Update code.md (#36)

* Update code.md

* Update code.md

* Update code.md

* Update code.md

Author: odow

pages/code.md

@@ -2,19 +2,62 @@
 title:  "The JuMP ecosystem"
 ---
 
-The JuMP project consists of the main [JuMP](https://github.com/juliaopt/JuMP.jl)
+The JuMP project consists of the main [JuMP](https://github.com/jump-dev/JuMP.jl)
 package, and a large collection of supporting Julia packages.
 
 The JuMP source code can be found at [https://github.com/jump-dev/JuMP.jl](https://github.com/jump-dev/JuMP.jl).
 
-Beneath JuMP, there is an abstraction layer called MathOptInterface ([source code](https://github.com/jump-dev/MathOptInterface.jl)). MathOptInterface defines an API that solvers
-should implement so that they can be used by JuMP, handles the automatic
-reformulation of problems via _bridges_, and has a large infrastructure for
-automatically testing solvers.
+## MathOptInterface
 
-At the bottom of the stack, there are solver wrappers. These packages wrap the
-solvers, which are often written in C or C++, and implement the API defined by
-MathOptInterface.
+Beneath JuMP, there is an abstraction layer called MathOptInterface 
+([source code](https://github.com/jump-dev/MathOptInterface.jl)). 
+
+MathOptInterface defines an API that solvers should implement so that they can 
+be used by JuMP, handles the automatic reformulation of problems via _bridges_, 
+and has a large infrastructure for automatically testing solvers.
+
+## Solvers and solver-wrappers
+
+At the bottom of the stack, there are solvers. These packages are either 
+pure-Julia implementations of optimization algorithms, or they provide a Julia
+interface to external solvers (often written in C or C++). Each solver also 
+implements the API defined by MathOptInterface so that it can be used from JuMP.
 
 A non-exhaustive list of solvers available through JuMP is available in the
 [JuMP documentation](https://jump.dev/JuMP.jl/stable/installation/#Getting-Solvers-1).
+
+## JuMP extensions
+
+JuMP extensions are Julia packages which extend JuMP's algebraic modeling language
+by providing additional syntax and functionality for specific problem classes.
+
+Examples of JuMP extensions include:
+ * [BilevelJuMP](https://github.com/joaquimg/BilevelJuMP.jl), which extends JuMP
+   to support bi-level programs.
+ * [Coluna.jl](https://github.com/atoptima/Coluna.jl), which extends JuMP to 
+   support a branch-and-cut-and-price solution framework.
+ * [InfiniteOpt](https://github.com/pulsipher/InfiniteOpt.jl), which extends 
+   JuMP to support infinite-dimensional optimization problems.
+ * [Plasmo.jl](https://github.com/zavalab/Plasmo.jl), which extends JuMP to
+   support a graph-based algebraic modeling framework.
+ * [SDDP.jl](https://github.com/odow/SDDP.jl), which extends JuMP to support 
+   multistage stochastic programs.
+ * [StochasticPrograms.jl](https://github.com/mbiel/StochasticPrograms.jl), which
+   extends JuMP to support stochastic programs.
+ * [SumOfSquares](https://github.com/jump-dev/SumOfSquares.jl), which extends
+   JuMP to support polynomial optimization.
+ * [vOptGeneric.jl](https://github.com/vOptSolver/vOptGeneric.jl), which extends 
+   JuMP to support multiobjective programs.
+
+Note that with the exception of SumOfSquares, these JuMP extensions are not part of 
+the core JuMP-dev ecosystem, but are developed independently by the community.
+ 
+(This list of JuMP extensions is open to new contributions! If you know one that 
+isn't listed here, tell us by making a pull-request to edit the file [code.md](https://github.com/jump-dev/jump-dev.github.io/blob/master/pages/code.md).)
+
+## Convex.jl
+
+An alternative to JuMP is [Convex.jl](https://jump.dev/Convex.jl/stable/). 
+Convex.jl is a Julia package for disciplined convex programming, built on-top-of
+MathOptInterface. Thus, it can use all of the same MathOptInterface-compatible
+solvers as JuMP.