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AMI Remote Procedure Calling (RPC)

AMI Remote Procedure Calling (RPC) Overview

AMI RPC leverages the HTTP CORS (Cross Origin Resource Sharing) standard to provide a mechanism for separate AMI dashboards within the same domain to communicate with each other.  As such, different teams working on distinct dashboards/use cases can easily integrate them.  For example, there are two teams, one building a dashboard for viewing orders and a second team building an order analytics dashboard. The first team could configure the order-dashboard such that when the user clicks on an order, an RPC instruction is sent to the other team’s dashboard, which in turn  displays analytics about the selected order. This paradigm promotes seamless integration across any number of dashboards at scale, providing users with a simple workflow accordingly.

How AMI RPC Works (User Perspective)

If a user is logged into two or more dashboards built on the AMI platform, then it's possible for the dashboards to call ami script across those dashboards.

Dashboards must be opened in the same browser space. For example, if one dashboard is opened in Chrome then the other dashboard must be opened in Chrome as well. Additionally, if one dashboard is opened in non-cognito mode then the other must also be opened in non-cognito mode.

Although it is not necessary for both dashboards to be logged in with same user ID, it can be enforced if necessary.

How AMI RPC Works (Configuration Perspective)

This is done by way of configuring custom AmiScript methods such that one dashboard can execute a custom AmiScript Method on another dashboard.  Communication supports full round trip, meaning the calling dashboard sends arguments to the receiving dashboard and then the receiving dashboard can respond to the call with data as well.

The target of such a call is identified using a host and method name combination.  It is common for the builder of the target dashboard to properly determine the host(s), method(s) and structure of the request and response payloads, which in aggregate is considered an API. This "API" is then communicated to those teams wishing to use the API.

For further reading on the general usage of CORS visit https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS

Please note that both dashboards must be hosted within the same domain, ex: analytics.acme.com and orders.acme.com are both in the acme.com so they can communicate via CORS, despite having different subdomains.  It's important that the all references to the domains use the fully qualified domain.

Creating a Method for being remotely called

Create a custom method with a predetermined "well-known" name that returns a Map, and takes an RpcRequest object as a single Argument of the form:

Map myMethod (RpcRequest request){
    Map requestArgs = request.getArguments();
    //Do something here
    Map responseArgs = new Map("key","someReturnValue");
    return responseArgs;
}

Important: Please note that the return type of Map and argument type of RpcRequest is required and specifically indicates that the method can be called remotely.

Calling a Method remotely

Use the callRpcSnyc(RpcRequest) method on the session object. The RpcRequest constructor takes these 3 arguments.

target - URL of the host that you wish to call the method on.

methodName - Name of the method to call (in the example above, it's myMethod).

Arguments - Key/value pair of data to send. Note that the data will be transported using JSON, so complex objects, such as panels, cannot be referenced.

For Example, let’s say the example above is running on a dashboard at some.host.com:33332. This would call that method:

Map requestArgs=new Map("key","someRequestValue");

String host="http://some.host.com:33332/";

RpcRequest request=new RpcRequest(host,"myMethod",requestArgs);

RpcResponse response = session.callRpcSync(request);

Map responseArgs=response.getReturnValues();

HOW AMI RPC Transport Works

1. The Source dashboard calls session.callRpcSync(...)
2. The Source dashboard creates a JSON request that is sent to the dashboard via websockets
3. AMI's javascript forwards the JSON to the target Server (the browser will do CORS authentication against the target web server, which AMI is compatible with)
4. The target webserver will receive the JSON, confirm headers and create an RpcRequest object for processing
5. The target dashboard's amiscript custom method will process the request and produce a response
6. The reply from the target server is sent back to the web browser in the http response as JSON
7. The response is forwarded back to the source webserver via web sockets
8. AMI converts the JSON to an RpcResponse which is passed back to the dashboard for processing

 

Error Condition Handling

The session.callRpcSync(...) method will always return an RpcResponse object. You can inspect the Error for the success or failure status.

Here are the possible return values of getError:

Return Value	Description
null	The rpc call executed successfully
"NO_RESPONSE"	The server failed to respond, this is generally caused if the user refreshes the webpage while the rpc request is inflight, which will reset the connection.
"CONNECTION_FAILED"	The CORS could not successfully establish a connection. This may be because the target url does not point to an existing AMI instance.
"INVALID_URL"	The format of the target url is not valid.
"ERROR_FROM_SERVER"	The server responded with an error.
"ERROR_FROM_SERVER_ORIGIN_NOT_PERMITTED"	The origin was not permitted (based on the ami.web.permitted.cors.origins option)
"ERROR_FROM_SERVER_USER_NOT_LOGGED_IN"	The user does not have a browser open which is logged into the server
"ERROR_FROM_SERVER_NO_SUCH_METHOD"	The dashboard does not have a custom method of the supplied name. Or the method does not return a Map, or the method does not take an RpcRequest as it's single argument.
"ERROR_FROM_SERVER_METHOD_EXCEPTION"	The method was executed but threw an unhandled exception.
"ERROR_FROM_SERVER_USERNAME_MISMATCH"	The RpcRequest constructor was supplied a requiredUserName, which did not match the username currently logged in on the target dashboard.
"ERROR_FROM_SERVER_LAYOUT_NAME_MISMATCH"	The RpcRequest constructor was supplied a requiredLayoutName, which did not match the name of the layout on the target dashboard.
"ERROR_FROM_SERVER_LAYOUT_NAME_MISMATCH"	The RpcRequest constructor was supplied a requiredSessionId, which did not match the sessionId of the layout on the target dashboard.

