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Messages: 28
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Ralf Westphal asks: should ObjectSpaces be orthogonal?
In his weblog, Ralf Westphal asks the heretical question of whether striving for object persistence orthogonality--as ObjectSpaces tries to--is really a Good Thing after all. His reasoning? Watching what happened when developers tried to do the same with MTS and COM+.
From his blog: "I saw what happened to MTS and then COM+. Many developers did not understand, that designing classes to be run in an application server is different from designing classes to be run in a rich client (aka winforms client)."
Agree or disagree? I'll even go one step further--do we need O/R mapping technologies at all, or is this a Holy Grail that we'd be best off just abandoning?
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Message #109441
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very chismoso
What I would like to know is "what kind of database layer are the .NET guys using in reality? Stored procedures? The data classes in Microsoft Application Blocks for .NET? O/R? Homegrown?
Regards
Rolf Tollerud
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Message #109449
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very chismoso
We currently use stored procedures (bank standard) and I have also used O/R tools before with .Net applications (homegrown) while working for a software shop. The value we gained was not writing data access code for every database our customers wanted and better time to market for CRUD based apps.
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Message #109452
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very chismoso
I use a completely home grown O/R mapping lawyer. For a matter fo fact, I ported that same layer that I used in a major j2ee app that I worked on. Pretty much using the Data layer patterns that fowler listed in his book. QueryObject, DomainObjects, xml Metadata and reflection for generating objects.
-M
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Message #109459
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very chismoso
Marlon and Mackie,
I would be interesting to see your solutions, any possibility for a case study?
Did you try out some of,
LLBLGen, ORM.NET, TierDeveloper, Persistence.Net, Sisyphus,EntityBroker,Nolics.net, OS (ObjectSpaces)?
What was the rationale for making your own solution?
More questions,
What is MS Business Framework (MBF)?
Will MBF and OS come at no cost?
Will there be an OS provider for Oracle?
What about QPath queries in OS?
Regards
Rolf Tollerud
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Message #109508
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Hibernate
I have used Hibernate on Java projects before and it works wonderfully. I think those guys have a really good handle on what makes a robust (and unobtrusive) ORM layer. I would love it if the ObjectSpaces implementation follows their lead.
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Message #109534
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generic database access
What would be interesting is to se statistics,
O/R systems x %
Datasets y %
DAL generators z %
etc..
Myself, I balk when I see classes like "customersclass", "ordersclass" and so on. I like my system to be easily extensible by third party as well as allow other systems to access my database, in short - to be a good citizen.
Why can you not build up your queries like,
SqlQuery sql = New SqlQuery();
sql.AddCmd("select");
sql.AddCols("name", "zip");
sql.AddFromClause("customers");
sql.AddWhereClase("ID=1081");
or just,
SQlquery sql = New SQlquery();
sql.AddCmd ="select";
sql.AddCols="name, zip";
sql.AddFromClause="customers";
sql.AddWhereClase="ID=1081";
and then solve the mapping by adding a prefix to the table-names, like this
(assuming your prefix is "mir"),
cmd =sql.BuildSql();
cmd = Regex.Replace(cmd, "(\\w*\\.\\w*)|mir\\w*", new MatchEvaluator(map.realName));
In a separately compiled class you implement the method to switch the alias table and field-names to the real names.
The result command you can throw at anything that need an sql expression.
Regards
Rolf Tollerud
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Message #109558
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generic database access
We are using Microsoft Application Blocks for .NET in our company here.
I am of the opinion that most applications do not need the overhead of dataset and can make it work using datareaders
what do u think?
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Message #109566
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generic database access
No wonder you wont never ever master session management... just an advice, go and copy what hibernate does but in .NET. Then u may be able to learn something.
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Message #109580
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generic database access - lean and mean
BK,
> "do not need the overhead of dataset and can make it work using datareaders"
Agree. In our current application all data access is in the Web Service and we use datareaders to do the XML-transformation, it is faster.
