Retrograd

Retrograd is networking library for JSON RPC 2.0 services. Inspired by Retrofit. Uses reflection under the hood.

Installation

You should add repository with this library to your repositories list. For Gradle

repositories {
    // ...
    jcenter()
}

Android users should place this into the allprojects section of base build.gradle file.

And add dependency

dependencies {
    implementation 'com.github.mikhail57:Retrograd:0.3.1'
}

Please, check current version of the library at Bintray!

For the other build systems guides, please visit Bintray

Current limitations

• Supports only Single<T> as a return type
• Supports only GSON as a converter
• Current library API is under construction, so there might be some changes over 0.x versions
• Not full support of Kotlin language

Usage example

Interface

Interface for JSON RPC 2.0 API endpoint

@JsonRpcSerivce("inquiry/rpc")
interface InquiryApi {
    @JsonRpcMethod("get")
    fun getInquiry(
            @JsonRpcParam("sessionId") sessionId: String,
            @JsonRpcParam("service") service: String,
            @JsonRpcParam("params") params: Map<String, Any>
    ): Single<InquiryResult>
}

@JsonRpcSerivce("inquiry/rpc") - required annotation for the interface. As an optional parameter you can provide URL to be resolved against baseUrl (described below).

@JsonRpcMethod("get") - annotation to mark current method as JSON RPC method. Return type of the function marked with this annotation currently should be Single<*>. As the parameters there is parameters for remote method (will be used in JSON RPC 2.0 request). You can specify, whenever this remote procedure is accepting named or unnamed params, by specifying namedParams param of this annotation. When it's true, method will be invoked with named params, otherwise with unnamed params.

@JsonRpcParam("sessionId") - annotation used to mark current param as a named param in JSON RPC 2.0 method call. As an annotation parameter there is a name of this named param. RPC method with unnamed params will ignore name.

Retrograd object creation

val retrograd = Retrograd.Builder()
            .baseUrl(ApiConfig.getServerUrl() + "/api/v1.1/")
            .gson(gson)
            .client(okHttpClient)
            .build()

There is a builder to build Retrograd object. You can specify GSON and OkHttpClient that will be used over the request.

Retrograd client creation

To create API instance, you should call create method of Retrograd. For example

val api: InquiryApi = retrograd.create(InquiryApi::class.java)

Kotlin extensions

You can create API instance via Kotlin extension function, like

val api: InquiryApi = retrograd.create()