I've been doing some research on finding an embedded database to be used with Silverlight/isolated storage. Everyone says SQLite will not work with Silverlight due to unmanaged code.
From my experience there is just a dll named System.Data.SQLite.DLL which I believe I either got from installed SQLite.NET or from the NHibernate build.
When configuring in c# code you can use a file based database and just specify a file to use.
So my question is where is the unmanaged code? And why wouldn't using file based database and writing it to isolated storage work? And now that Silverlight 4 supports OOB does that have any impact on this?
Answers appreciated ahead of time.
Regards
I'm not sure what features you need, but you might also want to check out Sterling
Sterling is a lightweight
object-oriented database
implementation for Silverlight and
Windows Phone 7 that works with your
existing class structures. Sterling
supports full LINQ to Object queries
over keys and indexes for fast
retrieval of information from large
data sets.
Here is the introduction blog post about this project.
Note: At the time of this post Sterling has not been released. You can download the source code though.
SQLite as downloadable from sqlite.org is written in ANSI-C (see the features page). That's what most people are thinking of when you say "SQLite" and it's definitely unmanaged code.
System.Data.SQLite.DLL appears to be "An open source ADO.NET provider for the SQLite database engine" and is "a complete drop-in replacement for the original sqlite3.dll (you can even rename it to sqlite3.dll if you're using it natively)" which seems pretty cool.
However, reading on, I see "The desktop native SQLite library and the ADO.NET wrapper are combined into a single mixed assembly" which seems to be saying that the DLL contains both managed and unmanaged code, which may be a problem.
There is no ADO.Net in Silverlight 4
Related
My scenario is as follows, a .NET 4.0 Solution with several projects (one host and some dlls), one (dll) in particular making use of the MySQL .NET Connector in order to only call upon stored procedures. I've also signed all my assemblies with a private key.
I'm curious if a hacker could somehow obtain the password to the database user from the connection string (even though that user only has permission to EXECUTE).
Also I'm curious whether a hacker would be able to find out the stored procedures I call on and whether he could Select/Insert/Delete arbitrarily with the use of my stored procedures.
All this with the presumption that the hacker only has a copy of the compiled solution.
If you have hard-coded the user name and password in your code, or even if you store the credentials in an encrypted file, but the encryption key is hard-coded in your code, it is easily hackable because .NET assemblies are not compiled to machine code. When you build a .NET assembly, it converts your VB.NET code into MSIL code, which is just a lower level programing language which is still easily readable. Microsoft provides a free tool (as part of the .NET Framework SDK) called MSIL Disassembler which allows you to easily view all the MSIL code for any compiled assembly. There are many tools available which allow you to easily take the MSIL code and "decompile" it to VB or C# code. You'd be amazed at how easy it is to reproduce your original code with a .NET decompiler. If the PDB's are available, the output is shockingly similar to the original code. So, unless you are using some third-party code obfuscation or assembly encryption tool, your "compiled" assemblies are very easily reverse engineered. Usually this isn't a big deal, but if avoiding hacking is a high concern, you certainly shouldn't be putting any secrets in your code.
Are you confident that all of the code in the project is safe from things like SQL Injection vulnerabilities and Local File Inclusion vulnerabilities (and will remain so, as it evolves)?
I need a low level OLE control for reading, creating and modifying pdf files. I will use it with Visual FoxPro. By low level I mean that I won't need any extra software to install on the client machine.
Long story short, I need something like iText.
Preferably free or cheap.
Thanks.
QuickPDF includes a pure Win32 DLL based version and is reasonably cheap at $249 with no runtime license fees. You would just need to copy the DLL in the same directory as your application.
www.quickpdf.com
I don't know what you mean about "open"ing DLLs, however, VFP CAN make calls to DLLs via DECLARE statements to expose them... its done quite regularly with many Windows API calls.
However, you specific need of dealing with PDFs to modify poses another question... What is it you plan on trying to "modify"?
I've got a game in VB6 and it works great and all, but I have been toying with the idea of creating a scripting engine. Ii'm thinking I'd like VB6 to read in flat text script files for me and then lex/parse/execute them.
I have good programming experience, and I've built a simple C compiler, as well as a LOGO emulator before.
My question is:
Are there any tools that I can use, like Lexx/Yakk/Bison to help me? How should I approach this problem in regards to lexing, parsing, and feeding the commands back to VB6 so I can handle them? Is this idea a BAD IDEA in the sense that there are too many obstacles in the way (For example, building minesweeper in assembly, though not impossible, is very difficult, and a bad idea.)?
