I was wondering if anyone has seen a library that abstracts away SQLite and Tokyo-Cabinet to the same API. Basically I'm looking for something that will allow me to test and dev with SQLite, and later move to TC for production.
Anyways the language I'm using specifically is Lua, but I'm sure such a library doesn't exist for Lua, so a Library that does this in any other language is also ok since I can develop something similar for Lua based on that.
DataMapper, the default ORM for Merb (written in Ruby), might help. Take a look at an experimental DataMapper adapter for Tokyo-Cabinet. DataMapper's already got SQLite3 support so you may be able to compare the two.
I don't know for sure, but since Carbonado supports RDBMSs (Oracle) and "persisted b-trees" (BDB), it could definitely support both.
Related
I am going to implement Lucene search into my project and I want to make a best start.
So I consider between 3 versions of Lucene (Java/C#.Net/C++) which is the best version upon these criterias :
1.performance
2.easy to implement
3.plenty of documents ?
Assume the system is Window server, and I ask it for a long-term use.
Thanks
I would say Java. Lucene was initially developed in Java and I would think there are bigger community, more documentation and bigger deployments using Java.
Granted, Windows is not usually considered as primary platform for deploying Java services but it still would work with flying colors. Many people using Windows for Java development and even deployment so I don't expect any major issues.
Unless you've got a specific feature you need, I would look at best being:
a) Whatever platform you are developing the program in -- there are lots of advantages to not having to switch tools/contexts/platforms to muck around with the search internals.
b) Whatever platform your ops guys want to deal with -- I know lots of windows ops guys hate dealing with java as it is a strange foreign language. For example.
c) All of the above being equal, Java is the real flagship lucene project that everyone else is keeping up with with and that has the most tools & resources. It is the way to go if you don't have any reason not to use java. Solr is another advantage here -- you can pretty easily use a pre-wrapped fully functional lucene http server.
In any case, keep in mind that at least theoretically any lucene index written on one platform is readable by others so you don't necessarily have to fully commit to a single platform.
Does anyone know if there are any ORM tools or Code Generation tools that work against an Advantage Database?
It would be helpful to know what development environment you use.
For .net:
Microsoft Entity.NET Framework
Telerik
Developer Express (Express Persistent Objects)
For Delphi:
I believe REM Objects has a framework that works with Advantage too.
Probably yes, but you'll need to write a NHibernate.Driver.IDriver implementation.
Don't worry, it's easy. You can start from any of the most simple ones at https://nhibernate.svn.sourceforge.net/svnroot/nhibernate/trunk/nhibernate/src/NHibernate/Driver/
Also, you should write a NHibernate.Dialect.Dialect implementation, or you'll only be able to use the basic functionality provided by GenericDialect.
Somebody posted C# source for an Advantage Database NHibernate dialect/driver to the nhibernate-development google group; you should be able to use this with any current ADS ADO.NET provider.
However, you should take note of NH-3078 "TimeAsTimeSpanType issue when using Sybase Advantage Database", which doesn't seem to be fixed yet as of now.
I'm playing WoW for about 2 years and I was quite curious about Lua which is used to write addons. Since what I've read so far about Lua was "fast", "light" and "this is great", I was wondering how and when to use it.
What is the typical situation where you will need to embed a script language like Lua in a system ?
When you need end users to be able to define/change the system without requiring the system to rewritten. It's used in games to allow extensions or to allow the main game engine to remain unchanged, while allow content to be changed.
Embedded scripting languages work well for storing configuration information as well. Last I checked, the Mozilla family all use JavaScript for their config information.
Next up, they are great for developing plugins. You can create a custom API to expose to the plugin developers, and the plugin developers gain a lot of freedom from having an entire language to work with.
Another is when flat files aren't expressive enough. If you want to write data driven apps where behavior is parameterized, you'll get really tired of long strings of conditionals testing for config combinations. When this happens, you're better off writing the rules AND their evaluation into your config.
This topic gets some coverage in the book Pragramtic Programmer.
