Makumba Specification

Types, objects, databases

Data definitions describe data types (or classes). They are placed in files contained in directory hierarchies, and the directory name is part of the type name (similar to Java packages). For example the file best/Student.mdd describes the type best.Student. Type names can contain letters, digits, underscores and dashes and cannot contain slashes and dots. Usually, the directories are used to separate organisations and projects.

Data objects (records) are stored in databases.

The actual implementation of the database is not part of this specification but implementation suggestions will be made. Data can be copied and/or replicated between different databases, even between different DB engine types.

Fields

Every data definition file contains field definitions, separated by newline.

A field definition looks like:

fieldname= [attributes] fieldtype [parameters] [; description]

(Automatic labeling: The field description might be used at interface levels to present that field. It is typically shown at the left of, or somewhere near to, the input control (text box, radio button, chooser, etc) that allows for data input in that field. If a field description is not present, its field name stands for its description by default.)

Comment lines can be inserted in the data definition files as follows:

# your comment...

Default fields

Every datatype has some additional fields by default, as follows:

• Primary Key field, consisting of two parts [DBSV with 8 bits | UID with 24 bits]:
  • Database identifier (DBSV). It is unique (within the webapp) per database. All objects created thru that webapp and in that database get the same value. It is set by property dbsv in the database config file.
  • Object identifier (UID): unique id for the object in the given database.
  
  This combination ensures that no two objects of one type have the same primary key field. See how to configure this.
  The name of the primary key field is the same with the last part of the type name. If another field by that name is defined by the makumba user, this field will be renamed in the database.
• Object creation time
  Can be accessed as TS_create.
• Last modification time. Updates whenever the object is changed. The initicial value is TS_create.
  Can be accessed as TS_modify.

Simple field types

int

A 32-bit integer. For example

shoeSize= int; Shoe size

If the int can have a limited number of values, it can be described as follows

gender= int{ "male"=0, "female"=1 }; Sex

This will help the presentation layer to present a suitable input control (e.g. male female )

real

A real number with double precision with (2-2^-52)·2¹⁰²³ as max value and 2^-1074 as min value. For example:

high= real; high of a person

char

A char field contains a number of characters. Maximal width must be specified and is limited to 255. (Optionally a minimal number of characters (lesser than max) can be indicated). Both must be positive integers. For example:

#fieldName= char[maxWidth]
name= unique char[80]; Username
password= encrypted char[6..10]; Secret password

"unique" and "encrypted" are field attributes, explained below.

DEPRECATED (use int{...} instead): If the char can have a limited number of value, it can be described as follows

gender= char{ "male", "female" }; Sex

This will help the presentation layer to present a suitable input control (e.g. a HTML SELECT)

boolean

A boolean, that can take as values true or false. For example:

hasChildren= true; whether this person has children

text

An unlimited-length string of characters. This type is designed to accommodate large text content. It is implemented with LONGTEXT or its counterparts, depending on the underlying DB engine. The text data-type is ready for accepting data in UTF-8 encoding.

application= text ; Application letter
description=text  ; Description of object

binary

An unlimited-length field designed for binary content. In contrast to the text data type, binary will always be of 8 bit length. It is implemented with LONGTEXT or its counterparts, depending on the underlying DB engine. This type is meant for storing only raw binary data, for storing files along with meta-data like a file name, content type, etc., you should rather use the file data type.

singature= binary    ; a binary digital signature

date

A date and/or time.

birthdate= date; Date of birth
arrivalTime= date; Arrival time

Structural (relational) types

Pointers (ptr)

Pointers define a reference to an object of a certain type. For example

citizenship= ptr general.Country; Citizenship

The type can be defined on-the-spot for a single usage. For example

addres= ptr ; Address
address->street= char[80]; Street
address->number= int; Number

address= ptr{
    street= char[80]; Street
    number= int; Number}; address

Sets (set, bag, list)

Sets define a number of references to multiple objects of a certain type. For example:

language= set general.Language; Spoken languages

This type accomodates sets, bags and lists. The set and list constraints (sets have to contain only one element of a certain value and lists have to be ordered) have to be cared for by the programmer. Lists are easy to represent, just having an integer field, for the order.

The type which the set is made of can be defined on the spot:

addresses= set; Addresses
  addresses->street= char[80]; Street
  addresses-> number= int; Number

addresses: set{
    street: char[80]; Street
    number: int; Number }; Addresses

The set can contain enumerated int values :

place= set int {"home"=1, "away"=0} ; Home or away

DEPRECATED: The set can contain enumerated char values :

place= set char {"home", "away"} ; Home or away

File

A file data-type is a kind-of record containing several fields needed when wanting to store files. These fields are:

• content (binary): the actual binary data of the file.
• name (char): the file name.
• originalName (char): the original file name.
• contentType (char): the MIME content-type of the file.
• contentLength (int): the content length in byte.
• imageWidth (int): (only for images) the image width.
• imageHeight (int): (only for images) the image height.

image= file    ; Picture attachment

All fields are automatically set by Makumba, all needed to do is to make a <mak:input> on the field name.

This type should be used in favour of the binary data type when you don't want to store only the raw binary data, but also meta-data as in the fields above.

Macro types

A name can be defined for a more complex type and it can be reused in the file. This can be done with a !type directive

!type.yesno= int{"yes"=1, "no"=0}
!type.rank= int{"neutral"=0, "very good"=5, "very bad"=-5}
married=yesno
happyInLife=rank

Field attributes

• fixed fields can only set during the record's insertion in the database. The subsequent updates will not update the field
• not null fields will produce a exception if an attempt is made to insert/update without them being initialized
• unique fields have a unique value in the respective object, for the respective type
• (encrypted fields are encrypted when written to the database and decrypted when read)

Object title

One of the fields is always the object title, and is normally presented differently from other fields in user interface. For example, when you have a field that is a set and you use a mak:input on that field, Makumba will automatically create a list with all the items in the set and it will use the object title to know what field to display. The default is the field called "name" if that exists, otherwise it is the first non-pointer field in the record description. If another field needs to be title, it can be specified like

!title=gender

address->!title= street

Include mechanism

A record description can include text from one or more files. This is declared as

!include=name_of_included_type

The included file has the idd extension and is found in a similar way like the data definitions.