Use the Microsoft® Windows® Script Control because it is easy to integrate into existing VB6 applications. The control supports VBScript, JScript, or any other "Active Script" implementation.
I have used the Windows Script Control in four projects and it works extremely well. Very easy to integrate. I wish Microsoft would have given us a replacement in .NET, and made it as easy to use. (I understand the control is not needed in .NET, but having the ability to simply create an object that handles everything is nice.)
Windows Script Control
The Microsoft® Windows® Script Control
is an ActiveX® control that provides
developers with an easy way to make
their applications scriptable. This,
in turn, enables users to extend
application functionality through
scripts, much as they do with macros
today.
INFO: Where to Obtain the Script Control at http://support.microsoft.com/kb/184739. Includes links to other howto support articles.
Chapter 13: Adding Scripting Support to Your Application at http://msdn.microsoft.com/en-us/library/aa227413(VS.60).aspx
Designing a Calculator at http://msdn.microsoft.com/en-us/library/aa227421(VS.60).aspx
How To Use Script Control Modules and Procedures Collections, Inserted from http://support.microsoft.com/kb/184745
How To Use the AddObject Method of the Script Control, Inserted from http://support.microsoft.com/kb/185697
SAMPLE: SCRIPTEX.EXE Uses the ScriptControl with Visual Basic, Inserted from http://support.microsoft.com/kb/189484
Windows Script Control can be downloaded at http://www.microsoft.com/downloads/details.aspx?familyid=d7e31492-2595-49e6-8c02-1426fec693ac&displaylang=en. (Supported Operating Systems: Windows 2000; Windows 98 Second Edition; Windows ME; Windows NT; Windows Server 2003; Windows XP)
MSDN Search of "MSScriptControl.ScriptControlClass" at http://social.msdn.microsoft.com/Search/en-US?query=%22MSScriptControl.ScriptControlClass%22&ac=8
MSDN Search of "Windows Script Control" at http://social.msdn.microsoft.com/Search/en-US?query=%22Windows+Script+Control%22&ac=8
MSDN Search of "MSSCRIPT" at http://social.msdn.microsoft.com/Search/en-US?query=MSSCRIPT&ac=8
Unless you're doing it for your own instruction, you may want to try using Lua: VB6 - Lua Integration
If you're willing to use VBScript rather than VB6 you might be able to just use the MSScriptControl to run the commands rather than creating your own. Here's an article discussing using it from a .Net app, though it's an ActiveX control so should give you quite a bit of flexibility.
The control can be downloaded from here.
I've actually seen some quite reasonable implementations of compilers/interpreters in VB6[1] - It's not the language I would choose (few functional features, insufficent static type system), but with experience, you can outweigh these drawbacks and be quite productive - So why not.
You can use the GOLD parser generator that supports VB6 as a start.
[1]: Somewhere on PSC or in this download repository I think ...
Note that there is the MSScriptControl too.
There also appears to be an additonal alternative for VB6:
SadScript is an variant of VB6 most prominently used for VB6 as an scripting engine in MMORPGS .
See here for more : What is sadscript? Can I use it in vb.net? Why hasn't anyone I have asked heard of it?
I own a copy of vb2005 professional.
I need to migrate a vb6 project to vb.net
Is there any difference in terms of effort to migrating to these
editions of vb.net
thanks
I think it's slightly easier to target the later versions. I believe the PowerPack 3.0 was added for Visual Studio 2005: it included extra support for emulating the VB6 Printer object and shape controls.
Anyone who's read my other answers about VB6 migration should stop reading now because I've said this before... but I think it's relevant, so I'll say it again anyway.
Check out the Microsoft UK advice with a screencast explaining the 5 basic options for .Net migration. Decide which is best. People may advise you to just rewrite from scratch in .Net. Be cautious about this - you say your codebase is big, which is a danger sign for rewriting. Microsoft UK say
Performing a complete rewrite to .NET is far more costly and difficult to do well [than converting] ... we would only recommend this approach for a small number of situations.
I'm rewriting a lot of VB6 currently and what I've found so far is that the previous developers had to use a lot of third party and custom modules to implement what they need when a lot of it has been included in the base class library for .Net since then.
