State Management

Re: Caching in a web farm

jimmy q — Sat, 19 May 2007 00:49:21 GMT

freakshow:
You might have a look at the Caching Application Block, using a database as a backing store.

Hi freakshow,

I have never used the Application Blocks but on the top of my head wouldnt using a database as the cache store defeat the purpose of caching as i will need to hit the db to get the cached items?

Re: Caching in a web farm

freakshow — Fri, 18 May 2007 23:21:46 GMT

You might have a look at the Caching Application Block, using a database as a backing store.

Re: Caching in a web farm

jimmy q — Fri, 18 May 2007 13:45:16 GMT

Ah bugger.

I was hoping that cache data can be shared across in a web farm. It now looks like i have to weigh up whether caching is a good thing versus implementing my own synchronisation code with the extra complexity and overhead.

Re: Caching in a web farm

Rex Lin - MSFT — Fri, 18 May 2007 09:17:49 GMT

Hi, jimmy:

I suppose no:

The Cache object lives inside the current AppDomain (ie. ASP.NET Application Scope) and it stores its entries in a Hashtable.

More Details:

http://west-wind.com/weblog/posts/1214.aspx

I hope the above information will be helpful. If you have any issues or concerns, please let me know. It's my pleasure to be of assistance

Re: Caching in a web farm

jimmy q — Fri, 18 May 2007 07:40:00 GMT

Thanks for your reply Anton.

I am not sure whether you understood my question.

I have a web application that i need to deploy onto a web farm, therefore i need out of process session management and i have chosen to use the ASP.NET session server service to manage my sessions across multiple web servers.

In this web application, i also make sure of the Cache object to minimise requests to external resources etc. Would the ASP.NET session server service enable the Cache data collection to be synchronised across all the web servers? Or will the cache collection data be specific to each individual web server's appdomain/asp.net worker process?

Would the ASP.NET State server service also synchronise the Application collection variable?

So in short i understand the ASP state service is an out of process modal that can synchronise Session data across multiple webservers, the answer i need to know is

Does the ASP.NET state service or the SQL Server state server

1/. synchronise Application variables

2/. synchronise Cache variables

If i have misunderstood your reply anton, i apologise.

Thanks

Jimmy

Re: Caching in a web farm

antonpious — Fri, 18 May 2007 07:18:38 GMT

Hi Jimmy,

I am afraid you have to handle the caching strategy differently.

While session is common to a user the cache is common to all users and behaves very much like an application variable and stored in memory for the appDomain.

You have to handle Caching seperately.

Have a look at MemCache which uses an external process where others can store and retrieve cached information.

Happy Programming,
Anton

Caching in a web farm

jimmy q — Fri, 18 May 2007 01:31:11 GMT

I understand that to maintain sessions across a web farm i need to either implement an ASP.NET state server service or a SQL Server State database.

However, does either of the 2 solutions for managing state across a web farm also synchronise cached objects?