October 30, 2018

The use of TypeScript. Why?


I am searching for the real use of TypeScript.


disclaimer: I am going to write TypeScript as Typescript, just as a heads-up for the critical reader.


In my life as a developer I tried to understand why people want to make certain choices for languages and tools. I don’t want to go pick a tool or language just because people order me to do that. I always wonder why they do that. Is it policy or is did they actually think of it.
I mean I understand why people want to use Typescript from certain perspectives.


  • The use of types,
  • My framework uses typescript (Eg. Angular),
  • The ease of use of OOP programming,
  • My Java developers can immediately start programming because of the familiarity Typescript has with Java,
  • Typescript allows me to use my tooling like autocompletion,


Of all these arguments I can just as easily say a counter argument. For me the only really valid point is the second argument in above list.  
When you choose a framework where all the documentation is written in a language it is hard to break out of that language.

Let me try to explain why I am not convinced in these arguments.

Types


In using good programming (mind you I say programming not Typescript) we make use of Types (often seen as objects in OOP).Types are defined by a contract not by using a keyword that loses its purpose in runtime.
The use of types in Typescript are only used to satisfy the compiler, but then we added this compiler as a language tool (like any compiler). But here it comes, the angular compiler is not so much as a compiler but more of a transpiler. It transforms the Typescript to Javascript and it erases all type information once the resulting code is left as Javascript. Also what I have found is that the use of types is often neglected as I will argue in a later reasoning here.

I like dynamic languages. The give me an feeling of productivity that I cannot achieve with statically typed languages like Java (or Typescript).
I like to work with the mantra: 
if it walks like a duck and if it talks like a duck, it's probably a duck
For me this is all about the contract. 
When the object in question does not follow the contract it just isn't the type we need in this context. If we use Typescript to define our types we know it is fine during compilation however in runtime there is no such confirmation or construct that we are using the expected type. The only way to way to verify this is to test. 
Why do I say we have no such confirmation in runtime? Well too often I see developers make use of the 'any' type. 'any' basically says: I don't know what type we're using here but trust me it's gonna be alright.... 😑
This 'any' and the loosing of typing in runtime can give us false safety.

Frameworks


Currently amongst the most used frameworks in the enterprise is Angular. Angular is written in Typescript. All the documentation is written in Typescript. All the examples likewise. I understand this as a valid point in using Typescript. It makes your productivity much higher especially when you program and use the likes as stack overflow and the official examples as your way to solve your programming issues. No questions asked no answers given. I take this as fact. However, I still wonder why these frameworks would be written in Typescript in the first place.

OOP

Typescript promotes the use of object oriented programming. I agree. Since Typescript is modelled after C# and Java, it promotes the use of the class construct and hence object constructs. Typescript however also is a so called supertyped javascript it allows you to write plain javascript without the added features Typescript has. The class construct is not the classical construct as we know from Java and C#, basically it is syntactic sugar over the prototypal inheritance structure Javascript offers.
In fact ES6 offers this construct so it is not even exclusive to Typescript.

Now I favor the use of functional programming over oop, while this is not entirely so. I really prefer the use of a hybrid approach of using both functional and oop in my code.
I see the use of services best described in a functional pattern, not in the way Java promotes. Java services are often a collection of related methods combined in an object. To me this is more or less a Façade without the usage of multiple delegated extra components. 

Coming from a different language

I heard a few of my peers tell me: "well thanks to Typescript my java developers were able to code for the frontend because the language is practically the same."
There is so much wrong with this argumentation, I hardly know where to begin. Let me try though.
Being able to program in another language because the syntax is so familiar is like saying you can use oranges for your apple pie because they are both fruits and hang both on a tree and you have to peel their skin off.
Go and tell an average Java programmer to start programming in C# because the syntax is nearly the same. It just doesn't work that way. Sure the programmer is able to produce some code, but let's call it at that ok? Tell a windows engineer to setup a linux server, they are both servers and have a cli. I think you got my meaning.
apples and oranges who cares?


Typescript is just no Java. Don't pretend it is because of syntax similarity. We hide behind a layer of semantics that we try to map on javascript. 
We hide the concept of the actual workings of prototypal inheritance in Typescript or even in ES6 for that matter. The interface semantics are different in Typescript than in Java. In Java an interface is meant to be a contract, in Typescript it is meant as a struct a type without any specific behaviour. Though the documentation claims the interface to be a contract as well, I even see this construct in a Typescript interface:
[propertyName: string]: any;
What this allows you to do, is to basically say: any property you add to this interface is allowed.
Object literal? Any? (pun intended).
We basically leave the contract so wide open it basically becomes void.