We have choosen not to use direct XML queries for various reasons, one for example that it only works with SQL Server. We keep to ANSI-SQL and concentrate upon the main databases, SQL Server, MySQl and Oracle.
In this way we also can handle dynamic sql-queries depending on user input.
We can handle the main databases. We can handle name-changes in tables and fields. There is no reason to use ObjectSpaces or any other O/R IMO.
Smaller is faster!
Regards
Rolf Tollerud
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Message #109596
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generic database access
<Just a Software developer>mmm... what do u mean by "most applications"?? </Just a Software developer>
I should have said Most asp.net applications. It is due to the stateless nature of web applications you do not want to recreate dataset at evry load of the page.
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Message #109711
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The Holy Grail is here today!
I found that using a framework which has a persistence layer that is fully customizable cuts down development time for the complete project roughly in half. Greater acceleration can be achieved when combining such a persistence layer with a business layer that uses a UML model as metadata. Using lazy load as default but being able to use different load schema?s (which specifies what ?related? data needs to be retrieved at the same time) in different Use Cases gives excellent performance. And since web and windows applications have indeed different characteristics your persistence layer must be flexible enough to be configured to support both.
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Message #109720
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Object facade for ADO.NET
About a year ago we started the development of an 'occasionally-connected' client application; an application that manipulates information stored in a database but does so without being connected to it all the time. DataSets (in the ADO.NET sense) seemed to be ideally suited to this scenario but we quickly found that they were quite low-level and not very object-oriented.
So, we set out to develop an object wrapper around ADO.NET and a dynamic SQL generator to manage persistence. The result is now available as open source in the form of the Neo project (links below). In hindsight it ended up looking a lot like SDO, which is IBM and BEA's new take on data programming.
http://neo.codehaus.org
http://dev2dev.bea.com/technologies/commonj/sdo/index.jsp
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Message #109763
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The Holy Grail has been here for a while...
just have a look at scaffolds, chordiant, metamor, etc. I can understand for you MS guys this may seem the holy grail but its been around for a while...
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Message #109764
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generic database access
No wonder you wont never ever master session management... just an advice, go and copy what hibernate does but in .NET. Then u may be able to learn something.
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Message #109777
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generic database access - lean and mean
<Rolf>Agree. In our current application all data access is in the Web Service and we use datareaders to do the XML-transformation, it is faster.
</Rolf>
Why would you use a webservice for data access in intranet application? (I am assuming you were talking about an intranet app)
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Message #109779
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The Holy Grail has been here for a while...
>I can understand for you MS guys this may seem the holy grail but its been around for a while...
O/R is not by ant measure a "holy grail", just useful.
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Message #109795
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Intranet, Extranet, Web Applications
BK,
There are almost no pure intranet applications anymore, rather extranets. The right word is more "Enterprise business applications" as opposite to ordinary sites.
The problem is that the terms are so floating. In my book "Web application" is a real application- say a CRM system, not a common advertising or promotion "website".
But I notice that many people use the word "Web application" for in principle anything.
I am trying to set up a test, comparing O/R mapping to my handcrafted code. The problem is to choose the right tool, there are more than 30 out there!
http://www.theserverside.com/news/thread.jsp?thread_id=23762#109679
Regards
Rolf Tollerud
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Message #109825
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Each can form his own private speculation
After a lot of research on Google I finally found 3 products to choose between, Entity Broker, Pragmatier and TierDeveloper. Having nothing to go upon I arbitrary picked TierDeveloper from AlachiSoft, installed and generated the Northwind web sample project
Examination revealed that each table, in addition to the usual - in the case of customers, customers.aspx, customers.aspx.cs, had 3 more files attached to it, CustomersHelper.cs (17K), Customers.cs (31K) and CustomersInfo.cs (3K).
That is compared to my old app that had 3 files for the generic datalayer, + one codebehind file for every aspx = 28 files, I now had 97 files (3 X as much), 52 for the app and 45 for the datalayer.
