B4J Question [Server] Handling Cache

aeric · Jun 30, 2022

EnriqueGonzalez said:
aeric said:

8. Enable or disable Caching

Click to expand...

I guess you can use server.CreateThreadSafeMap
but it may be better to wrap a library like:

Lettuce Reference Guide

lettuce.io

This is something beyond my knowledge and always a nightmare of mine when developing web applications.

If I want to build a web framework/application, I need to consider/overcome this problem. Caching can be a culprit to the issue of the static content not refresh. This usually happen if I overwrite the CSS or replace a new image with the same file name. The workaround is to append a new value to the GET request in the calling URL to force the server thinks that this resource should not already existed.

My question is, if I generate dynamic content from the database query or programming function to generate some kind of data model to pass to a template engine like FreeMarker, would I getting any issue? I am referring to jServer (jetty) application.

EnriqueGonzalez said:
freemarker

aeric · Jun 30, 2022

Is the template caching handle by the library automatically so I don't need to be worry about it? Hence no any configuration needed for B4J server.

Template loading

freemarker.apache.org

MicroDrie · Jun 30, 2022

The nature of HTML solution is that you send information to the user (that's under your control) and the user can provide information (which is not under your full control). Annyway, the result is in the DOM.
The underlying challenge is of course what is the displayed information worth? You can choose to read out the information displayed by the DOM so that the stored information is equal to what the user sees when (s)he give a update command therby ignoring the previously displayed value in an older situation.

aeric · Jun 30, 2022

At this point, I don't want to worry about it until I hit the issue. I am sure there would be a workaround then. Just want to hear any opinions from the floor.

EnriqueGonzalez · Jun 30, 2022

aeric said:
static

In the context of servers static has a different meaning.
Usually it means that it is the same now a minute ago and a minute from now.

But on servers it means that you will send html that doesn't need to change in order to be seen.

Think of Vue, Vue is dynamic because you have to send the JavaScript to the browser and then the page is made on the browser.

This html doesn't have to come from a file, usually it will not, it can be a string created from a stringbuilder in B4j.

aeric said:
I generate dynamic

To have the concept clear, you will create static content from dynamic sources.

aeric said:
would I getting any issue?

None. In the past frameworks like ASP handled this so wrong that broke our minds forever, you can pass anything you want and the browser will render it just fine.

aeric said:
FreeMarker

Free marker allows you to mix a template with a dynamic content and convert that into a string that will be sent thru the resp class to the browser.

You don't call the template directly nor create an html file from the result.

EnriqueGonzalez · Jun 30, 2022

When I meant by cache (like maps and lettuce) is that at some point the database may reach a limit of connections or processing,

So instead of calling the db form something continuous like session handling, its better to use a cache system

Btw, jetty already uses a cache system called sessions in the request class.

aeric said:
I don't want to worry about it

By all means, don't. I use my framewrok with 100 hundred customers concurrently and I haven't hit a single issue on performance.

aeric · Jun 30, 2022

EnriqueGonzalez said:
In the past frameworks like ASP handled this so wrong that broke our minds forever

What was wrong? You mean ASP.NET code behind or Classic ASP 3.0 using <%%> ?

EnriqueGonzalez · Jun 30, 2022

aeric said:
What was wrong?

what is wrong. i made an app with ASP a short time ago with what was the latest version (5.x) and i had to press F5 everytime to recache everything on the server. This is a mecanism they use so they spare some IO, it may be helpful in the past when we used HDD but on current NVME era, it is nonsense.

aeric · Jun 30, 2022

EnriqueGonzalez said:
what is wrong. i made an app with ASP a short time ago with what was the latest version (5.x) and i had to press F5 everytime to recache everything on the server. This is a mecanism they use so they spare some IO, it may be helpful in the past when we used HDD but on current NVME era, it is nonsense.

You worked on ASP .NET Core?
I never work on something beyond .NET 4.5
I am not sure how terrible it is.

aeric · Jun 30, 2022

EnriqueGonzalez said:
When I meant by cache (like maps and lettuce) is that at some point the database may reach a limit of connections or processing,

So instead of calling the db form something continuous like session handling, its better to use a cache system

Btw, jetty already uses a cache system called sessions in the request class.

By all means, don't. I use my framewrok with 100 hundred customers concurrently and I haven't hit a single issue on performance.

Do you have example how I can I mplement lettuce in jServer? I need to create a Redis client?
What is jetty build-in cache system? How is it different? Any example?

EnriqueGonzalez · Jun 30, 2022

aeric said:
You worked on ASP .NET Core?

Yes i did

aeric said:
I never work on something beyond .NET 4.5

It gets better and better, yet i prefer Jserver a 100 times

aeric said:
I am not sure how terrible it is.

It is not, there are better things

aeric said:
Do you have example how I can I mplement lettuce in jServer?

i do not sorry, i played with it directly on java.

aeric said:
need to create a Redis client?

Start installing Redis SERVER on your PC, i think you cant install it on windows, if that is so you may want to use one form the Cloud
you dont need a redis client, Lettuce and therefore your app will be the redis client!

aeric said:
What is jetty build-in cache system

in your handlers you have a req object (servletrequest)
the cache is in:
req.GetSession
and the methods
GetAttribute
SetAttribute

these 2 work like if you were connecting to redis, the difference is that if you kill the server the cache is cleaned (thats actually what a cache is, ephimeral)

EnriqueGonzalez · Jun 30, 2022

aeric said:
etty build-in cache system

by the way, one of the features of the jetty cache is that you can save Objects like classes and maps and not only scalar values (like strings) therefore you may find it more useful at the start of your project than redis

aeric · Jun 30, 2022

EnriqueGonzalez said:
i think you cant install it on windows

I have Redis in Laragon server but I never know how to use it.

EnriqueGonzalez · Jun 30, 2022

aeric said:
Laragon server

i am not familiar with laragon but Redis uses a TCP connection with a port. if you have the IP and the port that redis is using you can actually issue some commands to it.

if you want to begin playing with redis then install the redis-cli

https://redis.io/docs/latest/develop/tools/cli/

aeric · Jun 30, 2022

EnriqueGonzalez said:
i am not familiar with laragon but Redis uses a TCP connection with a port. if you have the IP and the port that redis is using you can actually issue some commands to it.

if you want to begin playing with redis then install the redis-cli

https://redis.io/docs/latest/develop/tools/cli/

I have checked on the UI for Redis from Laragon days ago. It just look like a MySQL db for me.

EnriqueGonzalez · Jun 30, 2022

aeric said:
It just look like a MySQL db for me.

It is kinda similar, you could say that redis is a NOSQL database like mongo,

The extra that redis gives you is in memory data handling and a pub sub system. The later is just for advanced stuff

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