Applying the "Configuration By Exception" concept more extensively

[Jacopo Cappellato-4]

A decent description of the "Configuration By Exception" concept is the following [*]:

"Java EE 5 introduced the idea of configuration by exception (sometimes referred to as programming by exception or convention over configuration). This means, unless specified differently, the container or provider should apply the default rules. In other  words, having to supply a configuration is the exception to the rule. This allows you to write the minimum amount of code to get your application running, relying on the container and provider defaults."

To some extent the OFBiz framework already applied this pattern is some areas (you may remember when we made the entity group-name "org.ofbiz" the default value and then were able to remove a bunch of configuration files); however I see a lot of room for further apply it, starting from the ofbiz-component.xml files.

For example, considering the ofbiz-component.xml file in framework/example:

<ofbiz-component name="example"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="http://ofbiz.apache.org/dtds/ofbiz-component.xsd">
    <!-- define resource loaders; most common is to use the component resource loader -->
    <resource-loader name="main" type="component"/>

    <!-- place the config directory on the classpath to access configuration files -->
    <classpath type="dir" location="config"/>
    <classpath type="dir" location="dtd"/>

    <!-- load single or multiple external libraries -->
    <classpath type="jar" location="build/lib/*"/>

    <!-- entity resources: model(s), eca(s), group, and data definitions -->
    <entity-resource type="model" reader-name="main" loader="main" location="entitydef/entitymodel.xml"/>
    <entity-resource type="model" reader-name="main" loader="main" location="entitydef/entitymodel_view.xml"/>
    <!-- <entity-resource type="eca" reader-name="main" loader="main" location="entitydef/eecas.xml"/> -->
    <entity-resource type="data" reader-name="seed" loader="main" location="data/ExampleTypeData.xml"/>
    <entity-resource type="data" reader-name="seed" loader="main" location="data/ExampleSecurityData.xml"/>
    <entity-resource type="data" reader-name="seed" loader="main" location="data/ExamplePortletData.xml"/>
    <entity-resource type="data" reader-name="seed" loader="main" location="data/ExamplePortalSeedData.xml"/>
    <entity-resource type="data" reader-name="seed" loader="main" location="data/ExampleHelpData.xml"/>
    <entity-resource type="data" reader-name="demo" loader="main" location="data/ExampleDemoData.xml"/>

    <!-- service resources: model(s), eca(s) and group definitions -->
    <service-resource type="model" loader="main" location="servicedef/services.xml"/>
    <service-resource type="eca" loader="main" location="servicedef/secas.xml"/>
    <!--
    <service-resource type="group" loader="main" location="servicedef/groups.xml"/>
    -->

    <test-suite loader="main" location="testdef/tests.xml"/>

    <!-- web applications; will be mounted when using the embedded container -->
    <webapp name="example"
        title="Example"
        menu-name="secondary"
        server="default-server"
        location="webapp/example"
        base-permission="OFBTOOLS,EXAMPLE"
        mount-point="/example"/>
    <webapp name="birt"
        title="BIRT"
        server="default-server"
        location="webapp/birt"
        base-permission="OFBTOOLS,WEBTOOLS"
        mount-point="/birt"
        app-bar-display="false"/>
       
</ofbiz-component>


If we assume that the "default" layout of an OFBiz component is the one used by the "example" component (and actually by all our components) we could simply have:

<ofbiz-component name="example"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="http://ofbiz.apache.org/dtds/ofbiz-component.xsd">
    <!-- define resource loaders; most common is to use the component resource loader so we use it; if you want a different one then use the resource-loader element-->
    <!-- the following folders, if present, will be added to the classpath: config, dtd; use the "classpath" element with attribute type="dir" to add more -->
    <!-- all the jar files in the following folders, if present, will be added to the classpath: build/lib, lib; use the "classpath" element with attribute type="jar" to add more -->
    <!-- all the entity definitions files and eca definition files and group definition files in the folder "entitydef" will be loaded using the reader-name="main" and loader="main"; use the element "entity-resource" to specify different resources -->
    <!-- the data files in the "data" subfolders will be loaded considering the subfolder name as the "reader-name": for example data/seed/ will be loaded when seed data are loaded, data/demo will be loaded when demo data is loaded; you can create a new reader-name simply adding a new subfolder -->
    <!-- service definition files, eca(s) and group definitions will be loaded from the servicedef folder; use the service-resource element ...-->
    <!-- all the test suites in the testdef folder will be executed using the loader="main"; use "test-suite" to specify a different resource -->
    <test-suite loader="main" location="testdef/tests.xml"/>

    <!-- web applications; will be mounted when using the embedded container -->
    <!-- I am pretty sure we could simplify these ones as well, but at this point you get the idea... -->
    <webapp name="example"
        title="Example"
        menu-name="secondary"
        server="default-server"
        location="webapp/example"
        base-permission="OFBTOOLS,EXAMPLE"
        mount-point="/example"/>
    <webapp name="birt"
        title="BIRT"
        server="default-server"
        location="webapp/birt"
        base-permission="OFBTOOLS,WEBTOOLS"
        mount-point="/birt"
        app-bar-display="false"/>
</ofbiz-component>

It should be possible to create a component that uses default resource names and locations without the need to define the ofbiz-component.xml file; for special components that require non-standard configurations then the ofbiz-component.xml file will be used as we are doing now.

