In our company we use an Wiki to document our projects.

I am missing a way to sketch simple overview diagrams.

Now I search a tool to create such diagrams.

Requirements:

 - read ascii/utf (not svg)
 - re-usable entities: Figures for database, actor (person), internet (cloud), ... should be easy to re-use.
 - output format: svg or png.
 - Relations between the entities

Main focus is on easy of use. I don't need all things which are possible in UML.

Use case: I want to draw images like this:

[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/nrxXY.jpg