Bearbeiten von „Exhibition-RestServer“

= Links =
* [[Exhibition]]

= Introduction =
The restserver 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 restserver is done via HTTP in the  REpresentational State Transfer design pattern.
* The program of the restserver 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:
<pre>---
# 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
</pre>

== 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.
<pre>---
# 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;"
</pre>

= Installation =
The rest_server must be installed on a backend server. During development that can be localhost.
== Preparation ==
<source lang="bash">tools/PackRestServer
</source>
* The script creates two files: InstallRestServer and rest_server.tgz
* Put that to the '''backend server''', e.g. into the /tmp directory

<source lang="bash">cd /tmp
./InstallRestServer
</source>
* 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
<source lang="bash">
PROJECT=exhibition
systemctl restart $PROJECT
</source>