Modernizing Java Ser ver Pages By Transformationpost.queensu.ca/~trd/research/pres/WSE2005.pdf ·...

Modernizing Java Server Pages By

TransformationS h a n n o n X u

T h o m a s D e a nQ u e e n ’ s U n i v e r s i t y

Background CSER - Consortium for Software Engineering Research Dynamic Web Pages

Multiple Technologies - CGI, shtml, JSP, ASP, .NET Mixing Code and Data

Ok for small projects, seems to be proving a detriment to larger projects

Separate Concerns: Application Code and Graphics Design

Abstract User Interface [Schneider 2001] Custom Tags (JSP)

replaces code with abstract tags

JSP Basics

Mix Java and Template Text Template Text is sent to browser

modified by inline Java HTML, Javascript, Applet Tags, CSS

Java Code + standard Actions <% for (int i = 0; i < bean.titles.length; i++) {

%> <jsp:useBean> forward pages, import classes, declare fields

and methods

Custom Tags<%taglib uri=”xxx” prefix=”mylib”%>…<mylib:cdtitle/>…

<taglib> <uri>xxx</uri> <tag> <name>cdtitle</name/> <tag_class>CdTitle</tag_class> </tag></taglib>

CdTitle.class

Requirements

No Change to Functionality Identical Behaviour

No change to Appearance Same HTML / Javascript is generated

to browser Same web site structure (paths to pages) Keep Code Comments

Maintenance Issue

MuiltiLingualGrammar [Synytskyy03]

HTML Base Grammar

ASPGrammar


HTML Base Grammar

JSPGrammar

[Li 2004]


HTML Base Grammar

JSPGrammar

Custom TagGrammar

TLD XMLGrammar

[Li 2004]

[Xu 2005]

Parsing JSP …<table> <%for(i=1;i<10;i++){%> <th><td><%=i%></td></th>

<%}%> </table>…

Interesting

<table>

Interesting

<%for(i=1;i<10;i++){%>

Interesting

<%=i%>

Interesting

<%}%>

Interesting

</table>

Parsing JSP …<table> <%for(i=1;i<10;i++){%> <th><td><%=i%></td></th>

<%}%> </table>…

Interesting

<table>

Interesting

<%=i%>

<%

</table>

}

%>

for(i=1;i<10;i++){

<% %>for_statement

Java statements, expressions and declarations are moved to custom tag classes

HTML code moved out of Java strings

out.println(“<TR><TD>”)

%> <TR><TD> <%

General Approach

Java Bean action elements translated to equivalent Java Code

<jsp:useBean><jsp:getProperty><jsp:setProperty>

JSP Page import directive generates an import statement in the resulting class

<%@page import=”java.sql.ResultSet” %><% import java.sql.ResultSet; %>

General Approach

Normalization

4 General Cases

General Transformation

Case 1– Simple Code<HTML><BODY><% HttpSession s = request.getSession(true); String userId = ((String) s.getValue(“userId”)).trim(); s.putValue(“username”, userId);%></BODY></HTML>

<HTML><BODY><mylib: userSession></mylib:userSession></BODY></HTML>

Case 1b – Simple Code<HTML><BODY><% HttpSession s = request.getSession(true); String userId = ((String) s.getValue(“userId”)).trim();%> Welcome<% s.putValue(“username”, userId); %></BODY></HTML>

<HTML><BODY><mylib: userSession> Welcome</mylib:userSession></BODY></HTML>

Case 2 - Nested Code<HTML><BODY><% HttpSession s = request.getSession(true); String userId = ((String) s.getValue(“userId”)).trim(); s.putValue(“username”, userId);%>Welcome <%= username %></BODY></HTML>

<HTML><BODY><mylib: userSession> Welcome <mylib:userName/> </mylib:userSession></BODY></HTML>

Case 3 – Choice<HTML><BODY><% …

if (condition) {%> HTML TEXT <% } else {%> … }%></BODY></HTML>

Case 3 – Choice<HTML><BODY><% … bool choice = condition; if (choice) {%> HTML TEXT <% } if (!choice) {%> … }%></BODY></HTML>

Case 3 – Choice<HTML><BODY><mylib:checkCondition> <mylib:validCondition> HTML TEXT </mylib:validCondition> <mylib:invalidCondition> </mylib:invalidCondition></mylib:checkCondition></BODY></HTML>

CASE 4 - Iteration<HTML><BODY><% … while(condition){%> HTML TEXT <%}%></BODY></HTML>

<HTML><BODY><mylib:whileCondition> HTML TEXT</mylib:whileCondition></BODY></HTML>

The 4 cases compose to cover all code cases

Case 2 provides basis for nesting

tags are nested, classes are not

classes find the class for the parent tag at runtime using JSP API

Add get/set routines for variables

Composing Cases

Nesting Cases 4,2<HTML><BODY><% … while(condition){%> HTML <%= value %> TEXT <%}%></BODY></HTML>

<HTML><BODY><mylib:whileCondition> HTML <mylib:getValue/> TEXT</mylib:whileCondition></BODY></HTML>

Implementation

TXLSource Transformation LanguageGrammar + Transformation Rules

Markup ApproachIdentify key statements of each case

if statements, while statements (both with HTML text)

propagate markups to include all statements

Implementation

Preprocessing

Grouping

Original JSP

Naming

Postprocesing

Page and TLDClass Gen

TLD Pages Tag Classes

Implementation

Preprocessing

Grouping

Original JSP

Naming

Postprocesing



Normalization& Lexical Issues

Implementation

Preprocessing

Grouping

Original JSP

Naming

Postprocesing



Custom Tag Identification

Implementation

Preprocessing

Grouping

Original JSP

Naming

Postprocesing



Namesfor Tags

Implementation

Implementation

Preprocessing

Grouping

Original JSP

Naming

Postprocesing



Move to Java

Implementation

Preprocessing

Grouping

Original JSP

Naming

Postprocesing



RemoveJava

Implementation

Preprocessing

Grouping

Original JSP

Naming

Postprocesing



Comments

Final Words

Tested on 4 small systems (14 files)

Each case generates separate custom tags

Implementation is a greedy approach

Better separation into tags

Data and Control Flow Analys

Clones

E.g. Session management code

Questions?

Modernizing Java Ser ver Pages By Transformationpost.queensu.ca/~trd/research/pres/WSE2005.pdf ·...

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