The included file is inserted instead of the !include line. There can be more include lines in a record description file. If a field is defined that exists also in the included metadata, the defined field takes precedence. If

fieldname=

it means that it does not actually exist. this can be used to cancel an included field.

Validation Rules

Validation rules are defined inside a data definition, and allow Makumba to automatically validated form data input.

The general syntax of a validation rule definition is as follows:

[fieldName or ruleName]%[ruleType] = [validation rule] : [error message]

FieldName / ruleName and ruleType

For validation rules that operate on one specific field only, you have to use the name of the field; this applies to number range, string length and regular-expression rules. For other rules, instead of a field name, you specify the validation rule name, which serves an identifier which should be unique. The exact usage of the identifier is not yet specified, but it could be used in the future to centralise error messages or provide translations into other languages, etc.

The ruleType can be one of the following: [range | length | matches | compare | unique]

Validation rule

The validation rule specifies what should be validated, and can be one of the following

[range validation | string length | regular expression | comparison | multi-field uniqueness]

Number range rule

The range definition rule applies for Number types, i.e. int and real. The [validation rule] is defined as:

[fieldName]%range = [1..10]

Using ? allows to keep one parameter unbound, which will default to java.lang.Integer.MIN_VALUE and java.lang.Integer.MAX_VALUE, respectively, i.e. +/- 2³¹-1.

To require that the age needs to be between 12 and 99:

age%range = [12..99] : Age must be between 12 and 99!

To define that we need to be at least 5 year old, but without any upper limit:

age%range = [5..?] : Age must be at least 5!

String length rule

The length definition rule is very similar to the range definition, but applies for string types, i.e. char and text. The [validation rule] is defined as:

[fieldName]%length = [1..10]

Using ? allows to keep one parameter unbound, which will default to a minimum length of 0 and a maxium length of 255

To define that the CV needs to be at least 100 characters, define:

cv%length = [100..?] : CV must be of decent length!

Regular expression rule

The string regular expression rule applies for string types, primarily for char, but also for text. The [validation rule] is defined as:

[fieldName]%matches = regular expression

Regular expressions must be valid regular expressions in Java, for more details please refer to the specification and tutorial.

To compare if a field contains a valid e-mail address, define:

email%matches = .+@.+\.[a-z]+ : Email address is not valid!

Comparison rule

This rule allows to compare a field to a constant value or simple function calls.

The following constants are currently available:

The following functions are currently available:

date($now,$now,$now - 5)

Valid comparison operators are the ones defined in Java:

To compare if someone is at least 15 years old, define the following validation rule:

minimumAge%compare = birthdate >= date($now,$now,$now - 15) : You have to be at least 15 years old!

To ensure that a field doesn't contain only lower-case values, define this rule:

nameNotAllLower%compare = lower(name) != name : Your name must not contain only lower-case letters!

Two fields can be compared in a similar way

graduationCheck%compare = birthdate < graduationDate : You cannot finish school before your birthdate!

Multi-field uniqueness definition

Similar to the unique field attribute, you can also define multi-field uniqueness contraints. These constraints can even span over several data definitions, if they are related via pointers.

Multi-field uniqueness can be defined as follows

uniqueAgeEmail%unique = age, email : the combination of age and email must be unique! 

Error message

The error message that will be displayed if the validation fails.

MQL

As of Makumba version 0.8.1., the default query language is 'MQL', Makumba Query Language. MQL builds upon Hibernate's HQL.

MQL Functions

MQL provides support for functions that will translate into SQL functions. Currently, the following functions are supported:

String functions

SELECT 'makumba!' REGEXP '[a-z]*'; 
 -> 1

Date functions

SELECT EXTRACT(YEAR_MONTH FROM '2009-07-02 01:02:03');
 -> 200907

SELECT '2008-12-31 23:59:59' + INTERVAL 1 SECOND;
 -> '2009-01-01 00:00:00'

OQL

Before Makumba version 0.8.1, the default query language was OQL. OQL is similar to SQL, a specification can be found at http://www.odmg.org (or check this PDF). Makumba recognized a subset of OQL, which it translated to the host SQL when necessary. The following language was accepted ([] means optional, {} means any number of repetitions):

SELECT expression [[AS] label] {, expression [[AS] label] }
FROM {type [AS] label | label.field{.field} [AS] label }
[   WHERE expression
    [    GROUP BY expression {,expression}
        [  HAVING expression {,expression}  ]
    ]
]
[ORDER BY expression {,expression} [(ASC|DESC)] ]

Notations like label.field{.field} only allow "field" to be of pointer type in expression and set type in FROM. In expressions, also label.ptr{.ptr}.simplefield is valid.

If a label, representing a type, appears alone in an expression, a default field will be added. The default field depends on the type of the label:

• for set XXX types (sets of foreign objects), the label denotes the pointer to the set member
• for set int { } and set char { } types, the label denotes the set member (i.e. and int or a string)
• for all other types, the label denotes the pointer to that object

ms.account_active=1 OR ms.account_active=nil

Hibernate Query Language - HQL

Makumba also integrates Hibernate, thus allowing to take full advantage of hibernate's query language HQL. For documentation, please see the Hibernate Query Language BNF.

