Develop Reference

How to Add and update the comments for the PDF file using c#

Now I am working in the process of Insert and Update the comment for the pdf file using c# code. I want to Know the any possible way to insert a comment inside the pdf file. Anyone Know about this, Please reply and some reference for this process.

Microsoft does have very limited support for PDF in operating system APIs and it has come only recently in Windows 8 for modern applications (now called UWP) and that support doesn't go as far as updating comments.
So you need to use the 3rd party library. As far as I can tell SharpPDF is the only free library worth something, but I failed to open many PDFs in it so I can't recommend it. So I think you would need to search for some commercial library, I am aware of several of them that can do the job (e.g XfiniumPDF, iTextSharp etc) and you'll get the documentation when you license them.

Library for creating PowerPoint-Presentations

is there a (.net-)library for creating PowerPoint-Presentations (PPTX => OpenXML).
For creating Excel-sheets I like ClosedXML-Library and would love something similar for PowerPoint.
I can't and don't want to use Microsoft Interop because it is an ASP.NET Web-App.
Does someone has any experiences creating PowerPoint-Slides in ASP.NET?
P.S.: I had a look at Aspose but found it little to expensive.

You mentioned OpenXML but have you tried the OpenXML SDK?
Download from: http://www.microsoft.com/download/en/details.aspx?id=5124

Google SpreadSheet API based applications

I am trying to learn Google Spreadsheet API. Any open source applications that are using this API would be great source to start learning it. I need suggestion on any such applications with code available online.

The Google Spreadsheets Documentation pages have info about the general protocol, and Java example code that uses the Client Library.
For a C# example you may find this answer helpful.

C# System.Drawing.Printing.PrintDocument to PDF Recommendation?

We are developing a C# Application that supports printing multiple views and we would like to add printing to PDF. This application has several 3rd party controls that handle the printing on their own so adding something like SharpPDf will not work for us we don't believe.
Either we need a 3rd party component that takes a Print document as source and produces a PDF from that, or we need a good 3rd party print driver.
I was surprised that Adobe does not offer a Distributable version of the PDF printer they bundle with Acrobat as that would be ideal. Anyone have recommendations as to what is the best path for us on this?
Thanks in Advance,
Jeff
UPDATE: So after all the suggestions and a ton of research here is what I ended up doing. We are buying a license to Novapdf sdk for our product (http://www.novapdf.com/en/pdf-sdk.html). I looked at over 15 different products and we went with nova because of the ease of which we could implement this in our code and the cost was right ($899 for novaPDF SDK Single Application v7.) The code could not have been simpler and you can start developing before you actually have the license. Thanks again to everyone for their suggestions.

as a PDF printer, you can use PDF Creator, that it's free:
http://www.pdfcreator.com/
However, i'm using SharpPDF and works fine.

The best free tool I found is ITextSharp. It's very easy to use, and has a lot of examples online.
You can find it information at http://itextsharp.com/

we are using Billzip http://www.bullzip.com/products/pdf/info.php. There is also a COM interface to define how you want the output file handled. Here is the COM object info http://www.biopdf.com/guide/.

Programmatically access a Microsoft Project (MPP) file from C#

What are my options for programmatically accessing a Microsoft Project file? What are the pros and cons of each approach?
I will basically need to import all data from the file into another data structure. Using the Office Interop assembies is low on the preference scale.

The MPXJ (mpxj.sf.net) library comes in both Java and .Net flavours and will allow you to read and write multiple Microsoft Project file formats using a single consistent API. I am aware of commercial products which use both the Java and the .Net versions of MPXJ without any issues.
Disclaimer: I'm the maintainer of MPXJ.

You may use Aspose.Tasks for .NET. This component allows you to work with Microsoft Project files. It doesn't require MS Office to be installed on the server, unlike Office Interop. The API is very simple and easy to use. And it provides a rich set of features to read, edit, write, and convert MPP files.
This component is a normal .NET assembly which can be used with your .NET applications. It works on any Windows OS and in 32/64-bit environments as well.
Disclosure: I work as developer evangelist at Aspose.

Here are the options:
Interop (messy and horribly slow for
large projects)
Save project in XML and work with it
(messy)
Save project in the database (that's
not publishing and it is available
for project 2003 only - see ODBC
option while saving). I've seen it
being used a lot in the integration
scenarios
Projette (commercial, $10 per
license)
ILog Project Viewer (also
commercial)

The Microsoft Office API provides programmatic access to MS Project. I have only used it for Word and Excel so I don't know how rich the interface is - you will have to do some digging around on MSDN to find out what you can and can't do.
One of the Java projects at my company uses a commerical product by Aspose which allows applications to manipulate Office documents including Project. It works well for their purposes, but again, they have only used it for Word and Excel so can't offer much advice on Project.
EDIT (2019): I can confirm that it is a very capable product.

Sourcefourge.net offers a component in Java which can be integrated with .net applications to read MPP files upto MPP 2007 the link is
http://mpxj.sourceforge.net/getting-started.html