Web Application Maker:a declarative web database tool

Miguel Calejo, Mário Araújo, Sónia Mota Araújo, Nuno Soares, Rui MaranteDeclarativa, Portugal

http://www.declarativa.com

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Declarativa, 24-Oct-2003

• 31/2 years, 5 engineers, tools

• Two areas of declarative development– InterProlog: Java JFC/Swing + Prolog

– WAM: browser+Active Server Pages+SQL Server

• Contracts with XSB Inc./DoD (USA); ME, CVRVV, CRAT, Servisoft (Portugal)

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http://www.declarativa.com

More about Declarativa

• Microsoft Certified Partner...– ...with a grain of salt

• Incubated at Servisoft– Early Web Information System adopter

– Administrative support

– Internet

– Building

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WAM projects: DoD/XSB, Inc.

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WAM projects: CVRVV

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WAM projects: Servisoft

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Spaghetti code in the internet era

Developer

DBMSCGIBrowserUser

… (HTML)… (JScript at client)… (JScript at server)… (SQL)

…<form … action='…'>Customer <input … name='name'>Phone #<input … name='phone'></form>…

…<script>if (isNaN(phone)) alert('Not a number');</script>…

…<%while (! results.EOF) …%>…

SELECT name, phoneFROM customer

customer

name varchar(50)phone int

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More declarative scenario

… WAM Objects

Developer

DBMS CGI Browser User

customer name varchar(50) phone int

… r = new WAMRow(customer); …

"Phone #", "Customer",…

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Enter: declarative web development

• Web Application Maker (WAM)– Model-driven, based on SQL Server– Given a DB schema with triggers, constraints, etc...– ...get web interface with user profiles, etc.– Flexible: GUI generators exposed to the developer

• Follow any software engineering method, .... – ...and use the resulting database

• Part of Declarativa’s Web Information Systems Toolkit

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The WAM pictureServers

Customcode

ApplicationDB

WAMmodel

WAM“interpreter”

SQL ServerIIS (ASP engine)

Workstation

BrowserMyApplication

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WAM “Equations”

• Web interface = WAM(DB Meta Information + WAMmodel) + CustomASP pages using WAM objects+ other pages

• Default web interface =WAM(DB Meta Inf. + Default WAMmodel)

• An acceptable interface working sooner is better than a fancy one later!

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WAMmodel

• Information added to the database schema to allow reasonable GUI generation– WAM_PRESENTATION

– WAM_LIST, WAM_LIST_COLUMN

– WAM_LOOKUP_COLUMN

– WAM_PROCEDURE_CALL

• 10 tables total

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WAM: a web GUI fragment factory

• Entry page

• (Regular) Lists, List columns

• Detail lists– Stand-alone

– Embbeded

• Search Criteria

• Rows, Row fields, Lookup fields

• Context path, procedure callers, error reporting

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Fragment example: lookups

Pick from master list

See master row direct lookup

inverse lookup

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Demo – “Northwind” database

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Entry page

A default entry page, with all lists plus direct navigation to “interesting” tables

Uses WAM_TABLE_GROUP

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A user-configurable list

Automatic joins, both detail master and master detail

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Row with embedded list and 3 LKs

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Relational navigation extreme

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Editing the WAMmodel

• SQL client tools, or...

• WAMAdmin– A WAM application – Standard lists and rows for all WAMmodel tables

– Some utilities

– Complemented by runtime “edition mode”, adequate for administrators/power users

– Try it at http://showroom.declarativa.com

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WAMAdmin

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Editing the WAMmodel for a row

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Editing a WAMmodel tuple

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Back to the WAM equations

• So far we’ve seen...

• Web interface = WAM(DB Meta Information + WAMmodel)

+ Custom ASP pages using WAM objects+ other pages

• Default web interface =WAM(DB Meta Inf. + Default WAMmodel)

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Customized ASPs:WAM API

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An ASP invoked from a WAM list

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Beyond WAM – WIS Toolkit

• Making Web Information Systems real • The WIS Tookit contains WAM plus...

– “Calibrated” HTML printing

– Automatic email/fax communications

– Template-based document generator

– Automatic URL validation

– Extraction of structured data from (HTML) organizational knowledge documents

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Web Information Systems Toolkit

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WAM - Near Future

• Upcoming features– External documents/workflow

• Glean link structure, extended navigation

– PocketPC (with WAM’s WAP interface)– Full historical data, with interface– More data type-dependent formatting

• FLUX – “FleXible Logical Updates” project– “establish a flexible declarative language for the

specification of dynamic knowledge, and to apply it to realistic application domains”

– Universidade Nova de Lisboa + Declarativa– WAMmodel manipulation in Prolog

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Initial FLUX experiments(1)

• WAMmodel export/import utility (SQL/XSBProlog)– WAMmodel tables & views Prolog relations

• “Embedding detail lists that belong to aggregations”:- foreignKey(FK,Detail,Master,DColumns,MColumns),

table(Detail,_,BT), tableIndex(BT,PKcols,primaryKey), columnSubset(DColumns,PKcols), !, retractall(lookupColumn(FK,FK,_,_,_,_,_)).

columnSubset([],_) :- !.columnSubset([FKC-_|FKcols],PKcols) :- member(FKC-_,PKcols), columnSubset(FKcols,PKcols).

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Initial FLUX experiments(2)

• “Disable interface for columns changed by server code”:- uses(Type,_,table,Table,Column,update),

(Type=procedure;Type=trigger), assert(rowColumn(Table,Column,0,1,0)), fail.

• “Creating stored procedure calls”:- procedure(P,Args), not uses(_,_,procedure,P,_), table(T,Columns,BT), tableIndex(BT,PKcols,primary),

compatibleArgs(Args,PKcols,Columns), assert(procedureCall(T, row, P, 1, 0)), fail.

compatibleArgs(...) .- ...

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Conclusion

• How to reproduce the Demo• Pushing focus to the database layer

– The Declarativa project distortion field • Statistics

– Simple effort metrics

• Prospects for academic R&D– Make your models run

• How to build a tool in the “real world”– On adult supervision, genes and memes