To enable Hibernate in JSP pages, you have to import a different TLD than normally:

<%@ taglib uri="http://www.makumba.org/view-hql" prefix="mak" %>

Makumba focuses on combining query fragments to obtain high-performance systems with a minimum number of queries sent to the database back-end, while keeping its concerns about easy learnability and rapid development. The mak:list engine already combines query fragments for embedded mak:lists by combining their FROM and WHERE sections, but we found a need for a better formalization and sharing of query fragments across the sytem. The elementary concept of such formalization is the MDD function.

MDD Functions

A simple function for an MDD called Leveler that has a level integer field looks like

level=int

function(int a) { level+a }

SELECT label.function($param) FROM Leveler label

SELECT label.level + $param FROM Leveler label

Some properties of MDD functions:

• If the underlying query language allows it, functions can use subqueries.
• If functions wish to refer to the owner object, functions can use this which will be inlined with the label or the expression denoting the object in the query
• If a function is not using MDD fields at all, then it is static and can be invoked like MDDname.function(params)
• If functions wish to define labels, they can use a FROM section and if needed a WHERE section to constrain the labels defined.

The main uses of MDD functions are:

• reuse of query code
• query simplification and improved lisibility
• authentication using well-known function names
• authorisation using well-known function names
• data view using well-known function names

Function specification

The complete specification of function definition is as follows:

[sessionVar%]function([type parameter]*){ expression [FROM supplementaryLabels [WHERE condition]]} [errorMessage] [; comment]

• sessionVar may be used for MDDs that define actors (or those related to them) to indicate the name of a session variable where the function result will be stored. This is only possible for functions with no parameters. (this is currently implemented but may be deprecated)
• parameter type can be either the primitive types (int, char, date, text, binary, boolean) or an MDD name
• expression is a query language expression and may use MDD field names, this, function parameter names, supplementary labels (see below), other functions calls, actor invocations and $attributes from the query context
  • Since functions are inlined, recursive calls are not possible
    (this is not yet checked though)
  • $attributes are discouraged because using them would mean counting on "global variables", it is advised that they are passed as function parameters (in case of e.g. page parameters or page/request attributes), or that actor invocations are used to retrieve session attributes
• supplementaryLabels may need to be defined, in which case a normal query language FROM section is used
• sometimes conditions are needed to join the supplementary labels with this.
  • supplementaryLabels and WHERE conditions are currently not implemented
• if the function is boolean and returns false, an error message will be needed to construct an exception e.g. when an actor() function fails (UnauthenticatedException) or when a canRead() function fails (UnauthorizedException). If that functions calls other functions, their error messages might be composed to provide a more accurate reason for failure.

actor(MDDname) invocations and actor() functions

Actors are a special type of function that, when mentioned in queries or functions, may trigger authentication. An actor invocation looks like

actor(MDDName)

and a query invoking it may be

SELECT actor(Person).name 
SELECT obj.hasDoneJob(actor(Person)) FROM SomeType obj

These queries are inlined as follows:

SELECT actor_Person.name FROM Person actor_Person WHERE actor_Person=$actor_Person
SELECT obj.hasDoneJob($actor_Person) FROM SomeType obj 

(in the second example, the function hasDoneJob() will be inlined further)

$actor_Person is a special attribute retrieved from the query context. The query context handler will check for the attribute and if it is not defined, it will look in the MDD indicated by the actor attribute name (Person) for actor functions. Assuming that Person has a username and a passoword field, some actor functions may look like

username=char[255]
password=char[255]
actor(char[] user){username=user }
actor1(char[] admin){ username=admin }
actor2(char[] user, char []pass){ username=user AND password=pass }

First, the context handler will look for a suitable function to use. For example if the attribute user is defined in the context, the first function (actor()) will match. However if both the attributes user and pass are defined in the context, the actor2() function will match (so the function with most matching parameters will be chosen). Finally, if the admin attribute is found, the actor1() function will match.

The functions above correspond to different authentication mechanisms that may be used. The first two functions use an external authentication mechanism, where the role of a correctly authenticated user is provided. In such a case, the Makumba query context handler will define an attribute with th role as name (user, admin) and the username as value. The third function (actor2()) will be useful when authentication is managed by the web application (for example using the mak:login feature) and the authentication data is passed as request parameter, in this case they are expected to be called user and pass.

Once a function has been selected (say actor2()) the following query is ran:

SELECT x FROM Person x WHERE x.actor($user, $pass)

which inlines to

SELECT x FROM Person x WHERE x.username=$user AND x.password=$pass   

Once the actor is authenticated, the $actor_Person attribute is put in the session part of the query context. It can be removed using <mak:logout actor="Person" /> . Some fields of Person (the MDD declaring the actor) may also be put in the session, along with the results of functions with no parameters, and along with related objects.

Explicit authorisation constraints

Explicit authorisation constraints are associations between web application paths and query language expressions. When an access is made to a resource whose path matches an authorisation constraint (partial matches supported, longest match considered), the corresponding expression is evaluated. If the expression produces an error (like UnauthenticatedException), that will be handled. If the exception returns 0, false or null an UnauthorizedException is raised with an error message indicated in the constraint.

Currently explicit authorisation constraints can be put in the file MakumbaController.properties. authorisation constraints looks like:

authorize%/={actor(Person)}
authorize%/admin=(char[]admin){actor(Person).username=admin} You are not an administrator 

The first example makes the whole site accessible to users who can authenticate as a Person actor.

The second example makes the /admin part of the site accesible only if there is an admin attribute in the context, and if that is the username of the Person actor. If any constraint fails, an UnauthorizedException will be raised. The second example also shows how to indicate a specific message for the exception, which will then be displayed to the user.