I just think you just need to take the fear of using a different language away from the Java developer Typescript is just another trick to persuade the Java developer to become a frontend developer, but it leaves the developer in no-mans land. 
The real solution is to just educate the Java developer in javascript. But don't fool the developer. It's just not right. Either point out he has to do the dam job and suck it up or stay out of webdevelopment, just be honest.

Tools

tools

Typescript allows me to use tooling for my productivity.
Well this seems to me it's the other way around. Aren't tools used to enhance our productivity? Shouldn't tools provide a means to make our work easier? In that way Typescript is a tool but so is javascript. And this is exactly my question: Why should I use Typescript? 

Visual Studio is an editor that allows me to use plugins to enhance my writing of code. but it also allows me to enhance me my writing of javascript code, not just Typescript.
Personally I have a multitude of tools I write my code in. I am a vim user (neovim for that matter). I have found lots of ways to increase my productivity in that editor.

Do I want to be convinced to use Typescript?
Well I certainly want to understand why I should use Typescript over javascript. I just don't see it.
I would be very happy if someone could point out to me what I am missing. I want to share knowledge and I certainly will try to provide this found knowledge to others in helping them.

August 13, 2014

Becoming DevOps

I've been working on creating development environments a while now and my current employer wants to have a quick way of setting up a development environment for the projects that we do.
Since I've worked with Vagrant before it befell to me to do the setting up of it all.

Vagrant is a tool that can make use of virtualisation software like Virtualbox or VMWare. It provides means to run the vm image (box) with a provisioned state specifically for your (development) needs.

I started by making use of packer. Packer allows me to setup a vagrant box in much less time than it would take me to if I used Vagrant itself for creating boxes.
Packer allows you to select the iso and the virtualisation software and also provides hooks to provision the box with the tools you would need to do your job once you start developing on the box within your project.
This provisioning is obviously the hard part and needs the play-rewind-repeat cycle to really put the stuff on the box that you want.

Let me tell you what I did without the repeat cuz of course I did it right in one time *cough*.

I found a set of packer templates on the web that allowed me to jumpstart the creation of the boxes.
Although I might now use PuPHPet with some adjustments I learned quite a bit about provisioning.
First the basics:
I modified the template I needed and I added an extra script for my provisioning needs.

I added this script in my template.json.

Then I added the puppet locations to my template.json within the provision section:
  {
"type": "puppet-masterless",
"manifest_file": "/tools/vagr_build/puppet/manifests/default.pp",
"manifest_dir": "/tools/vagr_build/puppet/manifests",
"module_paths": ["/tools/vagr_build/puppet/modules"]
    }
Obviously I have my build environment in tools/vagr_build as you can see here, you might have other locations.
I also make use of puppet-masterless because we do not have a puppet server within our company and I didn't want to invest time to set that up as well.

Now comes the big part, the real provisioning. I created my provisioning command in the default.pp file
I first install some base packages and mysql with apache. Then comes the PHP part and this part needed some extra configuration
To configure PHP correctly I needed to create a php.ini within /etc/php5/conf.d/ I updated its content using a tool called augeas Puppet knows how to use this but it needs to be installed serparately, so I did that with the base packages.
Note the context within a augeas part starts with /files/ this is a nessecary part to edit files.

From here I made my box file:
> packer build -only=virtualbox-iso .\template.json
and once this was done I did
> vagrant box add ubuntu_12_php53 .\ubuntu-12-04-x64-virtualbox.box
to place my box with vagrant

Later use of this box is just how you would normally use a vagrant box.

December 19, 2013

Debugging python with vim in a virtualenv

Yay I finally got it working my debugging of a python script with Vdebug in vim
Vdebug is a vim plugin that lets you debug all kinds of scripts/languages in vim.
It supports these languages:
Python
Perl
PHP
Ruby
Node.js

At work I use it to debug Perl code and I wanted to use it to debug my python code for personal projects.

the key is: pip install  komodo-python-dbgp within your virtualenv once that is done it will create the executable pydbgp in your virtualenv. so you can launch in vim vdbug and then in the shell:
pydbgp <script>

December 16, 2013

Working on a new web project

Ok, so I started working on a web project for a friend of mine.
I want to work with some new stuff so I decided to implement this application with some neat new technologies (well new for me anyway).