What do you think? If we start to think in this direction I am pretty sure we could be able to simplify a lot of the OFBiz configuration files (service definitions, entity definitions etc...).

Kind regards,

Jacopo


[*]: http://moon26.blogspot.com/2011/04/configuration-by-exception_13.html

[Jacques Le Roux]

This sounds good to me. I'm all for simplification. Step by step seems feasible. I see no problems separating data (seed from demo,
etc.) but this part may need the more work (I did not check, just thinking out loud)

Jacques

From: "Jacopo Cappellato" <[hidden email]>

>A decent description of the "Configuration By Exception" concept is the following [*]:
>
> "Java EE 5 introduced the idea of configuration by exception (sometimes referred to as programming by exception or convention over
> configuration). This means, unless specified differently, the container or provider should apply the default rules. In other
> words, having to supply a configuration is the exception to the rule. This allows you to write the minimum amount of code to get
> your application running, relying on the container and provider defaults."
>
> To some extent the OFBiz framework already applied this pattern is some areas (you may remember when we made the entity group-name
> "org.ofbiz" the default value and then were able to remove a bunch of configuration files); however I see a lot of room for
> further apply it, starting from the ofbiz-component.xml files.
>
> For example, considering the ofbiz-component.xml file in framework/example:
>
> <ofbiz-component name="example"
>        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
>        xsi:noNamespaceSchemaLocation="http://ofbiz.apache.org/dtds/ofbiz-component.xsd">
>    <!-- define resource loaders; most common is to use the component resource loader -->
>    <resource-loader name="main" type="component"/>
>
>    <!-- place the config directory on the classpath to access configuration files -->
>    <classpath type="dir" location="config"/>
>    <classpath type="dir" location="dtd"/>
>
>    <!-- load single or multiple external libraries -->
>    <classpath type="jar" location="build/lib/*"/>
>
>    <!-- entity resources: model(s), eca(s), group, and data definitions -->
>    <entity-resource type="model" reader-name="main" loader="main" location="entitydef/entitymodel.xml"/>
>    <entity-resource type="model" reader-name="main" loader="main" location="entitydef/entitymodel_view.xml"/>
>    <!-- <entity-resource type="eca" reader-name="main" loader="main" location="entitydef/eecas.xml"/> -->
>    <entity-resource type="data" reader-name="seed" loader="main" location="data/ExampleTypeData.xml"/>
>    <entity-resource type="data" reader-name="seed" loader="main" location="data/ExampleSecurityData.xml"/>
>    <entity-resource type="data" reader-name="seed" loader="main" location="data/ExamplePortletData.xml"/>
>    <entity-resource type="data" reader-name="seed" loader="main" location="data/ExamplePortalSeedData.xml"/>
>    <entity-resource type="data" reader-name="seed" loader="main" location="data/ExampleHelpData.xml"/>
>    <entity-resource type="data" reader-name="demo" loader="main" location="data/ExampleDemoData.xml"/>
>
>    <!-- service resources: model(s), eca(s) and group definitions -->
>    <service-resource type="model" loader="main" location="servicedef/services.xml"/>
>    <service-resource type="eca" loader="main" location="servicedef/secas.xml"/>
>    <!--
>    <service-resource type="group" loader="main" location="servicedef/groups.xml"/>
>    -->
>
>    <test-suite loader="main" location="testdef/tests.xml"/>
>
>    <!-- web applications; will be mounted when using the embedded container -->
>    <webapp name="example"
>        title="Example"
>        menu-name="secondary"
>        server="default-server"
>        location="webapp/example"
>        base-permission="OFBTOOLS,EXAMPLE"
>        mount-point="/example"/>
>    <webapp name="birt"
>        title="BIRT"
>        server="default-server"
>        location="webapp/birt"
>        base-permission="OFBTOOLS,WEBTOOLS"
>        mount-point="/birt"
>        app-bar-display="false"/>
>
> </ofbiz-component>
>
>
> If we assume that the "default" layout of an OFBiz component is the one used by the "example" component (and actually by all our
> components) we could simply have:
>
> <ofbiz-component name="example"
>        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
>        xsi:noNamespaceSchemaLocation="http://ofbiz.apache.org/dtds/ofbiz-component.xsd">
>    <!-- define resource loaders; most common is to use the component resource loader so we use it; if you want a different one
> then use the resource-loader element-->
>    <!-- the following folders, if present, will be added to the classpath: config, dtd; use the "classpath" element with attribute
> type="dir" to add more -->
>    <!-- all the jar files in the following folders, if present, will be added to the classpath: build/lib, lib; use the
> "classpath" element with attribute type="jar" to add more -->
>    <!-- all the entity definitions files and eca definition files and group definition files in the folder "entitydef" will be
> loaded using the reader-name="main" and loader="main"; use the element "entity-resource" to specify different resources -->
>    <!-- the data files in the "data" subfolders will be loaded considering the subfolder name as the "reader-name": for example
> data/seed/ will be loaded when seed data are loaded, data/demo will be loaded when demo data is loaded; you can create a new
> reader-name simply adding a new subfolder -->
>    <!-- service definition files, eca(s) and group definitions will be loaded from the servicedef folder; use the service-resource
> element ...-->
>    <!-- all the test suites in the testdef folder will be executed using the loader="main"; use "test-suite" to specify a
> different resource -->
>    <test-suite loader="main" location="testdef/tests.xml"/>
>
>    <!-- web applications; will be mounted when using the embedded container -->
>    <!-- I am pretty sure we could simplify these ones as well, but at this point you get the idea... -->
>    <webapp name="example"
>        title="Example"
>        menu-name="secondary"
>        server="default-server"
>        location="webapp/example"
>        base-permission="OFBTOOLS,EXAMPLE"
>        mount-point="/example"/>
>    <webapp name="birt"
>        title="BIRT"
>        server="default-server"
>        location="webapp/birt"
>        base-permission="OFBTOOLS,WEBTOOLS"
>        mount-point="/birt"
>        app-bar-display="false"/>
> </ofbiz-component>
>
> It should be possible to create a component that uses default resource names and locations without the need to define the
> ofbiz-component.xml file; for special components that require non-standard configurations then the ofbiz-component.xml file will
> be used as we are doing now.
>
> What do you think? If we start to think in this direction I am pretty sure we could be able to simplify a lot of the OFBiz
> configuration files (service definitions, entity definitions etc...).
>
> Kind regards,
>
> Jacopo
>
>
> [*]: http://moon26.blogspot.com/2011/04/configuration-by-exception_13.html
>
>

