Unbound Map, architecture question

Hey guys,
I have the following question. The core of our system is a singleton which
maintains a Map of String->Object bindings. This is a relatively small Map,
hardly ever over 20 objects. Now I want to store this Map in the database.
The Objects in the Map are objects in the database already, however the
singleton itself shouldn't be in the database. The Map is only bound to the
singleton. No other object can get to it directly. How can I model this?
Greetings,
Martin van Dijken

A little bit of everything :)
Martin van Dijken wrote:
Think I'll go for the Object method. Don't really like the singleton in
database method.
Thanks.
BTW, isn't it around midnight on the east coast right now? Are you a
european employee or just that loyal( /dumb;) )?
I see. I personally would recommend enforcing at load time if that is
best for you. Alternatively, you could of course store each row as its
own app-id PC with the singleton loading from the extent instances of
key-oid pair. I guess it depends on how often the state of the map
changes (each row as currently built doesn't have opt-locking
capabilities), whether app-id makes sense for your map rows and how much
state management you want in your singleton.
On second thought, my leaning is towards the latter idea but I think
both have their strengths and weaknesses.
Martin van Dijken wrote:
Here's the idea:
We have a system of objects. These objects of course have their own ids.
Now
in our HTML at some points we have places where we want to open 1specific
object. However if we put the id at that place, and someone deleted our
object, we'd be lost. So, instead of putting the id of an application inthe
HTML, we place a String in the HTML. Through a simple web-interface it's
possible to alter to what object the String points. Then the firstobject
can safely be deleted. This simple interface also allows the creation ofnew
keys.
Now in our current system, these string-keys and ids are simply storedin
one table.
|Table Mapping |
------------------+
|key |objectid |
------------------+
When the singleton is loaded, it retrieves the entire Map and it is theonly
object that can edit anything in the map.
So what you're suggesting is storing the Singleton in the database andthen
manually guaranteeing it's a singleton at load time?
Martin
Stephen Kim
[email protected]
SolarMetric, Inc.
http://www.solarmetric.com
Stephen Kim
[email protected]
SolarMetric, Inc.
http://www.solarmetric.com

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Little architectural question: why is all the stuff
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>
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patriot87 wrote:
Strange... I have also tried with 200k and same results... :D
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import java.util.Hashtable;
import java.util.Map;
import java.util.Random;
public class HashMapTest
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   private static Random gen = new Random();
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for (int i = 0; i < objs.length; i++)
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map.get("ID" + randomInt);
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class MapObject
String name;
String id;
public MapObject (String id, String name)
this.id = id;
this.name = name;
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[pre]class java.util.HashMap: 343
class java.util.Hashtable: 500
class java.util.HashMap: 313
class java.util.Hashtable: 328
class java.util.HashMap: 453
class java.util.Hashtable: 313
class java.util.HashMap: 296
class java.util.Hashtable: 454[/pre]
Edited by: endasil on 13-Nov-2009 10:34 AM

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Doug

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Manish,
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          >
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          >
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So far, the presentation tier consists of an Apache Tomcat Server to run Servlets and generate one HTML page. The HTML page contains an embedded MDI style Applet with inner frames, etc.; hence, the solution is Applet-centric rather than HTML-centric. The low volume of HTML is why I decided against JSPs for now.
Business Tier
I am planning to use the J2EE 1.4 Application Server that is included with the J2EE distribution. All database transactions would be handled by Entity Beans and for computations I'll use Session Beans. The most resource intensive computational process will be a linear optimization program that can compute large matrices.
Enterprise Tier
I?ll probably use MySql, although we have an Oracle 8 database at our disposal. Disadvantage of MySql is that it won't have triggers until next release, but maybe I can find a work-around for now. Advantage is that an eventual migration to Linux will be easier on the wallet.
Additional Information
We plan to use the system within our company at first, with probably about 5 or less simultaneous users. Our field engineer will also have access from his laptop. That means he?ll download the Applet-embedded HTML page from our server via the Internet. Once loaded, all navigation will be Applet-centered. Data transfer from the Applet to Servlet will be via standard HTTP.
Eventually we would like to give access of our system to a client firm. In other words, we would be acting as an application service provider and they would access our application via the Internet. The Applet-embedded HTML page would load onto their system. The volume would be low--5 simultaneous users max. All users are well-defined in advance. Again, low volume HTML generation--Applet-centric.
My Questions
1). Is the J2EE 1.4 Application Server a good production solution for the conditions that I described above? Or is it better to invest in a commercial product like Sun Java System Application Server 7 ? Or should I forget the application server concept completely?
2). If I use the J2EE Application Server, is this a good platform for running computational programs (via Session Beans)? Or is it too slow for that? How would it compare with using a standalone Java application--perhaps accessed from the Servlet via RMI? I guess using JNI with C++ in a standalone application would be the fastest, though a bit more complex to develop. I know it is a difficult question, but what is the most practical solution that strikes a balance between ease-of-programming and speed?
3). Can the J2EE 1.4 Application Server be used for running the presentation tier (Servlets and HTML) internally on our intranet? According to my testing, it seems to work, but is it a practical solution to use it this way?
4). I am running Tomcat between our inner and outer firewalls. The database would of course be completely inside both firewalls. Should the J2EE (or other) Application Server also be in the so-called ?dmz? with Tomcat? Should it be on the same physical server machine as Tomcat?
5). Can Tomcat be used externally without the Apache Web Server? Remember, our solution is based on Servlets and a single Applet-embedded HTML page, so high volume HTML generation isn?t necessary. Are there any pros/cons or security issues with running a standalone Tomcat?
So far I've got Tomcat and the J2EE Application Server running and have tested my small Servlet /Applet test solution on both. Both servers work fine, although I haven't tested any Enterprise Beans on the application server yet. I?d really appreciate if anyone more experienced than I can comment on my design, answer some of my questions, and/or give me some advice or insights before I start full-scale development. Thanks for your help,
Regards,
Itchy

