Exhibition-RestServer

Links

• Exhibition

Introduction

The rest_server is a sub project of the dev-app implementing a backend for managing the data storage in a MySql database.

Features

• The communication between the dev-app (as a client) and rest_server is done via HTTP in the REpresentational State Transfer design pattern.
• The program of the rest_server is a static piece of software written in Dart, the customizing is done with configuration in some files. This sub project does not have dependencies on Flutter.
• The server is a multithreaded HTTP server, the number of threads (Dart isolates) may be configured.
• The Sql statements must be specified with "named parameters". But the dart module mysqldb cannot handle named parameters. Therefore the statements will be converted into "positional parameters" automatically.

Configuration

Main Configuration

The main configuration is done by a yaml file:

---
# Example configuration file for the rest server. Created by rest_server.
service:
  address: 0.0.0.0
  port: 58031
  dataDirectory: /tmp/unittest/data
  sqlDirectory: ${path.dirname(sqlFile)}
  threads: 1
  watchDogPause: 60
  # logFile: /var/log/local/exhibition.log
trace:
  answerLength: 200
db:
  db: dbtest
  user: dbtest
  code: "TopSecret"
  host: localhost
  port: 3306
  primaryTable: persons
  timeout: 30
  traceDataLength: 200
clientSessionTimeout: 900

Sql Configuration

The SQL statements for each module must be specified in a yaml file.

Note: Normally this file is generated by the meta_tool from the metadata.

---
# SQL statements of the module "Persons":
module: Persons
list:
  type: list
  parameters: []
  sql: select * from persons;
byId:
  type: record
  parameters: [ ":id" ]
  sql: "select * from persons where person_id=:id;"
update:
  type: update
  parameters: [":id", ":name", ":email", ":changedby"]
  sql: "UPDATE persons SET
    person_name=:name, person_email=:email, person_changed=NOW(), person_changedby=:changedby
    WHERE person_id=:id;"
insert:
  type: insert
  parameters: [":name", ":email", ":createdby"]
  sql: "INSERT INTO persons(person_name, person_email, person_created, person_createdby)
    VALUES(:name, :email, NOW(), :createdby);"
delete:
  type: delete
  parameters: [':id']
  sql: "DELETE FROM persons WHERE person_id=:id;"

Installation

The rest_server must be installed on a backend server. During development that can be localhost.

Preparation

tools/PackRestServer

• The script creates two files: InstallRestServer and rest_server.tgz
• Put that to the backend server, e.g. into the /tmp directory

cd /tmp
./InstallRestServer

• Note: $PROJECT is the name of the project
• The script creates the directories /usr/share/$PROJECT and /etc/$PROJECT
• Adapt the configuration in /etc/$PROJECT
• Than restart the service

PROJECT=exhibition
systemctl restart $PROJECT