How to keep dynamically populated datasets to stay with the program?

Question

I have a winform application that uses some referenced web services to get data. The data returned is an array of objects that I loop through and add to a dataSet.

When I call the service, it can often take 2 or 3 minutes to get all the data.

If the user exits the program and comes back later, I don't want them to have to re-download all the data again.

When I run the app in debug mode, there's no persistence of the downloaded information; which worries me.

I'm still in "development mode", so I haven't really put together an installer yet to test if the information stays with the application.

I'm curious about a couple of things:

Does the data stored in the dataset remain after the user exits?
If not, what would you recommend on how to accomplish this?
I've considered XML for storage; is that the best option when you have 9-10 MB of data?
Edit: Final Outcome: OK - here's the final outcome (thank you everyone for your quick response)

When the application exits, I call a function to save the data. Here's a snippet:

   using System.IO;
   using System.Runtime.Serialization;
   using System.Runtime.Serialization.Formatters.Binary;            
   FileStream fs;
   IFormatter formatter = new BinaryFormatter();
    //activities
    if (actList.Length > 0)
    {
        fs = new FileStream("activities.bin", FileMode.Create, FileAccess.Write, FileShare.None);
        formatter.Serialize(fs, actList);
        fs.Close();
    }
    //users
    if (userList.Length > 0)
    {
        fs = new FileStream("users.bin", FileMode.Create, FileAccess.Write, FileShare.None);
        formatter.Serialize(fs, userList);
        fs.Close();
    }

The userList and actList parameters are List objects that came from the web services call.

another thing I implemented (slightly off topic) is to create an application setting to save when the user last did a download from the web service. It's saved as

Properties.Settings.Default.last_downloaded

If the user clicks the download button, they are prompted with the date they last performed the download and are given a chance to say "no".

Thanks again for your help!

If you are web-service based, consider ClickOnce instead of a regular installer - much simpler to deploy. — Marc Gravell, Feb 05 '09 at 14:55
I don't think I can use ClickOnce and persist the data at the same time, can I? I thought that with ClickOnce, I can't "leave behind" any data: http://msdn.microsoft.com/en-us/library/ms973805.aspx — JayTee, Feb 05 '09 at 15:40

score 2 · Accepted Answer · edited May 23 '17 at 12:01

2

A .NET object has no persistance unless you write it yourself - for example by serializing to a file in the user's profile (or isolated storage for ClickOnce).

Note: personally, I wouldn't use DataSet at all in this scenario; if you are downloading the data as a list of objects, then just keep them like that - List<T> etc.

Re xml: 9-10Mb is big but not immense. It really depends on the nature of the data and other requirements; unless you are already using web-compression (GZIP etc), you might find that the data transfers quicker with a more compact format, such as csv, or a binary format such as protocol buffers.

edited May 23 '17 at 12:01

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answered Feb 05 '09 at 14:51

Marc Gravell

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I'm actually using the dataset as the source of data for a couple of datagridviews and listboxes; is there a way to use the list to populate those things? – JayTee Feb 05 '09 at 14:55
List can be used just fine as the DataSource for DataGridView and ListBox etc. – Marc Gravell Feb 05 '09 at 14:59
Strictly speaking, anything that is `IList` or `IListSource` will work - `List` benefits from a `public T this[int]` indexer which provides stronger metadata than just `IList`. But main point: there is no issue using `List` – Marc Gravell Feb 05 '09 at 15:01

score 1 · Answer 2 · answered Feb 05 '09 at 14:53

You need to manually persist any data that you want to save. What you can do is take your Dataset, and, when your application is closing, serialize the dataset to a file. Then when the app opens, if the file exists, deserialize the dataset from that file instead of calling the webservice.

How to keep dynamically populated datasets to stay with the program?

2 Answers2