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Article: What is Isolated Storage ? (.Net FrameWork Tools Series)

Hey Group,

After a long week end I am back again. Its nice and refreshing after a short
vacation so lets get started with .NET once again.

Today we will discuss about Isolated Storage. This is one of the topics
which I find interesting as I feel that it has a lot of practical usage or

We all know that all applications need some storage space to archive certain
application information like users preferences, appliction info, or certain
data which can be cached on the user's local machine etc. Initially all this
information was stored in .ini files which were simple to use and manage.
Being a flat file their access was easy and Microsoft also provided us with
API's to access these files. But the only problem with .ini files was where
do u put these ini files and if the files were lost it would result in an
application nightmare.

To solve this problem microsoft came up with an another idea for storing
application related information i.e. The Windows Registry. Although registry
was good for storing application related information it was very slow coz of
its hierarcial nature. Loading information of all the applications in the
machine's registry made the search slow. Secondly application downloaded
from the web can not be granted access to the local machines registry. Hence
it could not be used for web apps.

To solve all the above problems Micorsoft with .NET has now come up with the
idea of Isolated Storage.

Isolated storage enables paritally trusted applications to store data as per
computer's security policy esp. the web app's and other downloaded
components. Code running on the local computer ,local network or the
Internet is granted the right to use this isolated storage.
Isolated storage isolates data by user or by assembly. Credentials such as
the origin, strong name of the assembly or application domain can be used to
isolate data.

But what is isolated storage ?

Well Isolated storage is a special folder on your harddisk which allows your
application to store its application specific data. Isolated stores are put
up at Microsoft\IsolatedStorage directory.Change folder settings to show
hidden files and folders in order to see isolated storage.

On Windows 2000 you will be able to view "IsolatedStorage" folder at :-

Roaming-enabled stores = <drive>\Documents and Settings\<user>\Application

Non-roaming stores = <drive>\Documents and Settings\<user>\Local
Settings\Application Data

All applications have a special allocated place to store their data which is
a data folder containing one or more isolated storage files, called stores
in this folder. These stores contain the actual directory locations where
data is stored. The data saved in the store can be any kind of data from
user's preference information to application state.

To access isolated storage the code must be have appropriate
IsolatedStorageFilePermissions and all necessary native platform

operating system rights.

e.g. On an OS like Win 2000 the access control lists (ACLs) controls which
users have the rights to use the file system. Hence web applications dont
have access to the local hard disk. But these applications have access to
the Isolated storage folder on the client machine to store any application
data. Thus inspite of not having access to the local harddisk web app can
store data related to their application in the IsolatedStorage folder.

Microsoft .NET Framework applications already have operating system rights
to access isolated storage unless they perform

Let us use the storeadm.exe tool to list ,add and delete isolated stores.

1) You can go to the VS.NET command prompt and type storeadm.exe /? to view
all the options.

Usage : StoreAdm [options]

options :[/list][/REMOVE] [/ROAMING] [/QUIET]

/LIST : Displays the existing isolated storage for the current user.

/REMOVE : Removes all existing isolated storage for the current user.

/ROAMING : Select the roaming store.

/QUIET : Only error messages will be output.

2) Use the storeadm /LIST option to list all the stores on your machine.
This will list all the stores in your local machine.

You can use isolated storage just like any other file system folder. There
are special IsolatedStorageFileStreams to create files and directories.
Tomorrow we will see how we can create these isolated stores.

-- Please post your queries and comments for my articles in the usergroup
for the benefit of all. I hope this step from my end is helpful to all of


Namratha (Nasha)

Nov 17 '05 #1
0 1651

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