Architecture Issue (MVC)

Question

ARCHITECTURE DESIGN COMMENTS
We have designed a java system for one of the crucial projects.After that due to some reasons we are asked to restructure it. Here I?m presenting 2 variations with all the details.
I sincerely request your comments on this, and if you have a better solution with the existing means(jsp,javabean,servlet) please let us know.
The basic things I need to know is that:
1. Feasibility of this model.
2. performance.
3. Any drawbacks and how to over come them.
I MODEL
(valueobject)
jsp----->Servlet(Controller)------------------------------->(DBMangager)--------->Database
(Since this is not taking the image-i could not able to draw the entire thing properly)
Process
The process in the first model is that
1. All the parameter names and values are collected in a HashMap in the controller.
Ex. Request.getParameterNames()
while ( e.hasMoreElements () )
String name = ( String ) e.nextElement () ;
String val[] = request.getParameterValues ( name ) ;
hm.put ( name , val ) ;
2. Then the controller sends it to the constructor of the Assembler.
try
fv = new FwAssembler ( hm , txn_no , comp_code ) ;
3. The assembler segregates the code and assigns to the corresponding value objects.Here value objects are parameters to the Assembler.Means once the corresponding value objects are set, these value objects are set to the Assembler with setValueObjects. So that now the assembler contains value objects which represent the data.
An extract:
public FwAssembler(HashMap hm, String tx_no, String comp_code)
setComp_code(comp_code);
setTxn_no(tx_no);
ftran = new FwTransaction(tx_no);
aprofile = new ApplcantProfile(comp_code);
cvo=new CompProductsVO(tx_no);
lfile.logErr("FwAssembler","1");
The following corrosponds to the automation plan.
Depending upon the value of strAutomation remaing values will be considered.
String n1[] = (String[]) hm.get("strAutomation");
strAutomation = n1[0];
ftran.setStrAutomation(strAutomation); // this gives whether automation plan is yes or no
String n270[] = (String[]) hm.get("strDateimplemen");
try
if (strAutomation.equalsIgnoreCase("y"))
String n2[] = (String[]) hm.get("strDateimplemen");
strDateimplemen = n2[0];
ftran.setStrDateimplemen(strDateimplemen);
String n3[] = (String[]) hm.get("decCostinvolve");
decCostinvolve = Double.parseDouble(n3[0]);
ftran.setDecCostinvolve(decCostinvolve);
String n4[] = (String[]) hm.get("vcPartauto");
vcPartauto = n4[0];
ftran.setVcPartauto(vcPartauto);
String n5[] = (String[]) hm.get("intNoworkers");
intNoworkers = Integer.parseInt(n5[0]);
ftran.setIntNoworkers(intNoworkers);
catch (Exception kk)
lfile.logErr("strAutomation", "Exception kk", kk.toString(),
kk.getMessage());
4. Once the Assembler is set, the controller will send Assembler to the DBManager.
try{
b = fbean.insertFwworker(fv, txn_no, comp_code);
catch(Exception bean)
lfile.logErr("","bean",bean.toString(),bean.getMessage());
5. DBManger, with the help of value objects will insert the data into the data base.
6. This method will return true, and if it is true the controller will send it to the next jsp page.Else it will display the error page.
I I? MODEL
In my model II- the most significant difference is that :
While sending the data from Controller to the Assembler I have not used a HashMap, but in my model II, I just send the request object.
cassembler=new CfcAssembler(request,txn_no,comp_code);
ofcource what I?m planning is that:
Instead of putting it in a Constructor I want to send it in a method in that class.
I had the following advantages got by doing so:
1. My coding is considerable reduced to a greater extent.
public CfcAssembler(HttpServletRequest request,String tx_no, String comp_code)
setStrTrxn(tx_no);
setStrCompCode(comp_code);
setSelIcfctype(request.getParameter("selIcfctype"));
setStrCfcdesc1(request.getParameter("strCfcdesc1"));
if(request.getParameter("decQty")!=null)
setDecQty(Double.parseDouble(request.getParameter("decQty")));
else
setDecQty(decQty);
setStrPurpose(request.getParameter("strPurpose"));
if(request.getParameter("cbEmail")!=null)
cbEmail=request.getParameter("cbEmail");
if(request.getParameter("cbPhone")!=null)
cbPhone=request.getParameter("cbPhone");
if(request.getParameter("cbPost")!=null)
cbPost=request.getParameter("cbPost");
strMethodNotify+=cbEmail+cbPhone+cbPost;
setStrMethodNotify(strMethodNotify);
2. My performance I think is improved, because I?m not using any String Arrays.
3. The readability of the code is also good.
Where I?m not sure
In the Assembler class I?m importing the package javax.servlet.HttpServletRequest.
1.Can this Assembler class is made as a java bean.
2. Will this model also fulfills the MVC architecture.
Please fill in me with all the details.Your earliest reply in this matter is highly appreciated,as we are at a crucial stage.
Thanking you
pressy

Answer 1

I would be surprised if your scaling bottleneck occurs dumping an HttpServletRequets parameter list into a Map. So, while there may be a slight performance/memory hit in populating the Map, it should be negligible as everything is already in memory.
From a design perspective, I like #2 better. You don't want to import the http.servlet classes everywhere in your domain model. You should theoretically be able to switch either your view or your persistence tier without affecting the domain model.
Servlet classes are tied to a web presentation framework. Not that a sane person would do such a thing, but what if you decided to switch your UI to Swing? Now, all those HttpServletReqeust objects are useless, but a Map still works fine.
On a more realistic example, what if you decided to switch to SOAP and web services instead? The ServletRequest and SOAP request could both have adapters written that generate the same Map. Now, all your code past the Map is the same regardless of what type of request you receive.
Now, I have never completely changed my view or even my persistence tier in a real-world application. However, I do see the validity or keeping the model agnostic. So... no Servlet classes should go there. IMHO, that is.
- Saish
"My karma ran over your dogma." - Anon