Implicit authorisation constraints (not yet implemented)

Implicit authorisation constraints are defined in functions like canRead(), canInsert(), canUpdate(), canDelete() in the respective MDDs. These functions will be used whenever a mak:list, mak:object or mak:*Form attempts to view, create, change or delete an obect of the respective type. The following features are intended:

• filter out from mak:list and mak:object objects that the user is not authorized to see, but do not raise any exception if there are such objects.This will probably be the default for mak:list
• block access to the whole page if the user is not authorized. This will probably be the default for mak:object, and mak:*Form
• not link to a page that is not authorized

Query execution context

A query execution context is a set of known attributes. In the case of JSP this concept maps on the page, request, and session attributes, as well as request parameters. If however application logic is executed before launching a JSP, the context will be made of the session and request attributes and of request parameters. This is managed by two different query context handlers (implementing the interface Attrributes) and other such handlers can be defined.

Actor functions define a special type of session attributes that are computed based on other attributes from the query context.

Makumba in Java Server Pages

Makumba tags are written according to Servlet 2.3 specification and JSP 1.1 specification. You will need a so-called "servlet container" that supports them both, such as Apache Tomcat. The corresponding WEB-INF/makumba.tld is already included in the distribution makumba.jar. The example WEB-INF/web.xml can be found in Makumba cvs repository.

Before using Makumba tags in your JSP pages you also need to declare the taglib with:

<%@ taglib uri="http://www.makumba.org/presentation" prefix="mak" %>

A few resources on JSPs (don't be afraid to try first, read later) :

• JSP documentation by Sun
• J2EE web services documentation by Sun. This is an introduction on the various technologies that you might use when building webapplications using Java2 (J2EE).
• Gentle introduction to JSPs

Makumba Controller

The makumba controller is a component running in the 'servlet container'. When a request for a makumba page enters the servlet container, the controller will intercept the request, and perform its "controller" activities (cfr. the model-view-controller pattern) :

• checking if the page has the appropriate attributes (see handler initialisation; e.g. force login).
• checking if the page request is the result of a form submit or a deleteLink. If so, perform the relevant actions in the handler and database.
• deal with problems (exceptions) during the controller activity:
  • if org.makumba.LogicException is thrown, the Exception can write a message to the <mak:response> in the requested page.
  • org.makumba.UnauthenticatedException and org.makumba.UnauthorizedException will force login (although UnauthorizedException probably shouldn't, bug 444)
  • if another exception occurs, an errorPage will be shown instead of the requested page.

For this to work, the correct configuration must be applied in WEB-INF/web.xml (example file). The following would tell the makumba controller to filter all requests for .jsp files.

  <filter>
     <filter-name>makumba_controller</filter-name>
     <filter-class>org.makumba.controller.http.ControllerFilter</filter-class>
  </filter>

  <filter-mapping>
    <filter-name>makumba_controller</filter-name>
    <url-pattern>*.jsp</url-pattern>
  </filter-mapping>

Note that if (in this example) the result page for a makumba form would be an .html page, then the makumba controller would not intercept the .html page request, and the actions implied by the form, would not be performed.

JSP tag parameters

JSP-tag parameter values are either FIXED or RTEXPR (runtime expression). A FIXED tag parameter must have a constant, literal value, while an RTEXPR can also be of the form <%= java_expression %>. On the other hand, some FIXED parameters can contain jsp attributes like $attr in makumba tags.

All parameters are optional unless specifically mentioned as being mandatory.

Specific concern can be the parameter quoting. Tag parameters can be written as name="value" or name='value' (note: the stringLiteral on DATE must be quoted with "). The choice of quote can be determined by the need to use either double or single quote as part of the value itself. If the quote is also present within the value, it must be escaped by a backslash.

  <mak:list from="general.Person p" where="p.gender=\"male\"" >
  <mak:list from="general.Person p" where='p.gender="male"' >
  <mak:list from="general.Person p" where="p.gender='male'" >
  <mak:list from="library.Book b" where="b.publisher=\"O'Reilly\" " >    
  <mak:list from="library.Book b" where='b.publisher="O\'Reilly" ' >

Quotes in extra HTML formatting parameters, such as styleClass, title, styleId, onClick ... need some special attention with quotes. The parameter values are copied verbatim (with no modifications by makumba) to the resulting HTML, always surrounded with double quotes ("). This means that you have to use other quotes, like single one ('),
If you need to pass a literal backslash (\) you have to escape it with a preceeding backslash (\\).

  <mak:input ... onClick="alert(this.value);"/>
  <mak:input ... onClick="alert('Hello world!');"/>
  <mak:input ... onClick="alert('Hello\\nWorld');"/>

Unfortunately the idea to use a sequence of escapes, eg writing \\\' in the JSP page to set the tag attribute to \', which could be handy for javascript tag attributes, is confusing the Tomcat servlet container.

<mak:response/>

<mak:response/> prints information about the results of the actions that were performed by the makumba controller (e.g. for a form submit or deleteLink): It either displays the message="..." parameter of the form tag (in green) in case of success, or (in red) the message of a uncaught LogicException resulting from Business Logic. Other exception types will provoke an exception page.

The unformatted message is available as request-scope attribute makumba.response. The jsp page can get hold of the message using e.g.

<% String s = (String) request.getAttribute("makumba.response") %>

Similarly, request-scope attribute makumba.successfulResponse is set only in case of successful action execution.

<% if (null == request.getAttribute("makumba.successfulResponse")) { /* action failed */ } %>

(A body-tag style (<mak:response>...</mak:response>) will be added later, to display different messages for different circumstances (errors). It will also be possible to get hold of the actual exception object. )

<mak:list...>...</mak:list>

Performs a query on the database. The body of the list, if present, is run once for every item in the resulting data (size 0..N), e.g. to display it. Queries are generated on the spot and can be nested.