[Adrian Crum-3]

I don't think we can eliminate the seed/demo data readers. In most
cases, data loading must be done in a certain order.

-Adrian

On 3/1/2012 2:53 PM, Jacopo Cappellato wrote:

> A decent description of the "Configuration By Exception" concept is the following [*]:
>
> "Java EE 5 introduced the idea of configuration by exception (sometimes referred to as programming by exception or convention over configuration). This means, unless specified differently, the container or provider should apply the default rules. In other  words, having to supply a configuration is the exception to the rule. This allows you to write the minimum amount of code to get your application running, relying on the container and provider defaults."
>
> To some extent the OFBiz framework already applied this pattern is some areas (you may remember when we made the entity group-name "org.ofbiz" the default value and then were able to remove a bunch of configuration files); however I see a lot of room for further apply it, starting from the ofbiz-component.xml files.
>
> For example, considering the ofbiz-component.xml file in framework/example:
>
> <ofbiz-component name="example"
>          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
>          xsi:noNamespaceSchemaLocation="http://ofbiz.apache.org/dtds/ofbiz-component.xsd">
>      <!-- define resource loaders; most common is to use the component resource loader -->
>      <resource-loader name="main" type="component"/>
>
>      <!-- place the config directory on the classpath to access configuration files -->
>      <classpath type="dir" location="config"/>
>      <classpath type="dir" location="dtd"/>
>
>      <!-- load single or multiple external libraries -->
>      <classpath type="jar" location="build/lib/*"/>
>
>      <!-- entity resources: model(s), eca(s), group, and data definitions -->
>      <entity-resource type="model" reader-name="main" loader="main" location="entitydef/entitymodel.xml"/>
>      <entity-resource type="model" reader-name="main" loader="main" location="entitydef/entitymodel_view.xml"/>
>      <!--<entity-resource type="eca" reader-name="main" loader="main" location="entitydef/eecas.xml"/>  -->
>      <entity-resource type="data" reader-name="seed" loader="main" location="data/ExampleTypeData.xml"/>
>      <entity-resource type="data" reader-name="seed" loader="main" location="data/ExampleSecurityData.xml"/>
>      <entity-resource type="data" reader-name="seed" loader="main" location="data/ExamplePortletData.xml"/>
>      <entity-resource type="data" reader-name="seed" loader="main" location="data/ExamplePortalSeedData.xml"/>
>      <entity-resource type="data" reader-name="seed" loader="main" location="data/ExampleHelpData.xml"/>
>      <entity-resource type="data" reader-name="demo" loader="main" location="data/ExampleDemoData.xml"/>
>
>      <!-- service resources: model(s), eca(s) and group definitions -->
>      <service-resource type="model" loader="main" location="servicedef/services.xml"/>
>      <service-resource type="eca" loader="main" location="servicedef/secas.xml"/>
>      <!--
>      <service-resource type="group" loader="main" location="servicedef/groups.xml"/>
>      -->
>
>      <test-suite loader="main" location="testdef/tests.xml"/>
>
>      <!-- web applications; will be mounted when using the embedded container -->
>      <webapp name="example"
>          title="Example"
>          menu-name="secondary"
>          server="default-server"
>          location="webapp/example"
>          base-permission="OFBTOOLS,EXAMPLE"
>          mount-point="/example"/>
>      <webapp name="birt"
>          title="BIRT"
>          server="default-server"