Lua is:
Lightweight
Easy to integrate, even in an asynchronized environment such as a game
Easy to learn for non-programmer staff such as integrators, designers and artists
Since games usually require all those qualities, Lua is mostly used there. Other sitation could be any application that needs some scripting functionality, but developers often opt for a little more heavy weight solution such as .Net or python.
In addition to the scripting and configurability cases mentioned, I would simply state that Lua+C (or Lua+C++) is a perfect match for any software development. It allows one to make an engine/usage interface where engine is done in C/C++ and the behaviour or customization done in Lua.
OS X Cocoa has Objective-C (C and Smalltalk amalgam, where language changes by the line). I find Lua+C similar, only the language changes by a source file, which to me is a better abstraction.
The reasons why you would not want to use Lua are also noteworthy. Because it hardly has a good debugger. Then again, people hardly seem to need one either. :)
a scripting language like Lua can also be used if you have to change code (with immediate effect) while the application is running. one may not see this in wow, because as far as i remember the code is loaded at the start (and not rechecked and reloaded while running).
but think of another example: webserver and scripting language - (thankfully) you can change your php code without having to recompile apache or restart apache.
steve yegge did that thing for his own mmorpg engine powering wyvern, using jython or rhino and javascript (can't remember). he wrote the core engine in java, but the program logic in python/javascript.
the effect of this is:
he doesn't have to restart the core engine when changing the scripts, because that would disconnect all the players
he can let others do the simpler programming like defining new items and monsters without exposing all the critical code to them
sandboxing: if an error happens inside the script, you may be able to handle it gracefully without endangering the surrounding application
Rapid development for application with real-time constraints. Computer games are one of these ;-)
It's a valid solution if you want to allow third parties to develop plug-ins or mods for your software.
You could implement an API in whatever language you are using, but a script language like LUA tends to be more simple and accessible for casual developers.
In addition to all the excellent reasons mentioned by others, Embedding Lua in C is very helpful when you need to manipulate text, work with files, or just need a higher level language. Lua has lots of nifty feature (Tables, functions are first class values, lots of other good stuff). Also, while lua isn't as fast as C or C++, it's pretty quick for an interpreted language.
I wanted to know, while deciding which language or technology to use for implementing an idea; a design, what are the factors involved in making a decision? Specifically talking about popular scripting languages, why would one choose to use ruby over python or perl or vice-versa? All these scripting languages have proved their worth, so how does one decide?
I just came across this comparison, b/w Ruby and Python, which is in terms of performance and memory management.
A fair comparison can be found here. Further, I tend to agree with all the three answers above.
Besides any hype that one language receives and the other doesn't, I think two factors play a role: mastership of the language, and availability of libraries. If you know Ruby already, you are more likely to use it again, and also to recommend it when asked; likewise for Python. Wrt. libraries: if you want to use Ruby-on-Rails (which you may have chosen for some reason), you have to use Ruby; likewise, if you want to use Django, you have to use Python. Etc.
It's going to depend a lot on what you want to do (the stock answer).
There aren't huge differences between Ruby and Python - both are object oriented languages with more similarities than differences, really. I'd suggest you try each of them out for a moderate sized programming project - say something that might take 2 or 3 hours. You'll notice some things about each of them that will perhaps rub you the wrong way (indentation as syntax puts some people off when it comes to Python, for example.) A lot of the choice is going to come down to your personal tastes.
If this is a standalone project you're thinking of implementing then it probably doesn't matter which of the two languages you choose. If you need to interact with some existing infrastructure then it may matter a great deal - for example, if you need to work with some Rails related infrastructure then you'll probably want to go with Ruby, if it's Django, then you'll want Python.
I would look at these factors when making a decision -
Your Comfort Level and your teams
Your Ability and your teams
Your Resources
Requirements
Platform Maturity
Support
I am developing a cocoa application that will be making heavy use of both web services and a standard dbms (most likely MySQL) and I am wondering if anyone has a good option for a database library or ORM solution they have used. CoreData is not an option due to the need to support a standard DBMS and to be able to modify the data outside of the normal application operation.
I have found a number of possible options from new open source libraries:
http://github.com/aptiva/activerecord/tree/master
To writing my own wrapper for the C MySQL api.