Example:

<mak:list from="best.Student s, s.person p" where="p.gender=\"male\""
          orderBy="p.name">

    <c:if test="${mak:count()==1}">
       <p> There are ${mak:maxCount()} male students:
    </c:if>

    <br> <%= counter %>.
    <mak:value expr="p.name"/>
    <mak:value expr="p.surname"/> <br>
    <mak:list from="p.addresses a">
       <mak:value expr="a.streetno"/> <mak:value expr="a.city"/>
    </mak:list>
</mak:list>

<c:if test="${mak:lastCount()==0}"> There are no male students. </c:if>

<mak:object  ...>.... </mak:object>

Like list, but the query can only have zero or one result. A zero value for maxCountVar and countVar indicate that the object does not exist.

Example: See <mak:list>.

Attributes and OQL in <mak:list > and <mak:object >

Attributes are accessible through $AttributeName to any makumba tag. Typically they will be present in OQL sections instead of $number attributes (therefore the OQL sections of these tags is not "pure"). For example:

<mak:list from="best.internal.Lbg"
          where="lbg.country=$country"
          orderBy="lbg.$lbg_order">
  .....
</mak:list>

If a $ (dollar) sign needs to be in the string, the escape is $$.
If at the end of an attribute there has to be a Java identifier letter, the attribute name can be written as text1$attrName$text2, that is, with $ at both ends.

The http parameters are automatically set as page attributes. Other attributes can be set by the Java code as attributes in any scope (page, request, session, application) using pageContext.setAttribute(name, value, scope).

The query generator is setting all the attributes that are logically possible as prepared query parameters. For example, the $country above is a query parameter since it's a value, but the $lbg_order will not be accepted as query parameter, since it's a field name.

If an attribute has multiple values, it is expanded into multiple OQL parameters. For example:

<mak:list from="best.internal.Lbg" where="lbg.status in set($status)" >

<mak:value  .../>

Displays the value of an expression from within the query.

Example:

<mak:list from="best.Student s, s.person p"
 where="p.gender=\"male\"" orderBy="p.name">
    <mak:value expr="p.name"/>
    <mak:value expr="p.surname"/>
    <mak:value expr="p.birthdate" var="birth" printVar="printBirth"/>
    <% // we only print the birthdate if it's after some date
         if ( ((java.util.Date)birth).after(new java.util.Date(1980, 0, 1)) )
             out.print(printBirth);
    %>
    <mak:value expr="s.person.favoriteQuote" maxLength="60" addTitle="auto" />
</mak:list>

mak:count(), mak:maxCount(), mak:lastCount()

• mak:count() gives the number of the current iteration inside a mak:list or mak:object. It has no value outside that tag.
• mak:maxCount() gives the total number of iterations inside a mak:list or mak:object (1). It has no value outside that tag.
• mak:lastCount() gives the total number of iterations of the previous mak:list or mak:object, respectively. It has no value inside the mak:list/object.
  Note: if you want to store the value of some mak:list/object for usage in/after a later mak:list/object, you can do that with <c:set var="someVariableName" value="${mak:lastCount()}" just after that mak:list/object.

<mak:list ...>
   <c:if test="${mak:count()==1}">These are the list elements: </c:if>
   <tr bgcolor="${mak:count()%2==1?"white":"grey"}">
       <td>this shows in alternative colors</td>
   ...
   <c:if test="${mak:count()!=mak:maxCount()}">
       a separator where we can have any <b>tag</b> 
       we don't want separators to be shown after the last element 
   </c:if>
</mak:list>
<c:if test="${mak:lastCount()==0}">These are no elements </c:if>

<mak:if  ...> ... </mak:if>

Displays the body of the tag only if the OQL expression evaluates to true.

Example :

<mak:list from="best.Student s"
   where="s.person.birthdate <> nil" orderBy="s.name">
   <mak:value expr="s.person.name"/>
   <mak:if test="s.person.hideAge = 0">
      was born on <mak:value expr="s.person.birthdate" />
   </mak:if>
</mak:list>

<mak:pagination  .../>

Provides pagination of the results in an enclosing <mak:list>. The tag provides links to the first, previous, next and last item in the result set, and the page number currently displayed.
To achieve this, pagination makes use of the information provided by the enclosing <mak:list>, i.e. the offset and limit, and automatically computes the total of rows that would be returned by the list, if no limit was specified.

Example:

<mak:list from="best.Student s" offset="$offset" limit="$limit" defaultLimit="25" orderBy="s.name">
  <mak:pagination action="studentList.jsp" title="true" itemName="Students" />
  <mak:value expr="s.person.name"/>, born on <mak:value expr="s.person.birthdate" />
  <mak:pagination action="studentList.jsp" title="true" itemName="Students" />
</mak:list>

<mak:attribute  .../>

Displays the value of an attribute, or sets it to a Java variable.

Example:

<mak:attribute name="pattern" var="pattern" exceptionVar="exception"/>

<% if (exception!=null) {
     pageContext.setAttribute("pattern", (String)pattern+"%");
%>
   <mak:list from="type t" where="t.field like $pattern" >...</mak:list>

<% } else { %>
   No pattern argument. Please indicate one.
<% } %>

Makumba can produce four types of forms: new, add, edit and generic forms.

All forms have a number of common features: They can include <mak:input > tags. They all can have "action", "method", "handler", "name" and "message" arguments.

Handler methods (if they exist) are executed by the makumba controller, when the form is submitted to another makumba page.

Non-generic (type specific) forms
New, edit and add forms are type specific. Their fields must be named after the fields in the respective type (and related fields).

If there is a business logic class, the engine will look (once after each page compilation) for the corresponding handler method. The handler methods are executed before the default action and may prevent the action from being executed by throwing an exception. Some forms also have an after-action handler method.