Hi Itchy,
Sounds like a great problem. You did an excellent job of describing it, too. A refreshing change.
Here are my opinions on your questions:
>
My Questions
1). Is the J2EE 1.4 Application Server a good
production solution for the conditions that I
described above? Or is it better to invest in a
commercial product like Sun Java System Application
Server 7 ? Or should I forget the application server
concept completely?
It always depends on your wallet, of course. I haven't used the Sun app server. My earlier impression was that it wasn't quite up to production grade, but that was a while ago. You can always consider JBoss, another free J2EE app server. It's gotten a lot of traction in the marketplace.
2). If I use the J2EE Application Server, is this a
good platform for running computational programs (via
Session Beans)? Or is it too slow for that? How
would it compare with using a standalone Java
application--perhaps accessed from the Servlet via
RMI? I guess using JNI with C++ in a standalone
application would be the fastest, though a bit more
complex to develop. I know it is a difficult
question, but what is the most practical solution that
strikes a balance between ease-of-programming and
speed?
People sometimes forget that you can do J2EE with a servlet/JSP engine, JDBC, and POJOs. (Plain Old Java Objects). You can use an object/relational mapping layer like Hibernate to persist objects without having to write JDBC code yourself. It allows transactions if you need them. I think it can be a good alternative.
The advantage, of course, is that all those POJOs are working objects. Now you have your choice as to how to package and deploy them. RMI? EJB? Servlet? Just have the container instantiate one of your working POJOs and delegate to it. You can defer the deployment choice until later. Or do all of them at once. Your call.
3). Can the J2EE 1.4 Application Server be used for
running the presentation tier (Servlets and HTML)
internally on our intranet? According to my testing,
it seems to work, but is it a practical solution to
use it this way?
I think so. A J2EE app server has both an HTTP server and a servlet/JSP engine built in. It might even be Tomcat in this case, because it's Sun's reference implementation.
4). I am running Tomcat between our inner and outer
firewalls. The database would of course be completely
inside both firewalls. Should the J2EE (or other)
Application Server also be in the so-called ?dmz? with
Tomcat? Should it be on the same physical server
machine as Tomcat?I'd have Tomcat running in the DMZ, authenticating users, and forwarding requests to the J2EE app server running inside the second firewall. They should be on separate servers.
>
5). Can Tomcat be used externally without the Apache
Web Server? Remember, our solution is based on
Servlets and a single Applet-embedded HTML page, so
high volume HTML generation isn?t necessary. Are
there any pros/cons or security issues with running a
standalone Tomcat?
Tomcat's performance isn't so bad, so it should be able to handle the load.
The bigger consideration is that the DMZ Tomcat has to access port 80 in order to be seen from the outside without having to open another hole in your outer firewall. If you piggyback it on top of Apache you can just have those requests forwarded. If you give port 80 to the Tomcat listener, nothing else will be able to get it.
>
So far I've got Tomcat and the J2EE Application Server
running and have tested my small Servlet /Applet test
solution on both. Both servers work fine, although I
haven't tested any Enterprise Beans on the application
server yet. I?d really appreciate if anyone more
experienced than I can comment on my design, answer
some of my questions, and/or give me some advice or
insights before I start full-scale development. Thanks
for your help,
Regards,
Itchy
There are smarter folks than me on this forum. Perhaps they'll weigh in. Looks to me like you're doing a pretty good job, Itchy. - MOD

Enterprise Manager 11g Sybase Plugin architecture question

Hi,
have successfully installed and configured Grid 11g on RedHat Enterprise 5.5. Deployed and configured agents to solaris and linux environments..so far so good.
However, we're going to test the Sybase ASE plugin to monitor ASE with EM. My question is a simple one and I think I know the answer but I'd like to see what you guys think of this.
We'd like to go with a simple centralised agent rather than one agent/plugin per sybase machine, atleast for the tests. No doubt there may be pro's (first one clearly being one of a single point of failure - welll we can live with this for now) to this approach. My instinct is to install the oracle agent/plugin on a machine other than the grid machines itself, however the question arose - why not install the ASE plugin on the grid infrastructure machine agents themselves? Pros and cons?
The architecture we have currently : repository database configured to failover between 2 redhat boxes. 2 OMS running 1 on each of these boxes configured behind SLB using nfs based shared upload directory. One 'physical agent' running on each box. Simple for now. But I have the feeling , given that the Sybase servers will communicate or be interrogated via the sybase plugin directly to the grid infrastructure machines placing load etc on them , and in case of problems might interfere with the healthy running of the grid. Or am I being over cautious?
John
Edited by: user1746618 on 12-Jan-2011 09:01

well I have followed the common sense approach and avoided the potential problem by installing on a remote server and configuring the plugin on this.
Seems to be working fine and keeps the install base clean..

Unbound Map, architecture question

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