Make the rest of the services have a similar raw/user interface structure.

service/taskqueue/interface.go

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package taskqueue
 
 // Interface is the full interface to the Task Queue service.
 type Interface interface {
-        Add(task *Task, queueName string) (*Task, error)
+        // NewTask simply creates a new Task object with the Path field populated.
+        // The path parameter may be blank, if you want to use the default task path
+        // ("/_ah/queue/<queuename>").
+        NewTask(path string) *Task
+
+        Add(task *Task, queueName string) error
         Delete(task *Task, queueName string) error
 
-        AddMulti(tasks []*Task, queueName string) ([]*Task, error)
+        AddMulti(tasks []*Task, queueName string) error
         DeleteMulti(tasks []*Task, queueName string) error
 
-        Lease(maxTasks int, queueName string, leaseTime int) ([]*Task, error)
-        LeaseByTag(maxTasks int, queueName string, leaseTime int, tag string) ([]*Task, error)
-        ModifyLease(task *Task, queueName string, leaseTime int) error
+        // NOTE(riannucci): No support for pull taskqueues. We're not planning on
+        // making pull-queue clients which RUN in appengine (e.g. they'd all be
+        // external REST consumers). If someone needs this, it will need to be added
+        // here and in RawInterface. The theory is that a good lease API might look
+        // like:
+        //
+        //   func Lease(queueName, tag string, batchSize int, duration time.Time, cb func(*Task, error<-))
+        //
+        // Which blocks and calls cb for each task obtained. Lease would then do all
+        // necessary backoff negotiation with the backend. The callback could execute
+        // synchronously (stuffing an error into the chan or panicing if it fails), or
+        // asynchronously (dispatching a goroutine which will then populate the error
+        // channel if needed). If it operates asynchronously, it has the option of
+        // processing multiple work items at a time.
+        //
+        // Lease would also take care of calling ModifyLease as necessary to ensure
+        // that each call to cb would have 'duration' amount of time to work on the
+        // task, as well as releasing as many leased tasks as it can on a failure.
 
         Purge(queueName string) error
 
-        QueueStats(queueNames []string) ([]Statistics, error)
+        Stats(queueNames ...string) ([]Statistics, error)
+
+        Raw() RawInterface
 }