>          location="webapp/birt"
>          base-permission="OFBTOOLS,WEBTOOLS"
>          mount-point="/birt"
>          app-bar-display="false"/>
>
> </ofbiz-component>
>
>
> If we assume that the "default" layout of an OFBiz component is the one used by the "example" component (and actually by all our components) we could simply have:
>
> <ofbiz-component name="example"
>          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
>          xsi:noNamespaceSchemaLocation="http://ofbiz.apache.org/dtds/ofbiz-component.xsd">
>      <!-- define resource loaders; most common is to use the component resource loader so we use it; if you want a different one then use the resource-loader element-->
>      <!-- the following folders, if present, will be added to the classpath: config, dtd; use the "classpath" element with attribute type="dir" to add more -->
>      <!-- all the jar files in the following folders, if present, will be added to the classpath: build/lib, lib; use the "classpath" element with attribute type="jar" to add more -->
>      <!-- all the entity definitions files and eca definition files and group definition files in the folder "entitydef" will be loaded using the reader-name="main" and loader="main"; use the element "entity-resource" to specify different resources -->
>      <!-- the data files in the "data" subfolders will be loaded considering the subfolder name as the "reader-name": for example data/seed/ will be loaded when seed data are loaded, data/demo will be loaded when demo data is loaded; you can create a new reader-name simply adding a new subfolder -->
>      <!-- service definition files, eca(s) and group definitions will be loaded from the servicedef folder; use the service-resource element ...-->
>      <!-- all the test suites in the testdef folder will be executed using the loader="main"; use "test-suite" to specify a different resource -->
>      <test-suite loader="main" location="testdef/tests.xml"/>
>
>      <!-- web applications; will be mounted when using the embedded container -->
>      <!-- I am pretty sure we could simplify these ones as well, but at this point you get the idea... -->
>      <webapp name="example"
>          title="Example"
>          menu-name="secondary"
>          server="default-server"
>          location="webapp/example"
>          base-permission="OFBTOOLS,EXAMPLE"
>          mount-point="/example"/>
>      <webapp name="birt"
>          title="BIRT"
>          server="default-server"
>          location="webapp/birt"
>          base-permission="OFBTOOLS,WEBTOOLS"
>          mount-point="/birt"
>          app-bar-display="false"/>
> </ofbiz-component>
>
> It should be possible to create a component that uses default resource names and locations without the need to define the ofbiz-component.xml file; for special components that require non-standard configurations then the ofbiz-component.xml file will be used as we are doing now.
>
> What do you think? If we start to think in this direction I am pretty sure we could be able to simplify a lot of the OFBiz configuration files (service definitions, entity definitions etc...).
>
> Kind regards,
>
> Jacopo
>
>
> [*]: http://moon26.blogspot.com/2011/04/configuration-by-exception_13.html
>

[Jacopo Cappellato-4]

You are right Adrian... actually this would be the last thing to touch but we could use a different convention like:

data/<some name>_seed.xml
data/<some name>_demo.xml

or more simply:

data/seed.xml
data/demo.xml

(where the filename is the reader name) and then consider to merge all seed records in <some name>_seed.xml and all records for demo in <some name>_demo.xml

Jacopo

On Mar 2, 2012, at 9:06 AM, Adrian Crum wrote:

