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1. Install AVISO following instructions on: https://pyaviso.readthedocs.io/en/latest/guide/getting_started.html#installing 
   Configure MARS credentials following instructions on Access MARS
   
   
2. Create a configuration file in the default location  ~/.avisomarsrc/config.yaml Code Block

   language	yml

   username_file: mars.email and ~/.marsrc/mars.token files. mars.email file should contain “email” listed here: https://api.ecmwf.int/v1/key and mars.token file should contain “key” shown on the same page.

3. Create a configuration file in the default location ~/.aviso/config.yaml

   Code Block
   language yml
   username_file: ~/.marsrc/mars.email key_file: ~/.marsrc/mars.token key_file: ~/.marsrc/mars.token notification_engine: type: etcd_rest host: aviso.ecmwf.int port: 443 https: true configuration_engine: type: etcd_rest host: aviso.ecmwf.int port: 443 https: true schema_parser: ecmwf remote_schema: True auth_type: ecmwf

   
   

   
   
   
4. Create ~/.marsrc/mars.email and ~/.marsrc/mars.token files. mars.email file should contain “email” listed here: https://api.ecmwf.int/v1/key and mars.token file should contain “key” shown on the same page.
   Create your your listener configuration file(s) with following content:
   1. Example for dissemination:
      

      Code Block
      language yml title listener_diss.yaml
      listeners: - event: dissemination request: destination: <user_destination> class: od expver: 1 domain: g stream: enfo step: [1,2,3] triggers: - type: echo

      Note the dissemination event listener. request describes for which dissemination event users want to execute the triggers. It is made of a set of fields. Users have to specify only the fields they wants to use as filters. destination is a mandatory field and it is associated to one or more destinations which are linked to the user's ECMWF account. Only the notifications complying with all the fields defined will execute the trigger. The trigger in this example is echo. This will simply print out the notification to the console output.
      
      
   2. Example for MARS:
      

      Code Block
      language yml title listener_mars.yaml
      listeners: - event: mars request: class: od expver: 1 domain: g stream: enfo step: [1,2,3] triggers: - type: echo

      
      Note, in the MARS event listener, destination field is not present.
      You can see the the full list of allowed fields for MARS/ dissemination event listeners here.
      
      

      Warning

      Aviso will notify when data exists in MARS, but most users will not be able to retrieve this data before the scheduled time (Dissemination schedule). Triggering an automated retrieval of data will require adding logic to ensure you only retrieve data when you have respective permissions to do so. For automation of downstream time-critical workflows, this should mainly be based on dissemination events.

      
      
      
5. If AVISO is installed in Python virtual environment, activate the environment first:
   

   Code Block
   language bash
   source {PATH_TO_MY_ENV}/myenv/bin/activate

   
   
   
6. Launch the AVISO application to listen ECMWF defined in your configuration file:
   

   Code Block
   language bash
   aviso listen listener_diss.yaml #or aviso listen listener_mars.yaml

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• The dissemination event is submitted by the product generation. The related listener configuration must define the destination field. A notification related to a dissemination event will have the field location containing location.By default, the location field contains the URL to the product notified .

• The mars event is designed for real-time data from the model output. The related listener configuration has no mandatory fields. Moreover the related notification will not contain the location field because users will have to access to it by the conventional MARS API.

Request

The table below shows the full list of fields accepted in a request block. These fields represent a subset on the MARS language.

• and can be used to download the file. However, it is also possible to configure your Dissemination Host in ECPDS to send full path to the local copy of transferred file. This can be done by adding following option to the Dissemination Host:
  

  Code Block
  language java
  ectrans.location = "file:"

  With this option, the location field will have value:
  

  Code Block
  language bash
  file:/{Full Path on the Destination File System}/{File Name}

  
   

• The mars event is designed for real-time data from the model output. The related listener configuration has no mandatory fields. Moreover the related notification will not contain the location field because users will have to access to it by the conventional MARS API.

Request

The table below shows the full list of fields accepted in a request block. These fields represent a subset on the MARS language.

