Preserving Lives, Improving Lives, Teaching Others The return of PSA is a possibility that strikes terror in the heart of every radical prostatectomy patient; in fact, for many men, the dreaded follow-up PSA tests after surgery are almost worse than having the operation itself. What will you do if your PSA is no longer undetectable? Does the man have a local recurrence of cancer that would respond to radiation, or does this represent micrometastases to lymph nodes and bone? Until now, there has been no way to tell. In a landmark paper -- the largest, most complete study of the return of PSA after radical prostatectomy -- Hopkins doctors have developed guidelines to help patients and doctors know what to do if PSA comes back.

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The Model-View-Control MVC pattern, originally formulated in the late s, is a software architecture pattern built on the basis of keeping the presentation of data separate from the methods that interact with the data.

In theory, a well-developed MVC system should allow a front-end developer and a back-end developer to work on the same system without interfering, sharing, or editing files either party is working on. Even though MVC was originally designed for personal computing, it has been adapted and is widely used by web developers due to its emphasis on separation of concerns, and thus indirectly, reusable code.

The pattern encourages the development of modular systems, allowing developers to quickly update, add, or even remove functionality. This is definitely a read for anyone who has never coding with MVC before or those wanting to brush up on previous MVC development skills. Model The Model is the name given to the permanent storage of the data used in the overall design. It must allow access for the data to be viewed, or collected and written to, and is the bridge between the View component and the Controller component in the overall pattern.

It neither calls nor seeks a response from the other parts; its sole purpose is to process data into its permanent storage or seek and prepare data to be passed along to the other parts. The Model, however, cannot simply be summed up as a database, or a gateway to another system which handles the data process. The Model must act as a gatekeeper to the data itself, asking no questions but accepting all requests which comes its way. View The View is where data, requested from the Model, is viewed and its final output is determined.

The View also ignites reactions from the user, who then goes on to interact with the Controller. The basic example of this is a button generated by a View, which a user clicks and triggers an action in the Controller. There are some misconceptions held about View components, particularly by web developers using the MVC pattern to build their application.

For example, many mistake the View as having no connection whatsoever to the Model and that all of the data displayed by the View is passed from the Controller. In reality, this flow disregards the theory behind the MVC pattern completely.

They then go on to educate others incorrectly. The View is really much more than just a template, however modern MVC inspired frameworks have bastardised the view almost to the point that no one really cares whether or not a framework actually adheres to the correct MVC pattern or not. As I mentioned when discussing the Model, there is no direct relationship between the View and the Controller without the Model in between them.

Controller The final component of the triad is the Controller. Its job is to handle data that the user inputs or submits, and update the Model accordingly.

It is the only part of the pattern the user should be interacting with. The Controller can be summed up simply as a collector of information, which then passes it on to the Model to be organized for storage, and does not contain any logic other than that needed to collect the input. The Controller is also only connected to a single View and to a single Model, making it a one way data flow system, with handshakes and signoffs at each point of data exchange.

The most common mistake made by developers is confusing the Controller for a gateway, and ultimately assigning it functions and responsibilities that the View should have this is normally a result of the same developer confusing the View component simply as a template.

The View holds all of the functionality as the example is purely for display purposes. Stay tuned! Image via Fotolia Comments on this article are closed. Why not ask it on our forums?


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