Any advice is welcome,
Thanks!
Paul
We faced a similar question when we first started work on Checkout, our solution was to code the entire app in Python, using PyObjC. Checkout 1 had an sqlite backend, Checkout 2 has a postgres backend.
There are a couple of really mature and powerful ORMs on the Pyton side, such as SQLObject, which is pretty simple to work with (we used it for Checkout 1.0) and SQLAlchemy, which is more powerful but a bit harder to wrap your brain around (we used it for Checkout 2.0).
One approach you could evaluate, is building the application in Objective-C, but writing the data model and database connectivity/adminstration code in Python. You can use PyObjC to create a plugin bundle from this code, that you then load into your app That's more or less the approach we took for Checkout Server, which uses a Foundation command-line tool to administer a postgres server and the databases in it, this CLI tool in turn loads in a Python plugin bundle that has all of the actual database code in it. End-users mostly interact with the database through a System Preferences pane, that has no clue what the database looks like, but instead uses the command-line tool to interact with it.
Loading a plugin is simple:
NSBundle *pluginBundle = [NSBundle bundleWithPath:pluginPath];
[pluginBundle load];
You will probably need to create .h files for the classes in your bundle that you want to have access to from your Obj-C code.
You might also want to check out the BaseTen framework. It is a Core Data-like framework (in fact, it can import Core Data models), but works with PostgreSQL (though not MySQL, as far as I know). It includes some very nice features such as schema discovery at run time. It also includes an NSArrayController subclass that automatically handles locking and synchronizing across multiple users, so you can continue to make use of Apples Key-value Binding in your UI.
I have personal experience with this particular problem. I even started down the road of writing my own wrapper for the C MySQL API.
The eventual conclusion was: Don't!
The solution that worked in my case was to communicate with the MySQL server via PHP. If you are familiar with web services, chances are that you know about PHP, so I don't won't go into loads of detail about that.
To read from the database:
The cocoa app sends a request for a URL on the server: http://theserver.com/app/get_values.php
The get_values.php script handles the database query, and returns the data in xml format
The cocoa app loads and parses the xml
To write to the database:
The cocoa app sends a more complex request to the server: http://theserver.com/app/put_values.php?name="john doe"&age=21&address=...
The put_values.php script parses the input and writes to the database
The beauty of this solution is that PHP is great for working with MySQL, and cocoa has some handy built-in classes for working with XML data.
edit: one more thing:
One of the key things you have to figure out with this approach is how much processing should be done on the server, and how much should be done in the app itself. Let cocoa do the things that cocoa is good at, and let PHP and MySQL do the things that they are good at.
You could write a generic PHP script to handle all queries: perform_query.php?querystring="SELECT * FROM .....", but that is hardly an optimal solution. Your best bet is several smaller PHP scripts that handle individual datasets for you. In my case, there was one to get the list of users, one to get the list of transactions, etc. Again, it all depends on what your app is going to do.
GDL2 is a nice example, based on EOF.
Instead of reinventing the wheel by writing your own communication wrapper to deal with MySQL from Cocoa, you could try the SMySQL framework (a.k.a. MCPKit), it was part of the CocoaMySQL application that evolved into the Sequel Pro project. It works with varying versions of MySQL, and seems to be quite robust.
If you need to understand how to incorporate it into your application, there's not much documentation around, but it has an easy to understand interface and you can see it working by looking at the source of Sequel Pro, which is downloadable from Google code.
There is also the CocoaMySQL-SBG fork of the CocoaMySQL project, but that seems to be out of date and I couldn't get it to build properly.
I've also implemented a simple object persistence framework based on sqlite, but it certainly wasn't trivial to do. I agree with eJames' conclusion- don't implement one yourself if you don't have to.
If you aren't committed to programming in Objective-C you might want to take a look at PyObjC which would allow you to program the database portion in Python. You can use the MySQLdb module for DB access and there are plenty of tutorials online for its use. It isn't hard to stuff the data back into Cocoa/CF classes and pass them back to your app.
The main caveat with PyObjC is that at the moment it doesn't work with Tiger.