If the handler class exists but no handler method can be found, an error is thrown (the site is not allowed to do the operation, e.g. StudentHandler will never have a on_newLibraryBook() method). If the handler class wishes to allow the action, it can define an empty handler method.

Multiple forms
- addForms can add to the subsets of object produced by the enclosing newForm.
- any number of levels of form inclusion is possible but only the outermost form can have an action, onSubmit, and method and other attributes specific to HTML forms.
- all form actions take place in a single transaction, which is rolled back by the controller filter if there is an error.
- after_ methods are not executed in correct order (bug 689)

<mak:form action="blabla">
<%-- the topmost form, will result in a HTML form, may or may not have logic, 
     or it can be a specialized form (new, edit, add...)
--%>

  <mak:input name="first" /> <%-- the topmost form can have fields of its own --%>

<mak:list .... > 
  <mak:addForm object="bla" field="bla" >
  <%-- note that there is no action indicated here, it's the action of the 
       topmost form a normal on_add BL method will be called 
   --%>
     <mak:input name="second" /><%-- the topmost form can have fields of its own, 
                                     even repeated in loops 
                                --%>
     ...
  </mak:addForm>
</mak:list>

<mak:list .... > <%-- there can be more than one loop in a root form -- %>
...
</mak:list>
<input type=submit> <%-- it's easy to add a submit button anywhere --%>
</mak:form>

(Later, new and edit forms that have no body, will build default forms. )

Form annotation
Form validation errors are either reported in the Makumba response which would be displayed on the form action page, or can for improved usability be annotated in the form itself. In the latter case, on a form validation error, the form page itself would be displayed again, and errors are displayed next to the inputs that failed validation.
An example can be seen below:

The annotation message will be put inside a <span class="formAnnotation">; this CSS-class can be used to add custom formatting to the message.

Reloading the form page on errors can be triggered by the attribute reloadFormOnError, the location of the annotation message by the attribute annotation.

Additionally, form validation can be done also on the client-side, i.e. in the browser. Client-side validation can be either live, i.e. on entering data in an input, or before form submission; this is controlled by the attribute clientSideValidation.

<mak:newForm  ...>.... </mak:newForm>

Makes a form for creating a new object of the indicated type.

Example (personNew.jsp):

<mak:newForm type="general.Person" action="personList.jsp" method="post">
        <mak:input name="name"/>
        <mak:input name="surname"/>
        <input type="submit">
</mak:newForm>

Multiple submission of forms

If new forms are submitted more than once (intentionally or by accident, e.g. impatient users pressing twice one a submit button, reloading a form result page, ...), problems might occur in the data integrity.
Makumba has a built-int mechanism to prevent multiple submission of forms; a ticket will be generated on form load, containing a form-specific key and a time stamp. Each ticket is only valid for a single form submission. Upon subsequent submission of the very same form, an error message will be displayed.

At form response, makumba (controller) invokes the following methods:

1. By defining on_new*, the handler class gets the opportunity to validate/change the data. If the data is not correct, the handler can throw an exception to prevent insertion in database.

   handler.on_newTypeName(data, attr, db);
   

2. The standard Database call for insertion:

   Pointer created= db.insert(type, data);
   

3. By defining after_new*, the handler class gets the opportunity to do supplementary operations with the inserted record.

   handler.after_newTypeName(created, data, attr, db);
   

If the handler class is present but both handler methods are missing (on_new and after_new), the action is not allowed.

At response the following calls are executed (in this order):

PersonLogic handler_obj; // see handler discovery
handler_obj.checkAttributes(attr, db);
handler_obj.on_newGeneralPerson(data, attr, db);
Pointer created= db.insert("general.Person", data);
handler_obj.after_newGeneralPerson(created, data, attr, db);

<mak:addForm  ...>.... </mak:addForm>

Makes a form for creating a sub-object of the mandatory enclosing <mak:object> (e.g. a language of a student, an address for a person).

Example:

<mak:object from="best.Student s" where="s=$student">
    <mak:addForm object="s" field="languages"
         action="studentView.jsp" method="post">
        <mak:value expr="s.name"/>
        <mak:input name="level"/>
        <mak:input name="comments"/>
    </mak:addForm>
</mak:object>

This will call the handler methods: (the argument names are adapted to the example. Note the changed pointer argument in the methods.)

on_addBestStudentLang(Pointer student, Dictionary languageData, Attributes pageParams, Database db)
after_addBestStudentLang(Pointer address, Dictionary languageData, Attributes pageParams, Database db)

<mak:editForm  ...>.... </mak:editForm>

Makes a form for editing the object indicated by any of the labels of the mandatory enclosing <mak:object> or <mak:list>. Also linked objects can be edited through the same form.

Example:

<mak:object from="best.Student s, s.person p" where="s=$student">
    <mak:editForm object="s" action="studentView.jsp" method="post">
        <mak:input name="person.name"/>
        <mak:input name="person.surname"/>
        <mak:input name="graduated"/>
    </mak:editForm>
</mak:object>

The response will call the handler method: (the argument names are adapted to the example)

on_editBestStudent(Pointer student, Dictionary fieldsToChange, Attributes pageParams, Database db)

<mak:form  ...>....</mak:form>

Creates a generic form, that may call a handler method in response. It allows the JSP author to make any kind of form. They are suitable for more complex operations than new, add, edit.

Example:

<mak:object from="best.Student s" where="s=$student">
    <mak:form handler="doSomething" action="studentView.jsp" method="post">
        <mak:input name="xxx" value="s.person.name"/>
        <input type=submit>
    </mak:form>
</mak:object>

<mak:input... />

An input field to be created, depending on the makumba type of the field.

Set and pointer inputs will render as select boxes. Sometimes you may need to use two select boxes whereby the user can move items from one box to the other, which is illustrated in this example.

