© MIT 2000

Building Web Applications With Building Web Applications With WebjectsWebjects

Michael D. BarkerThe MIT Educational Media Creation

Center

November 2001

© MIT 2001

Key Parts of This PresentationKey Parts of This Presentation

n What's a Webject?n Graphic Views of the Servletsn Configuration Filesn Parameters

© MIT 2001

What's a What's a WebjectWebject??n Webject as one set of data (and a webjectlist as

a collection of webjects!)n A set of servlets, allowing handling of several

"standard" operations on data over the web by setting up the correct forms and configuration files. Notice that I did not say writing code –the servlets are deliberately designed to be generic, so that changes are made in the forms and configuration files, not the code.

n At this point in time, there are six webject servlets: Capture, Lister, Displayer, Revise, Deleter, and Publisher.

© MIT 2001

Key Parts of This PresentationKey Parts of This Presentation

n What's a Webject?n Graphic Views of the Servletsn Configuration Filesn Parameters

© MIT 2001

CaptureCapture

HTML Form

Capture Servlet Webject

List

Capture is used to collect information from a web form for ONE webject. Often, the web form is just a simple html page, with form action posting to capture.

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ListerLister

HTML Form

Lister ServletWebject

List

Lister generates a web form displaying information from all the webjects in a list.

HTMX Template

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DisplayerDisplayer

HTML Form

Displayer ServletWebject

List

Displayer generates a web form displaying information from a single webject.

HTMX Template

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ReviseRevise

HTML Form

Revise Servlet Webject

List

Revise is used to collect information from a web form to make changes for ONE webject. Almost always the web form is generated by displayer.

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DeleterDeleter

HTML Form

Deleter Servlet Webject

List

Deleter is used to remove one webject from the list. Often, it is invoked from a form generated by lister, although it is often useful to use displayer to generate a form showing the details of the webject being deleted to confirm that the correct object has been selected. (There is no undelete!)

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PublisherPublisher

HTMLFile

Publisher ServletWebject

List

Publisher generates a file containing a web form displaying information from all the webjects in a list.

HTMX Template

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Typical ApplicationTypical Application

(with apologies for torturing English)n Collect information (using Capture)n Display a list of results (using Lister)n With edit buttons (using Displayer) that

bring up forms whose submit changes the information (using Revise)

n And delete buttons (that bring up a form to confirm, then invoke Deleter)

© MIT 2001

Key Parts of This PresentationKey Parts of This Presentation

n What's a Webject?n Graphic Views of the Servletsn Configuration Filesn Parameters

© MIT 2001

Parameters, XML files, and Parameters, XML files, and suchsuch

n Every servlet has some parameters.n webject specification file n webject list file n Configuration in servlet zone properties

file (this will change with Tomcat!)n page templates (htmx templates)

© MIT 2001

Webject Webject Specification FileSpecification File<?xml version="1.0" encoding="UTF-8"?><defnspec docclass="edu.mit.emcc.webject.XMLObjectSpecFile" >

<parameter name="term" required="1" errorRequired="You must provide a term to be defined."

/>

<parameter name="definition" required="1"errorRequired="You must provide a definition for the term."

/>

<parameter name="SUBMIT" ignored="1"/><parameter name="Submit" ignored="1"/>

</defnspec>

Replace the parameter definitions with your data fields.

© MIT 2001

Possible AttributesPossible AttributesAmong the attributes that can be specified for a parameter are: n name="name" The name of the parameter. Required.n required="1" n errorRequired="message"n optional="1" (default)n ignored="1" (discard even if value present – good for discarding

submit)n multiple="1" May have multiple valuesn default="value"n equals="name" use value of namen defaultequals="name" use value of name as defaultn format="type" where type is one of name, extphone, phone, email,

state, zipcode, password

© MIT 2001

Webject Webject List FileList File

<?xml version="1.0" encoding="UTF-8"?><iplist type="iprange"specfile="../conf/iplistspec.xml" docclass="edu.mit.emcc.webject.WebjectList" webjectclass="edu.mit.emcc.webject.Webject"> <lastid>1</lastid></iplist>

