![\"\"](\"http:\/\/ebixio.com\/blog\/wp-content\/uploads\/2010\/12\/AndroidIPC.png\" "\\"AndroidIPC\\"")
<\/a><\/p>\n- \n
BinderDriver<\/code>: This is the core of IPC system. It passes data between aServiceProvider<\/code>(s) and aServiceUser<\/code>(s). This kernel component is provided by Android.<\/li>\nServiceProvider<\/code>: Provides some kind of service. It parses the received RPC data from theBinderDriver<\/code> and does the real work. Application developers will either make use of existing service providers (such as theCamera<\/code> orAudioFlinger<\/code>), or in some cases will write their own.<\/li>\nServiceManager<\/code>: This is a special singleton ServiceProvider that provides service manager services for other service providers. This component is provided by Android.<\/li>\nServiceUser<\/code>: This is the client. It remote calls theServiceProvider<\/code> by generating an RPC and sending it to theBinderDriver<\/code>. Application developers typically write their ownServiceUser<\/code> as part of their application.<\/li>\n<\/ul>\nHere is a typical flow of events for a fictitious
MultServiceProvider<\/code> (a service provider that multiplies two numbers for a client) and aMultServiceUser<\/code> client which doesn’t know how to do multiplication (maybe because the numbers are quaternions) and needs to use theMultServiceProvider<\/code>:<\/p>\n- \n
ServiceManager<\/code> runs first (at power-up) and registers a special node (node O) with theBinderDriver<\/code>.<\/li>\n- The
MultServiceProvider<\/code> gets anIServiceManager<\/code> proxy object for the special node O by calling the globaldefaultServiceManager()<\/code> function.<\/li>\n- The
MultServiceProvider<\/code> then callsdefaultServiceManager()->addService(\"Multiplier\", new MultServiceProvider())<\/code> to add itself as a service provider and then waits in an infinite loop for someone to request its services. TheaddService<\/code> RPC call is routed to theServiceManager<\/code> through theBinderDriver<\/code>.<\/li>\n- The
BinderDriver<\/code> notices that the RPC is for theServiceManager<\/code> to add a new service, so besides routing the RPC to theServiceManager<\/code> it generates another node (let’s call it node M), for the newMultServiceProvider<\/code>.<\/li>\n- The
ServiceManager<\/code> reads the data from theBinderDriver<\/code> and processes theIServiceManager::addService<\/code> RPC call.<\/li>\n- The
MultServiceUser<\/code> client process gets anIServiceManager<\/code> proxy object for the special node O (again by usingdefaultServiceManager()<\/code>).<\/li>\n- The client does an
IServiceManager::getService(\"Multiplier\")<\/code> RPC call to get theMultServiceProvider<\/code>. This call is routed to theServiceManager<\/code> through theBinderDriver<\/code>.<\/li>\n- The
ServiceManager<\/code> reads the RPC data from theBinderDriver<\/code>, processes theIServiceManager::getService<\/code> request and returns back the node representing theMultServiceProvider<\/code>.<\/li>\nMultServiceUser<\/code> callsMultServiceProvider::multiply(a, b)<\/code>. This call is routed to\u00a0 theMultServiceProvider<\/code> by theBinderDriver<\/code>.<\/li>\n- The
MultServiceProvider<\/code> handles theMultServiceProvider::multiply<\/code> RPC call and sends the product of the 2 numbers in a reply to theBinderDriver<\/code>.<\/li>\n- The
BinderDriver<\/code> routes the reply back to the client.<\/li>\n- The client reads the data from the
BinderDriver<\/code> which contains the result of “a * b”.<\/li>\n<\/ol>\nIn a future post I hope to discuss the whole architecture in more detail, with concrete code examples for how to use
IBinder<\/code>,IInterface<\/code>,BBinder<\/code>,BpInterface<\/code>,BnInterface<\/code>, etc… to create aServiceProvider<\/code> and aServiceUser<\/code> all in native C++ code on Android.<\/p>\n","protected":false},"excerpt":{"rendered":"The information below comes from a number of sources, including my own experiments with the Android IPC and some disparate internet sources. The overall architecture of the Android IPC system is shown in the diagram below. It consists of four major blocks; one in kernel space, and the other three in user space. The dashed […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[1],"tags":[33],"class_list":["post-303","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-android"],"_links":{"self":[{"href":"http:\/\/ebixio.com\/blog\/wp-json\/wp\/v2\/posts\/303","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/ebixio.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/ebixio.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/ebixio.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/ebixio.com\/blog\/wp-json\/wp\/v2\/comments?post=303"}],"version-history":[{"count":10,"href":"http:\/\/ebixio.com\/blog\/wp-json\/wp\/v2\/posts\/303\/revisions"}],"predecessor-version":[{"id":651,"href":"http:\/\/ebixio.com\/blog\/wp-json\/wp\/v2\/posts\/303\/revisions\/651"}],"wp:attachment":[{"href":"http:\/\/ebixio.com\/blog\/wp-json\/wp\/v2\/media?parent=303"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/ebixio.com\/blog\/wp-json\/wp\/v2\/categories?post=303"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/ebixio.com\/blog\/wp-json\/wp\/v2\/tags?post=303"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
- The