> I don't think we can eliminate the seed/demo data readers. In most cases, data loading must be done in a certain order.
>
> -Adrian
>
> On 3/1/2012 2:53 PM, Jacopo Cappellato wrote:
>> A decent description of the "Configuration By Exception" concept is the following [*]:
>>
>> "Java EE 5 introduced the idea of configuration by exception (sometimes referred to as programming by exception or convention over configuration). This means, unless specified differently, the container or provider should apply the default rules. In other  words, having to supply a configuration is the exception to the rule. This allows you to write the minimum amount of code to get your application running, relying on the container and provider defaults."
>>
>> To some extent the OFBiz framework already applied this pattern is some areas (you may remember when we made the entity group-name "org.ofbiz" the default value and then were able to remove a bunch of configuration files); however I see a lot of room for further apply it, starting from the ofbiz-component.xml files.
>>
>> For example, considering the ofbiz-component.xml file in framework/example:
>>
>> <ofbiz-component name="example"
>>         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
>>         xsi:noNamespaceSchemaLocation="http://ofbiz.apache.org/dtds/ofbiz-component.xsd">
>>     <!-- define resource loaders; most common is to use the component resource loader -->
>>     <resource-loader name="main" type="component"/>
>>
>>     <!-- place the config directory on the classpath to access configuration files -->
>>     <classpath type="dir" location="config"/>
>>     <classpath type="dir" location="dtd"/>
>>
>>     <!-- load single or multiple external libraries -->
>>     <classpath type="jar" location="build/lib/*"/>
>>
>>     <!-- entity resources: model(s), eca(s), group, and data definitions -->
>>     <entity-resource type="model" reader-name="main" loader="main" location="entitydef/entitymodel.xml"/>
>>     <entity-resource type="model" reader-name="main" loader="main" location="entitydef/entitymodel_view.xml"/>
>>     <!--<entity-resource type="eca" reader-name="main" loader="main" location="entitydef/eecas.xml"/>  -->
>>     <entity-resource type="data" reader-name="seed" loader="main" location="data/ExampleTypeData.xml"/>
>>     <entity-resource type="data" reader-name="seed" loader="main" location="data/ExampleSecurityData.xml"/>
>>     <entity-resource type="data" reader-name="seed" loader="main" location="data/ExamplePortletData.xml"/>
>>     <entity-resource type="data" reader-name="seed" loader="main" location="data/ExamplePortalSeedData.xml"/>
>>     <entity-resource type="data" reader-name="seed" loader="main" location="data/ExampleHelpData.xml"/>
>>     <entity-resource type="data" reader-name="demo" loader="main" location="data/ExampleDemoData.xml"/>
>>
>>     <!-- service resources: model(s), eca(s) and group definitions -->
>>     <service-resource type="model" loader="main" location="servicedef/services.xml"/>
>>     <service-resource type="eca" loader="main" location="servicedef/secas.xml"/>
>>     <!--
>>     <service-resource type="group" loader="main" location="servicedef/groups.xml"/>
>>     -->
>>
>>     <test-suite loader="main" location="testdef/tests.xml"/>
>>
>>     <!-- web applications; will be mounted when using the embedded container -->
>>     <webapp name="example"
>>         title="Example"
>>         menu-name="secondary"
>>         server="default-server"
>>         location="webapp/example"
>>         base-permission="OFBTOOLS,EXAMPLE"
>>         mount-point="/example"/>
>>     <webapp name="birt"
>>         title="BIRT"
>>         server="default-server"
>>         location="webapp/birt"
>>         base-permission="OFBTOOLS,WEBTOOLS"
>>         mount-point="/birt"
>>         app-bar-display="false"/>
>>
>> </ofbiz-component>
>>
>>
>> If we assume that the "default" layout of an OFBiz component is the one used by the "example" component (and actually by all our components) we could simply have:
>>
>> <ofbiz-component name="example"
>>         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
>>         xsi:noNamespaceSchemaLocation="http://ofbiz.apache.org/dtds/ofbiz-component.xsd">
>>     <!-- define resource loaders; most common is to use the component resource loader so we use it; if you want a different one then use the resource-loader element-->
>>     <!-- the following folders, if present, will be added to the classpath: config, dtd; use the "classpath" element with attribute type="dir" to add more -->
>>     <!-- all the jar files in the following folders, if present, will be added to the classpath: build/lib, lib; use the "classpath" element with attribute type="jar" to add more -->
>>     <!-- all the entity definitions files and eca definition files and group definition files in the folder "entitydef" will be loaded using the reader-name="main" and loader="main"; use the element "entity-resource" to specify different resources -->
>>     <!-- the data files in the "data" subfolders will be loaded considering the subfolder name as the "reader-name": for example data/seed/ will be loaded when seed data are loaded, data/demo will be loaded when demo data is loaded; you can create a new reader-name simply adding a new subfolder -->
>>     <!-- service definition files, eca(s) and group definitions will be loaded from the servicedef folder; use the service-resource element ...-->
>>     <!-- all the test suites in the testdef folder will be executed using the loader="main"; use "test-suite" to specify a different resource -->
>>     <test-suite loader="main" location="testdef/tests.xml"/>
>>
>>     <!-- web applications; will be mounted when using the embedded container -->
>>     <!-- I am pretty sure we could simplify these ones as well, but at this point you get the idea... -->
>>     <webapp name="example"
>>         title="Example"
>>         menu-name="secondary"
>>         server="default-server"
>>         location="webapp/example"
>>         base-permission="OFBTOOLS,EXAMPLE"
>>         mount-point="/example"/>
>>     <webapp name="birt"
>>         title="BIRT"
>>         server="default-server"
>>         location="webapp/birt"
>>         base-permission="OFBTOOLS,WEBTOOLS"
>>         mount-point="/birt"
>>         app-bar-display="false"/>
>> </ofbiz-component>
>>
>> It should be possible to create a component that uses default resource names and locations without the need to define the ofbiz-component.xml file; for special components that require non-standard configurations then the ofbiz-component.xml file will be used as we are doing now.
>>
>> What do you think? If we start to think in this direction I am pretty sure we could be able to simplify a lot of the OFBiz configuration files (service definitions, entity definitions etc...).
>>
>> Kind regards,
>>
>> Jacopo
>>
>>
>> [*]: http://moon26.blogspot.com/2011/04/configuration-by-exception_13.html
>>

