Monthly Archives: February 2018

C#

Timeout Process

Leave a comment

When you are dealing with large amounts of data or processes that are very time hungry you sometimes need the ability to timeout that task and continue.

Here is a snippet of code that loops around that takes 1 second, and you can set a timeout to any time you like, but if it is less than 1 second, it will cancel the task and free up resources.

class Program
 {
 public static void Main()
 {
 int timeOutInMilliseconds = 450;
 var startTime = DateTime.Now;

var cTokenSource = new CancellationTokenSource();

// Create a cancellation token from CancellationTokenSource
 var cToken = cTokenSource.Token;
 // Create a task and pass the cancellation token
 var t1 = Task<int>.Factory.StartNew(() => GenerateNumbers(cToken), cToken);

// to register a delegate for a callback when a cancellation request is made
 cToken.Register(() => cancelNotification(cTokenSource));


 while (true)
 {
 if(t1.IsCompleted)
 { 
 Console.WriteLine("Finished Processing");
 break;
 }

if (DateTime.Now > startTime.AddMilliseconds(timeOutInMilliseconds))
 {
 Console.WriteLine("Timed out");
 cTokenSource.Cancel();
 break;
 }
 }

Console.WriteLine("finished");
 Console.ReadLine();
 }

private static Task HandleTimer(CancellationTokenSource cancellationTokenSource)
 {
 cancellationTokenSource.Cancel();
 Console.WriteLine("\nHandler not implemented...");
 return Task.Run(() => { var a = 0; });
 
 }

static int GenerateNumbers(CancellationToken cancellationTokenSource)
 {
 int i;
 for (i = 0; i < 10; i++)
 {
 Console.WriteLine("Method1 - Number: {0}", i);
 Thread.Sleep(100);

// poll the IsCancellationRequested property
 // to check if cancellation was requested
 if (cancellationTokenSource.IsCancellationRequested)
 break;
 }
 return i;
 }

// Notify when task is cancelled
 static void cancelNotification(CancellationTokenSource cancellationTokenSource)
 {
 cancellationTokenSource.Cancel();
 }
 }

Source: Parallel

SQL

Search every column in a SQL Server Database

Leave a comment

Following on from the Search every table and field in a SQL Server Database article I posted last week, I thought it would be useful also to be able to search every column for some text and return where it was found.

Here is the script that I have produced which does the job and is quick in its response.

CREATE PROC [SearchAllColumns]
(
 @SearchStr nvarchar(100)
)
AS
 
BEGIN
 
 SELECT COLUMN_NAME AS 'ColumnName',
 TABLE_NAME AS 'TableName'
 FROM INFORMATION_SCHEMA.COLUMNS
 WHERE COLUMN_NAME LIKE '%' + @SearchStr + '%'
 ORDER BY TableName,
 ColumnName;

END

 

API, Web API

Versioning

Leave a comment

In the article we are going to look at the importance of a good version control system, and why it is crucial when it comes to API versioning.

It is essential that we deploy a Web API version control from an early stage in our project. Versioning will ensure that the project is built on a solid base and that a standard is maintained. A good version control system will enable us to collaborate and scale in a managed way, and as such will provide our customers with a more straightforward progression through our upgrades.

The first point to note we should always version our Web API, while at the same time keeping as much of the same URI as possible, with the possibility of newer versions having a different URI and a clear upgrade path.

What is versioning?

Versioning is a thoughtful application of changes to a system that is already in production.

