Hi,

first of all I got the feedback that "Castle" is the wrong naming... so for clarification: with Castle the whole technology-stack of http://www.castleproject.org/ is meant including (especially) DynamicProxy and Windsor.

Further research brought me to the follow up question whether it is possible to implement a service with a non-empty (standard) constructor. Yes, this is also possible ( stackoverflow.com ). You simply need to:

create a Custom-ServiceHostFactory (base class: ServiceHostFactory) and
override CreateServiceHost which should create a Custom-ServiceHost.
Each implemented service contract (loop over this.ImplementedContracts.Values) should get a Custom-Behavior (interfaces: IContractBehavior and IInstanceProvider) added.
In the instance provider happens the magic of creating a service with new (override the two GetInstance-methods).

A step-by-step guide can be found on MSDN here. Here a quote of the github answer referenced above:

You can easily generalize this approach, and in fact some DI Containers have already done this for you (cue: Windsor's WCF Facility).

A tutorial how to use the WCF facility can be found here and here. A walk-through "DI in WCF in 5min" can be found here (this article shows perfectly that DefaultServiceHostFactory enables you to create services with the full power of DI).

I am looking forward to test that approach with "RouteTable.Routes.Add(new ServiceRoute(...))".

kr, d

Thursday, June 16, 2016

Castle and WCF

Hi,

it is a quite hard task to build a good and stable back-end. The request/response interfaces therefore are often full of boiler plate code. In my .NET applications I rely on WCF and REST services. First questions:

Can I create services on the fly or do I have to create a *.svc-file as described in 90% of the tutorials?

Answer: Yes... with ServiceHostFactory ( http://stevemichelotti.com/restful-wcf-services-with-no-svc-file-and-no-config/ )

Can I/Do I have to still use IIS?

Answer: Both is possible

Do I need to be a web.config expert?

Answer: You can config your stuff in code too.

So summarized: I can create ServiceHostFactories on the fly and can use Castle to inject the dependencies... great. Castle provides even more: WCF Integration Facilities... https://github.com/castleproject/Windsor/blob/master/docs/wcf-facility.md

There seemed to be an active community on writing facility based, config less, castle-driven backends like at https://github.com/vcaraulean/WcfWithoutConfigFile/blob/master/WcfWithoutConfigFile.WebHost.Castle/Global.asax.cs

... really cool... I am looking forward to use that stuff and post some first results...

kind regards,
Daniel