[Paul Foxworthy]

Hi all,

I definitely like the basic idea of configuration by exception, but I also like having separate files for major categories of seed and demo data. If you wanted to customize OFBiz for a particular purpose, having separate files makes it easier to include or exclude data.

How about using file names for ordering, like Unix System V init scripts? Perhaps also different directories for seed, demo and so on.

So the names might end up like

data/seed/10_ExampleTypeData.xml
data/seed/20_ExampleSecurityData.xml
data/seed/30_ExamplePortletData.xml"
data/seed/40_ExamplePortalSeedData.xml
data/seed/50_ExampleHelpData.xml

Cheers

Paul Foxworthy

Jacopo Cappellato-4 wrote

You are right Adrian... actually this would be the last thing to touch but we could use a different convention like:

data/<some name>_seed.xml
data/<some name>_demo.xml

or more simply:

data/seed.xml
data/demo.xml

(where the filename is the reader name) and then consider to merge all seed records in <some name>_seed.xml and all records for demo in <some name>_demo.xml

Jacopo

On Mar 2, 2012, at 9:06 AM, Adrian Crum wrote:

> I don't think we can eliminate the seed/demo data readers. In most cases, data loading must be done in a certain order.
>
> -Adrian
>
> On 3/1/2012 2:53 PM, Jacopo Cappellato wrote:
>> A decent description of the "Configuration By Exception" concept is the following [*]:
>>
>> "Java EE 5 introduced the idea of configuration by exception (sometimes referred to as programming by exception or convention over configuration). This means, unless specified differently, the container or provider should apply the default rules. In other  words, having to supply a configuration is the exception to the rule. This allows you to write the minimum amount of code to get your application running, relying on the container and provider defaults."
>>
>> To some extent the OFBiz framework already applied this pattern is some areas (you may remember when we made the entity group-name "org.ofbiz" the default value and then were able to remove a bunch of configuration files); however I see a lot of room for further apply it, starting from the ofbiz-component.xml files.
>>
>> For example, considering the ofbiz-component.xml file in framework/example:
>>
>> <ofbiz-component name="example"
>>         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
>>         xsi:noNamespaceSchemaLocation="http://ofbiz.apache.org/dtds/ofbiz-component.xsd">
>>    
>>     <resource-loader name="main" type="component"/>
>>
>>    
>>     <classpath type="dir" location="config"/>
>>     <classpath type="dir" location="dtd"/>
>>
>>    
>>     <classpath type="jar" location="build/lib/*"/>
>>
>>    
>>     <entity-resource type="model" reader-name="main" loader="main" location="entitydef/entitymodel.xml"/>
>>     <entity-resource type="model" reader-name="main" loader="main" location="entitydef/entitymodel_view.xml"/>
>>    
>>     <entity-resource type="data" reader-name="seed" loader="main" location="data/ExampleTypeData.xml"/>
>>     <entity-resource type="data" reader-name="seed" loader="main" location="data/ExampleSecurityData.xml"/>
>>     <entity-resource type="data" reader-name="seed" loader="main" location="data/ExamplePortletData.xml"/>
>>     <entity-resource type="data" reader-name="seed" loader="main" location="data/ExamplePortalSeedData.xml"/>
>>     <entity-resource type="data" reader-name="seed" loader="main" location="data/ExampleHelpData.xml"/>
>>     <entity-resource type="data" reader-name="demo" loader="main" location="data/ExampleDemoData.xml"/>
>>
>>    
>>     <service-resource type="model" loader="main" location="servicedef/services.xml"/>
>>     <service-resource type="eca" loader="main" location="servicedef/secas.xml"/>
>>    
>>
>>     <test-suite loader="main" location="testdef/tests.xml"/>
>>
>>    
>>     <webapp name="example"
>>         title="Example"
>>         menu-name="secondary"
>>         server="default-server"
>>         location="webapp/example"
>>         base-permission="OFBTOOLS,EXAMPLE"
>>         mount-point="/example"/>
>>     <webapp name="birt"
>>         title="BIRT"
>>         server="default-server"
>>         location="webapp/birt"
>>         base-permission="OFBTOOLS,WEBTOOLS"
>>         mount-point="/birt"
>>         app-bar-display="false"/>
>>
>> </ofbiz-component>
>>
>>
>> If we assume that the "default" layout of an OFBiz component is the one used by the "example" component (and actually by all our components) we could simply have:
>>
>> <ofbiz-component name="example"
>>         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
>>         xsi:noNamespaceSchemaLocation="http://ofbiz.apache.org/dtds/ofbiz-component.xsd">
>>    
>>    
>>    
>>    
>>    
>>    
>>    
>>     <test-suite loader="main" location="testdef/tests.xml"/>
>>
>>    
>>    
>>     <webapp name="example"
>>         title="Example"
>>         menu-name="secondary"
>>         server="default-server"
>>         location="webapp/example"
>>         base-permission="OFBTOOLS,EXAMPLE"
>>         mount-point="/example"/>
>>     <webapp name="birt"
>>         title="BIRT"
>>         server="default-server"
>>         location="webapp/birt"
>>         base-permission="OFBTOOLS,WEBTOOLS"
>>         mount-point="/birt"
>>         app-bar-display="false"/>
>> </ofbiz-component>
>>
>> It should be possible to create a component that uses default resource names and locations without the need to define the ofbiz-component.xml file; for special components that require non-standard configurations then the ofbiz-component.xml file will be used as we are doing now.
>>
>> What do you think? If we start to think in this direction I am pretty sure we could be able to simplify a lot of the OFBiz configuration files (service definitions, entity definitions etc...).
>>
>> Kind regards,
>>
>> Jacopo
>>
>>
>> [*]: http://moon26.blogspot.com/2011/04/configuration-by-exception_13.html
>>

