But what I am thinking of what tools we can use to design OSB components. I bet the quickest answer is the OSB IDE. But this is a developer tool not a designer one. So the real question is do we really need a desinger software to model the components? The answer is not easy. I have to admit I did not have to use always this kind of software when developing OSB. And I can't state whether You really need it or You don't.
It is always good to use a designer tool but I think the main reason to use it is to generate code from model.
The proxy services don't contain deep business logic (except maybe the newly created enterprise services) so it is unnecessary to model it.
It is hard to model the input / output data without so much as not to implement them. I think to model the detailed input / output data and message flow is not reasonable. So we should model the services (proxy, business) and their structures (see the previous blog). In some cases there might be justified to design the data structures but You need to make up Your mind the resolution level.
I have already told the magic word: code generation. It means code can be generated from model. You are creating the model adding stereotypes and properties to the components and the code generator will create folders, XML files (for proxy / business services), project descriptors files, etc.
This is a sample model which I created in the designer tool (this is the model of the topic of previous blog ):
You can assign properties to the stereotype and set those ones when creating the model. In this case I have defined if the proxy service is atomic or it isn't.
What are the advantages? You have got the model of the OSB components. You can review the model easier than the real services in the OSB IDE or console. But You can say now 'a model is never static it is changing often!' Yes, You are right it is not. If your model is being changed and You have to regenerate the source code then the code which You implemented after the previous generation will be lost (because we have got a source code on the computer which we maintain).
However the good news is this is not an obstacle for our generator. It can merge the old source code (the result of the earlier generation) and the new one! So our work can't disappear. The trick is You have to define read only and modifiable parts in your template and the developers can change the modifiable ones (check the //<%startUserCode%> code in the sample below). If they will write into the read only parts of generated code then this new code will really be lost at next code generation event.
The above ones were the advantages but there are some drawbacks as well. You have to write the code generation algorythms. It might be huge work and depends what exactly You want to generate from model. If You want to create more code from model (e.g. not just services but input / output data as well) then You have to deal more time with the code generator. This effort is worth if You have got a lot of services / components on the OSB.
This is a sample for OSB proxy service template:
<%
metamodel http://www.eclipse.org/uml2/2.1.0/UML
import com.astron.uml2.java.services.Uml2Services
import com.astron.uml2.java.services.StringServices
%>
<%script type="Class" name="fullFilePath"%>
<%if (hasStereotype("ProxyService")) {%>
/<%name.toU1Case()%>PS.xml
<%}%>
<%script type="Class" name="generate" file="<%fullFilePath%>"%>
<?xml version="1.0" encoding="UTF-8"?>
<xml-fragment xmlns:ser="http://www.bea.com/wli/sb/services" xmlns:tran="http://www.bea.com/wli/sb/transports" xmlns:env="http://www.bea.com/wli/config/env" xmlns:http="http://www.bea.com/wli/sb/transports/http">
<ser:coreEntry isProxy="true" isEnabled="true">
<ser:binding type="abstract XML"/>
<ser:monitoring isEnabled="false">
<ser:aggregationInterval>10</ser:aggregationInterval>
<ser:pipelineMonitoringLevel>Pipeline</ser:pipelineMonitoringLevel>
</ser:monitoring>
<ser:reporting>true</ser:reporting>
<ser:logging isEnabled="true">
<ser:logLevel>debug</ser:logLevel>
</ser:logging>
<ser:sla-alerting isEnabled="true">
<ser:alertLevel>normal</ser:alertLevel>
</ser:sla-alerting>
<ser:pipeline-alerting isEnabled="true">
<ser:alertLevel>normal</ser:alertLevel>
</ser:pipeline-alerting>
</ser:coreEntry>
<ser:endpointConfig>
<tran:provider-id>http</tran:provider-id>
<tran:inbound>true</tran:inbound>
<tran:URI>
<env:value>/OSB/<%name.toU1Case()%>PS</env:value>
</tran:URI>
<tran:inbound-properties/>
<tran:provider-specific>
<http:inbound-properties/>
</tran:provider-specific>
</ser:endpointConfig>
<ser:router>
//<%startUserCode%> for messageFlow
//<%endUserCode%> for messageFlow
</ser:router>
</xml-fragment>And here it is a sample for Java template as well:
<%
metamodel http://www.eclipse.org/uml2/2.1.0/UML
import com.astron.uml2.java.services.Uml2Services
import com.astron.uml2.java.services.StringServices
%>
<%script type="Class" name="fullFilePath"%>
<%if (hasStereotype("entity")) {%>
/<%getProperty("package.server.hibernate").toPath()%>/<%name.toU1Case()%>Dao.java
<%}%>
<%script type="Class" name="generate" file="<%fullFilePath%>"%>
package <%getProperty("package.server.hibernate")%>;
import java.util.List;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.Transaction;
import com.astron.common.exception.DaoException;
import com.astron.common.hibernate.SessionFactoryUtil;
//<%startUserCode%> for imports
//<%endUserCode%> for imports
/**
* Data Access Object
* Generated by Astron MDA tools
*/
public class <%name.toU1Case()%>Dao {
/*
* Get all <%name%> entities
*
* @return a list which contains <%name%> objects
*/
public static List<<%name%>> getAll<%name.toU1Case()%>s() {
Transaction tx = null;
Session session = SessionFactoryUtil.getInstance().getCurrentSession();
try {
tx = session.beginTransaction();
List<<%name%>> <%name.toL1Case()%>s =
session.createQuery("select h from <%name.toU1Case()%> as h").list();
//<%startUserCode%> for getAll
//<%endUserCode%> for getAll
tx.commit();
return <%name.toL1Case()%>s;
}
catch (RuntimeException re) {
if (tx != null && tx.isActive()) {
try {
tx.rollback();
}
catch (HibernateException he) {
throw new DaoException("Hibernate: error at rollback!", he);
}
throw new DaoException("Hibernate: error at list<%name.toU1Case()%>()!", re);
}
}
return null;
}
...I recommend two open source products to generate code:
- Topcased (http://www.topcased.org/) - for designing
- Obeo (http://obeo.fr/pages/acceleo/en) - for code generating
To use this technique You have to create some roles in Your IT department. Have a look at the next figure:
As You can see on the figure above at least three different roles must exist:
- MDA architect
The responsibility of this role is to maintain the Source Code Generator Framework (SCGF). And what does the SCGF mean? It contains:
- templates: Each artifacts which You want to create from the model need a template (these artifacts for eample: proxy / business service XML files, XSD's). The generated code will be created from these templates.
- SCGF package for developers: Usually the developers don't need to know anything about the code generation. Their task is to implement the business logic so they have to put the least effort to generate the code. Due to this fact the MDA architect must create a generator package for developers which they just download from the version control system configure at the beginning of the project (e.g. what is the path of thier sour code or model) and use it simply (e.g. they have to execute a batch file on windows systems)
- designer
The designer will create the initial model and modify it according to the requirements. They have to upload the modified model to the version control system from where the developers can download it to (re)generate their code.
- developers
The developers maintain the source code. They download the model and the SCGF package from version control system and generate the first version of the code fill the empty places of code and regenerate it if necessary.
The MDA architect role is project independent but the designer and developers roles are not.
The MDA based code generation is not a magic wand to build something from nothing. You have to create the SCFG Yourself and this might be a huge work. But it could be an enormous help to create the frame of the code easily and quickly.
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