How to open Excel file with Read Only protection?

Question

I have opened Excel file in my C# WinForm Application adding reference to Microsoft.Office.Interop.Excel.dll and using DSO FRAMER CONTROL. But i want to open my excel file with read only protection.I have successfully done this for WORD Application like this

Word.Document wordDoc = (Word.Document)axFramerControl1.ActiveDocument;
Word.Application wordApp = wordDoc.Application;
wordDoc.Protect(Word.WdProtectionType.wdAllowOnlyReading);

In the same i want to do this work for Excel.But i couldn't able to protect Excel file on that way.

string path = "C:\\test-wb.xlsx";
axFramerControl1.Open(path, true,"excel.sheet", "", "");

Excel._Workbook excelDoc   =(Microsoft.Office.Interop.Excel._Workbook)axFramerControl1.ActiveDocument;
Excel.Application excelApp =excelDoc.Application;
//What code should i write to protect Excel Workbook with read - only.
excelDoc.Protect(misval, true, misval);//It is not working.

Answer 1

Call theOpen method with third parameter (ReadOnly) = true.

See MSDN documentation :

ReadOnly
Optional Object. True to open the workbook in read-only mode.

Answer 2

The WorkBook class has a Protect method, similar (but not identical) to the one supported by Word. I can't find the COM/interop documentation, but the VSTO documentation covers the same ground, and the method signatures are the same:

Protect

Protects a workbook so that it cannot be modified.

public virtual void Protect (
    [OptionalAttribute] Object Password,
    [OptionalAttribute] Object Structure,
    [OptionalAttribute] Object Windows
)

(This all assumes that what you wanted to achieve was to protect the document, since that's what the Word code does, as opposed to opening the document read only, which is what your narrative seems to be saying, in which case, @gdoron's answer is more suitable