Date inputs are slightly different than normal inputs, as they are rendered with several input fields (for the day, month, year, hours, minutes and second, depending on the date/time format). Additionally, a JavaScript-based calendar widget can be used, as shown in an example.

The difference between <mak:input > and normal HTML <input> in a makumba form are:

• <mak:input> produces objects prepared for setting/comparing makumba fields (e.g. Pointer, Date, Text).
• the fields produced by <input> will be available as page $attributes but will all be of type String
• the fields produced by <mak:input> are available separately as a Dictionary to the handler method

<mak:object from="best.Student s, s.person p" where="s=$student">
    <mak:editForm object="p" action="studentView.jsp" method="post">
        name      <mak:input name="name"/>
        surname   <mak:input name="surname"/>
        gender    <mak:input name="gender" type="tickbox" />
        dob       <mak:input name="birthdate" format="yyyy-MM-dd" />
    </mak:editForm>
</mak:object>

Fields of related records can be reference and edited as well, via pointers. In this (somewhat strange) example, one can edit the name of the capital city of the country of which person is a citizen, through the person edit form :

<mak:input name="person.citizenship.capital.name" />

Restrictions for different field types:

• fixed fields: cannot be edited
• relational and index pointer: cannot be edited
• timestamps (create and modify): cannot be edited
• subset, subpointer: cannot be edited as a field, only as a separate object

<mak:option....>...</mak:option>

Text inside mak:option will become an option title. The value attribute will become the option. Text inside the mak:input that is not inside a mak:option amd is not blank (whitespace) will be assumed to separate groups of options and will be rendered. For options that render HTML SELECTs, this is only accepted for multiple SELECTs which will create several SELECT boxes of equal size, one for each option group.

If mak:option doesn't have a value indicated, it will produce a nil option. Such nil options will be ignored at form submission.

If an option value appears many times it will only be shown the first time it occurs.

<mak:input name="some" dataType="ptr T">
<mak:option>Please choose:</mak:option>
<mak:list from="T choice" where="someCondition" >
    <mak:option value="choice"><mak:value expr="choice.someField" /></mak:option>
</mak:list>
<mak:option> -------- separator----------</mak:option>
<mak:list from="T choice" where="someOtherCondition" >
   <mak:option value="choice"> <mak:value expr="choice.someField /></mak:option>
</mak:list>
</mak:input>

<mak:action>....</mak:action>

If the action URI of a form or deleteLink is more complex, possibly including other makumba tags, the action parameter of the form tag can be omitted, and the action URI can be indicated in a mak:action, anywhere inside the form tag.

Example:

<mak:editForm object="ins" method="post">
  <mak:action>memberView.jsp?person=<mak:value expr="p"/></mak:action>
...
</mak:editForm>

<mak:delete>...</mak:delete>

Produces a form or a link to an action page that will delete the object indicated by any of the labels of the mandatory enclosing <mak:object> or <mak:list>

Example:

<mak:object from="best.Student s, s.languages l" where="s=$student AND l.lang.name=$langname">
  <mak:delete object="l" action="studentView.jsp">
   Delete <mak:value expr="l.lang.name"/>
  </mak:delete>
</mak:object>

DEPRECATED: The usage of <mak:deleteLink> is deprecated, and should be replaced by the equivalent:

<mak:delete widget="link">

The response will call the handler method: (the argument names are adapted to the example)

on_deleteBestStudentLang(Pointer lang, Attributes pageParams, Database db)

<mak:searchForm>...</mak:searchForm>

Produces a form to search for records in the database.
Search forms are in principal related to mak:forms, i.e. attributes allowed there are also allowed in search forms. Additionally, the following attributes are defined.

Example:

<mak:searchForm in="general.Person" name="searchPerson">
  ....
</mak:searchForm>

If you want to do more advanced things in the search page, e.g. sorting of the parameters, you might need to access the pageContext attributes describing the search and the results. They are as follows:

<c:if test="${<searchFormName>Done}"/> Do something when the search was done </c:if>

<a href="searchPage.jsp?${<searchFormName>QueryString}&sortBy=name">

<mak:criterion>...</mak:criterion>

Adds a search criterion to the form. This does not create any inputs, but should be used in combination with <mak:searchField>

Example:

<mak:searchForm in="best.Student" name="searchPerson">
  <mak:criterion fields="name"> ... </mak:criterion>
</mak:searchForm>

<mak:searchField/>

Enclosed inside a <mak:criterion>, generates an input for that criterion. This tag is based on the <mak:input/> tag, and provides additionally the following attributes:

Example:

<mak:searchForm in="best.Student" name="searchPerson">
  <mak:criterion fields="name"> <mak:searchField /> </mak:criterion>
  <mak:criterion fields="place"> <mak:searchField forceInputStyle="single" /> </mak:criterion>  
</mak:searchForm>

<mak:matchMode/>

Enclosed inside a <mak:criterion>, generates a select input to specify how that criterion should be matched. Applies only to char, text for string matching; int, real for number comparisons; date types for date comparisons; and int, real and date for range matching.

Example:

<mak:searchForm in="best.Student" name="searchPerson">
  <mak:criterion fields="name"> <mak:matchMode matchModes="contains, equals, begins, ends"> <mak:searchField /> </mak:criterion>
</mak:searchForm>

<mak:resultList>...</mak:resultList>

Similar to, and based on the <mak:list>, this tag automatically iterates over the results from a specified search form. On top of <mak:list>, the following attributes are available:

Example:

<mak:resultList resultsFrom="searchPerson">
  Name: <mak:value expr="o.name"/> <br/>
</mak:resultList>

Attributes

Java Server Pages use attributes to keep the state of the application. Makumba builds upon that its own notion of Attributes that keep the read-only state of a makumba task. They represent the "environment" of that makumba task. The typical example is a JSP page during execution, with its HTTP and session parameters as attributes. Since other kinds of attributes are possible, the attribute specification is kept HTTP-independent. Makumba BL code sees the attributes as an org.makumba.Attributes object.