© MIT 2001

Webject Webject List With Files FileList With Files File<?xml version="1.0" encoding="UTF-8"?><iplist type="iprange"specfile="../conf/iplistspec.xml" docclass="edu.mit.emcc.webject.WebjectList" webjectclass="edu.mit.emcc.webject.Webject"filestoredir="directory" (relative to the webject

file itself)filedirmaxsize="bytecount"fileurlprefix="url/prefix" > <lastid>1</lastid></iplist>

© MIT 2001

HTMX TemplatesHTMX Templatesn Normal HTML plus(Displayer and Lister)n <WEBJECTDATA name> : the value of name n <WEBJECTDATACHECK name>: CHECKED if

non-blank value n <WEBJECTDATASELECT name=value> :

SELECTED if valuen <WEBJECTDATAHTML name>: value escaped for

use in html form (e.g. " becomes &quot;)(Lister only)n <WEBJECTLIST count>: number of items in listn <FRAGREPEAT WEBJECT>...</fragrepeat>: repeat

for all elements in list

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HTMX TemplatesHTMX Templates

n <WEBJECTFILETYPE name> content-type of file

n <WEBJECTFILEURL name> URL for the file

n <WEBJECTFILETIMESTAMP name> last update time

© MIT 2001

Key Parts of This PresentationKey Parts of This Presentation

n What's a Webject?n Graphic Views of the Servletsn Configuration Filesn Parameters

© MIT 2001

Capture ParametersCapture ParametersMinimum:n servlet.AddTicket.code=edu.mit.emcc.webject.Capture

(alias)n servlet.AddTicket.initArgs=root=/development (root

directory to prepend to all other file names)n servlet.AddTicket.initArgs=capturepage=ListTickets or

servlet.Register.initArgs=capturepage=../lobby/register.html (html form, allows gets to servlet to redirect to form)

n servlet.AddTicket.initArgs=webjectlist=data/ccoach/accessinfo/tickets.xml (the webject list)

© MIT 2001

Capture ParametersCapture ParametersAdditional:n servlet. SomeName.initArgs=templatedir=<filename>

Directory where HTML templates are storedn servlet. SomeName.initArgs=successtemplate=<filename>

for successful submissions (default: capturesuccess.htmx)n servlet. SomeName.initArgs=errortemplate=<filename>

for validation errors (captureerror.htmx)n servlet.SomeName.initArgs=duplicatetemplate=<filename

> for duplicate keys (captureduplicate.htmx)n There is also a set of parameters to generate email – read

the code for details (list follows)

© MIT 2001

Capture Parameters (email)Capture Parameters (email)n servlet.SomeName.initArgs=mailserver=(address)n servlet.SomeName.initArgs=partialemailtemplate=(filename) n servlet.SomeName.initArgs=partialto=(address)n servlet.SomeName.initArgs=partialsubject=(subject)n servlet.SomeName.initArgs=partialfrom=(address)n servlet.SomeName.initArgs=completeemailtemplate=(filename) n servlet.SomeName.initArgs=completeto=(address)n servlet.SomeName.initArgs=completesubject=(subject)n servlet.SomeName.initArgs=completefrom=(address)

© MIT 2001

Capture Parameters (file Capture Parameters (file upload)upload)

n servlet.SomeName.initArgs=filetempdir=(directory)n servlet.SomeName.initArgs=filemaxpostsize=(int)Note: must be coordinated with change in webject list

file (see Webject List with Files)

© MIT 2001

Lister ParametersLister ParametersMinimaln servlet.SomeName.code=edu.mit.emcc.webject.Lister

