Passing SortedList via WebServices [Q&A]
Classes which implements IDictionary are very useful for developers. Concept of key - value addressing could be applied in many areas, including web services.
however, when you try to return a SortedList, ListDictionary or Hashtable from webservice you get run-time error when accessing web service:
System.NotSupportedException: The type System.Collections.SortedList is not
supported because it implements IDictionary.
Cheapest server side solution is to return array of DictionaryEntry filled by SortedList.CopyTo method. Sample code is :
[WebMethod]
public DictionaryEntry[] HelloWorld()
{
SortedList sl = new SortedList();
sl.Add("Key","Value");
DictionaryEntry[] deArray = new DictionaryEntry[sl.Count];
sl.CopyTo(deArray, 0);
return deArray;
}
And on client side you need to create SortedList and fill it manually.
Please note, that you can export entries from one list and add it to another. For example, server can use HashTable for better performance and client SortedList in order to display items ordered for end user.
Applies to all dotnet languages: C#, VB.NET, C++.NET, J#Idea of this topic was suggested by google search engine.
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ReadOnly SortedList [Coding]
Overview
It's common task to hold information in some kind of array or collection and provide user's of your component with read only access. For example we have
ArrayList.ReadOnly(ArrayList list) for
System.Collection.ArrayList. It creates read only array wrapper for you data. However, we do not have same feature for sorted list, which is also very good for storing internal data.
Implementation
SortedList have virtual property
bool ReadOnly which always return false by default. When we override it, we will have possibility to control this feature.
In current implementation I've implemented 2 methods -
LockReadOnly and
UnlockReadOnly, which change state of
ReadOnly property. To ensure that only correct code able to change list, Lock return a random key which is required to unlock a list.
Sources here [4k], written on C#.
Applies to all dotnet languages: C#, VB.NET, C++.NET, J#
Custom files in Assembly [Coding]
Custom files in Assembly
Main dificulty with placing files in assembly and reading it is namespaces.
Path to your file consist from:
- Default Namespace from project properties
- Folder structure in project
- filename itself
To divide folders and namespaces, '.' (dot) is used.
Warning: When you change default namespace in project properties, filename folder will be changed immediately in compilation
Full source code (reading text file from assembly) is here [5K].
Main lines are:
private const string RESOURCE_NAME = "Folder.resource.txt";
System.Type type = typeof(Class1);
Stream stream = type.Assembly.GetManifestResourceStream(type, RESOURCE_NAME);
if (stream == null)
throw new Exception("System could not load resource");
OR
stream = Assembly.GetAssembly(typeof(Class1)).GetManifestResourceStream(typeof(Class1).Namespace + "." + RESOURCE_NAME);
Applies to all dotnet languages: C#, VB.NET, C++.NET, J#