Java handler classes

Java handler classes are classes that implement the "business logic" of the organisation. Every makumba page will look for a handler, and will call its methods when needed. Check also the <mak:newForm> to know which methods are called. If a handler class exists, then some operations cannot be performed if these methods are not defined in the handler class.

Handler Discovery

Each page will determine its handler class on first access, after being compiled. If the class changes on disk, a webapp reload is generally needed for the new class to take effect.

The handler is 'discovered' by decomposing the full path of the JSP page, and finding a class with a matching name. Decomposition breaks the full path at every capital letter, or forward slash. For example, with the page path /student/mycv/indexPersonal.jsp, the following criteria are applied, in order:

The class name prefix (e.g. java package name) can be regulated per parts of the site in a file called MakumbaController.properties which can be found in the CLASSPATH (just like MakumbaDatabase.properties). For example, the file can contain:

/student=org.eu.best
/makumba=org.makumba
/=test

There are good reasons to take into account the name of the response page of a form when looking for the business logic. Still, it is the name of the page that contains the form which matters not the name of the action page. It is good practice for both pages to actually have the same handler class.

All methods of the handlers are http-independent. Methods are non-static, so the handler classes can use inheritance to their advantage. Still, handler classes are singletons (only one instance of a certain class in a JVM). For example, the validation of a form can be in a class that is closer to the actual JSP application (view level) while the more view-independent methods can be in the parent of that class. For example:

org.eu.best.minerva.StudentHandler extends org.eu.best.StudentHandler

Role of Java handlers

1. find attributes unknown by pages. e.g.

   <mak:object from="best.Student stud" where="stud=$student"> ...</mak:object>
   

   If the $student attribute is not known in the page (from a http argument) or in the session, the find{AttributeName}(Dictionary existingAttributes, Database d, String expression) method is called for the Handler object. In this case findStudent(). The handler has to compute the attribute, based on existing attributes, making DB accesses.

   The find{AttributeName} method's name is constructed literally from the name of the attribute (capitalising only the first letter), so dots and other illegal characters for java identifier names, are not to be used. Also, one shouldn't use 2 attribute names that differ only in the capitalisation of the first letter.

   For example "lbg.$lbg_order" (in an example elsewhere in the specs), will generate a call findLbg_order(otherAttributes, db) and the Java handler will return the default ordering for LBGs (say "name").

   If the attribute is computed successfully, it is associated with the session (i.e. set as JSP attribute in session scope)

   If not, an exception will be thrown (typically org.makumba.UnauthenticatedException), and the engine will act accordingly (i.e. ask for authentication).

2. execute action methods in response to makumba forms. See makumba forms and actions below.

3. ( later: return query parts, as methods. e.g. <mak:value expr="lbg.$title()" /> will generate a call to method BestInternalLbgTitle(lbg) which can return an OQL expression "concat(lbg.id, \"-\" lbg.name)" (such methods can be put directly in the Makumba data definitions) For now, OQL only accepts count() and sum(), but that can be easily fixed, till then, the method can be replaced by hand: <mak:value expr="lbg.id"/>-<mak:value expr="lbg.name"/> )

Handler Initialization

Whenever a handler is used in a new context (i.e. with a different set of attributes, e.g. a new page access), a method called checkAttributes(Attributes a, Database db) is looked for and executed, if it is defined.

checkAttributes can perform sanity checks for attributes used in the respective logic (in case of mismatches, org.makumba.UnauthorizedException is usually thrown), can load attributes that are absolutely needed for page execution (formerly given by the requiredAttributes() method), etc.

Transaction provider configuration

Most handlers provide a Transaction that can be used to perform addition database operations in the Business Logic. The class of this handler can be configured by providing a getTransactionProvider() String, that returns the fully-qualified name of the transaction provider implementation. For the moment, possible values are org.makumba.db.makumba.MakumbaTransactionProvider (native Makumba database layer) and org.makumba.db.hibernate.HibernateTransactionProvider (Hibernate-driven database layer)

Login

If the attribute cannot be found due to wrong login information, org.makumba.UnauthenticatedException is usually thrown.

The principal (the person who logs in) can have more members (e.g. group, Lbg, Company representatives). E.g. the findCompany() method will check to see if the authentication (email_address and password) corresponds to any company representative of that company. If yes, it will return that company.

Login can be done in 2 ways:

1. (Http basic authentication login: will set the attributes $username, $password )
2. cookie login: done in a page called login.jsp, in the same directory or (if missing) in any of the parents. It should contain at least:

   <mak:login>
     <input type=text name=username>
     <input type=password name=password>
     <input type=submit>
   </mak:login>
   

   The login form will pass further (as hidden arguments) all the http parameters it got. Note that <mak:login> is only needed upon automatic login (a page displayed when the user requested another page, that needs authentication). If you wish to ask for login manually in a startup page, a normal HTML form is enough.

To cancel out a certain attribute, in order to produce a new login, the logout tag is available

<mak:logout actor="student"/>

You can remove (cancel-out, logout) multiple attributes from the session by using <mak:logout actor="attribute name"> several times and/or by using the star (*) wildcard, e.g.:

<mak:logout actor="demo_*"/> (attributes whose names start with "demo_")
<mak:logout actor="*app"/> (attributes whose names end with "app")
<mak:logout actor="*"/> (all attributes; this "invalidates" the session)

This table describes the data types and their default user interface representation. That user interface can be altered with the Presentation language described below. Orientative SQL and Java types are presented.