Performance was down by 50% and the whole application more difficult to test and maintain. I can no longer have dynamically generated sql depending on user input. If I want to make small changes in the database structure I have to regenerate all. The really big problem though is when you have complicated joins and transactions in some parts that you have to hand code - after you can kiss goodby to try decrypt the application or auto-generate.
*On the pro side you gain some in productivity*.
So what is the moral? Industrial mass production can never be the same quality as careful handcraft. The time you save in the beginning you pay for later. Small, lean and faster is always better than big, fat and slow. It can suffice for quick and dirty contract jobs - the clients are used to be cheated anyway - never for a product.
Regards
Rolf Tollerud
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Message #109858
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Each can form his own private speculation
"It can suffice for quick and dirty contract jobs - the clients are used to be cheated anyway - never for a product. " ---> I for sure wont recommend my company to do business with you. Just read what you write.
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Message #109882
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one time I was as innocent and naive as you!
(hmm, what happened?)
When you grow older you will realize that contract programming is just one step away from high way robbery, and that "contract programmer" is about equal to "horse thief" or "used car dealer".
Regards
Rolf Tollerud
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Message #109889
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one time I was as innocent and naive as you!
"When you grow older you will realize that contract programming is just one step away from high way robbery, and that "contract programmer" is about equal to "horse thief" or "used car dealer". "---> Being a former MS consultant, I know what you mean. That's why I quit. You can quit too.
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Message #109897
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to waist money like water
And how many millions and billions do you think the Java zealots have destroyed with all large scale over-architected J2EE projects (70-80% project failure rate according to Gartner?).
http://www.zdnet.com.au/news/business/0,39023166,20269968,00.htm
And then again even if they against everybody?s expectation succeed to deploy the project it is down one day in seven.
But the Java community is very good at squirming excuses. At least they are innovative in one area!
Regards
Rolf Tollerud
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Message #110220
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to waist money like water
is that your lame excuse???
hahahahahahahahaha...
"When you grow older you will realize that contract programming is just one step away from high way robbery, and that "contract programmer" is about equal to "horse thief" or "used car dealer". "---> Being a former MS consultant, I know what you mean. That's why I quit. You can quit too.
never is late to repent my dear ChingadorDetUmAdre!!!
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Message #113143
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Business case for MDA/ORM tools
Business case for MDA/ORM tools
Rolf, I have the greatest respect for your benchmarking of TierDeveloper vs. Homegrown.
However there are other benchmarks out there, e.g. http://www.middleware-company.com/casestudy/mda.pdf.
My decision for a fat C# WinForm + SQL Server DB (2-tier) multi-user solution was ECO from Borland (f.k.a. Bold from BoldSoft).
Still haven?t experienced all the pitfalls and having to live with vendor lock-in and black box dependence, I?d say that you can cut *a lot* of implementation hours if you have the same architecture as us and (this is very important) very complex business rules.
If the latter isn?t fulfilled (i.e. a simple CRUD scenario) I would go the ADO.NET route, but Table Module (Fowler) and complex business rules don?t play well together IMHO.
// Martin R-L
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Message #113151
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to waist money like water
> And how many millions and billions do you think the Java zealots have destroyed with all large scale over-architected J2EE projects (70-80% project failure rate according to Gartner?).
> http://www.zdnet.com.au/news/business/0,39023166,20269968,00.htm
...
> Regards
> Rolf Tollerud
I read that article completely, did you? Heres a couple of quotes for you:
"To date, around 70 percent of initial Java implementations have been unsuccessful, according to new research from Gartner Group. "
"However, Microsoft shouldn't draw any comfort from those figures as it seeks to promote its .NET technology strategy either. In all likelihood, the failure rate for early implementations of .NET systems will be similar, Driver said."
Now, you wouldn't be backing up your arguments with selective evidence would you?
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