[Adrian Crum-3]

Using folders to categorize data is a good idea. I use that pattern now
on large projects that have many files.

-Adrian

On 3/2/2012 12:09 PM, Paul Foxworthy wrote:

> Hi all,
>
> I definitely like the basic idea of configuration by exception, but I also
> like having separate files for major categories of seed and demo data. If
> you wanted to customize OFBiz for a particular purpose, having separate
> files makes it easier to include or exclude data.
>
> How about using file names for ordering, like Unix System V init scripts?
> Perhaps also different directories for seed, demo and so on.
>
> So the names might end up like
>
> data/seed/10_ExampleTypeData.xml
> data/seed/20_ExampleSecurityData.xml
> data/seed/30_ExamplePortletData.xml"
> data/seed/40_ExamplePortalSeedData.xml
> data/seed/50_ExampleHelpData.xml
>
> Cheers
>
> Paul Foxworthy
>
>
> Jacopo Cappellato-4 wrote
>> You are right Adrian... actually this would be the last thing to touch but
>> we could use a different convention like:
>>
>> data/<some name>_seed.xml
>> data/<some name>_demo.xml
>>
>> or more simply:
>>
>> data/seed.xml
>> data/demo.xml
>>
>> (where the filename is the reader name) and then consider to merge all
>> seed records in<some name>_seed.xml and all records for demo in<some
>> name>_demo.xml
>>
>> Jacopo
>>
>> On Mar 2, 2012, at 9:06 AM, Adrian Crum wrote:
>>
>>> I don't think we can eliminate the seed/demo data readers. In most cases,
>>> data loading must be done in a certain order.
>>>
>>> -Adrian
>>>
>>> On 3/1/2012 2:53 PM, Jacopo Cappellato wrote:
>>>> A decent description of the "Configuration By Exception" concept is the
>>>> following [*]:
>>>>
>>>> "Java EE 5 introduced the idea of configuration by exception (sometimes
>>>> referred to as programming by exception or convention over
>>>> configuration). This means, unless specified differently, the container
>>>> or provider should apply the default rules. In other  words, having to
>>>> supply a configuration is the exception to the rule. This allows you to
>>>> write the minimum amount of code to get your application running,
>>>> relying on the container and provider defaults."
>>>>
>>>> To some extent the OFBiz framework already applied this pattern is some
>>>> areas (you may remember when we made the entity group-name "org.ofbiz"
>>>> the default value and then were able to remove a bunch of configuration
>>>> files); however I see a lot of room for further apply it, starting from
>>>> the ofbiz-component.xml files.
>>>>
>>>> For example, considering the ofbiz-component.xml file in
>>>> framework/example:
>>>>
>>>> <ofbiz-component name="example"
>>>>          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
>>>>
>>>> xsi:noNamespaceSchemaLocation="http://ofbiz.apache.org/dtds/ofbiz-component.xsd">
>>>>
>>>>      <resource-loader name="main" type="component"/>
>>>>
>>>>
>>>>      <classpath type="dir" location="config"/>
>>>>      <classpath type="dir" location="dtd"/>
>>>>
>>>>
>>>>      <classpath type="jar" location="build/lib/*"/>
>>>>
>>>>
>>>>      <entity-resource type="model" reader-name="main" loader="main"
>>>> location="entitydef/entitymodel.xml"/>
>>>>      <entity-resource type="model" reader-name="main" loader="main"
>>>> location="entitydef/entitymodel_view.xml"/>
>>>>
>>>>      <entity-resource type="data" reader-name="seed" loader="main"
>>>> location="data/ExampleTypeData.xml"/>
>>>>      <entity-resource type="data" reader-name="seed" loader="main"