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A notification is a dictionary whose keys can be used in the parameter substitution mechanism described above. Here an example of a notification:described above. Here an example of a notification:

{
    "event": "dissemination",
    "request": {
        "class": "od",
        "date": "20191112",
        "destination": "FOO",
        "domain": "g",
        "expver": "0001",
        "step": "001",
        "stream": "enfo",
        "time": "18",
		"target": "E1"
    },
    "location": "/home/ecpds/xxx.xx"
}    

Here an example file of a listener command triggering a bash script executing a MARS request.

Post

This trigger allows the user to send as HTTP POST message the notification received and formatted accordingly to the CloudEvents specification

{triggers:
  -  "event"type: "dissemination",post
    "request"protocol: {
      type:  "class": "od",
cloudevents_http
          "date": "20191112",
        "destination": "FOO",
        "domain": "g",
url: http://my.notification.system/api

This is the basic configuration. More parameters can be specified to customise the CloudEvents message. More info the reference documentation.

The CloudEvents message sent would look like the following: 

{
  "type" : "aviso",        "expver": "0001",
        "step": "001",
        "stream": "enfo",
   # this is customisable by "time": "18",
		"target": "E1"
the user
  "data": {      },
    "location": "/home/ecpds/xxx.xx"
}       

Here an example file of a listener command triggering a bash script executing a MARS request.

Post

This trigger allows the user to send as HTTP POST message the notification received and formatted accordingly to the CloudEvents specification

triggers:
  - type: post
    protocol: 
      type: cloudevents_http
     # url: http://my.notification.system/api

This is the basic configuration. More parameters can be specified to customise the CloudEvents message. More info the reference documentation.

The CloudEvents message sent would look like the following: 

{
  "type" : "avisothis is aviso specific
    "event": "dissemination",                    
    "request": {
	  "target": "E1",
  # this is customisable by the user"class": "od",
  "data": {   "date": "20190810",
      "destination": "FOO",
      "domain": "g",
      "expver": "1",
      "step": "1",
      # this is aviso specific
"stream": "enfo",
      "eventtime": "dissemination0",     
    },
   "location": "/home/diss/foo/bar/20190810/xyz", # location on ceph or  s3
    "request": {
	},
  "targetdatacontenttype": "E1application/json",
      "classid": "od0c02fdc5-148c-43b5-b2fa-cb1f590369ff",
  # UUID random generated by aviso
  "datesource": "20190810https://aviso.ecmwf.int",
      "destination": "FOO",
     # "domain": "g",
    this is customisable by the user
  "expverspecversion": "1.0",
      "steptime": "12020-03-02T13:34:40.245Z",
       "stream": "enfo",
    # Timestamp "time": "0",
    },
   "location": "/home/diss/foo/bar/20190810/xyz", # location on ceph or s3
  },
  "datacontenttype": "application/json",
  "id": "0c02fdc5-148c-43b5-b2fa-cb1f590369ff",  # UUID random generated by aviso
  "source": "https://aviso.ecmwf.int",           # this is customisable by the user
  "specversion": "1.0",
  "time": "2020-03-02T13:34:40.245Z",            # Timestamp of when this message is created
}

...

of when this message is created
}

Aviso can also post events to a AWS Simple Notification Service (SNS) topic. See the relevant documentation page for more details: https://pyaviso.readthedocs.io/en/latest/reference/triggers.html#post

Combining multiple trigger types into sequence

An example of the triggers block with multiple sequence of triggers is given below:

triggers:
  - type: echo
  - type: log
    path: testLog.log
  - type: command
    working_dir: $HOME/aviso/examples
    command: ./script.sh --stream ${request.stream} --date ${request.date} --time ${request.time} --step ${request.step}
    environment:
      STEP: ${request.step}
      TIME: "The time is ${request.time}"

Aviso as a Python API

Aviso can be used as a Python API. This is intended for users that want to integrate Aviso in a bigger workflow written in Python or that simply have their trigger defined as a Python function. Below an example of a python script that defines a function to be executed once a notification is received, creates a listener that references to this function trigger and finally passes it to aviso to execute.

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