Knowledgebase

The Knowlege base arranges tips and userful informations scattered on the web.
For more information, take a look to the introduction

Avoid Kafka if unsure (think twice series)

Some co-workers started using Apache Kafka con a bunch of our Customers. Apache Kafka is a community distributed event streaming platform capable of handling trillions of events a day. Initially conceived as a messaging queue, Kafka is based on an abstraction of a distributed commit log[*]. To get this goal, Apache Kafka needs a complex …

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Docker tips

Use docker in docker to drive docker from a container Working under windows, sometimes docker slow down. Sometimes you need to access to the MobyVM. With this line: docker run –rm -ti -v “/var/run/docker.sock:/var/run/docker.sock” -v /:/host docker sh you run a container which will removed upon exit. This container can access to docker daemon (via …

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isync: free IMAP and MailDir mailbox synchronizer

isync: free IMAP and MailDir mailbox synchronizerisync is a command line application which synchronizes mailboxes; currently Maildir and IMAP4 mailboxes are supported. New messages, message deletions and flag changes can be propagated both ways. isync is suitable for use in IMAP-disconnected mode.Synchronization is based on unique message identifiers (UIDs), so no identification conflicts can occur …

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Fail2Ban

On these days I decided to tune a bit my new shiny linux server box. I started to set up fail2ban. I think fail2ban is very imporant nowadays because it is a good example of a tool for slowing down attacks without closing your server too much. Fail2ban is a daemon: it wll monitor your …

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Thinking in Angular 4: Templates

To understand Angular 4, after the “Hero” tutorial you should start from the Template syntax.  We highlighted some statement in red below: Data direction Syntax Type One-way from data source to view target {{expression}} [target]=”expression” bind-target=”expression” Interpolation Property Attribute Class Style One-way from view target to data source (target)=”statement” on-target=”statement” Event Two-way [(target)]=”expression” bindon-target=”expression” Two-way …

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L’ovviologo

Ci sono una nuova generazione di “nullasapienti”, persone che con una inutile laurea (tipicamente in legge) diventano giornalisti dilettanti, seguono i trend della “blogosfera” e leggono magari qualche bel libro di comunicazione. Il risultato è che pubblicano video che non sono scontati, non sono banali ma non sono neppure perle di saggezza. Sono ovvi. La …

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Removing duplicate rows in PostgreSQL, Oracle and SQLite

Sometimes you need to remove nasty duplicate on a table, based on a subset of the column. On every big database there is something called “rowid” which can be used to indentify a column in a unique way. On PostgreSQL is called ctid, as we shall see: Oracle way: DELETE FROM your_table WHERE rowid not …

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Oracle SQL Developer Keep Alive plugin

On some environment, on some customers, Oracle connections are drop after some idle time (i.e. 2 minutes). I have found a small plugin for Sql Developer to solve this issue: it is very handy and logs its usage. Code is also very clean keepalive extension for Oracle SQL Developer 4+https://github.com/scristalli/SQL-Developer-4-keepalive11 forks.89 stars.7 open issues.Recent commits: Fix …

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La mia esperienza nell’open source

Nel 2011,  per studiare node js creai un progetto chiamato OrgModeParser. Org Mode è un package per l’editor Emacs, ed è pensato per tenere note strutturate, pianificare progetti con una schedulazione, mantenere una lista di cose da fare e generare poi documenti word o html da tali file in modo piuttosto efficace. Il package è …

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AngularJS alterantive: Micro JavaScript framework on the 2017

AngularJS is indeed a good framework, but if you lose some grip on it (i.e. you go in vacation for 2 weeks), it is very complex to re-grasp. Also I have seen junior JavaScript developer confused my $scope use. JavaScript on client side has damned destiny: it is too easy to develop a framework from …

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Oracle Auto increment trigger HOWTO

Oracle SQL Developer is full of nice feature, damned by a overwhelming options pane, like the one I will describe to you right now. Even if  Oracle databases (<12) does not support auto increment, you can easily ask to your sql data modeler to generate for you a sequence and a trigger in a automatic …

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