ASP.NET

17-Dec-06 7:51

I am using content and master pages. The content page has to query the database to get the master page name (among other things), which is done in ‘Page_PreInit’, and then the master page has to query the database to get some layout options, done in ‘Page_Load’.

Is it possible for the master page to use the existing open connection, or am I forced to close the connection in the content page and open up a new connection in the master page? I’ve tried various things without success.

The second question is, does it matter? Will opening and closing two connections be much slower than opening and closing one?

Colin Angus Mackay17-Dec-06 8:27

17-Dec-06 8:27

BigPaul wrote:
Is it possible for the master page to use the existing open connection, or am I forced to close the connection in the content page and open up a new connection in the master page? I’ve tried various things without success.

You are not forced into any particular way of doing things. However, the prefered method is aquire-execute-release (in other words, open a connection, execute the SQL then close the connection).

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BigPaul17-Dec-06 8:46

17-Dec-06 8:46

Thanks for the reply.

My question is really concerning whether it is possible for the master page to access the connection already opened by the content page. So far I haven’t found a way to do this.

Not Active17-Dec-06 11:46

Not Active

17-Dec-06 11:46

Yes, it is possible, just as it is possible to drop bowling balls on your feet to get out of ballroom dancing with your girl friend. Hardly the best way of doing it. Just as Colin said, aquire-execute-release.

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Guffa17-Dec-06 9:01

Guffa

17-Dec-06 9:01

It's possible to use the same connection, if you have a method in the master page where you do the database work, which you call from the contents page. However, as you open the connection before the master page is even loaded, you would have to keep the connection open from one event to another, which would make it much harder to ensure that the connection is always closed correctly.

It's hard to tell if opening another connection will be slower or not, but it's safe to say that the difference is not that big. As long as you use an identical connection string the connections are pooled, which means that they are never really closed between the times they are used. So if you keep the connection alive or let the pool do it shouldn't matter much when it comes to speed. As it's much safer to leave it to the pool, you should do that.

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It's amazing to see how much work some people will go through just to avoid a little bit of work.

BigPaul17-Dec-06 9:54

17-Dec-06 9:54

I figured the easiest way to do it would be to open the connection in the content page PreInit and close it in the content page Unload. This way the connection is open when the master page Load event fires, which is when it should be used. But, I can’t find a way to access the open connection.

I’m not sure how to access a master page function from the contents page, bearing in mind that the master page is defined at runtime.

Colin Angus Mackay17-Dec-06 12:27

17-Dec-06 12:27

BigPaul wrote:
I’m not sure how to access a master page function from the contents page, bearing in mind that the master page is defined at runtime

You can access the master page from the content page by using the content page's Master property. However, the best solution is to aquire-execute-release in the master and aquire-execute-release in the content page. Actually, a better solution would be to move all the data access out of the presentation layer altogether.

Daniel Fisher (I think) at the DDD4 conference I was at earlier this month gave some pretty sage advice: If you are using anything in the System.Data namespace in your code behind classes (e.g. The code behind for Master pages or Content pages) then there is something wrong with your design.

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BigPaul17-Dec-06 13:06

17-Dec-06 13:06

I was under the impression (clearly the wrong impression) that opening and closing a connection twice would be slower than doing it once, and that opening a connection in one event and closing it in another immediately-following event would not be a problem – i.e. this it was essentially an ‘acquire-execute-release’ approach.

However, having since read up on connection pooling, it is obviously not necessary to try and keep the connection open.

Colin Angus Mackay wrote:
Daniel Fisher (I think) at the DDD4 conference I was at earlier this month gave some pretty sage advice: If you are using anything in the System.Data namespace in your code behind classes (e.g. The code behind for Master pages or Content pages) then there is something wrong with your design.

Is there a disadvantage to accessing a database from the code-behind class? The data access for my master pages is handled in a separate class, but the content page accesses the database directly. I’m interested to know if there is a more efficient approach.

Colin Angus Mackay17-Dec-06 14:03

17-Dec-06 14:03

BigPaul wrote:
Is there a disadvantage to accessing a database from the code-behind class?

Yes. It reduces maintainability of the appliction.

BigPaul wrote:
I’m interested to know if there is a more efficient approach.

Efficiency (or performance, what ever you want to call it) is usually not one of my top priorities when writing software. Maintainability and Readability come first unless performance considerations are an explicit part of the specification.

I will always go for readability or maintainability even if it costs me a few extra clock cycles because nothing is worse than having to debug code written using the "Giant Ball of Mud" pattern.

If you separate out the database access into its own class (or classes) you get improved readability because your code behind is not cluttered with calls to open connections, set up queries, execute queries and close everything down again - You let the DAL (Data Abstraction Layer - the class[es] that you write) handle that.

You get improved maintainability because all your data access code in in one place (the DAL). This means that if you have to make any substantial changes to the database you don't have to go looking over an entire code base.

You can even get improved efficiency with a DAL if you work it right. For example, you would normally get a connection string out of the config file. The DAL can do that once then cache it. The DAL is always using the cached connection string so that connection pooling works better (there is no accidental use of a slightly different connection string to get to the same thing - which creates a new pool).

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Guffa17-Dec-06 14:57

Guffa

17-Dec-06 14:57

BigPaul wrote:
and that opening a connection in one event and closing it in another immediately-following event would not be a problem

It is a problem if the second event never is executed. If you encounter an error somewhere in your code between opening and closing the connection, the event that closes the connection will never be executed and the connection will be left open.

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It's amazing to see how much work some people will go through just to avoid a little bit of work.

Help

deeptis17-Dec-06 7:45

deeptis

17-Dec-06 7:45

Hi I am working on asp.net and i want to write a program in asp.net i.e to get the date and time of different countries on selecting the countries name.So can any one help me out?

Thanks...
Deepti

Re: Help

Colin Angus Mackay17-Dec-06 8:28