Transcription
From REST to gRPC:An API Evolution StoryJoe RundeIBM@joerundeMichael KeelingIBM@michaelkeeling
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What is gRPC?Open source Remote Procedure Call framework3
What is gRPC?Open source Remote Procedure Call framework“ a modern, bandwidth and CPU efficient, low latencyway to create massively distributed systems that spandata centers”4
Why should we use gRPC?5
Why is gRPC awesome?Performance6
Performance BenefitsHTTP / REST7
Performance BenefitsHTTP / RESTgRPC8
How does gRPC improve performance? HTTP/2 transport protocol Binary encodings via protocol buffers No more parsing text! Compression Streaming9
Why is gRPC awesome?Performance10
Why is gRPC awesome?PerformanceRemote Procedure Calls11
REST setup is tediousheaders roximateFoo.toHeaderString())12
REST setup is tediousPublic class Foo {@JsonProperty(name ”foo id”)String id;@JsonProperty(name ”bar”)int bar;.}13
REST setup is tediousPublic class Foo {.publicFoo(@JsonProperty(“foo id”,required true)String id,@JsonProperty(“bar”,required true)int bar){ . }}14
RPC setup is easyrequest Bar(foo.getBar()).build();response fooClient.DoFooBar(request);15
Why is gRPC Awesome?PerformanceRemote Procedure Calls16
Why is gRPC Awesome?PerformanceRemote Procedure CallsStrategic Direction of our Platform17
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insert slick demo here 19
Just one problem Our current microservicesall use REST.20
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Business Constraints22
The Transition Plan Phase 1: Design gRPC API Phase 2: Run REST and gRPC services Phase 3: Transition functional tests Phase 4: Remove REST functionality23
DESIGN THE APIPhase I24
Designing a gRPC APIREST:gRPC:POST/api/foorpc AddFoo(Foo)returns FooID;GET/api/foo/{foo id}rpc GetFoo(FooID)returns Foo;25
Designing a gRPC APIREST:gRPC:POST/api/foomessage Foo {FooID id 1;repeated Bar bars 2;}GET/api/foo/{foo id}message FooID {string val 1;}26
Designing a gRPC APIREST:gRPC:POST/api/foo/{foo id}/barrpc AddBar(Bar)returns BarID;GET/api/foo/{foo id}/bar/{bar id}rpc GetFoo(BarID)returns Bar;27
Designing a gRPC APIREST:gRPC:POST/api/foo/{foo id}/barrpc AddBar(Bar)returns BarID;GET/api/foo/{foo id}/bar/{bar id}rpc GetFoo(BarID)returns Bar;28
Designing a gRPC APIREST:POST/api/foo/{foo id}/barGET/api/foo/{foo id}/bar/{bar id}gRPC:message Bar{BarID id 1;int baz 2;}message BarID {FooID foo id 1;string bar id 2;}29
Designing a gRPC APIBar service:/api/foo/{foo id}/bar/{bar id}Buzz service:/api/foo/{foo id}/buzz/{buzz id}30
SERVE REST AND GRPCPhase II31
Current: REST OnlyRESTCallerFooBarService32
Future: REST and gRPCRESTCallergRPCCallerFooBarService33
We need to evolve our API withoutdamaging basic functionality.34
Current: Layers ViewRest ServiceCode PackageBusiness Logicis allowed touseModelsDatastore Access35
Future: Layers ViewRestServicegRPCServiceCode PackageBusiness Logicis allowed touseModelsDatastore Access36
Layer Pattern Rocks!A code review comment:"What's with the servicelayer? This just passesits inputs to our businesslogic functions, it'sredundant cruft!"37
Evolving the code went really well 38
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Things that suddenly became a problem Health Checks API Discovery No curl Headers? SSL? Simple community examples40
TRANSITION FUNCTIONAL TESTSPhase III41
Specification by Example42
Specification by Example- REST43
Ruby metaprogrammingChoice of programming language really paid offrequest Object::const get(”FooBar::#{message name}").decode json(json)response client.method(method name.to sym).call(request)44
Specification by Example- gRPC45
200 tests transitioned in 1 week46
Why did this go so well? Expressiveness of spec by example Flexibility of Ruby gRPC can decode JSON47
REMOVE REST FUNCTIONALITYPhase IV48
rm –rf src/*rest*49
We need to retain some REST endpointsRESTCallergRPCCallerFooBarService50
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Current Layered ArchitectureServiceRestServicegRPCServiceBusiness LogicModelsFooBarServiceDatastore Access52
Layers Forked – Two ServicesREST ServiceFooBarProxygRPC ClientsServicegRPC ServiceBusiness LogicModelsFooBarServiceDatastore Access53
Evil wizards strike again!54
NOW WE’RE READY FORRELEASE ?55
New problems we created Health Checks API Discovery No curl Headers? SSL?56
New problems we created Health Checks API Discovery No curl Headers? SSL?57
API Discovery REST – Ask the service! gRPC – Find the (correct) proto file?58
API Discovery REST – Ask the service! gRPC – Find the (correct) proto file? Standard InfoService serves github url version Snapshot proto files with releases Client vendors the proto files they use59
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Tools support Basically Nonexistent Our solutions: Hand roll mocks for testing Write new functional tests each time wewanted to use curl61
Adios,REST!62
INTERESTING THINGS WELEARNED63
The right kinds of abstractions promoteextensibility Focus on the domain model Create a specification by example Take care when choosing frameworks Deal with risks of technology adoption64
Would we do it again?65
Would we do it again?Yes. Super easy to integrate with a service Promotes small polyglot services Difficult to do bad things Performance is 66
Thank you!Michael Keeling@michaelkeelingneverletdown.netJoe Runde@joerundeBuy Design It! now athttp://bit.ly/2pJOrly
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Flexibility of Ruby gRPC can decode JSON. REMOVE REST FUNCTIONALITY Phase IV 48. 49 rm -rf src/*rest* We need to retain some REST endpoints 50 REST Caller gRPC Caller FooBar Service. 51. Current Layered Architecture 52 Models Rest Service Business Logic Datastore Access gRPC Service FooBar Service
