CODEWITHSUNDEEP
c#memorystream
Corey Burnett
Corey Burnett

Reputation: 7340

What is the best way to work with files in memory in C#?

I am building an ASP.NET web application that creates PowerPoint presentations on the fly. I have the basics working but it creates actual physical files on the hard disk. That doesn't seem like a good idea for a large multi-user web application. It seems like it would be better if the application created the presentations in memory and then streamed them back to the user. Instead of manipulating files should I be working with the MemoryStream class? I am not exactly sure I understand the difference between working with Files and working with Streams. Are they sort of interchangeable? Can anyone point me to a good resource for doing file type operations in memory instead of on disk? I hope I have described this well enough.

Corey

Upvotes: 1

Views: 1589

Answers (2)

saluce
saluce

Reputation: 13360

Files and streams are similar, yes. Both essentially stream a byte array...one from memory, one from the hard drive. If the API you are using allows you to generate a stream, then you can easily do that and serve it out to the user using the Response object.

The following code will take a PowerPoint memory object (you'll need to modify it for your own API, but you can get the general idea), save it to a MemoryStream, then set the proper headers and write the stream to the Response (which will then let the user save the file to their local computer): 

SaveFormat format = SaveFormat.PowerPoint2007;
Slideshow show = PowerPointWriter.Generate(report, format);
MemoryStream ms = new MemoryStream();
show.Save(ms, format);

Response.Clear();
Response.Buffer = true;
Response.ContentType = "application/vnd.ms-powerpoint";
Response.AddHeader("Content-Disposition", "attachment; filename=\"Slideshow.ppt\"");
Response.BinaryWrite(ms.ToArray());
Response.End();

Upvotes: 1

Steven Doggart
Steven Doggart

Reputation: 43743

Yes, I would recommend the MemoryStream. Typically any time you access a file, you are doing so with a stream. There are many kinds of streams (e.g. network streams, file streams, and memory streams) and they all implement the same basic interface. If you are already creating the file in a file stream, instead of something like a string or byte array, then it should require very little coding changes to switch to a MemoryStream.

Basically, a steam is simply a way of working with large amounts of data where you don't have to, or can't, load all the data at into memory at once. So, rather than reading or writing the entire set of data into a giant array or something, you open a stream which gives you the equivalent of a cursor. You can move your current position to any spot in the stream and read or write to it from that point.

Upvotes: 0

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