原创作者:李贞
restQL is a microservice query language that makes easy to fetch information from multiple services in the most efficient manner. http://restql.b2w.io/
restQL的设计是用来简化客户端查询,特别是在微服务时代,对于一个复杂的页面,可能需要调用多个服务的接口,获得数据渲染页面。这对于客户端来说,这有着极大的消耗。而 restQL较好的解决的这个问题,并且使用restQL对原来API server无需改动。
restQL支持以下几种查询方式。
并行调用(Parallel calls)
他们所产生的查询,是并发进行的,等待所有的处理完成后将直接返回。
from hero with name = "Restman" from villain with name = "SOAPLord"
链式调用(Chained invocations)
第二个查询依赖第一个查询的结果,所以需要等待第一个查询结束后,才会调用第二个查询,最终返回结果。
from hero with name = "Restman" from sidekick with hero = hero.id
Multiplexed invocations
这个同样是第一个查询依赖第二个查询,但是第一个查询出来的是一个array,并对于array中的每个元素,调用第二个查询,处理完成后返回。
from search with role = "hero" from hero as heroes with name = search.results.name
详细介绍见: http://restql.b2w.io/
restQL依赖一个restQL-http对外提供服务,由restQL-http解析restQL的查询语言并且调用资源服务(API server)
下载restQL-http到任意目录,并且解压,这里安装的是:
## 下载 curl -O https://github.com/B2W-BIT/restQL-http/releases/download/v3.5.5/restql-http-v3.5.5.zip
unzip -d restql-http restql-http-v3.5.4.zip
cd restql-http
planets=https://swapi.co/api/planets/:id ./bin/run.sh
对于入门最好的方式,莫过于官方文档了( http://docs.restql.b2w.io/#/restql/getting-started )。
官网是以swapi.co的API作为测试,这里也将使用这个服务作为简单的入门使用。如果需要配置更高级的使用方式( http://docs.restql.b2w.io/#/restql/config )。
运行
cd restql-http planets=https://swapi.co/api/planets/:id ./bin/run.sh
启动成功后,将会默认监听9000端口, http://localhost:9000 ,也可以通过设置环境变量的方式,使其端口改变。
export PORT=1456 planets=https://swapi.co/api/planets/:id ./bin/run.sh
restQL提供的接口路径是 : http://localhost:9000/run-query
可以通过curl方式调用服务,检查是否启动正常
curl -d "from planets as allPlanets" -H "Content-Type: text/plain" localhost:9000/run-query
正常情况下将会得到类似以下的输出
{ "allPlanets": { "details": { "success": true, "status": 200, "metadata": {} }, "result": ... } }
查询一条数据
restQL 查询语句
from planets with id = 1
调用接口,这里推荐使用Postman、Insomnia等工具测试
curl -d "from planets with id = 1" -H "Content-Type: text/plain" localhost:9000/run-query
将会得到以下数据
{ "planets": { "details": { "success": true, "status": 200, "metadata": {} }, "result": { "surface_water": "1", "climate": "arid", "residents": [ ... ], "orbital_period": "304", "name": "Tatooine", "diameter": "10465", "created": "2014-12-09T13:50:49.641000Z", "gravity": "1 standard", "edited": "2014-12-21T20:48:04.175778Z", "films": [ ... ], "population": "200000", "terrain": "desert", "url": "https://swapi.co/api/planets/1/", "rotation_period": "23" } } }
语法
查询语句的顺序,对于 restQL 异常的重要
[ [ use modifier = value ] ] METHOD resource-name [as some-alias] [in some-resource] [ headers HEADERS ] [ timeout INTEGER_VALUE ] [ with WITH_CLAUSES ] [ [only FILTERS] OR [hidden] ] [ [ignore-errors] ]
Methods
restQL 提供了HTTP常用的几个 methods (GET,POST,PUT, PATCH, DELETE)
from - HTTP GET to - HTTP POST into - HTTP PUT update - HTTP PATCH delete - HTTP DELETE
from
planets = https://swapi.co/api/planets/:id
restQL 语句
from planets with name = "Restman" id = 1
将会映射到以下调用
GET https://swapi.co/api/planets/1?name=Restman
to
planets = https://swapi.co/api/planets
restQL 语句
to planets with name = "Restman"
将会映射到以下调用
POST https://swapi.co/api/planets BODY {"name": "Restman"
}
into
planets = https://swapi.co/api/planets/:id
restQL 语句
into planets with id = 1 name = "xxxx"
将会映射到以下调用
PUT https://swapi.co/api/planets/1 BODY {"name": "xxxx"
}
update
planets = https://swapi.co/api/planets/:id
restQL 语句
update planets with id = 1 name = "abc"
将会映射到以下调用
PATCH https://swapi.co/api/planets/1 BODY {"name": "abc"
}
delete
planets = https://swapi.co/api/planets/:id
restQL 语句
delete planets with id = 1
将会映射到以下调用
DELETE https://swapi.co/api/planets/1?name=Restman
这里将以 https://api.spacexdata.com/ 作为数据服务,接下来的所有数据,都是由它来提供。( https://docs.spacexdata.com/?version=latest )
restQL 支持多种资源映射方式,可以通过环境变量,也可以通过restql.yml的方式亦或者通过restQL-manager( http://docs.restql.b2w.io/#/restql/manager )前面演示了通过环境变量的方式,这里将通过restql.yml,在restql-http目录创建restql.yml文件。
restql.yml
mappings: launches: "https://api.spacexdata.com/v3/launches"
执行
./bin/run.sh
启动成功后,将可以看到类似这样的输出
2019-11-08 14:46:03,239 INFO restql.http.plugin.core [main] No plugins to load 2019-11-08 14:46:03,244 INFO restql.http.server.core [main] Server starting with {:port 1456, :executor-utilization 0.5, :executor-max-threads 512, :executor-control-period 1000} 2019-11-08 14:46:03,465 INFO restql.http.server.core [main] Server started!
