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The blogged wandering of Robert W. Anderson

Digipede + Velocity

Last week Microsoft released the first CTP of the Microsoft Distributed Cache (code-named Velocity). deatlefast2

I am definitely excited about this release.  While Microsoft is not breaking new ground here, the addition of a distributed cache to .NET is a great addition to the platform.  Certainly there are competing technologies, but Velocity will be a very simple choice for developers and ISVs because we’ll be able to count on its availability. 

This ISV is interested, so we tried it out.

We have many customers who use our Executive pattern to load and cache job-specific data for compute-intensive jobs on the Digipede Network.  These data are often fetched through WS calls or directly from SQL databases.  Often this is performed in the Executive.Start method.  Before Velocity, the code might look like this:

protected override void Start() {
    // read the CBOData object from the database.
    _cboData = ReadCboData(cache.Get(JobTemplate.Parameters["CBODataStore"].Value));          
}

Including Velocity in this example is really easy.  The following snippet adds use of the Velocity cache:

protected override void Start() {
    // get cache 
    CacheFactory factory = new CacheFactory();
    Cache cache = factory.GetCache("CBOCache");
    // see if our CBOData object is already there
    string key = JobTemplate.Parameters["CBODataKey"].Value;
    _cboData = (CBOData)cache.Get(key);
    // if not, read it from the database.
    if (_cboData == null) {
        _cboData = ReadCboData(cache.Get(JobTemplate.Parameters["CBODataStore"].Value));
        // store it in the cache for later use
        cache.Put(key, _cboData);
    }          
}

With a few lines of code, we reduce the load on the database server and network and spend more time computing.  (I’m making an assumption with this simple code that all Executives don’t start at once, an assumption made obsolete by seeding the cache from a master application).

Of course, this is a simple example, but there are many other use cases.  For example,:

  • Digipede-enabled applications can share results; 
  • master applications can load the cache with job-specific data; and,
  • others where baking Velocity deeply into the Digipede Network start looking pretty interesting.

I have seen many posts on “must-haves” for a Velocity RTM.  I mostly agree with the lists I have seen.  I’ll have a list too mostly from the ISV perspective.

Cool stuff.

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