(alias)n servlet. SomeName.initArgs=projectroot=<directory>

(root of files)n servlet. SomeName.initArgs=webjectlist=<filename>

(data list)n servlet. SomeName.initArgs=templatedir=<filename>

(where are the templates)

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Lister ParametersLister ParametersOptionaln servlet. SomeName.initArgs=listtemplate=<filename>Defaults to listtemplate.htmxn servlet. SomeName.initArgs=mimetype=<mime-type>Defaults to text/htmln servlet. SomeName.initArgs=sortby=<fieldname>n servlet. SomeName.initArgs=sortmethod=<text|date>Defaults to textn servlet. SomeName.initArgs=daysback=<number>How many days back to include (defaults to all) Often

entered in url (servlet name?daysback=5 for example)

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Lister Request ParametersLister Request Parametersn daysback=nn sortby=fieldnamen sortmethod=text|daten selectby=fieldnamen selectvalue=value

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Publisher ParametersPublisher Parametersn All the Lister parameters plus:n servlet.Publisher.initArgs=success=[filename]

(relative to templatedir)n servlet.Publisher.initArgs=failure=[filename]

(relative to templatedir)n servlet.Publisher.initArgs=outfile=[filename]

(relative to projectroot)

© MIT 2001

Displayer ParametersDisplayer Parameters

Minimaln servlet.SomeName.code=edu.mit.emcc.webject.Displayer

(alias)n servlet.SomeName.initArgs=projectroot=<directory> (root

for files)n servlet.SomeName.initArgs=webjectlist=<filename> (data

list)n servlet.SomeName.initArgs=templatedir=<filename>

© MIT 2001

Displayer ParametersDisplayer ParametersOptionaln servlet.SomeName.initArgs=webjecttemplate=<filename>Defaults to webjecttemplate.htmxn servlet.SomeName.initArgs=notfoundtemplate=<filename>Defaults to notfoundtemplate.htmxn servlet.SomeName.initArgs=idsource=<param|auth|username>How to get id of webject. Defaults to parameter (ID=xxx).Also accepts auth (look up user in webject list) andusername (a username parameter will be supplied)

© MIT 2001

Revise ParametersRevise Parameters

Minimaln servlet.SomeName.code=edu.mit.emcc.webject.Revise

(alias)n servlet.SomeName.initArgs=projectroot=<directory>n servlet.SomeName.initArgs=editpage=<URL>n servlet.SomeName.initArgs=webjectlist=<filename>n servlet.SomeName.initArgs=templatedir=<filename>

© MIT 2001

Revise ParametersRevise Parameters

Optionaln servlet.SomeName.initArgs=successtemplate=<filename>Defaults to revisesucess.htmxn servlet.SomeName.initArgs=errortemplate=<filename>Defaults to reviseerror.htmx

© MIT 2001

DeleterDeleter ParametersParameters

Minimaln servlet.SomeName.code=edu.mit.emcc.webject.Deleter (alias)n servlet.SomeName.initArgs=projectroot=<directory>n servlet.SomeName.initArgs=webjectlist=<filename>n servlet.SomeName.initArgs=templatedir=<filename>

Runtimen SomeName?ID=xxxxx

OrSomeName?id=xxxxxx

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DeleterDeleter ParametersParameters

Optionaln servlet.SomeName.initArgs=deletedtemplate=<filename>Defaults to deletedtemplate.htmx

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Likely Future Additions to the Likely Future Additions to the Webject Webject LibraryLibrary

n "archive" – put a class of webjects into another file and remove from the "active" file

n Conversion to use mySQL, Oracle, or other database

n Multi-valued field displayn Faster listern Basic webject build tool

© MIT 2001

For Additional InformationFor Additional Information

n <https://web.mit.edu/emcc/Private/library/webjects.html> Brian Bermack's original documentation

© MIT 2001

You Can Reach Us...You Can Reach Us...

n Michael Barker– mbarker@mit.edu– 617/253-0119

nEMCC website: http://web.mit.edu/emcc/