>>>> location="data/ExampleSecurityData.xml"/>
>>>>      <entity-resource type="data" reader-name="seed" loader="main"
>>>> location="data/ExamplePortletData.xml"/>
>>>>      <entity-resource type="data" reader-name="seed" loader="main"
>>>> location="data/ExamplePortalSeedData.xml"/>
>>>>      <entity-resource type="data" reader-name="seed" loader="main"
>>>> location="data/ExampleHelpData.xml"/>
>>>>      <entity-resource type="data" reader-name="demo" loader="main"
>>>> location="data/ExampleDemoData.xml"/>
>>>>
>>>>
>>>>      <service-resource type="model" loader="main"
>>>> location="servicedef/services.xml"/>
>>>>      <service-resource type="eca" loader="main"
>>>> location="servicedef/secas.xml"/>
>>>>
>>>>
>>>>      <test-suite loader="main" location="testdef/tests.xml"/>
>>>>
>>>>
>>>>      <webapp name="example"
>>>>          title="Example"
>>>>          menu-name="secondary"
>>>>          server="default-server"
>>>>          location="webapp/example"
>>>>          base-permission="OFBTOOLS,EXAMPLE"
>>>>          mount-point="/example"/>
>>>>      <webapp name="birt"
>>>>          title="BIRT"
>>>>          server="default-server"
>>>>          location="webapp/birt"
>>>>          base-permission="OFBTOOLS,WEBTOOLS"
>>>>          mount-point="/birt"
>>>>          app-bar-display="false"/>
>>>>
>>>> </ofbiz-component>
>>>>
>>>>
>>>> If we assume that the "default" layout of an OFBiz component is the one
>>>> used by the "example" component (and actually by all our components) we
>>>> could simply have:
>>>>
>>>> <ofbiz-component name="example"
>>>>          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
>>>>
>>>> xsi:noNamespaceSchemaLocation="http://ofbiz.apache.org/dtds/ofbiz-component.xsd">
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>      <test-suite loader="main" location="testdef/tests.xml"/>
>>>>
>>>>
>>>>
>>>>      <webapp name="example"
>>>>          title="Example"
>>>>          menu-name="secondary"
>>>>          server="default-server"
>>>>          location="webapp/example"
>>>>          base-permission="OFBTOOLS,EXAMPLE"
>>>>          mount-point="/example"/>
>>>>      <webapp name="birt"
>>>>          title="BIRT"
>>>>          server="default-server"
>>>>          location="webapp/birt"
>>>>          base-permission="OFBTOOLS,WEBTOOLS"
>>>>          mount-point="/birt"
>>>>          app-bar-display="false"/>
>>>> </ofbiz-component>
>>>>
>>>> It should be possible to create a component that uses default resource
>>>> names and locations without the need to define the ofbiz-component.xml
>>>> file; for special components that require non-standard configurations
>>>> then the ofbiz-component.xml file will be used as we are doing now.
>>>>
>>>> What do you think? If we start to think in this direction I am pretty
>>>> sure we could be able to simplify a lot of the OFBiz configuration files
>>>> (service definitions, entity definitions etc...).
>>>>
>>>> Kind regards,
>>>>
>>>> Jacopo
>>>>
>>>>
>>>> [*]:
>>>> http://moon26.blogspot.com/2011/04/configuration-by-exception_13.html
>>>>
> -----
> --
> Coherent Software Australia Pty Ltd
> http://www.cohsoft.com.au/
>
> Bonsai ERP, the all-inclusive ERP system
> http://www.bonsaierp.com.au/
>
> --
> View this message in context: http://ofbiz.135035.n4.nabble.com/Applying-the-Configuration-By-Exception-concept-more-extensively-tp4435195p4438250.html
> Sent from the OFBiz - Dev mailing list archive at Nabble.com.