160 lines
3 KiB
Markdown
160 lines
3 KiB
Markdown
# DAL Internal Architecture
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- The Client is written in TypeScript.
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- The DAL server written in Golang.
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## Components
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(Top to bottom)
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- NodeJS Client
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- Protocol
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- Builder
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- DB Adapter
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## NodeJs Client
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Client consists of a query builder and protocol decoder/encoder.
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- Query Builder is a light builder which constructs the query object for the server.
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- Protocol is a decoder/encoder that utilizes messagepack.
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```bash
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------------------
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|- dal
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|- Builder.ts
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|- Protocol.ts
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|_ index.ts
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|...
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```
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## Protocol
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Protocol utilizes messagepack for encoding and decoding the messages.
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There following types of encoded data:
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- Row stream
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- Query (request)
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- Response (exec result)
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Locations:
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```bash
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------------------
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|- dal
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|- Protocol.ts
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|_...
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|- pkg
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|- proto
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|...
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|...
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```
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### Row Stream
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- The server sends streaming (chunked) data to the client, every chunk is a row.
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- Every row starts with a 3-byte header `{0x81, 0xa1, 0x72}`
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- The first row is the header row, which contains the column names.
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Parsing the row stream (pseudo code):
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```
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header = [0x81, 0xa1, 0x72]
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input: byte[]
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buffer: byte[]
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output: byte[][]
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while i < input.length:
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if input[i] != 0x81:
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buffer << input[i]
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i += 1
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else if input[i:3] == header:
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output << header + buffer
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buffer = []
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i += 3
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output << header + buffer
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```
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MessagePack schema for the row stream:
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```go
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type Row struct {
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Data []interface{} `msg:"r"`
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}
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// { r: [] }
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```
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### Query
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- The client utilizes a "light builder" which prepares a list of callbacks for the SQL query builder.
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- The Query consits of the following fields:
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- Id: uint32 (optional)
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- Db: string (required, database name)
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- Commands: []BuilderMethod (required, list of Builder arguments)
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```go
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type BuilderMethod struct {
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Method string `msg:"method"`
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Args []interface{} `msg:"args"`
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}
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type Request struct {
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Id uint32 `msg:"id"`
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Db string `msg:"db"`
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Commands []BuilderMethod `msg:"commands"`
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}
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```
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### Response
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The response is inteneded for operation results that don't return rows.
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```go
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type Response struct {
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Id uint32 `msg:"i"`
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RowsAffected int64 `msg:"ra"`
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LastInsertId int64 `msg:"li"`
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}
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```
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## Builder
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The builder is a set of methods that are used to construct the SQL query.
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- The sql query is constructed by the server.
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- The client utilizes a "light builder" which prepares a list of callbacks for the server builer.
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Locations:
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```bash
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------------------
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|- dal
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|- Builder.ts
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|_...
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|- pkg
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|- builder
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|...
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|- filters
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|...
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|...
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```
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### Builder Methods
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Raw|In|Find|Select|Fields|Join|Group|Sort|Limit|Offset|Delete|Insert|Set|Update|OnConflict|DoUpdate|DoNothing
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[TS Docs]()
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[Golang Docs]()
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## DB Adapter
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- Adapter provides the interface for the database driver.
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- Adapter package also provides utilitities for specific SQL Dialects.
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Locations:
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```bash
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------------------
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|- pkg
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|- Adapter
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|...
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|...
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``` |