SWAB Online

A.K.A. FORTRAN on rails

Foxdog Studios

Lloyd Henning / Peter Sutton

MACE

Dr Wei Hu / Dr Maurice McCabe / Dr David Apsley / Prof Peter Stansby

The project

• Take existing code
• Developed during research
• Make it usable
• Web interface

The Code

Implements the SWAB Model

1-D nearshore wave simulation

This Talk

• Case study: SWAB on the web
• Experiences & lessons
• What you can do

Who's it for?

Researchers interested in sharing their tools

Web devs interested in making similar apps

Why share?

Reproducibility

&

Education

&

Research

SWAB 4.0

Written in FORTRAN

Command line tool

Parameters

&RUNVARS
    RUNNAME = '000-10-original'/
&WavesVARS
    HOUT = 10,
    NTPER = 1500,
    NCYCLE = 10,
    TNTIME = 'NCYCLE',
    RTF = 1,
    FMAX = 5,
    PERIOD = 8,
    HEIGHT = 2,
    SPECFUN = 'JONSWAP',
    GAMMA = 3.3,
    RANSEED = T,
    RANPUT = 1,
    TIDE = F,
    WAVETYPE = '000'
    TIDEFILE = '000-10-original/Tide.in' /
&BedVARS
    SEAWALL = T,
    CFCONST = 0.01,
    IWAVE = 100,
    XWAVE = 100,
    XIWAVE = 'IWAVE',
    xzFileType = 'IX-XZ',
    xzFile = '000-10-original/Bed.in' /
&BreakingVARS
    Cbreak = 0.6/
&OutputVARS
    NTPLOT = 2,
    NXPLOT = 3,
    TVAR = 'E, E0, EAV, U, HU, H, ADV, DIF, BOU, DHU, DEX, BRK, BED, QB, CHB',
    XVAR = 'E, E0, EAV, U, HU, H, ADV, DIF, BOU, DHU, DEX, BRK, BED, QB, CHB',
    OTHERVAR = 'BREAK, DXZ, SWASH, EIN, TRAIN, SF, AF, FORCE, VOLUME',
    OUTTIME = '1',
    OUTLOC = '110, 460',
    AUTO = F/
&WallForceVARS
    IWALL = '2',
    KWALL = '0.5'/

Outputs

0.00000000E+00  1.00000000E+01
2.39119500E-01  1.00000000E+01
4.78239000E-01  1.00000000E+01
7.17358500E-01  1.00000000E+01
9.56478000E-01  1.00000000E+01
1.19559750E+00  1.00000000E+01
1.43471700E+00  1.00000000E+01
1.67383650E+00  1.00000000E+01
1.91295600E+00  1.00000000E+01
2.15207550E+00  1.00000000E+01
2.39119500E+00  1.00000000E+01
2.63031450E+00  1.00000000E+01
2.86943400E+00  1.00000000E+01
3.10855350E+00  1.00000000E+01
3.34767300E+00  1.00000000E+01
3.58679250E+00  1.00000000E+01
3.82591200E+00  1.00000000E+01
4.06503150E+00  1.00000000E+01
4.30415100E+00  1.00000000E+01
4.54327050E+00  1.00000000E+01
4.78239000E+00  1.00000000E+01
5.02150950E+00  1.00000000E+01
5.26062900E+00  1.00000000E+01
5.49974850E+00  1.00000000E+01
5.73886800E+00  1.00000000E+01
5.97798750E+00  1.00000000E+01
6.21710700E+00  1.00000000E+01
6.45622650E+00  1.00000000E+01
6.69534600E+00  1.00000000E+01
6.93446550E+00  1.00000000E+01
7.17358500E+00  1.00000000E+01
7.41270450E+00  1.00000000E+01
7.65182400E+00  1.00000000E+01
7.89094350E+00  1.00000000E+01
8.13006300E+00  1.00000000E+01
8.36918250E+00  1.00000000E+01
8.60830200E+00  1.00000000E+01
8.84742150E+00  1.00000000E+01
9.08654100E+00  1.00000000E+01
9.32566050E+00  1.00000000E+01
9.56478000E+00  1.00000000E+01
9.80389950E+00  1.00000000E+01
1.00430190E+01  1.00000000E+01
1.02821385E+01  1.00000000E+01
1.05212580E+01  1.00000000E+01

Excel wrapper

Excel → parameter files → batch script

Can't we just share that?

We're not picking on SWAB 4.0

All native applications have these problems

Different operating systems (Linux/Windows/OSX...)

SWAB is a Windows .exe

Compiling source code - a mess of dependencies

SWAB 4.0 only compiles with the NAG compiler

Machine architectures (32 bit / 64 bit)

Excel wrapper written in VBA: 64 bit issues

Free download, requires proprietary software

Microsoft Excel / NAG compiler

And then

• Understanding inputs
• Visualising results
• Trapped results
• Horse power

more time getting it to work, than using it

The web solves all your problems

An Architecture For Long Jobs

Reusable experimental code

• Remove global state
• Generator pattern

Toy software

n = 5
x = 2

def simulate():
    y = 0

    for i in range(n):
        y += x
        print('%d) y = %d' % (i, y))

simulate()

Parameters

n = 5
x = 2

Simulation

def simulate():
    y = 0                            # Initialisation

    for i in range(n):
        y += x                       # Step
        print('%d) y = %d' % (i, y)) # Output

Driver

simulate()

Global state

n = 5
x = 2

def simulate():
    y = 0

    for i in range(n):
        y += x
        print('%d) y = %d' % (i, y))

simulate()

Global state

class Context:
    def __init__(self, n, x):
        self.n = n
        self.x = x

def simulate(ctx):
    y = 0

    for i in range(ctx.n):
        y += ctx.x
        print('%d) y = %d' % (i, y))

simulate(Context(5, 2))

for i in range(ctx.n):
    y += ctx.x
    print('%d) y = %d' % (i, y))

I can't change the output without change the simulation!

Generators

class Context:
    def __init__(self, n, x):
        self.n = n
        self.x = x
        self.i = None
        self.y = None

def simulate(ctx):
    ctx.y = 0

    for ctx.i in range(ctx.n):

        ctx.y += ctx.x
        print('%d) y = %d' % (ctx.i, ctx.y))

simulate(Context(5, 2))

Initialisation

def initialise(ctx):
    ctx.y = 0

Termination condition

def canstep(ctx):
    return ctx.i < ctx.n

Simulation step

def step(ctx):
    ctx.y += ctx.x
    ctx.i += 1

Output

def output(ctx):
    print('%d) y = %d' % (ctx.i, ctx.y))

Your driver

ctx = Context(5, 2)
initialise(ctx)

while canstep(ctx):
    step(ctx)
    output(ctx)

My driver

from pymongo import MongoClient
client = MongoClient()
results = client.experiments.results

ctx = Context(5, 2)
initialise(ctx)

while canstep(ctx):
    step(ctx)
    results.insert({'i': ctx.i, 'y': ctx.y})

Extra tips

• Using a database
• Native when necessary

Drawbacks

You're responsible for everything

Hardware

Cloud computing / Amazon EC2

What next?

• Undergraduate labs
• Lectures
• Publicity
• Link in publications

Questions

Interesting technologies

Meteor / D3 / threejs / RabbitMQ / MongoDB

Want to build a web application?

contact@foxdogstudios.com