简单查询
restql 语句
from launches
查询结果
{ "launches": { "details": { "success": true, "status": 200, "metadata": {} }, "result": [...] } }
如果想要查询 2017-06-22 到 2017-06-25 之间的数据,只需要给查询语句加上 with
from launches with start = "2017-06-22" end = "2017-06-25"
其他参数也按照这种方式。如果需要指定的获取某一条数据,调用的接口是
https://api.spacexdata.com/v3/launches/{{flight_number
}}
可以添加一条资源映射规则写入到restql.yml,
mappings: launches: "https://api.spacexdata.com/v3/launches" oneLaunches: "https://api.spacexdata.com/v3/launches/:flight_number"
例如查询的是 42
from oneLaunches with flight_number = 42
响应结果
{ "oneLaunches": { "details": { "success": true, "status": 200, "metadata": {} }, "result": { ... "flight_number": 42, ... } } }
过滤器(Filter)
restQL还支持一个filter特性,可以指定某个资源获取的数据,这样可以减少payload大小,对于移动客户端优化非常重要。
这里以 launches 作为演示。
from launches with start = "2017-06-22" end = "2017-06-25" only mission_name, flight_number, launch_site.site_id, ships, rocket.first_stage.cores.land_success
响应结果
{ "launches": { "details": { "success": true, "status": 200, "metadata": {} }, "result": [ { "mission_name": "BulgariaSat-1", "flight_number": 42, "launch_site": { "site_id": "ksc_lc_39a" }, "ships": [ "ELSBETH3", "GOQUEST", "GOSEARCHER", "OCISLY" ], "rocket": { "first_stage": { "cores": [ { "land_success": true } ] } } } ] } }
并行查询
并行调用,正是restQL需要处理的问题,能够有效减少客户端和服务器的连接数,对于微服务架构而言,可能一个页面所呈现需要的数个服务来提供。这就意味着需要创建数个连接获取资源,这对于客户端来讲,是非常糟糕的。
这里添加一个新的资源映射地址,作为一个测试
mappings: launches: "https://api.spacexdata.com/v3/launches" oneLaunches: "https://api.spacexdata.com/v3/launches/:flight_number" oneHistory: "https://api.spacexdata.com/v3/history/:id"
from launches with start = "2017-06-22" end = "2017-06-25" only mission_name, flight_number, launch_site.site_id, ships, rocket.first_stage.cores.land_success from oneHistory with id = 1
{ "launches": { "details": { "success": true, "status": 200, "metadata": {} }, "result": [...] }, "oneHistory": { "details": { "success": true, "status": 200, "metadata": {} }, "result": { "event_date_unix": 1222643700, "title": "Falcon 1 Makes History", "details": "Falcon 1 becomes the first privately developed liquid fuel rocket to reach Earth orbit.", "id": 1, "event_date_utc": "2008-09-28T23:15:00Z", "flight_number": 4, "links": { "wikipedia": "https://en.wikipedia.org/wiki/Falcon_1", "article": "http://www.spacex.com/news/2013/02/11/flight-4-launch-update-0", "reddit": null } } } }
链式查询
链式调用也是restQL的一个亮点,也简单做一下演示
from oneHistory with id = 1 from oneLaunches with flight_number = oneHistory.flight_number only mission_name, flight_number, launch_site.site_id, rocket.first_stage.cores.land_success
响应结果
{ "oneHistory": { "details": { "success": true, "status": 200, "metadata": {} }, "result": { ... "flight_number": 4, ... } }, "oneLaunches": { "details": { "success": true, "status": 200, "metadata": {} }, "result": { "mission_name": "RatSat", "flight_number": 4, "launch_site": { "site_id": "kwajalein_atoll" }, "rocket": { "first_stage": { "cores": [ {} ] } } } } }
这个的应用场景也是极为广泛的,特别在于页面信息极其复杂的情况下,在一次请求就可以获取到关联的数据。
多路调用
为了避免歧义,这里将添加一个新的映射地址,作为本次演示,编辑 restql.yaml文件
mappings: launches: "https://api.spacexdata.com/v3/launches" oneLaunches: "https://api.spacexdata.com/v3/launches/:flight_number" history: "https://api.spacexdata.com/v3/history" oneHistory: "https://api.spacexdata.com/v3/history/:id"
from history with start = "2016-06-22" end = "2017-06-25" only flight_number from oneLaunches with flight_number = history.flight_number only mission_name, flight_number,
响应结果
{ "history": { "details": { "success": true, "status": 200, "metadata": {} }, "result": [ { "flight_number": 38 }, { "flight_number": 41 } ] }, "oneLaunches": { "details": [ { "success": true, "status": 200, "metadata": {} }, { "success": true, "status": 200, "metadata": {} } ], "result": [ { "mission_name": "SES-10", "flight_number": 38 }, { "mission_name": "CRS-11", "flight_number": 41 } ] } }
restQL 还有几个高级特性,详情请见官网
http://docs.restql.b2w.io/#/restql/manager
http://docs.restql.b2w.io/#/restql/saved-queries
http://docs.restql.b2w.io/#/restql/plugins
参考链接
http://restql.b2w.io/
https://medium.com/b2w-enginee ... 09b40
https://github.com/B2W-BIT/restQL-http
原文链接: https://mp.weixin.qq.com/s/4fF19jc4Dgs92Q67MwN-Lw
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