From what I've seen there's no easy way to migrate from one to another. A lot of effort goes into these migrations. The best thing to consider is whether you want to try to go line by line or examine the code, document core functionality, evaluate how well the software has worked over it's lifetime and then engineer a new design.
That's what I've ended up doing because a line for line rewrite is nearly impossible and a large pain. Compiling libraries and modules into COM to bring the functionality into .Net applications is a lot of effort and kind of a "McGyver" approach. That's why I just documented everything well, understood the process, then wrote as .Net software.
Specifically, what functionality are you trying to maintain? Have you written in .Net before?
In my experience the "migrate" is really a rewrite so it doesn't make any difference what version of Visual Studio you use. I'd use the latest.
Since MS appears to have killed Managed JavaScript in the latest DLR for both server-side (ASP.NET Futures) and client-side (Silverlight), has anyone successfully used non-obsolete APIs to allow scripting of their application objects with JScript.NET and/or can explain how to do so? A Mono/JScript solution might also be acceptable, if it is stable and meets the requriements below.
We are interested in upgrading off of a script host which uses the Microsoft JScript engine and ActiveScript APIs to something with more performance and easier extensibility. We have over 16,000 server-side scripts weighing in at over 42MB of source, so rewriting into another scripting language is out of the question.
Our specific requirements are:
Noteably better performance than the Microsoft JScript (ActiveScript) engine
Better runtime performance and/or
Retention of pre-parsed or compiled scripts (don't reparse on every run)
Lower or equal memory consumption
Full ECMA-262 ECMAScript compatibility
a little porting can be tolerated
Injection of custom objects into the script namespace
.NET objects (not a hard requirement)
COM objects or COM objects wrapped in .NET
Instantiation of COM objects from Script
à la "new ActiveXObject(progid)"
Low priority given the preceeding
Include files
Pre-loading of "helper scripts" into a script execution context
An "include" function or statement (easy to create, given the above)
Support for code at global-scope
Execution of code the global scope
Retention of values initialized at global scope
Extraction of values from the global scope
Injection and replacement of values at the global scope
Calling of script-defined functions
with parameters
and with access to the previously initialized global scope
Source-level debugging
Commercial or Open Source Support
Non-obsolete APIs
I answered a similar question here. Have a look at IronJS, an implementation of JavaScript in F# running on the DLR.
Sooner or later, I imagine someone will write a DLR Javascript. I know that's not very convenient for you right now, but maybe you could start the project. I suspect it would have a better cost/benefit analysis to using JScript.NET.
If moving away from .NET and Microsoft is ok for you then you should try Mozilla's Rhino. It is an open-source implementation of JavaScript written entirely in Java. Alot of modern server side js libraries target this platform.
I have used CSScript.net as it will allow you to run C# as a scripting platform. From the site:
CS-Script combines the power and
richness of C# and FCL with the
flexibility of a scripting system.
CS-Script can be useful for system and
network administrators, developers and
testers. For any one who needs an
automation for solving variety of
programming tasks.
CS Script satisfies all the conditions that you laid out. I have used it in production as a substitute for Boo it has performed really well. You can see it in action here.
The use of Com interop means you are limited to an MS solution Java and Opensource want as little as possible to do with it.
I dont see any solution that supports all your requirements either you ditch all the COM/.NET stuff and go Java (Rhino) /Linux/Open source or you question the use of Javascript as your server language even in the Linux world we use PHP/Python/Ruby more on the server if we cant run Java. Your not going to see big performance gains with Java script as the language is the main barrier.
I wouldnt count on people writing a new DLR as server Java script is dying fast.
Considering you want performance ,what about F# , Microsoft will keep the Jscript engine supported for at least 5 years giving you time to create new stuff in F# while you slowly migrate the code.
Have you seen ROScript?
http://www.remobjects.com/script.aspx
Supports both PascalScript and ECMAScript (Javascript) syntax
The Jurrassic-Engine is alive and kicking.
From their codeplex site:
Supports all ECMAScript 3 and ECMAScript 5 functionality, including ES5 strict mode
Well tested - passes over five thousand unit tests (with over thirty thousand asserts)
Simple yet powerful API
Compiles JavaScript into .NET bytecode (CIL); not an interpreter
Deployed as a single .NET assembly (no native code)
Basic support for integrated debugging within Visual Studio
Uses light-weight code generation, so generated code is fully garbage collected
Tested on .NET 3.5, .NET 4 and Silverlight