# Friday, May 31, 2013

Building a Sharepoint "clone"

Well, from my previous post it should be clear that it will not be a "full" Sharepoint clone :) That would be a daunting task!
Anyway, for the kind of application I have in mind, I need to replicate the following functionalities:
  •     Everything is accessible via a web browser
  •     The basic data collection will be a list of "things" (more on that later)
  •     It will be possible to perform complex, collaborative, persisted, long-running operations to create and modify "things" and "list of things"
  •     Operations, lists and "things" need to be secured (have different accesses, with permissions assignable to users and roles)
  •     It is possible to define a "thing" (lists of them) (but only for users in the correct role)
  •     It is possible to define operations using predefined basic blocks ("steps")
  •     Steps will have automatically generated UI to gather user input, if necessary
For example: one of these "things" may be a project proposal.

Someone starts a project proposal, fills up some fields, and submit it to a manager. The manager can send it back, asking more details. Then someone is assigned to it, to explore the feasibility, for example. And many other steps can follow.

Each of these steps fills out a little part of the proposal (our "thing"). I want to discuss how I want to build "things", and which shape they will have. For now, let's focus on steps.
First of all, not that I have not used the word "workflow" up to now.
Yes, this kind of step-by-step operations fall nicely in a the definition of workflow; if you look at the company documentation, or even if you ask an employee to describe the procedure to submit a proposal, they are described in a graphical way, with boxes and arrows and diamonds: a flowchart.

WF (the .NET workflow engine) enforces this feeling by using a graphical language very similar to flowcharts as one of the ways to author a workflow. Besides the familiar authoring experience (which is, unfortunately, not without shortcomings in SP), WF adds many nice features we want in this kind of operations. Above all, we have  resilience-durability-persistence. This feature is really useful in our scenario: delays introduced by human interaction are very long, and a way to persist and resume programs is really useful to allow resilience and also scalability (programs can pause and resume, and migrate from one machine to another too).

The plan (for this blog):
- A series of posts about workflows
- Comparison with an interesting alternative: dataflows
- Building and persisting "things" (Dynamic types)
- Some nice ASP.NET MVC features used to put everything together (and make the actual users of all of this happy!)

Everything is accompanied by code.
I will try to put most of what I am discussing here on github, pushing new stuff as I blog about it.
Eventually, I hope to push all the code I wrote (and will write) for this project on github, but I will have to discuss it with my "investor" before doing that..

Next time: Part 1 of the workflow series!

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