All the while I have been dabbling with some stuff during the years now and I came up with a basic installation to get my workflow ready.
For this I am making use of a script that I execute to setup my projects environment:


This installs an isolated python environment and an isolated node.js environment for webdevelopment.
The script will also offer the option to work either with a Yeoman workflow or a Brunch based workflow.


When I start my work I just use another script that will launch my work environment in correct settings.
For that I make use of tmux a screen multiplexer that enters in the activated virtualenv:


I've decided to build this all with Angularjs in the frontend and flask or django on the backend. The backend I will decide later on.
For the workflow I will use Brunch because it is a fairly basic webapplication and the speed of usage in a Brunch workflow outweighs the flexibility/complexity of the Yeomand/Grunt  configuration.
I made a skeleton to work with coffeescript and Angularjs and made that available on github.

I will provide details of my progress.

October 14, 2011

VLC and AirportExpress

At work we got our hands on an Airport Express. So the first thing of course is "MUSIC".
Well we do have some people here that want to use iTunes. But for personal reasons I don't like iTunes.
So I normally use VLC like any sane person would do :) But while all of my co-workers were laughing at me cuz i couldn't join with the music streaming.
Not taken aback I was strolling the internet to find if there was a solution of streaming to Airport. There was a program called Airfoil but hey I'm dutch so i really don't want to pay for programs unless necessary. At the VLC forums i stumbled on a post by crzyhanko and he posted some great code you can put in the standard streamchain field of the VLC player:
#transcode{acodec=alac,channels=2,samplerate=44100}:raop{host=<ip address of airport express>,volume=175}
It works :D so who is laughing now

March 10, 2011

SQL remove of constraints

Note to self:

when doing large imports using a sql script in oracle. here's how to remove constrains and then enable them after insert:


This code is useful to disable the constraints in the database.
set serveroutput on;
begin
  for c in (select constraint_name, table_name from user_constraints where constraint_type='R') loop
    execute immediate('alter table '||c.table_name||' disable constraint '||c.constraint_name);
  end loop;
end;
/
the '/' at the end lets sql developer know that this is the end of an inline pl/sql script

then insert the normal sql insert script and when done include this code:
begin
  for c in (select constraint_name, table_name from user_constraints where constraint_type='R') loop
    execute immediate('alter table '||c.table_name||' enable constraint '||c.constraint_name);
  end loop;
end;
/
-- SHOW ENABLED --
select constraint_name, status from user_constraints where constraint_type='R';
When the last line still shows disabled constraints the data is corrupt.

Blobs of type String can be inserted via a workaround:
declare myBLobVar varchar2(32767) := 'paste string here' ;
begin
  update tableWithBlob set blobCol = myBlobVar where id = blah ;
end;

July 20, 2009

Eclipse Templates

Templates are a usefull thing when working with code as we know.
A simple template is a simple thing to do but using an import is a different beast.

so here is a example to make sure that the import is also included in the java file.

/** Tapestry render phase method. Called before component body is rendered.*/
@BeforeRenderBody
public void beforeRenderBody(){
${cursor}
}
${:import(org.apache.tapestry5.annotations.BeforeRenderBody)}


May 21, 2009

JTA

Most applications using ORM tooling have need of a transaction management system.
One of these transaction managers is Atomikos. Atomikos provides several products. One transaction essentials is an opensource variant.
However you cannot get it via a maven repository. You'll have to register for a download link.
Transaction essentials is easy embeddable within a jetty container or even within a spring context.

First here's how to implement transaction essentials within a jetty container configured with maven.

Lets start with the jetty configuration within a maven pom file:

<!-- Run the application using "mvn jetty:run" -->
            <plugin>
                <groupId>org.mortbay.jetty</groupId>
                <artifactId>maven-jetty-plugin</artifactId>
                <version>6.1.15</version>
                <configuration>
                    <!-- Log to the console. -->
                    <requestLog implementation="org.mortbay.jetty.NCSARequestLog">
                        <!--
                        This doesn't do anything for Jetty, but is a workaround for a
                        Maven bug that prevents the requestLog from being set.
                        -->
                        <append>true</append>
                    </requestLog>
                   