There are two types of versioning, they are:

  • Versioning Data – changing the way we lay out our data structures, name things and so on
  • Version SOAP Endpoints – adding or removing functionality, such as functions that can be called or changing parameters that can be called on those endpoints

Plan Versioning

How do we handle versioning?  We are producing a plan for the first release, and we need to do the following:

  • At the start
    • Pick a version-able identifier
    • pick a versioning pattern
  • Version-able identifiers
    • XML Data: XML Namespace
    • Things that listen at URL’s: URL Path
  • Numbering Pattern
    • https://yoururl.co.uk/[service name]/major.[minor].[build[
    • Each number increases monotonically: 1,2,3,4, …., 9, 10, 11
  • Date Pattern
    • https://yoururl.co.uk/[service name]/[yyyy]/[mm]/[dd]
    • https://yoururl.co.uk/[service name]/[yyyy].[mm].[dd]

The only time we ever need to version is when we change the contract with the client, we can change the contract in one of three ways:

  • Data
    • Add a new type
    • Removing a type
    • Change fields
    • Required fields
  • SOAP
    • Add/remove methods
    • Change parameter names
    • In session: change the set of initiating/termination actions
  • REST
    • Change URI structure
    • Add methods

Versioning Data

There are times when you need to version the data:

  • Reasons to version data
    • Name chooser picked terrible names (aka renames)
    • Adding/removing fields
  • Things to handle upon versioning data
    • Co-existing old/new clients
  • Reason not to version data
    • Re-ordering for aesthetic reasons

New Members

  • If a new member is required, define sensible default
    • Caveat: if no sensible default exists, you have a severe bug in a previous version
    • If you think you have no reasonable default and customers won’t change, you will suddenly find a sensible default
  • Place at the end
    • Some clients may be ordinal dependent, not name
    • Use DataMember.Order property
  • Or inherit Data Transformation Object if new item breaks old clients

Versioning SOAP Endpoints

  • Reasons to version endpoints
    • Name chooser picked terrible names (aka renames)
    • Adding methods
    • Removing methods
    • Updating method parameters (new version of old type)
    • Adding terminating functions (might already exist)
  • Things to handle upon versioning endpoints
    • Update old to call out to controller properly
  • Reasons not to version endpoint
    • Re-ordering for esthetic reasons (don’t do this!)

Handle Versioning

  • Keep services light
  • Keep details in separate class
  • Use MVC type pattern
    • DTO is Model
    • Service is View
    • “Separate class” is Controller
  • Benefits
    • Minimize code churn in services
    • Keep logic mapping DTO to Business in one place

Key Points

  • Keep service code clean, simple.
  • Think of service as a machine UI to the real object model.
  • Let internal logic worry about mapping DTO to the business objects.
  • Handle upgrade in one place, away from service.

Versioning REST Endpoints

  • Reasons to version REST endpoints
    • Name chooser picked terrible names
    • Paths don’t make sense
    • Updating data types, parameters (new version of old model)
  • Things to handle upon versioning endpoints
    • Update old to call out to controller properly
  • Reasons not to version endpoint
    • Supporting more of Uniform Interface (GET | HEAD, PUT, POST, DELETE)

Where to version?

  • New set of services in new directory
    • Pros: clean separation, small files, easy to read, allows for more natural deletion later
    • Cons: not necessary, moves logic to new file
  • Keep everything in one file, add new UriTemplates
    • Pros: All URLs in one place, easy to see what uses code, can see evolution in one place
    • Cons: Likely to clutter code, increase maintenance burden over time

Support Plans for Versioning

  • Need an SLA between service and consumers
  • Need to define
    • How long a consumer can depend on a version
    • What constitutes end of life for a version
  • Need to prepare for
    • Extensions to end of life
    • Presence of older clients
    • Work with client to update to latest

Assets to Create to Assist/Reduce Burden

  • Documentation on wire-level formats
    • XSD, HTML documents, sample code
  • SDKs in client languages
    • Java, Ruby, PHP, Python, .NET
    • Can ease migration.
      • Client uses new library, works till clean compile
      • Versioning issue becomes deployment issue
  • Support staff
    • Dedicate staff to help support clients who are migrating code.

