64d886f Sep 13, 2018
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Observability Analysis Language

Provide OAL(Observability Analysis Language) to analysis incoming data in streaming mode.

OAL focuses on metric in Service, Service Instance and Endpoint. Because of that, the language is easy to learn and use.

Considering performance, reading and debugging, OAL is defined as a compile language. The OAL scrips will be compiled to normal Java codes in package stage.


Scripts should be named as *.oal

METRIC_NAME = from(SCOPE.(* | [FIELD][,FIELD ...]))
[.filter(FIELD OP [INT | STRING])]


Primary SCOPEs are All, Service, ServiceInstance, Endpoint, ServiceRelation, ServiceInstanceRelation, EndpointRelation. Also there are some secondary scopes, which belongs to one primary scope.

Read Scope Definitions, you can find all existing Scopes and Fields.


Use filter to build the conditions for the value of fields, by using field name and expression.

The expressions support to link by and, or and (...). The OPs support =, !=, >, <, in (v1, v2, ..., like "%...", with type detection based of field type. Trigger compile or code generation error if incompatible.

Aggregation Function

The default functions are provided by SkyWalking OAP core, and could implement more.

Provided functions

  • longAvg. The avg of all input per scope entity. The input field must be a long.

instance_jvm_memory_max = from(ServiceInstanceJVMMemory.max).longAvg();

In this case, input are request of each ServiceInstanceJVMMemory scope, avg is based on field max.

  • doubleAvg. The avg of all input per scope entity. The input field must be a double.

instance_jvm_cpu = from(ServiceInstanceJVMCPU.usePercent).doubleAvg();

In this case, input are request of each ServiceInstanceJVMCPU scope, avg is based on field usePercent.

  • percent. The number or ratio expressed as a fraction of 100, for the condition matched input.

endpoint_percent = from(Endpoint.*).percent(status == true);

In this case, all input are requests of each endpoint, condition is endpoint.status == true.

  • sum. The sum calls per scope entity.

Service_Calls_Sum = from(Service.*).sum();

In this case, calls of each service.

All_p99 = from(All.latency).p99(10);

In this case, p99 value of all incoming requests.

All_heatmap = from(All.latency).thermodynamic(100, 20);

In this case, thermodynamic headmap of all incoming requests.

Metric name

The metric name for storage implementor, alarm and query modules. The type inference supported by core.


All metric data will be grouped by Scope.ID and min-level TimeBucket.

  • In Endpoint scope, the Scope.ID = Endpoint id (the unique id based on service and its Endpoint)


// Caculate p99 of both Endpoint1 and Endpoint2
Endpoint_p99 = from(Endpoint.latency).filter(name in ("Endpoint1", "Endpoint2")).summary(0.99)

// Caculate p99 of Endpoint name started with `serv`
serv_Endpoint_p99 = from(Endpoint.latency).filter(name like ("serv%")).summary(0.99)

// Caculate the avg response time of each Endpoint
Endpoint_avg = from(Endpoint.latency).avg()

// Caculate the histogram of each Endpoint by 50 ms steps.
// Always thermodynamic diagram in UI matches this metric. 
Endpoint_histogram = from(Endpoint.latency).histogram(50)

// Caculate the percent of response status is true, for each service.
Endpoint_success = from(Endpoint.*).filter(status = "true").percent()

// Caculate the percent of response code in [200, 299], for each service.
Endpoint_200 = from(Endpoint.*).filter(responseCode like "2%").percent()

// Caculate the percent of response code in [500, 599], for each service.
Endpoint_500 = from(Endpoint.*).filter(responseCode like "5%").percent()

// Caculate the sum of calls for each service.
EndpointCalls = from(Endpoint.*).sum()