                    <scanIntervalSeconds>0</scanIntervalSeconds>
                    <webAppConfig>
                      <contextPath>/rbudisplay</contextPath>
                      <tempDirectory>${project.build.directory}/work</tempDirectory>
                    </webAppConfig>
                    <jettyConfig>src/etc/jetty/tx-jetty.xml</jettyConfig>
                    <jettyEnvXml>src/etc/jetty/jetty-env.xml</jettyEnvXml>
                </configuration>
                <dependencies>
                    <dependency>
                        <groupId>javax.transaction</groupId>
                        <artifactId>jta</artifactId>
                        <version>1.1</version>
                    </dependency>
                    <dependency>
                        <groupId>com.atomikos</groupId>
                        <artifactId>atomikos-util</artifactId>
                        <version>3.5.4</version>
                    </dependency>
                    <dependency>
                        <groupId>com.atomikos</groupId>
                        <artifactId>transactions</artifactId>
                        <version>3.5.4</version>
                    </dependency>
                    <dependency>
                        <groupId>com.atomikos</groupId>
                        <artifactId>transactions-api</artifactId>
                        <version>3.5.4</version>
                    </dependency>
                    <dependency>
                        <groupId>com.atomikos</groupId>
                        <artifactId>transactions-jta</artifactId>
                        <version>3.5.4</version>
                    </dependency>
                    <dependency>
                        <groupId>com.atomikos</groupId>
                        <artifactId>transactions-hibernate3</artifactId>
                        <version>3.5.4</version>
                    </dependency>
                    <dependency>
                        <groupId>postgresql</groupId>
                        <artifactId>postgresql</artifactId>
                        <version>8.3-603.jdbc4</version>
                    </dependency>
                    <dependency>
                        <groupId>log4j</groupId>
                        <artifactId>log4j</artifactId>
                        <version>1.2.14</version>
                    </dependency>
                </dependencies>
            </plugin>

The jettyConfig tx-jetty contains the configuration for the atomikos usertransactionmanager and will be applied before other setting set in the maven pom:

<Call class="java.lang.System" name="setProperty">
      <Arg>com.atomikos.icatch.file</Arg>
      <Arg>src/etc/jetty/jta.properties</Arg>
   </Call>

   <!-- Atomikos -->
   <New id="tx" class="org.mortbay.jetty.plus.naming.Transaction">
      <Arg>
         <New class="com.atomikos.icatch.jta.UserTransactionImp" />
      </Arg>
   </New>

The jetty-env contains the configuration for a specif webapplication in jetty and consists in part of the datasources for the webapp:

<Set name="configurationClasses">
    <Array type="java.lang.String">
      <Item>org.mortbay.jetty.webapp.WebInfConfiguration</Item>
      <Item>org.mortbay.jetty.plus.webapp.EnvConfiguration</Item>
      <Item>org.mortbay.jetty.annotations.Configuration</Item>
      <Item>org.mortbay.jetty.webapp.JettyWebXmlConfiguration</Item>
      <Item>org.mortbay.jetty.webapp.TagLibConfiguration</Item>
    </Array>
  </Set>
 
  <!-- Add a mapping from name in web.xml to the environment -->
  <New id="map1" class="org.mortbay.jetty.plus.naming.Link">
    <Arg><Ref id='rbudisplay'/></Arg>
    <Arg>jdbc/rbuconverter</Arg> <!-- name in web.xml -->
    <Arg>jdbc/rbu</Arg>  <!-- name in environment -->
  </New>
 
  <New id="rbuconverter" class="org.mortbay.jetty.plus.naming.Resource">
     <Arg><Ref id="rbudisplay"/></Arg>
     <Arg>jdbc/rbu</Arg>
     <Arg>
      <New class="com.atomikos.jdbc.AtomikosDataSourceBean">
       <Set name="minPoolSize">2</Set>
       <Set name="maxPoolSize">50</Set>
       <Set name="xaDataSourceClassName">org.postgresql.xa.PGXADataSource</Set>
       <Set name="UniqueResourceName">rbuconverter</Set>
       <Get name="xaProperties">
         <Call name="setProperty">
            <Arg>databaseName</Arg>
            <Arg>rbuconverter</Arg>
         </Call>
         <Call name="setProperty">
           <Arg>serverName</Arg>
           <Arg>localhost</Arg>
         </Call>
         <Call name="setProperty">
            <Arg>portNumber</Arg>
            <Arg>5432</Arg>
         </Call>
         <Call name="setProperty">
           <Arg>user</Arg>
           <Arg>postgres</Arg>
         </Call>
         <Call name="setProperty">
           <Arg>password</Arg>
           <Arg>BlahBlah</Arg>
         </Call>
       </Get>
      </New>
     </Arg>
   </New>

The first part sets up the jetty plus environment for jndi.
The second part sets up the reference for the jetty-env configuration and to bind the datasource to jndi so the web.xml can make a refernce to the configured datasource.
The third part sets up the datasource itself. Here an XADataSource is configured for PostgreSQL Note that the com.atomikos.jdbc.AtomikosDataSourceBean is the prefered DataSource since Atomikos 3.4.x.