Summary

  • Versioning: The retrospective application of changes to a system.
  • Plan ahead
    • URL structure, version names, use MVC pattern
  • Changes hit in three, related areas: Data, SOAP Methods, REST
  • Manage changes
  • Create new endpoints for new data types
  • Use Data Transformation Objects
  • Keep logic to translate between Data Transformation Objects and business in one place

References

Versioning Strategies by Microsoft

Best Practices: Data Contract Versioning

ASP.NET Core RESTful Web API versioning made easy by Scott Hanselman

 

SQL

Search every table and field in a SQL Server Database

Leave a comment

One thing I do like about MySQL is when using phpMyAdmin is the ability to search the whole database for any string, this should only be available for developers who are searching for data in an extensive database.  It does take some time to run, but remember it has a lot to do.

Here is the script that Narayana Vyas Kondreddi has produced which does the trick and works very well.

CREATE PROC SearchAllTables
(
 @SearchStr nvarchar(100)
)
AS
 
BEGIN
 
 -- Copyright © 2002 Narayana Vyas Kondreddi. All rights reserved.
 -- Purpose: To search all columns of all tables for a given search string
 -- Written by: Narayana Vyas Kondreddi
 -- Site: http://vyaskn.tripod.com
 -- Updated and tested by Tim Gaunt
 -- http://www.thesitedoctor.co.uk
 -- http://blogs.thesitedoctor.co.uk/tim/2010/02/19/Search+Every+Table+And+Field+In+A+SQL+Server+Database+Updated.aspx
 -- Tested on: SQL Server 7.0, SQL Server 2000, SQL Server 2005 and SQL Server 2010
 -- Date modified: 03rd March 2011 19:00 GMT
 CREATE TABLE #Results (ColumnName nvarchar(370), ColumnValue nvarchar(3630))
 
 SET NOCOUNT ON
 
 DECLARE @TableName nvarchar(256), @ColumnName nvarchar(128), @SearchStr2 nvarchar(110)
 SET @TableName = ''
 SET @SearchStr2 = QUOTENAME('%' + @SearchStr + '%','''')
 
 WHILE @TableName IS NOT NULL
 
 BEGIN
 SET @ColumnName = ''
 SET @TableName = 
 (
 SELECT MIN(QUOTENAME(TABLE_SCHEMA) + '.' + QUOTENAME(TABLE_NAME))
 FROM INFORMATION_SCHEMA.TABLES
 WHERE TABLE_TYPE = 'BASE TABLE'
 AND QUOTENAME(TABLE_SCHEMA) + '.' + QUOTENAME(TABLE_NAME) > @TableName
 AND OBJECTPROPERTY(
 OBJECT_ID(
 QUOTENAME(TABLE_SCHEMA) + '.' + QUOTENAME(TABLE_NAME)
 ), 'IsMSShipped'
 ) = 0
 )
 
 WHILE (@TableName IS NOT NULL) AND (@ColumnName IS NOT NULL)
 
 BEGIN
 SET @ColumnName =
 (
 SELECT MIN(QUOTENAME(COLUMN_NAME))
 FROM INFORMATION_SCHEMA.COLUMNS
 WHERE TABLE_SCHEMA = PARSENAME(@TableName, 2)
 AND TABLE_NAME = PARSENAME(@TableName, 1)
 AND DATA_TYPE IN ('char', 'varchar', 'nchar', 'nvarchar', 'int', 'decimal')
 AND QUOTENAME(COLUMN_NAME) > @ColumnName
 )
 
 IF @ColumnName IS NOT NULL
 
 BEGIN
 INSERT INTO #Results
 EXEC
 (
 'SELECT ''' + @TableName + '.' + @ColumnName + ''', LEFT(' + @ColumnName + ', 3630) FROM ' + @TableName + ' (NOLOCK) ' +
 ' WHERE ' + @ColumnName + ' LIKE ' + @SearchStr2
 )
 END
 END 
 END
 
 SELECT ColumnName, ColumnValue FROM #Results
 DROP TABLE #Results
END

Original post