5 Software Architectures🔗

12 September 2024

Questions?

When people turn ideas (the dot on the white board) into an analysis and then a “requirements document,” they rarely aim for a blank-page arrangement of components. They typically have one in mind for the “big picture” components, and sometimes they mix-and-match (connect) well-known arrangements.

An architecture is a plan for arranging components and organizing their interactions. People who arrange components into organized settings are software architects, in analogy to building architects. There are a number of frequently-used architectures (just like there are certain types of family houses from the simple Cape to a Victorian).

5.1 Model View Control🔗

[10-15min]

F III relies on one particular architecture, occasionally called a pattern. It combines several patterns, which is why “architecture” is a better categorical name.

how it works, what its components are:

model — multiple views — multiple controls

how to implement it:

an observer can implement a view; the observer pattern helps realize one of these connections: from model to view

– sign up observers initially

– inform when things change

– dynamic addition of observers

also: interfaces between these pieces enable developers to write new implementations, swap out implementations, etc.

5.2 Pipelines🔗

[10-15min]

The designers of Unix came up with the first architecture: pipelines of programs.

pipe lines are essentially “function composition” for programs

convention: Unix programs consumes things from STDIN and send results to STDOUT.

pipes: are “devices” the rewire STDOUT from one to next etc.

Examples:

5.3 Client-Server🔗

[10-15min]

in principle: hub-and-spoke approach but with different communication patterns

example: web server, web browsers

dbs: database servers, clients

local vs distributed

5.4 Architectures for Bazaar🔗

[5-10min]

let students propose what we saw when we did the analysis?

client-server : inform about setup, grant turns, inform about winning/losing

model-view-control : for spectators

wire them up

5.5 Administrivia, Finally🔗

[5min]

key things:

– explain grades; points keep going up; how why?

– communicate: ofc hrs, staff

– when the various obligations kick in (xtest, readme, lab book, Make)

– don’t cheat; we’ll discover it and you will go to prison

Total: 40-60 mins (which does not include the Q&A period)