The web.xml needs to have these lines in place for the above configured datasource:

<resource-ref>
      <res-ref-name>jdbc/rbuconverter</res-ref-name>
      <res-type>javax.sql.DataSource</res-type>
      <res-auth>Container</res-auth>
   </resource-ref>

It is also possible to configure Atomikos transaction Essentials completely in a spring context. In this case do not use the jettyConfig and jettyEnvXml in the pom file and omit the resource-ref within the web.xml:
I have a tx-context.xml:

<bean class="com.atomikos.jdbc.AtomikosDataSourceBean" destroy-method="close" id="dataSource" init-method="init">
        <property name="uniqueResourceName" value="rbudatasource"/>
        <property name="xaDataSourceClassName" value="org.postgresql.xa.PGXADataSource"/>
        <property name="xaProperties">
              <props>
              <prop key="databaseName">rbuconverter</prop>
              <prop key="serverName">localhost</prop>
              <prop key="portNumber">5432</prop>
              <prop key="user">postgres</prop>
              <prop key="password">BlahBlah</prop>
              </props>
        </property>
        <property name="minPoolSize" value="5">
        <property name="maxPoolSize" value="50">
    </bean>

    <bean class="com.atomikos.icatch.config.UserTransactionServiceImp" destroy-method="shutdownForce" id="userTransactionService">
        <constructor-arg>
             <props>
                <prop key="com.atomikos.icatch.service">
                    com.atomikos.icatch.standalone.UserTransactionServiceFactory
                </prop>
                <prop key="com.atomikos.icatch.output_dir">/tmp</prop>
                <prop key="com.atomikos.icatch.output_dir">/tmp</prop>
            </props>
        </constructor-arg>
   </bean>           
 
   <!-- Construct Atomikos UserTransactionManager, needed to configure Spring -->
   <bean id="AtomikosTransactionManager" class="com.atomikos.icatch.jta.UserTransactionManager" init-method="init" destroy-method="close" depends-on="userTransactionService">
      <!-- when close is called, should we force transactions to terminate or not? -->
      <property name="forceShutdown" value="false" />
      <property name="transactionTimeout" value="300"/>
   </bean>

   <!-- Also use Atomikos UserTransactionImp, needed to configure Spring -->
   <bean id="AtomikosUserTransaction" class="com.atomikos.icatch.jta.UserTransactionImp" />

   <!-- Configure the Spring framework to use JTA transactions from Atomikos -->
   <bean id="transactionManager" class="org.springframework.transaction.jta.JtaTransactionManager" depends-on="userTransactionService">
      <property name="transactionManager" ref="AtomikosTransactionManager" />
      <property name="userTransaction" ref="AtomikosUserTransaction" />
   </bean>

April 4, 2009

Tapestry activation passivation

Tapestry 5 can make use of the client to make information set to a page from another page available to the client.
For instance Page Origin places a message during a submit onto Page Next and using the mechanism of passivation and activation
the client will act as the middle man to make this information available to the client itself.
Tapestry will issue an HTTP 302 redirect after the post and thus the passivation of Page Next so the client recieves some information and will ask tapestry for that information to be acted upon.
Here you see that the value of 'Howdy' is submitted and using a redirect is send to the server again to be used in its activation event.

February 2, 2009

Apache2 VirtualHost and trac behind a lighttpd proxy

Note to self:
setup of trac for Apache2

follow this instructions on this site: Robert Basic: Trac on Ubuntu.
Although I use mercurial as scm.
make sure that the line containing VirtualHost points to port 81 or another port except port 80.

<VirtualHost *:81>
and make sure apache listens to this port by changing /etc/apache2/ports.conf
NameVirtualHost *:81
Listen 81

Now install lighttpd:

sudo apt-get install lighttpd

edit /etc/lighttpd/conf-available/10-proxy

$HTTP["host"] == "localhost" {
proxy.debug = 1
proxy.server     = ( "/trac" =>
                     ( 
                       ( "host" => "127.0.0.1",
                         "port" => 81,
                       )
                     )
                    )
}
and symlink:
sudo ln -s /etc/lighttpd/conf-available/10-proxy /etc/lighttpd/conf-enabled/10-proxy


and start lighttpd
sudo /etc/init.d/lighttpd restart
et voilà
the trac instance works both under localhost/trac as well as localhost:81/trac