indexer: support data exporting/forwarding (#103)

To support more effective and flexible blockchain info exploring, we add
`indexer` package, defines the flow of indexer dameon, and integrate
into dex.Dexon fullnode.

For more export options, we use Golang built-in `plugin` package to
support mulitple implementations.

1 files changed, 19 insertions, 0 deletions

diff --git a/indexer/interfaces.go b/indexer/interfaces.go
new file mode 100644
index 000000000..f35bc6547
--- /dev/null
+++ b/indexer/interfaces.go
@@ -0,0 +1,19 @@
+package indexer
+
+// NewIndexerFuncName plugin looks up name.
+var NewIndexerFuncName = "NewIndexer"
+
+// NewIndexerFunc init function alias.
+type NewIndexerFunc = func(ReadOnlyBlockChain, Config) Indexer
+
+// Indexer defines indexer daemon interface. The daemon would hold a
+// core.Blockhain, passed by initialization function, to receiving latest block
+// event or other information query and interaction.
+type Indexer interface {
+	// Start is called by dex.Dexon if config is set.
+	Start() error
+
+	// Stop is called by dex.Dexon if config is set and procedure is
+	// terminating.
+	Stop() error
+}