Please Note, you can look at RpcResponse::getErrorMessage for further details.

Security

The ami.web.permitted.cors.origins option can be supplied (in the ami web's properties) to control which origins are accepted. See the Access-Control-Allow-Origin header for further information on how CORS origins works. Here are 3 separate examples:

# Disable CORS, no origins will be allowed to remotely call functions

ami.web.permitted.cors.origins=

# All origins are allowed

ami.web.permitted.cors.origins=*

# Allow a specific host

ami.web.permitted.cors.origins=http://myhost.com|http://thathost.com

Encrypting and Decrypting using tools.sh

The pdf below contains instructions on how to encrypt and decrypt using tools.sh

File:Instructions for encrypting and decrypting using tool.sh.pdf

AMI Center Replication

The pdf below contains instructions on how to replicate AMI Center(s)

File:AMI Center Replication.pdf

List of available AMI procedures

Parameters in bold indicate no null.

For the following procedure calls, refer to the pdf document in the previous section, AMI Center Replication

1. __ADD_CENTER

2. __REMOVE_CENTER

3. __ADD_REPLICATION

4. __REMOVE_REPLICATION

Note: to call a procedure in the frontend, e.g. in a datamodel, or an AMI editor, use this syntax:

use ds=AMI execute call... (your procedure here);

to use this in the AMIDB console, just use:

call... (your procedure here)

Example frontend usage:

use ds=AMI execute __RESET_TIMER_STATS("mytimer",true,true);

Example console usage:

call __RESET_TIMER_STATS("mytimer",true,true);

__ADD_DATASOURCE

__ADD_DATASOURCE(String name, String adapter_type, String url, String username, String password, String options¹, String relayId², String permittedOverrides³)

¹options refer to values under the Advanced section. Must be a comma delimited list.

Ex: “DISABLE_BIGDEC=true,URL_OVERRIDE=jdbc:mysql://serverUrl:1234/databaseName”

²relayId refers to “Relay to Run on” under the Configuration section.

³permittedOverrides refers to the checkboxes under the Security section. Must be a comma delimited list. The available values are URL, USERNAME, PASSWORD, OPTIONS, RELAY.

Ex: “URL,USERNAME” <- this will tick the URL and USERNAME checkbox.

Supported Adapter Types

Name	Alias (to be used in the procedure call)
AMI datasource	__AMI
Sybase IQ JDBC	SYBASE_IQ
Shell Command	SHELL
AMIDB	AMIDB
MySQL JDBC	MYSQL
KDB	KDB
SSH Command	SSH
Redis	Redis
Fred	FRED
SQLServer JDBC	SQLSERVER
Oracle JDBC	ORACLE
Sybase JDBC	SYBASE
RestAPI	RESTAPI
Postgres JDBC	POSTGRES
Flat File Reader	FLAT_FILE
Generic JDBC	GENERIC_JDBC
IMB DB2	IMBDB2
SQLITE JDBC	SQLITE
OneTick	ONETICK
Quandl	QUANDL

__REMOVE_DATASOURCE

Call __REMOVE_DATASOUCE(String DSName)

Use show datasources to see a list of datasources.

This procedure removes the specified datasource.

__RESET_TIMER_STATS

Call __RESET_TIMER_STATS(String timerName, Boolean executedStats, Boolean errorStats)

Use show timers to see information for all timers..

This procedure clears NextRunTime. Optionally clears ExecutedCount, MillisSpent, and AvgMillisSpent if ExecutedStats is set to true, and optionally clears ErrorCounts if ErrorStats is set to true.

__RESET_TRIGGER_STATS

Call __RESET_TRIGGER_STATS(String triggerName)

Use show triggers to see information for all triggers.

This procedure will reset ExecutedCount, MillisSpent, AvgMillisSpent, ErrorsCount, ReturnedFalseCount for a particular trigger.

__SCHEDULE_TIMER

Call __SCHEDULE_TIMER(String timerName, Long delayMillis)

This procedure schedules the timer to run after the specified number of milliseconds passes. For instance, call __SCHEDULE_TIMER(“mytimer”, 5000) means mytimer will start running after 5000 milliseconds, or 5 seconds.

__SHOW_TIMER_ERROR

Call __SHOW_TIMER_ERROR(String timerName)

This procedure shows you the last error the specified timer encountered in a table format.

__SHOW_TRIGGER_ERROR

Call __SHOW_TRIGGER_ERROR(String triggerName)

This procedure shows you the last error the specified trigger encountered in a table format.